Calculate Dimension of Electrical Panel from SLD


Introduction:

  • In Designing Stage , We need to calculate approximate Dimension of Electrical Panel to conclude Dimension of Electrical Room and Total Space requirement of Electrical Services.
  • Dimension of Electrical Panel’s is calculated from Electrical SLD.
  • Dimension of Electrical Panel mainly depends on
  1. Size of Main Incoming and Outgoing Circuit Barker.
  2. No of Outgoing Circuit Breakers.
  3. Panel’s Form Factor.
  4. Type of Panel (Indoor / Outdoor).
  5. Cable connection in Panel (Front Side / Back side of Panel).
  6. Installation of Circuit Breaker (Horizontal / Vertical)
  7. Height of Panel should not be more than 2200mm Due to Operation of Upmost Switchgear.

General Switchgear arrangements in Panel 

  • There are four compartments in Electrical Panel.
  1. Incoming Section
  2. Outgoing Section
  3. Busbar Chamber
  4. Cable Alley.

1

Factors to be considered to calculate Dimension of Panel:

  • Dimension of Panel mainly depends on following factors.
  1. Type of Panel (Indoor / Outdoor):

  • Depth of Panel is depending on Type of Panel.
  • If We have Indoor Type of Panel and there are no any issue regarding Water seepages near Panel than Double Door type of Panel is not required.
  • In Out Door Type Panel construction is mostly Double Door Type.
  • For Double Door Construction required more 100mm Panel Depth than actual .

2

  1. Form Factor of Panel:

  • Type of Form Factor decide Dimension of Panel.
  • For Same type and same rating of Switchgear Form 1 required less space compared to Form 2A, 2B, 3A, 3B, 4A, 4B.
  1. Position of Switch gear Installation

  • Panel’s Width and Height mostly depends on Position of Switchgear Installation.
  • If we installed Switchgear in vertical Position than Height of Panel is increased.
  • If we installed Switchgear in horizontal position than with of Panel is increased.
  • Most of manufacture prefer Horizontal position of Switchgear to easy termination of Incoming and Outgoing of Switchgear to Busbar.

3

  1. Height of Panel

  • Height of Panel should not more than 2200mm for easy operation of upmost Switchgear in Panel.
  • This 2200MM height concert increase width of Panel if we have multiple number of outgoing.
  • If we have 5 Nos of outgoing than it may require one No of Colum Section of Panel (400×5=2000mm).

  • But if we have 8 No’s of outgoing than we required two no of Colum Section in one Section 4 no of Outgoing Switchgear and in second Colum section for 3 no of Switch gear. 1 no of More cable alley section (300mm) required for cable termination.

4

  1. Cable Termination in Panel (Front Side / Back Side)

  • Front Side Cable Termination: If We Installed Panel In front of wall than Panel Back Side is not accessible hence We need Cable Termination on front side of Panel for this we need Cable Alley of 300mm for Cable Termination.
  • This arrangement increase width of 300mm for panel but depth of panel will not increase.
  • Back Side Cable Termination: If We Installed Panel at some distance from wall than Panel Back Side is accessible hence, we may do Cable Termination on back side of Panel for this arrangement we need more 300mm depth for Cable Termination.
  • This arrangement will not increase width of  panel but depth of panel will not increase 300mm.

5

General Compartment Size for various Switchgear in Panel.

Size of MCB / MCCB Compartment (Cable Connections are in front of Panel)

MCB / MCCB Size

Position

Width (mm)

Height (mm)

Depth (mm)

Up to 63A

Horizontal

300

275

300

63A to 100A

Horizontal

350

300

300

125A to 250A

Horizontal

350 to 400

300 to 350

300 to 350

400A to 630A

Horizontal

600

400

350 to 400

MCCB 800A

Horizontal

600

600

700

MCCB 1250A to 3200A

Horizontal

800

850

1000

* Cable Connections are in front side of Panel, If Cable Connection are in Back Side of Panel add 300mm in Depth of Panel

* Cable Termination Space in Panel (From Cable Entry at Panel to Termination Location) Up to 800A =more than 400 mm, above 800A It should be more than 800mm.

 

Size of ACB Compartment (Cable Connections are in front of Panel)

ACB Size

Position

Width (mm)

Height (mm)

Depth (mm)

800A

Horizontal

700

800

800

1600A

Horizontal

800

800

850

ACB up to 3200A

Horizontal

800

850

1000

ACB Above  3200A

Horizontal

1400

1000

1200

For Cable Entry from Bottom of Panel=Min 700mm Height from Bottom to Cable Termination

* Cable Termination Space in Panel (From Cable Entry at Panel to Termination Location) Up to 800A =more than 400 mm, Above 800A It should be more than 800mm.

 

Size of SFU Compartment (Cable Connections are in front of Panel)

SFU Size

Position

Width (mm)

Height (mm)

Depth (mm)

125A

Horizontal

400

350

300

200A

Horizontal

400

350

300

200A

Horizontal

400

400

300

* Cable Connections are in front side of Panel , If Cable Connection are in Back Side of Panel add 300mm in Depth of Panel

 

Size of ATS Compartment (Cable Connections are in front of Panel)

ATS Size

Position

Width (mm)

Height (mm)

Depth (mm)

100A

Vertical

400

700

350

160A

Vertical

400

900

350

200A

Vertical

400

750

350

400A

Vertical

400

750

350

630A

Vertical

400

1000

350

* Cable Connections are in front side of Panel , If Cable Connection are in Back Side of Panel add 300mm in Depth of Panel

 

Size of Motorized MCCB Compartment (Cable Connections are in front of Panel)

Motorized MCCB Size

Position

Width (mm)

Height (mm)

Width (mm)

125A

Vertical

500

500

300

200A

Vertical

500

500

300

400A

Vertical

500

500

300

* Cable Connections are in front side of Panel , If Cable Connection are in Back Side of Panel add 300mm in Depth of Panel

Size of Starter Compartment (Cable Connections are in front of Panel)

Motor KW

Position

Width (mm)

Height (mm)

Depth (mm)

Up to 6KW

Horizontal

500

300

300

7.5KW to 11 KW

Horizontal

600

200

300

15KW to 30KW

Horizontal

600

300

450

37KW to 55KW

Horizontal

600

400

600

55KW to 132KW

Vertical

600

600

800

250KW to 300KW

Vertical

800

1500

1000

* Cable Connections are in front side of Panel , If Cable Connection are in Back Side of Panel add 300mm in Depth of Panel

                 

 

Size of BUSBAR & Cable Alley Compartment

Type

Position

Width (mm)

Height (mm)

Depth (mm)

BUS BAR

Horizontal

300 to 400

300

BUS BAR

Vertical

300 to 400

300

CABLE ALLEY

Vertical

300 to 350

300

 

Size of MCB Compartment (For No’s of MCB)

MCB Size

Position

Width (mm)

Height (mm)

Depth (mm)

 

10A to 63A,4P MCB=5NO

Vertical

700

300

300

 

10A to 63A,4P MCB=5NO

Vertical

700

300

300

 

10A to 63A,4P MCB=3NO

Vertical

500

300

300

 

10A to 63A,4P RCCB=2NO+10A to 40A, SP MCB=20NO

Vertical

600

300

300

 

10A to 63A,4P RCCB=5NO+10A to 40A, DP MCB=2NO

Vertical

600

600

300

 

10A to 63A,4P MCB=2NO, ON/OFF

Vertical

350

300

300

 

*Required 25mm to 35mm for Each Pole, Ex for Four Pole MCB required 140mm Space

Calculation-1

  • Calculate Dimension of Panel for following Electrical SLD
  • Cable Termination are in front side of Panel ,Cable Entry are at bottom of the Panel ,Type of Panel is Indoor Type ,Switchgear will be installed in horizontal position.

6

Solution:

  • Incoming Switchgear= 1250A,4P, ACB
  • Outgoing Switchgear = 630A, TP, MCCB=2 No and 400A, TP, MCCB=3 No’s.

