Method for Installation of Cable Tray-(PART 1)


(1) Purpose:

This method explains the Procedures or sequence of activity for safely installation and Testing of cable tray, and it’s accessories as per the standard Practice and Code.

(2) General Equipment & Tools: . 

  • The equipment that will be engaged for Installation of Cable Tray will be
  • Tool Box with Screwdriver, Pliers, Spanner , Hammer
  • Drilling Machine with various Bits , Grinding & Cutting Machine
  • Electrical Tester , Continuity Tester ,Multi Meter
  • Cutter , Blower
  • Knockout punch and Flat File
  • Galvanizing paint
  • Marker, Measuring tape, Level gauge / Spirit level.
  • Ladder / Scaffolding / Mobile scaffold
  • Chain Block and Pipe Wrench
  • Portable Lights
  • Removable Barricades

(3) Storage & Material Handling: .

  • The storage area must be free from dust and Water leakages / seepages.
  • Manufacturer recommendation shall always be followed in loading/unloading and storing of Material.
  • Material and its accessories shall be unloaded handle with care in designated area of the Store (Do not directly drop to Ground) to avoid any damages.
  • Materials shall be stored in a dry place which is free from water or from weather effects and protection should be given to the material by means of covering the material with Tarpaulin sheet.
  • The Material will be stacked / unload in the site store on a proper stand on wooden loft on a flat surface at a sufficient height from Ground.
  • If Material are dispatch in packs or pallets, each pack or pallet shall be lifted individually with suitable lifting equipment.
  • The material shall be transported / Shifted in their original packing to Site location.
  • The Material should be visually inspected for damage, which may have occurred during transport.
  • When bringing down materials, they should be handled with care and lowered carefully to the ground. They should not be dropped.

  • To prevent damage to cable tray, never pull cable tray from a truck trailer by chaining to the bottom rung and dragging cable tray out of the trailer

  • If the Material is found defective it shall not be installed and the cable shall be returned to the supplier for replacement.
  • Cable Tray and its accessories (pre-galvanized, hot dipped galvanized) shall be stored in a dry place, fully enclosed / ventilated store.

(4) Inspection of Materials:

  • Check The Material according to its Type, Size, Make
  • Visual inspection:
  • Type of Cable Tray
  • Type of Cable Tray Material
  • Type of Cable Tray Coating
  • Standard width of Cable Tray
  • Standard length of Cable tray
  • Cable Tray thickness
  • Flange height of Cable Trays
  • Proper painting / Galvanization and identification numbers of the cable trays
  • Physical Damages Inspection:
  • Damage on trays and ladders
  • Damage on galvanizing
  • Fittings and accessories are of proprietary type
  • Testing of galvanizing:
  • Uniformity of coating Thickness Test
  • Electrical continuity of connection
  • TRs not more than five year old from date of purchase order shall be reviewed for acceptance. Otherwise test shall be carried out.

BS EN ISO 1461

Table-1 Control Sample Size Related to Lot Size

Number of Lot

Min. Sample

1 To 3

All

4 To 500

3

501 To 1200

5

1021 To 3200

8

3201 To 10000

13

>10000

20

Inspection Lot: Single Order or Single Delivery Order

 

ISO 1461:2009 TABLE-3

Minimum coating thickness and mass on samples that are not centrifuged

Article and its thickness

Local coating thickness (minimum)µm

Local coating
mass
(minimum)g/m2

Mean coating thickness (minimum)µm

Mean coating
mass
(minimum)g/m2

Steel > 6 mm

70

505

85

610

Steel > 3 mm to < 6 mm

55

395

70

505

Steel > 1.5 mm to < 3 mm

45

325

55

395

Steel < 1.5 mm

35

250

45

325

Casting > 6 mm

70

505

80

575

Castings < 6 mm

60

430

70

505

NOTE This table is for general use: individual product standards may include different requirements including different categories of thickness. Local coating mass and mean coating mass requirements are set out in this table for reference in such cases of dispute.

(5) Sequence of Cable Tray Installation Works:

(A) Installation of Cable Tray:

(i) Shifting of Cable Tray on Site

  • Cable Tray shall be carefully unloaded or shifted to the site by using Crane/Hydra or by sufficient manpower and moved to a defined installation location.
  • Remove the packing and ensure that the Cable Tray is free from transportation damages
  • Check and ensure that approved drawings, the correct size and type of cable trays, trunking & accessories are ready for installation.
  • Ensure that cable trays/trunking and accessories received from site store for the installation are free of rusty parts and damages.

 (ii) Marking the Route:

  • Mark the route of Cable Tray and Trunking as per approved drawings with marking threads. The route of Cable Tray and Trunking need to be coordinated with other services and shall be confirmed by the Site Engineer.
  • Minimum space from the building structure and other services to be maintained (200 mm from the nearest point) to facilitate easy handling and maintenance of cables.
  • If Possible, Do not install Cable trays below water/sewage pipes.

(iii) Hanging Support:

  • The location of hangers and supports should be carefully marked as per the approved specifications and Drawings.
  • Required sizes of holes should be marked and drilled by using a drilling machine.
  • The threaded rod (M12 steel) or Specified rod should be fixed carefully into the anchor using clamping tools for a balance smooth twist. The threaded rod should be necessary thickness and length. Sizes should be as approved in the drawing. It should be done in such a way as to avoid damage to the threaded rod.
  • When thread is done, a washer should be inserted into it. The washer should also be the required size and of quality. It should be fixed properly and the nut fastened tight to ensure that the threaded rod is strong and able to bare load.
  • Trays and ladders shall be securely anchored to supports. They shall be secured such that the tray or ladder system will not move during cable installation.
  • Ensure that rod is properly vertical under operating conditions.
  • Tighten hanger load nut securely to ensure proper hanger performance. Tighten upper nut after adjustment
  • The distance between supports is called SPAN. The support span should not be greater than the length of the tray. This will prevent two connecting points from being located within one support span.
  • The support span should not be greater than the straight section length, or as recommended by the manufacturer, to ensure that no more than one splice is located between supports.

  • Cable Tray and Trunking joints are to be positioned as close to the supports as possible, not more than 300 mm from either side.
  • Splice joints fall between the support and the quarter point. When installing a 12-foot long section, for example, a support spacing of 3.7 m (12 foot) causes the splice joints to fall at the same position every time.

  • The maximum tray overhang past the last support should not exceed 600 mm (2 ft).
  • At every maximum of 1200 mm horizontally and 1500 vertically supports should be installed.
  • Horizontal cable trays and ladders shall be supported by either wall mounted support bracket or a hanger rod system. The intervals between supports shall be as recommended by the manufacturer but this shall not exceed 1 meter for wall mounted support brackets, and 2 meter for the hanger rod system.
  • The hanger, hanging support, cable tray bracket and the ladder should be trimmed to required size and galvanizing paint should be applied on the edges.
  • Group parallel runs of trunking should be supported together where it is possible.

  • For shaft cable trays and ladders that are vertical, all supports and fixings should be done as approved.
  • Do not cut or drill structural building members (e.g., I-beams) without approval by the Main contractor.
  • Warning: Do not use a cable tray as a walkway, ladder, or support for people; cable tray is a mechanical support system for cables and raceways. Using cable trays as walkways can cause personal injury and can damage cable tray and installed cables.
  • Horizon Fitting Support: NEMA Standard
  • Supports for horizontal fittings should be located at a distance, no greater than 610 mm (24″) from each end of the