7

  • Height of Panel:
  • Height of Panel is decided from No of Outgoing Feeder and Switchgear Installation Position (Horizontal / Vertical). We will Installed Switchgear in horizontal position.
  • From Above Tables Height for MCCB Compartment for 400A to 630A MCCB=400mm
  • Total Height of panel for 5no of MCCB= 5×400=2000mm
  • Panel Base Frame is 75mm
  • Total Panel height is 2000+75=2075mm which is less than 2200mm
  • Width of Panel:
  • Width of Panel is decided from Incoming and Out Going Switchgear Section, Cable Termination from Front / Back Side and Switchgear installation position (vertical /Horizontal).
  • From above Table, Incoming Switchgear Compartment Size for 1250A,4P, ACB width is 800mm
  • Size of Busbar compartment =300mm
  • Size of Outgoing Switchgear compartment for 400A to 630A MCCB=600mm
  • Size of Busbar alley compartment (Front Side Cable Termination) =300mm
  • Total Width of Panel =800+300+600+300=2000mm
  • Depth of Panel:
  • Depth of Panel is decided from Incoming Switchgear (which has maximum depth) and Cable Termination in Panel (Front Side / Back Side)
  • From Above Table Depth of Switchgear compartment for 1250A ,4P, ACB=800mm
  • Total depth of panel=800mm
  • We can also choose different depth for Incoming Switchgear compartment and Outgoing Switchgear compartment.
  • In this example we can also choose depth of panel for incoming compartment=800mm and cable termination is front side of panel hence for Outgoing switchgear compartments=300mm.
  • Conclusion:
  • Total Width of Panel is 2000mm, Height of Panel is 2075mm, Depth of Panel is 800mm

WORKING SPACE FOR ELECTRICAL EQUIPMENTS / PANELS (PART-2)


(D) Illumination:

  • Service equipment, switchboards, panel boards, as well as motor control centers located in indoors must have illumination and controlled by automatic means only.

(E) Dedicated Equipment Space:

  • Switchboards, panel boards, and motor control centres must have dedicated equipment space as follows:

(1) Indoors (110.26 (E))

(a) Dedicated Electrical Space:

  • a dedicated electrical space is defined as the space equal to the width and the depth of the equipment extending from the floor to a height of 1.8 m above the equipment or the structural ceiling, whichever is lower.
  • No piping, ducts, or other foreign equipment can be installed in this dedicated Electrical footprint space.
  • Busways, conduits, raceways, and cables are permitted to enter through this Dedicated Electrical Space / zone.

A

(b) Foreign Systems:

  • Foreign systems can be located above the ded­icated space if proper protection is installed to prevent damage to the elec­trical equipment from condensation, leaks, or breaks in the foreign systems,
  • This can be achieved by installation of simple as a drip-pan.

B

(c) Sprinkler Protection (110.26(E)):

  • Sprinkler protection shall be permitted in the area above the dedicated electrical space if the electrical equipment is properly protected against Water leaks or breaks in the Sprinkler system.

  • Sprinkler System shall not be permitted in Working Space of Electrical Equipment.
  • Hence the sprinkler piping can run above the dedicated electrical space 1.8 m above equipment as long as the Electrical equipment below is protected from leaks, condensation, and even breaks by using dedicated Drip Pan.
  • But drip pans which may create an obstruction to sprinkler system discharge. So, it is always advisable to avoid locating sprinklers and sprinkler piping directly above electrical equipment and sprinklers and sprinkler piping are not permitted to be located directly within the working space for the equipment as shown in the figure

C

  • Where all of the following conditions are met, sprinklers shall not be required in electrical rooms
  • (1) The room is dedicated to electrical equipment only.
  • (2) Only dry-type or liquid-type with listed K-class fluid electrical equipment is used.
  • (3) Equipment is installed in a 2-hour fire-rated enclosure including protection for penetrations.
  • (4) Storage is not permitted in the room.

(d) Suspended Ceilings:

  • A dropped, Suspended or other similar hanging ceiling that does not add strength to the building structure is permitted to be located directly in the dedicated space, because they are not considered structural ceilings. Building structural members are also permitted in this space.

(2) OUTDOOR:

  • Outdoor Electrical installations must comply with the following:

(a) Installation Requirements:

  • Switchboards, switchgear, panel boards installed outdoors must be Installed in identified enclosures
  • Protected from accidental contact by unauthorized personnel, or by vehicular traffic.
  • Protected by accidental spillage or leakage from piping systems

(b) Work Space.

  • The working clearance space shall include the zone described in 110.26(A). No architectural appurtenance or other equipment shall be located in this zone.
  • Exception: Structural overhangs or roof extensions shall be permitted in this zone.

(c) Dedicated Equipment Space Outdoor.

  • The footprint space (width and depth of the equipment) extending from grade to a height of 6 ft above the equipment must be dedicated for the electrical installation.
  • No piping, ducts, or other equipment foreign to the electrical installation can be installed in this dedicated footprint space.

(F) Locked Electrical Equipment Rooms or Enclosures.

  • Electrical equipment rooms and enclosures housing electrical equipment can be controlled by locks because they are still considered to be accessi­ble to qualified persons who require access.

Enclosure for Electrical Installations (110.31)

  • Electrical installations in an Electrical Room, or closed area surrounded by a wall, screen, or fence shall be access or controlled by a lock(s) or other approved manners.
  • Electrical Installation Area (Indoor and Outdoor) shall be accessible to qualified persons only.
  • The type of enclosure used shall be designed and constructed according to the nature and degree of the hazard(s) associated with the installation.
  • For Outdoor Type Electrical installations shall be covered by Fence.

(a) Fence:

  • A fence shall not be less than 2.1 m (7 ft) in height or a combination of 1.8 m (6 ft) or more of fence fabric and a 300 mm (1 ft) or more extension utilizing three or more strands of barbed wire or equivalent.
  • The distance from the fence to live parts shall be not less than given in Table 110.31.

Min. Distance from Fence to Live Part Table 110.31

Nominal Voltage

Min. Distance from Live Part (Meter)

601 V   To 13799 V

3.05 Meter

13800 V   To 230000 V   

4.57 Meter

Above 230000 V   

5.49 Meter

(A) Electrical Room.

  • Where an electrical vault is required or specified for conductors and equipment 110.31(A)(1) to (A)(5) shall apply.
  • (1) Walls and Roof. The walls and roof shall be constructed of a minimum fire rating of 3 hours. For the purpose of this section, studs and wallboard construction shall not be permitted.
  • (2) Floors. The floors of vaults in contact with the earth shall be of concrete that is not less than 102 mm (4 in.) thick, but where the vault is constructed with a vacant space or other stories below it, the floor shall have adequate structural strength for the load imposed on it and a minimum fire resistance of 3 hours.
  • (3) Doors. Each doorway leading into a vault from the building interior shall be provided with a tight-fitting door that has a minimum fire rating of 3 hours.
  • (4) Locks. Doors shall be equipped with locks, and doors shall be kept locked, with access allowed only to qualified persons. Personnel doors shall swing out and be equipped with panic bars, pressure plates, or other devices that are normally latched but that open under simple pressure.

 (B) Enclosed Equipment Accessible to Unqualified Persons.

  • Ventilating or similar openings in equipment shall be designed such that foreign objects inserted through these openings are deflected from energized parts.
  • Where exposed to physical damage from vehicular traffic, suitable guards shall be provided.
  • Non-metallic or metal-enclosed equipment located outdoors and accessible to the general public shall be designed such that exposed nuts or bolts cannot be readily removed, permitting access to live parts.
  • Where non-metallic or metal-enclosed equipment is accessible to the general public and the bottom of the enclosure is less than 2.5 m (8 ft) above the floor or grade level, the enclosure door or hinged cover shall be kept locked.
  • Doors and covers of enclosures used solely as pull boxes, splice boxes, or junction boxes shall be locked, bolted, or screwed on.
  • Underground box covers that weigh over 45.4 kg (100 lb) shall be considered as meeting this requirement.

WORKING SPACE FOR ELECTRICAL EQUIPMENTS / PANELS (PART-1)


Electrical Equipment Space (As per NEC 110.26)

(A) Working Space:

  • Equipment that may need examination, adjust­ment, servicing, or maintenance while energized must have working space which is measured from the enclosure front, must not be less than the distances con­tained in Table 110.26(A)(1).

 (1) Depth of Working Space.

Table 110.26(A)(1) Working Space

Voltage-to-Ground One side of working Space having Pnel Exposed live parts and other side of Working Space having no live or grounded parts (including concrete, brick, or tile walls) One side of working Space having Panel Exposed live parts and other side of Working Space having live or grounded parts (including concrete, brick, or tile walls) Exposed live parts on both sides of the working space.
0 To 150V 3 Foot (900MM) 3 Foot (900MM) 3 Foot (900MM)
151V To 600V 3 Foot (900MM) 3.5 Foot (1000MM) 4 Foot (1200MM)
 601V TO 1000V 3 Foot (900MM)  4 Foot (1200MM)  5 Foot (1500MM)

A

(a) Rear and Sides. Working space isn’t required for the back or sides of assemblies where all connections and all renewable or adjustable parts are accessible from the front.

(2) Width of Working Space.

  • The width of the working space must be a minimum of 760MM (30 in) but in no case less than the width of the equipment.
  • The width of the working space can be measured from left-to-right, from right-to-left, or simply centered on the equipment, and the working space can overlap the working space for other electrical equipment.
  • In all cases, the working space must be of sufficient width, depth, and height to permit all equipment doors to open 90 degrees.

B

(3) Height of Working Space (Headroom).

  • The height of the working space in front of equipment must not be less than 2 Meter (6½ ft) measured from the grade, floor, platform, or the equipment height, whichever is greater.
  • Equipment such as raceways, cables, wireways, cabinets, panels, and so on, can be located above or below electrical equipment, but must not extend more than 6 in. into the equipment’s working space.

D

(B) Limited Access

  • Where equipment is installed above a lay-in ceiling, there shall be an opening not smaller than 559 mm × 559 mm (22 in. × 22 in.), or in a crawl space, there shall be an accessible opening not smaller than 559 mm × 762 mm (22 in. × 30 in.).
  • The width of the working space shall be the width of the equipment enclosure or a minimum of 762 mm (30 in.) whichever is greater.
  • All enclosure doors or hinged panels shall be capable of opening a minimum of 90 degrees.
  • The space in front of the enclosure shall comply with the depth requirements of Table 110.26(A)(1).
  • The maximum height of the working space shall be the height necessary to install the equipment in the limited space. A horizontal ceiling structural member or access panel shall be permitted in this space.

 (C) Entrance to and Egress from Working Space.

  •  (1) Minimum Required: At least one entrance of sufficient area must provide access to and egress from the working space.
  • (2) Large Equipment: An entrance to and egress from each end of the working space of for electrical equipment rated 1,200A or more and over 6 ft wide is required an entrance of Not Less than 600MM Wide and 1800MM Height at each end of Working Place.

E

  • A single entrance to and egress from the required working space is permitted where either of the following conditions is met:
  • (a) Unobstructed Egress. Only one entrance is required where the location permits a continuous and unobstructed way of egress travel.
  • (b) Double Workspace. Only one entrance is required where the required working space depth is doubled, and the equipment is located so the edge of the entrance is no closer than the required working space distance.

F

  • (3) Personnel Doors: If equipment with overcurrent or switch­ing devices rated 1,200A or more is installed, personnel door(s) for entrance to and egress from the working space located less than 25 ft from the nearest edge of the working space must have the door(s) open in the direction of egress and be equipped with panic hardware or other devices that open under simple pressure

G

Difference between PVC- LSF-LSHF- FR- FRLS -FRLSH Cables. (PART-2)


(B) Fire Rated Cable (Retardant / Resistance Cable)

  • Fire is one of the biggest risks in factories, public place and a majority of them occur due to electrical faults.
  • The terms Fire Resistant and Fire Retardant (both are commonly referred to as FR) terms are very similar and misused or confusing a lot.
  • Both are different in structure, in materials, in Application and react even differently in the event of a fire. If we required one but select other can lead the problem.

(1) Fire  Retardant Cables 

  • Insulating Material of Fire Retardant Cable is chemically treated to Retard or Slowdown ignition or Burning of Fire hence slow down the spreading of fire. It also actually self-extinguishes when exposed to an open flame.
  • Flame-retardant Cable is characterized by delaying the spread of flame along the cable so that the fire does not expand.
  • Fire-resistant cables and flame-retardant cables are different in structure and materials.
  • The basic structure of the flame retardant cable is:
  • The insulation layer uses flame retardant.
  • The inner sheath and outer sheath are made of flame retardant.
  • The tape and filling use of flame retardant material.

11

Advantage:

  • Low Cost compared to Fire Resistance Cable.
  • Produce Low Smoke

Disadvantage:

  • By Adding Fire Retardant Material / Filler in PVC it decreases insulation property at least 10% compare to normal PVC, however its conductor temperature withstanding capability (during overload) remains only at 70 deg C same as ordinary PVC cables.

Applications:

  • Control Wiring of Building
  • Fire Alarm Circuit

(2) Fire Resistant cables

  • The Fire resistance materials (non-flammable.) are designed to prevent / Resist the spread of fire (self-extinguishing) and will not melt or drip when in close proximity to a flame.
  • Because it self-extinguishes once the source of ignition is removed and does not melt or drip. Fire-resistant cables can maintain normal operation for a certain period under flame burning conditions and maintain the Circuit integrity and continue to work for a specified period of time under defined conditions hence improving the chances of escape and survival.
  • Because of Fire resistant fabrics are not usually made from 100% flame resistant materials, they will burn, but will do so very, very slowly and are often self-extinguishing.
  • A Fire-resistant cable is a cable that can maintain safe operation for a certain period under flame-burning conditions. Fire-resistant wires are widely used in high-rise buildings, subways, underground shopping malls, power stations, and important industrial and mining enterprises related to fire safety and fire rescue. For example, power supply wires and control wires for firefighting facilities.
  • Fire-resistant cable is divided into class A and class B.
  • Class B: Class B cable can be in 750 ℃ to 800 ℃ flame and rated voltage to withstand burning for at least 90min, and the cable is not broken.
  • In the refractory layer to improve the manufacturing process and increase the refractory layer and other methods based on
  • Class A: Class A fire rated cable can be 950 ℃ to 1 000 ℃ flame and rated voltage to withstand burning for at least 90min and the cable is not punctured.
  • Class A fire-resistant cable fire performance is better than class B.
  • Mineral Insulated Cable (MI): mineral insulated cable is a better performance of fire-resistant cables made of copper core, copper sheath, magnesium oxide insulation material processing, referred to as MI (mineral insulated cables) cable.
  • MI cable has good fire resistance characteristics and can work for a long time under 250 ℃ high temperature, but also explosion-proof, strong corrosion-resistance, high flow rate, radiation resistance, high mechanical strength, small size, lightweight, long life, and smokeless. However, the price is high. The process is complicated, the construction is difficult in the oil irrigation area, important public buildings, high-temperature places, and other fire-resistant requirements, and the economy can accept the occasion and use fire-resistant cable.

22

Advantage:

  • Produce Low Smoke compared to Fire Retardant Cable.

Disadvantage:

  • High Cost compared to Fire Resistance Cable.
  • By Adding Fire Retardant Material / Filler in PVC it decrease insulation property at least 10% compare to normal PVC, However its conductor temperature withstanding capability (during overload) remains only at 70 deg C same as ordinary PVC cables.

Applications:

  • In Fire Fighting System,
  • In Fire Alarm Circuit

(3) FRLS (Fire Retardant Low Smoke)

  • To overcome these deficiencies of FR Cable, FRLS Cable was developed.
  • FRLS has special flame retardant, low smoke emitting and toxic fumes suppressing properties.
  • In FRLS Cable, inner sheath and/or outer sheath is made material of Polyethylene Material having Fire Retardant Properties.
  • In the Case of fire, convectional PVC insulated wires give out thick black smoke and toxic fumes of hydrochloric acid gas. This impairs visibility and hampers rescues operations. But in FRLS Cable not only emits very little smoke and toxic gases, but also retards the spreading of fire. It is thus ideal of concealed and conduit wiring in multi-storied high-rise buildings such as hotels, banks, hospitals, factories, commercial complexes and residential apartments, etc

33

Advantages

  • Excellent flame-retardancy
  • Low smoke generation
  • Low toxic gas emission

(4) FRLSZH/ NHFR / ZHFR (Fire Retardant Low Smoke Halogen Free)

  • FRLSZH, Halogen Free Flame Retardant non-toxic smoke house wires for building wiring.
  • FRLSZH Wires are recommended especially in a situation where high degree of safety of personnel and equipment are obligatory like Hotels, Theatres, Hospitals, High-rise buildings, Commercial complexes, Centrally A.C. offices, Residential properties etc.
  • Owing to its special insulation characteristics the wires continue to provide uninterrupted power supply even during fire – keeping alive fire alarm circuits, exit lights, Lifts & other emergency Circuits.
  • As part of sustainable green building technology, to bringing down the use of hazardous PVC from green building. Normal PVC cables will be replaced with Green Cable.44

Advantages

  • Excellent flame-retardancy
  • Halogen Free
  • Low smoke generation
  • Low toxic gas emission
  • Better visibility help easy for people escape
  • Environment friendly
  • Benefit to environment
  • PVC is not only hazardous during the manufacturing process but also potential risk in case of fire. Green Cable is superior performance cable with utmost quality which is replacement for PVC cables.
  • Generally used where green environment and higher safety is expected for Human life and valuables

Disadvantages

  • Costly Compare to FR and FRLS Cables

Applications:

  • Airports
  • Centrally A. C. Buildings
  • Complexes
  • Educational Institutions
  • General House wiring
  • Green Buildings
  • High Raise Building
  • Hospitals
  • Hotels
  • Public Places, Theaters

Flame retardant (FR) or FRLS compounds are not suitable for building wires for the following reasons:-

  • FR & FRLS PVC compounds are said to be flame retardant because they have better LOI (Limiting Oxygen Index) and TI (Temperature Index) than ordinary PVC, but, only better LOI & TI does not guarantee better flame retardant properties. LOI & TI are only quality control tests and flame retardant testing is incomplete without finished cable testing as per IEC 332-1 &3.
  • Moreover, all the FR and FRLS PVC compounds contain Antimony Trioxide which is a probable carcinogen. When inhaled, ATO can cause irritation of the respiratory track, mouth, nose & stomach. It may also cause the heart to beat irregularly or even stop.
  • The use of FR & FRLS PVC compounds does not solve the issues of dense black smoke and HCL acid gas emitting from burning which are the main cause of loss of human lifes during fire accidents.
  • All PVC,FR & FRLS compounds also contain phthalate plasticizers. These plasticizers leach out of PVC compound after some time and results in PVC loosing its flexibility and other properties. Moreover most of the phalates presently used have been identified as suspected endocrine disrupters and reproductive toxicants

Difference between Fire Resistant vs. Fire Retardant Cable

  • Fire Resistant and Fire Retardant cables are being used increasingly due to their usefulness in the event of fire. However, though they both sound similar, they have vastly different uses and react differently in the event of a fire.
  • Heat resistant: It will operate as normal at high temperatures, but may not operate as normal in the event of a fire.
  • Fire retardant: It will not operate as normal within fire conditions, but will actively prevent the fire from spreading.
  • Fire resistant: It can operate as normal within fire conditions.
  • Conclusion:
  • In brief, Fire retardant cables are designed to resist the spread of fire into a new area. It would not maintain circuit continuity for Work.
  • Fire resistant or fire rated cables are designed to maintain circuit integrity and continue to work, allowing power to be transferred through it under defined for a specified period of time and conditions.
  • The distinction between the two is crucial when it comes to maintaining critical circuits required for life safety or for a safe and immediate plant shutdown.
  • Fire resistant cables are used in critical electrical circuits, such as safety circuits and life support circuits which are required to function in the case of emergencies.
  • Flame retardant cables on the other hand are used in all other circuits so if there’s a fire, they can curb its spread. A flame resistant cable will be passed as per IEC 60331 and are encased in a red outer sheathes. Flame retardant cables behavior under fire is predefined as per passing the IEC 60332 and are encased in a grey or black outer sheathe.
Fire resistant (fire rated) cables Continues to operate in the presence of fire, hence their reference as Circuit Integrity cables.
Flame retardant cables Fire performance limited to not propagating fire

Difference between FR vs PVC vs LSF vs LSHF Cables

  • FR Cables:
  • Fire resistant and fire retardant cable sheaths are design to resist combustion and limit the propagation of flames.
  • Fire Retardant (FR): Designed for use in fire situations where the spread of flames along a cable route needs to be retarded
  • Fire Resistant (FR): cables are designed to maintain circuit integrity of those vital emergency services during the fire
  • FR is for essential services such as fire alarms, emergency lighting, life safety and firefighting applications.
  • These systems have to operate during a fire to detect the fire, alert people and help them evacuate and also help emergency services do their job.
  • These circuits need to function fully and retain circuit integrity in the event of fire.
  • In case of fire, it does not emit toxic or corrosive gases, thereby protecting public health and avoiding any possible damage to electronic equipment
  • LSF, LSHF and PVC Cables
  • Low smokes cables have a sheath designed to limit the amount of smoke and toxic halogen gases given off during fire situations
  • Low Smoke and Fume (LSF): burns with very little smoke and fumes compared to standard PVC, fumes may contain halogens
  • Low Smoke Zero Halogen (LSZH): when burns there is very little smoke and fumes contains no Halogen (compared to standard PVC)
  • LSHF and PVC cables are used for non-essential services that do not need to operate in a fire.
  • These include all the usual power circuits in buildings for services such as general lighting or kitchen and office appliances like cookers or photocopiers.
  • These circuits are not essential for the safety of the public; they can fail in a fire with no increase in danger so they do not need to be fire resistant.
  • For public buildings however, all cables need to be low smoke and zero halogen type but in domestic premises and for buried cables they do not, so PVC is acceptable
  • Both LSZH and LSF are used to limit smoke, fumes and halogen given off in fire conditions.
  • In the event of a fire, both types will emit very low levels of smoke. LSF cable will emit toxic gases while LSZH will limit the emission of these (typically under 0.5% hydrogen chloride emission). In addition to being toxic, hydrogen chloride is corrosive to equipment. The use of LSZH cables protect both people and limit the amount of equipment damage during a fire situation.

Comparison of various cable

Comparison of various cable

Feature Normal PVC Wire Heat Resistant HR PVC Fire Retardant FR – PVC Fire Retardant Low Smoke FRLS Zero Halogen Low Smoke ZHFR
Insulation Material PVC PVC Special PVC Special PVC Special Polymer
Insulation Property Normal Good Good Good Very Good
Temperature Rating 700 C. 850 C. 70C. 700 C. 850 C.
Thermal Stability Normal Very Good Good Good Very Good
Flam Retardancy Good Good Very Good Very Good Excellent
Safety During Burning Average Average Good Good Excellent
Requirement of Oxygen to Catch Fire > 21% > 21% > 30% > 30% > 35%
Temperature Required to catch fire ( with 21% oxygen) Room Temp. Room Temp. > 2500 C. > 2500 C. > 3000 C.
Visibility during Cable burning < 20% < 20% < 35% < 40% < 80%
Release of Halogen Gas during burning < 20% < 20% < 20% < 20% 0%
Abrasion Resistance during Installation Good Good Good Good Good

Comparison various Specification’s of Cable

Test Function Specification Values of FRLS Compound Values of Halogen Free Compound Values of PVC
Critical Oxygen Index To Determine % of Oxygen Required For Supporting Combustion of Insulating Material at room temperature. ASTM–D-2863 > 29% More than 29% 23%
Temperature    Index To determine at What Temperature Normal Oxygen Content of 21% In Air will Support  Combustion of Insulating Material ASTM–D-2863 > 2500 C. More than       2500 C. 1500 C.
Smoke density Rating (Light Transmission) To Determine the visibility ( Light Transmission ) under Fire of Insulating Material ASTM-D-2843 > 40 % More than 80 % 10-15 %
Acid Gas Generation To ascertain the amount of Hydrochloric Acid Gas Evolved from insulation of Cable Under Fire. IEC – 754 – 1 < 20 % Less than 0.5 % 45-50 %

International Standards

Halogen & Smoke Emission, Corrosively & Toxicity Standards

  • IEC 60754-1/BS6425-1 – emission of halogen
  • IEC 60754-2 – corrosivity , Acid gas emission
  • IEC 61034-1/ ASTM E662 – emission of smoke
  • ISO4589-2/ BS2863 – oxygen index LOI
  • ISO4589-3/ BS2782.1 – temperature index TI
  • ASTM – D – 2863- Oxygen index
  • ES713 – toxicity index

Flame Retardant Standards

  • IEC 60332-1 / BS 4066-1 – flame test on single vertical insulated wires/cables
  • IEC 60332-3 / BS 4066-3 – flame test on bunched wires/cables
  • UL Standard for Fire Retardant Cable
  • NFPA -262 =CMP (Plenum Flame Test/ Steiner Tunnel Test)
  • UL1666=CMR (Riser Flame Test)
  • UL 1581=CM (Vertical Tray Flame Test)
  • UL1581=CMG (Vertical Tray Flame Test)
  • UL1581=CMX (Vertical Wire Flame Test)

Fire Resistance Standards

  • IEC 60331 – fire resistance test
  • BS 6387 / BS 8491: BS 8434/2 – fire resistance test (more stringent than IEC 60331)

Difference between PVC- LSF-LSHF- FR- FRLS -FRLSH Cables. (PART-1)


Introduction:

  • Due to lack of standardization and lack of awareness. While selecting of Cable, there is a lot of confusion and misunderstanding regarding the terminology associated with cables in terms of “LSF / LS” (Low Smoke), “LSZH / LSHF (Low Smoke Halogen Free),” FR” (Fire Retardant),”FR” (Fire Resistance) “FRLS” (fire resistant, low smoke), “FRLSZH” (Fire retardant Halogen-Free).

Cable / Wire Terminology  

  • According to type of Insulation Material around the conductor, we can classify Cables / Wire in Three main Categories PVC, Zero Halogen and Fire Retardant.
  • According to application we can mainly classified in to Two categories  

(A) Non-Fire Rated Cable

  1. PVC = Polyvinyl Chloride
  2. LS / LSF = Low Smoke / Low Smoke Fume
  3. LSHF / LSZH / LSNH = Low Smoke Halogen Free / Low Smoke Zero (No) Halogen
  4. LH / HF = Low Halogen / Halogen Free

(B) Fire Rated Cable

  1. FR =Fire Retardant
  2. FR =Fire Resistance
  3. FRLS = Fire Resistant, Low Smoke
  4. FRLSH= Fire Resistant, Low smoke, Low Halogen
  5. FRLSZH / NHFR / ZHFR / HFFR = Fire Retardant Low Smoke Zero Halogen / Non (Zero) Halogen Free, Fire retardant
  6. HRFR=Heat Resistance Fire Retardant
  • PVC, FRLS and FP cables, have conductors and insulation to manage the electrical current and voltage. Some also have extra physical protection, like steel wire armour.
  • PVC and FRLSH cables are different insulating materials around conductors for different application and performance.
  • The properties that distinguish one electrical insulation from the other are
  • (1) dielectric strength or break down voltage
  • (2) maximum permissible temperature
  • (3) dielectric loss
  • (4) permittivity; and some special properties to suit the application.
  • FRLS / FRLF is the quality of insulating material. It may be PVC or XLPE.

(A) Non-Fire Rated Cable

(1) PVC  Cable:

  • PVC (Polyvinyl Chloride) cables is usually made up of a PVC compound as an insulating Material.
  • PVC insulation has a temperature limit of about 70°C. From the point of view of maximum permissible temperature, it belongs to the lowest class of insulation, yet it serves the purpose as the voltages and power ratings involved are relatively low.
  • While burring of PVC in case of Fire produces dense of black smoke and produce large amount of toxic gas and cocktail of harmful chemicals.
  • Smoke:
  • Burning PVC has been reduced visibility in the surrounding area by 50% within 10 minutes. After 30 minutes, visibility can be reduced by as 90%
  • This reduced visibility could make it very difficult to escape a burning Area / Building.
  • The smoke and fumes produced during a fire can be more dangerous to people than the fire itself.
  • Toxic Chemicals:
  • Burning PVC produces a number of toxic chemicals, but the most problematic is hydrogen chloride (HCI). PVC emits approximately 28% of Hydrogen Chloride (HCI).
  • In natural state HCL is a pungent, almost colorless gas, which forms into white vapor clouds on contact with air.
  • Furthermore, when mixed with water it changes state yet again to form Hydrochloric Acid, whether it’s in gaseous, vaporized or liquid state it’s a highly toxic and corrosive substance.
  • There are numerous harmful effects that HCl can have on a person. If inhaled the lining of the throat can be irritated to such an extent that it swells, making breathing extremely difficult.
  • Contact with the eyes can be responsible for anything from severe irritation to permanent damage to the corneas. Similarly, lips and mucous membranes may be burned or even ulcerated, the severity dependent on the concentration of HCl and length of exposure.
  • Taking into account the combined effects on someone of the smoke and HCl produced during the burning process, it’s difficult to see and the victims have been rendered unconscious long before the flames have reached them.
  • Some extent Fire Retardant property:
  • PVC is resistant to Fire ignition.
  • PVC (polyvinyl chloride) is naturally Fire Retardant due to chlorine base. It contains a large number of chlorine ions in the molecular structure and these are particularly difficult to break off when exposed to heat.
  • If it does catch fire, PVC has a particularly slow spread of flame. PVC has one of the lowest flames spread ratings, meaning that it won’t typically contribute to the spread of a fire
  • The temperature required to ignite rigid PVC is more than 150 deg C higher than that required to ignite wood. The ignition resistance of common flexible PVC formulations is lower, but with specialized formulations it may be significantly increased.
  • The fire in the gets extinguished immediately on removal of the fire source.
  • In the Plant or Building, PVC cables are bunched in the cable shaft or on cable trays. In case of fire in these cables the fire becomes self-sustaining.
  • Moreover, due to the burning of PVC a dense corrosive smoke is emitted which makes firefighting very difficult, due to poor visibility and toxic nature of the smoke. HCL content of the smoke, not only damages other costly equipment lying nearby, but also penetrates the RCC and corrodes the steel reinforcement.
  • PVC have some Fire retardant Property due to halogen even though it may create an extensive damage to the property and harmful for human.

11

Advantage:

  • PVC is Cheap.
  • PVC offers greater flexibility and robust
  • PVC have a relatively long working life

Dis Advantage:

  • When PVC insulated cable burns it gives off a cocktail of chemicals and dense black smoke.

Application:

  • PVC cables are used for non-essential services that do not need to operate in case of fire
  • Mostly use for Domestic, Office for general lighting.
  • They are ideal for low-risk buildings, not generally for public or large commercial buildings.

(2) LS / LSF (Low Smoke & Fume) Cables:

  • LSF is also manufactured using PVC compounds.
  • LSF cables are usually made up of a modified PVC compound (varying degrees dependent on the manufacturer’s) which produces somewhat less HCI gas and smoke on burning than PVC.
  • However, it still produces 15% to 22 % (depending on quality) of HCI gas and due to the presence of PVC can still emit dense black smoke and HCl emissions.
  • It does contain halogen, so it shouldn’t be confused or similar with Low Smoke Halogen Free (LSHF) cables.
  • The amount of PVC present in these cables can differ from manufacturer to manufacturer which makes installing LSF cables in public places.

22

Advantage:

  • These cables are often purchased to cut cost or in confusion with LSHF cables.
  • They should be considered to be a small improvement over PVC cables.

Dis Advantage:

  • These cables are not recommended for public, large commercial buildings, near sensitive electronic equipment and where escape is limited in case of fire.

Application:

  • Mostly use for Domestic, Office for general lighting.

(3) LSHF / LSZH / LS0H (Low Smoke Halogen Free) Cables

  • LSHF cables are made up of halogen free compounds that are good fire retardants but emit less than 0.5% hydrogen chloride gas and smoke when burnt.
  •  In case of fire, LSHF cable produces only small amounts of light grey smoke and miniscule amounts of HCl, which as a result greatly increases a person’s chances of escape from a burning building in which it’s installed.
  • The reason LSHF products react so differently when exposed to fire in comparison to PVC & LSF cables is the complete absence of PVC.
  • The outer sheath / Jacketing and conductor insulation of these products are often made from polyethylene which contains little by way of chlorine, and low chlorine means low HCl and Low nontoxic gases emissions.
  • It emits <0.5 % of HCL gas thus providing a safer environment in the event of a fire.
  • There’s no PVC in these cables, hence no harmful fumes or dense black smoke are given off in case of fire and generation ensures evacuation routes and signage remain visible during a fire.
  • In Some Manufacture’s LSHF Cable use standard PVC cables over-sheathed with an LSHF jacket or cables with PVC insulation. When the jacket burns through, the PVC inner sheath or insulation will give off poisonous gases in just the same way as PVC Cable.

33

Advantage:

  • LSHF cables use in applications where smoke emission and toxic fumes could a risk to human health and essential equipment in the event of a fire.

Dis Advantage:

  • Costly compare to PVC and LSF
  • Not Flexible compared to PVC

Application:

  • Because of their low smoke and toxicity benefits, LSHF cables are often chosen for various Public, non / Poor ventilated Place and Essential applications.
  • Public space, Building like Railway and subway stations and cars, buses and bus stations, airplanes and airports, Carrier Ships, other mass transit facilities.
  • Any public underground or poorly ventilated location like elevators, subways
  • Public entertainment and sports facilities
  • Apartment buildings and hotels
  • Hospitals
  • Computer/data centers

Difference between PVC vs LSF vs LSZH

  • LSF cables are flexible and low-cost alternative to PVC cables but made from a modified version of PVC and can still produce a dangerous amount of toxic gas and large amounts of black smoke and hydrogen chloride gas when burned.
  • Black smoke can obscure exit routes in the event of a fire and hydrogen chloride gas can be deadly to both people and sensitive equipment.
  • Whereas LSHF cables are less flexible and a higher cost but due to absent of PVC reduce significant of toxic gas, smoke and no more than 0.5% HCL when burned. So in a high risk populated area where escape is limited, LHSF cables are strongly recommended.
  • But in low-risk areas where the evacuation is easy and high flexibility is required, PVC could still be a good choice.
  • One common misunderstanding is that LSF or LSHF cable is also flame retardant.  This is not necessarily true. The cables may spread the fire even though minimal fumes are being emitted

Forms of Separation for Panel (PART-2)


(C) Form 3

  • This is more complicated but safer than Form 2.
  • In form 3a, each device is isolated in a compartment that protects it from the effects of any incidents that may occur on another Part / Switchgear.
  • Busbars and functional units are segregated. Functional units are also separated from each other in cubicles, and terminals are then separated from functional units, but they are not segregated from other functional units’ terminals.
  • Busbar and Switchgear: Bus bars are separated from the Switchgear units,
  • Busbar and Termination: Bus bars are not separated from any incoming or outgoing terminations.
  • Switchgear and Switchgear units: Switchgear units are separated from each other.
  • Switchgear and Termination: Switchgear units are separated from any incoming or outgoing termination.
  • Termination and Termination: Incoming and outgoing terminals are not separated from each other
  • This is further classified into 2 categories.

FORM 3A

  • External cabling terminals are not segregated from busbars.

FORM 3B

  • External cabling terminals are separated from busbars

FORM 3B TYPE 1

  • As from 3 but: Busbar separation is achieved by insulated coverings, e.g. PVC sleeving, wrapping or coating.
  • Terminals are therefore separated from the busbars, but not from each other.

FORM 3B TYPE 2

  • As form 3 but: Busbar separations is achieved by metallic or non-metallic rigid barriers or partitions.
  • Terminals are therefore separated from the busbars, but not from each other. 1

 Advantages:

  • The advantages include safety, ease of maintenance and reliability because it’s possible to isolate and perform maintenance on each starter without having to power down the whole switchboard.
  • Serious faults within a starter are also more likely to be contained within a cubicle meaning adjacent starters are unaffected and can operate normally.

Electrical Safety:

  • More reliable and safer than Form-2 due to separation between live parts (Busbar and Switchgear, Switchgear and Switchgear).

Cost:

  • All these advantages come at a cost as a Form 3 board is significantly bigger and more expensive than a Form 1 or 2 board.

Application:

  • Form 3 segregation is typically used for Big projects and larger operations that have a greater number of loads, motors and critical processes.
  • They are utilised when safety, reliability and limited downtime are crucial.

(D) Form 4

 This is the highest form rating, as specified by AS/NZS / IEC 61439.1.

  • Busbars are separated from functional units
  • Functional units are separated from each other
  • Terminations to functional units are separated from each other
  • Busbar and Switchgear: Bus bars are separated from the Switchgear units,
  • Busbar and Termination: Bus bars are separated from any incoming or outgoing terminations.
  • Switchgear and Switchgear units: Switchgear units are separated from each other.
  • Switchgear and Termination: Switchgear units are separated from any incoming or outgoing termination.
  • Termination and Termination: Incoming and outgoing terminals are separated from each other
  • This is further classified into 2 categories.

FORM 4A

  • External cabling terminals are within the same cubicle as the corresponding functional unit.

FORM 4B

  • The external cabling terminals are not in the same cubicle as the corresponding functional unit, and they are separated from the terminals of other functional units.

CLASSIFICATION OF FORM 4B

TYPE Busbar Separation Termination Location Cable Gland
FORM 4B TYPE-1 PVC sleeving, wrapping or coating. Termination is within the same compartment as the functional unit. Common Gland Plate
FORM 4B TYPE-2 Rigid Barriers Termination is within the same compartment as the functional unit. Common Gland Plate
FORM 4B TYPE-3 Rigid Barriers Termination is within the same compartment as the functional unit. Individual Gland Plate
FORM 4B TYPE-4 PVC sleeving, wrapping or coating. Terminals are external to the functional unit and separated by insulated coverings, e.g. PVC Boots Common Gland Plate
FORM 4B TYPE-5 Rigid Barriers Terminals are external to the functional unit and separated by insulated coverings, e.g. PVC Boots Common Gland Plate
FORM 4B TYPE-6 Rigid Barriers Terminals are external to the functional unit compartment and enclosed in their own compartment by means of rigid barriers or partitions Common Gland Plate
FORM 4B TYPE-7 Rigid Barriers Terminals are external to the functional unit compartment and enclosed in their own compartment by means of rigid barriers or partitions complete with integral glanding facility Individual Gland Plate

2

  • The major difference between Forms 3 and 4 is the separation of the terminals of each functional unit the terminals of other units.

Advantages:

  • The main advantage of this model is the ability to safely connect and disconnect outgoing cables while the rest of the switchboard remains in operation.
  • In Large Panel access is required for inspection, to reset an auxiliary function. If the point of isolation and termination are each in their own individual box this can be deemed safer than if all the devices and connections are behind a single door

Electrical Safety:

  • More reliable and safer than Form-4 due to separation between live parts (Busbar and Switchgear, Switchgear and Switchgear, Termination and Termination).
  • Due to internal segregation is to limit the effects on adjacent circuits if something goes wrong. An external fault should cause a device to trip but this must not have any effect on any other circuits.

Cost:

  • Form 4 board is significantly bigger and more expensive than a Form 3 board.

Applications:

  • used in hospitals or for critical industrial processes.

SUMAMRY OF FORM OF SEPERATION OF PANEL

SUMAMRY OF FORM OF SEPERATION OF PANEL

SEPERATION BETWEEN FORM-1 FORM-2 FORM-3 FORM-4
BUSBAR–SWITCHGEAR NO YES YES YES
BUSBAR–TERMIATION NO NO / YES YES YES
SWITCHGEAR—SWITCHGEAR. NO NO YES YES
SWITCHGEAR–TERMIANTION NO NO NO YES
TERMIANATION–TERMIANTION NO NO NO YES

Forms of Separation for Panel (PART-1)


Introduction:

  • Forms of segregation have great importance in electrical Panel designs.
  • Form of segregation is the rule for provide separation from a one energizes function part to other energize function pant and access to a part of the assembly while other parts may remain energized. This can be achieved by using metallic or non-metallic physical barriers or insulation.
  • The form of segregation provides protection against four objectives.
  1. Protection against direct contact with live dangerous parts of adjacent functional units.
  2. Protection against the entry of solid objects from one unit of an assembly to an adjacent unit.
  3. Limitation of the effects of the spread of electric arcs.
  4. Facilitation of panel maintenance operations.

Type of Separation:

  • As specified by AS / NZS / IEC 61439, There are four main categories outlined by the standard for internally separating the switchgear units and busbars of a Panel are
  1. Form 1 (No segregation between busbar, terminals and Switchgear units)
  2. Form 2 (Separation between switchgear units and the busbar)
  3. Form 3 (Separation are between switchgear units and the busbar and Separation between Switchgear unit to Switchgear Unit)
  4. Form 4 (Segregation between busbar, terminals and Switchgear units)
  • The complexity of the forms increases with the numbers.

1

(A) Form 1:

  • A Form 1 Panel has no internal separation among busbar, switchgear and outgoing Cable Terminations.
  • All functional units are installed in one central section to provide protection against contact with any internal live parts.
  • Busbar and Switchgear: Bus bars are not separated from the Switchgear units,
  • Busbar and Termination: Bus bars are not separated from any incoming or outgoing terminations.
  • Switchgear and Switchgear units: Switchgear units are not separated from each other.
  • Switchgear and Termination: Switchgear units are not separated from any incoming or outgoing termination.
  • Termination and Termination: Incoming and outgoing terminals are not separated from each other

2

Advantage:

  • Simple Design and Less Space Required.

Electrical Safety:

  • Less due to No separation between live parts.
  • This form construction is rarely used.

Cost:

  • Less Cost

Application:

  • For small, low power switchboards.

(B) Form 2

  • Form 2a is the simplest for protecting against accidental contact with any internal live parts or components like the busbars, which are considered to be the most dangerous components.
  • In FORM-2, Busbar is Separate from the Switchgear units but may or may not be separate from Cable terminal.
  • Busbar and Switchgear: Bus bars are separated from the Switchgear units,
  • Busbar and Termination: Bus bars may or may not separate from any incoming or outgoing terminations.
  • Switchgear and Switchgear units: Switchgear units are not separated from each other.
  • Switchgear and Termination: Switchgear units are not separated from any incoming or outgoing termination.
  • Termination and Termination: Incoming and outgoing terminals are not separated from each other
  • This is further classified into 2 categories.

FORM 2A

  • Terminals are not separated from the busbars or each other.

FORM 2B

  • Terminals are separated from the busbars

FORM 2B TYPE 1

  • As form 2 but Busbar separation is achieved by insulated coverings, e.g. PVC sleeving, wrapping or coating.
  • Terminals are the therefore separated from the busbars, but not from functional units or each other.

FORM 2B TYPE 2

  • As from 2 but Busbar separation is achieved by metallic or non-metallic rigid barriers or partitions
  • Terminals are therefore separated from the busbars, but not from functional units or each other

3

Advantages:

  • There are several advantages to segregating functional units and busbars.
  • This model allows circuit breakers to be reset when the switchboard is live because the operator is not exposed to a live busbar.

Electrical Safety:

  • More than Form-1 due to separation between live parts (Busbar and Switchgear).

Cost:

  • More Costly than Form-1

Application:

  • For small, low power switchboards.

Measurement of LUX Level and Uniformity at Indoor and Outdoor Lighting (Part-3)


(3) Grid Method to measure illumination on the road

  • The arrangement of the measuring points depends on the distance between the Illumination Pole and the width of the Road.
  • The measurement of illuminance should be performed on the area in longitudinal direction two consecutive luminaires in the same row and in transverse direction the width of the area with the same illumination class, i.e. if the road and adjacent pavement or bicycle path have the same illumination class, they may be considered as one area during the measurements. The measuring points should be distributed evenly within the measuring field.
  • The distance between the measuring points (D in Meter) in the longitudinal direction should be calculated using the formula
  • The distance between the measuring point in longitude ( D)=S / N
  • where:
    S= the distance between the luminaires in [m],
    N= the number of measurement points in the longitudinal direction,
    for S ≤ 30 m, it is N = 10,
    for S > 30 m, the smallest integer giving D ≤ 3 m.
  • The distance between measurement points (d in Meter) in the transverse direction should be calculated with the formula:
  • The distance between the measuring point in transverse (d) = Wr / n
  • where: Wr= the width of the road or the area under consideration in Meter.
  • n = the number of measurement points in the transverse direction equal to 3 or more and being an integer giving d ≤ 1.5 m.
  • The distance between the points and the edges of the surface under consideration should be D/2 in the longitudinal direction and d/2 in the transverse direction. The location of the measurement points in the measuring field is shown in Figure.

1

(4) Equal Space Method

  • In this Method at least10 equal measuring Points are taken between two lighting Pole on one side of the Roadway.
  • These measurement points cannot be spaced more than 5 meters apart. Two lines of measurement points are needed per driving lane, one-half lane width apart.
  • Once you have taken all of your illuminance measurements, you can calculate an average illuminance for the section of roadway you have measured.

2

What is Lighting Uniformity

  • light uniformity refers to the uniformity of lighting in an environment. It is necessary to maintain the uniformity of light in order to make sure that everything is perfectly visible in the room.
  • Uniformity is the ratio of the minimum lighting level to the average lighting level in a specified area.
  • U1 = E Min / E Average
  • U2 = E Min / E Maximum
  • U & E stands for uniformity & illuminance respectively.
  • Uniformity is a quality parameter for the overall illuminance distribution.
  • It is quite useful to use this uniformity ratio to describe how the lights are evenly distributed on the ground. If the difference between minimum and average lux is small, then the ratio is high, which gives better light uniformity.
  • The maximum lighting uniformity is 1, which means the lux levels in all the sampling points are the same. However, it is very unlikely to achieve this maximum value for artificial lighting.
  • If the uniformity is very low for the outdoor or indoor lighting, the citizens, workers, or athletes might feel uncomfortable, and thus their vision is affected.
  • The more uniform the light distribution, the better the illuminance and the more comfortable the visual experience.  The closer the illuminance uniformity is to 1, the better, otherwise the smaller the more visual fatigue.

How to improve Lighting Uniformity

  • Adjust the aiming angle of the floodlight,
  • The lights irradiated by the floodlights should overlap each other,
  • Use pole lights, high-power floodlights, street lights, etc. to supplement lighting.

Light Uniformity Standard

  • There are different light uniformity standards that need to be followed depending on the nature of the environment
  • Most focus-intensive tasks require a uniformity index of around 0.6, whereas, technical drawing and other demanding tasks require a ratio of at least 0.7.
  • Uniformity value greater than 0,60 is recommended in working areas. Because, above this level, the change in light levels cannot be sensed by people and that makes them comfortable. Proper lighting of the environment also helps employees work more comfortably when looking at the computer screen.
  • Due to low uniformity in road lighting, the homogeneity of lighting will be distorted. So, very bright and very dark spots will occur on the road. If brightness changed very often, this will cause eye strain and stresses the drivers
  • In order to avoid these situations, average uniformity value greater than 0.35 or 0.4 is required according to road lighting class.
Standard Area Ratio of Minimum/Average Illumination
UK CIBSE and German DIN guidelines The general lighting scheme 0.6 and 0.8
NBC-2005, page no 759 Working Area Not Less than 0.7

Table-6: Recommended Levels of Illumination (BIS, 1981)

Type of Road Road Characteristics Ratio of Minimum/Average Illumination
A-1 Important traffic routes carrying fast traffic

0.4

A-2 Main roads carrying mixed traffic like city main roads/streets, arterial roads, throughways

0.4

B-1

Secondary roads with considerable traffic like local traffic routes, shopping streets

0.3

B-2 Secondary roads with light traffic

0.3

EUROPEAN STANDARD- EN 12464-1:2011

Space

 Uniformity U0 (Emin / Em

Areas with traffic and corridors

0.4
Stairways, escalators, and travelators

0.4

Lifts

0.4
Loading bays

0.4

Coffee-break rooms

0.4
Technical facilities

0.4

Storage spaces

0.4
Electronics workshops, testing, and adjustments

0.7

Ball-mill areas and pulp plants

0.4
Offices and writing

0.6

Check-out areas

0.6
Waiting rooms

0.4

Kitchens

0.6

Parking areas

0.4
Classrooms

0.6

Auditoriums

0.6

EUROPEAN STANDARD- EN 12464-1:2011

Task illuminance ≥ 0.7
Illuminance of immediate surrounding areas ≥ 0.5

Football Field Lighting Design

Nature of the Sports Field Required U1 Light Uniformity
Class I such as for a National Competition ≥ 0.7
Class II such as for a League ≥ 0.6
Class III such as for a Training Ball Field ≥ 0.5

Industrial and Commercial Lighting Uniformity Requirement

The Area The Light Uniformity Standard
Highway 0.4-0.6
Sports field 0.5-0.8
Office 0.4-0.6
Parking Lot 0.4-0.5
Warehouse 0.4-0.6
Running Track 0.3-0.5
Airport 0.2-0.3

Measurement of LUX Level and Uniformity at Indoor and Outdoor Lighting (Part-2)


(3) AS per Deutsch Norm DIN 5035

  • In this Method the working plane divide into a number of sections which are at least rectangular, of ratio of length to side not less than 1: 2 but which are preferably of square shape.
  • A square grid of minimum size 1 meter is established within each section with a measurement point at the centre of each square.
  • The grid module defining the measurement points is selected so as not to coincide with the luminaire grid in either principal direction.
  • In exceptionally large interiors the grid size may be up to 5 meters. there is not any mention of accuracy limits of the method, but this is not surprising given the flexibility which the user of the method is allowed in choice of grid size.
  • The DIN system is the only one of the three methods studied to give any advice concerning illuminance measurements in obstructed interiors. Areas of the working plane located between large obstructions are treated for measurement purposes as separate spaces.

1

OUTDOOR ILLUMINATION (LUX LEVEL) MEASUREMENT

 (1) Nine Point Method for Determining Lux Levels in Street Lighting

  •  The Lux Level of Street Light is measured by 9-point method.
  • We need to make two equal quadrants between two light poles and between Pole and Rode edge.
  • Two Measuring Points below Light Pole (A1,A2)  and Two opposite side of Pole at Road Edge (A3,A4).
  • Two Point between Pole and Road edge (B1,B3).
  • One Point Between Pole  (B2) and on One Point between opposite side of Pole at road edge (B4)
  • One Point is at centre (C1).
  • Average Lux = (A1+A2+A3+A4)/16 + (B1+B2+B3+B4)/8 +C1/4

2

  • Solution
26 Lux 27 Lux 13 Lux
12 Lux 15 Lux 14 Lux
26 Lux 32 Lux 22 Lux
  • Average Lux = (A1+A2+A3+A4)/16 + (B1+B2+B3+B4)/8 +C1/4
  • Average Lux = (26+26+13+22)/16 + (12+27+14+32)/8 +15/4
  • Average Lux =20Lux 
MIN 12 Lux
MAX 32 Lux
AVG 20 Lux
U1=MIN/AVG 0.58
U2=MIN/MAX 0.38

 (2) As per Grid Point Set Up Measurement

  • Identify a horizontal grid of measurement points on the Illumination Measurement site surface. Locate measurement points on gridlines covering the test measurement area.
  • Ensure that the spacing between measurement points is uniform in both directions and is less than one-half the pole height or less than 4.5 Meter, whichever is smaller.
  • For installations with lights spaced less than 4.5 Meter apart, locate measurement points no farther apart that one-half the pole height, with at least three points between poles in both directions.
  • Record the location of all measurement grids and point layouts with dimensions from surrounding poles or other structures. Provide this information, including a sketch or rendering of the grid layouts.
  • For open areas such as main parking, make the measurement grid large enough to cover at least four poles of this Area layout and at least two Pole are covered.
  • For site perimeter open areas or areas adjacent to a building edge establish the test area measurement grid in a typical perimeter or building edge area. The depth of the test area should extend from the paved site boundary or building edge inward to the nearest line of light poles that are at least 4.5 Meter from the boundary or building edge.
  • The width of the test area must cover at least two of the poles in the line that is at least 4.5 Meter from the boundary or building edge.

(A) In Open Area

3

(B) In the Area of Site Perimeter

4

(C) Near Site Boundary Area:

5

Measurement of LUX Level and Uniformity at Indoor and Outdoor Lighting (Part-1)


Introduction:

  • Working plane illuminance (Lux Level) need to be measured in the field for cross check of whether the existing installation meets a design requirement or not.
  • Field surveys may also be useful to identifying the causes of complaints about lighting, hence the results of field surveys may be useful for the designer, installers and end users.
  • There are various methods are developed for field measurement of Interior Lighting and External Lighting.
  • The Measurement Methods recommended by the various national lighting bodies are generally similar or slightly derivatives to each other. The most common method / Standard is BEE, CIBSE, IES and DIN code
  • The most of methods require to measurement of illuminance at points on a grid at working-plane height or at Floor, but the grid size and position of the measuring points may be differed from various standard to standard.
  • The IES method and its derivatives use the position of the grid according to the luminaire locations.
  • The CIBSE and DIN methods use a position of grid according to the room size.
  • The techniques of analysis of the field measurement results also differ

Basic Requirements for Exterior & Interior Light Level Measurement

  •  The following Points should be considered for accurate measurement of interior and exterior lighting Lux level.
  • Where possible, use the same calibrated illuminance measurement meter (LUX Meter) If the same meter is not available, use the same make and model of calibrated meter to minimize error.
  • When taking measurements, verify that any objects/materials are not blocking any light to the meter head. The use of a remote meter head cabled to the meter body is recommended to prevent the operator from blocking the meter’s “view” of the lighting system being measured.
  • In Outdoor Lighting it is essential to measure of illuminance should be done in night (proper dark).
  • For indoor lighting, measurements with lights ON and Lights OFF technique can be followed and the daylight variation is not too much and the survey time is not too long.
  • In an installation of fluorescent discharge lamps, the lamps must be switched on at least 30 minutes before the measurement to allow for the lamps to be completely warmed up.
  • In many situations, the measuring plane may not be specified or even non-existent. Hence it is necessary to define measurement height, typically 0.8 to 1 meter from the ground or floor level.
  • The lux measurement procedure simply requires positioning a meter’s sensor on the surface or location where you wish to measure the incident light.
  • The sensor should face the light source at a right angle. If the sensor is not perpendicular to the light, the measurement will be incorrect, though some lux meters have a cosine correction to account for the angle.
  • Meters that require a colour correction factor may have a means of inputting the CCF to adjust the result for LEDs or fluorescent lights; otherwise, you will have to manually multiply the measured lux by the CCF.

 INDOOR ILLUMINATION (LUX LEVEL) MEASUREMENT.

 (1) As per Room Index Method (as per BEE Code / CIBSE Code):

  •  This methos is more suitable where measuring Plan / Points for an interior is more rectangular than square. First, we need to be found Room Index.
  • Based on the room index, the minimum number of illuminance measurement points is decided by Room Index Number
  • Room Index (RI) = (L x W) / H x (L+ W)
  • Where L = Length of Room
  • W = Width of Room
  • H= Height of the luminaires above the plane of measurement 

Table 4-2: Number of points for measuring illuminance

Room index

Minimum number of measurement points

 

For ± 5% accuracy

For ± 10% accuracy

RI < 1

8

4

1 < RI < 2

18

9

2 < RI < 3

32

16

RI > 3

50

25

 Sample calculation

  • Measure Illumination Level of an office room have length, L = 7.5 m and width W = 5 m,
  • Solution:
  • Suppose Height of Illumination from Floor is 2 Meter
  • Room Index RI = (L x W) / H x (L+ W)
  • Room Index RI = (7.5 x 5) / 2 x (7.5+ 5)
  • Room Index RI = 1.5
  • From Table 4.2 minimum Illumination Measure Points should be 18 No’s
  • The illuminance measurements Points with Measured Value in Lux are marked on the grid.  

1

Measurement Reading Details

107 Lux

99 Lux

85 Lux

65 Lux

65 Lux

45 Lux

73 Lux

130 Lux

105 Lux

110 Lux

86 Lux

87 Lux

59 Lux

50 Lux

58 Lux

99 Lux

75 Lux

106 Lux

115 Lux

76 Lux

         

Min

45 Lux

     

Max

130 Lux

     

Average

85 Lux

     
         

U1=MIN/AVG

0.5 Lux

     

U2=MIN/MAX

0.3 Lux

     

 

 (2) As per Point Layout Method

  • For office and other task areas, identify a set of measurements points on desktops and other work surfaces that best represents lighting conditions in the space.
  • It may not be possible to develop a uniform spacing grid, but points should be chosen that represent the various lighting conditions across the space.
  • For each separate horizontal grid, identify a vertical plane representative of the lighting in the area (typically the gridline directly between two light fixtures).
  • On this vertical plane, set a grid (line) of points at 1.5 Meter above the site surface at each of the corresponding horizontal measurement points.
  • The following figures provide sample layouts for selecting horizontal measurement points for typical areas where lighting measurements are taken

2

Measurement Reading Details

107 Lux

80 Lux

100 Lux

75 Lux

100 Lux

65 Lux

73 Lux

70 Lux

75 Lux

60 Lux

99 Lux

87 Lux

95 Lux

58 Lux

98 Lux

60 Lux

65 Lux

63 Lux

66 Lux

78 Lux

75 Lux

78 Lux

62 Lux

99 Lux

87 Lux

95 Lux

58 Lux

98 Lux

         

Min

58 Lux

     

Max

107 Lux

     

Average

80 Lux

     
         

U0 or U1=MIN/AVG

0.7 Lux

     

Ul or U2=MIN/MAX

0.5 Lux

     

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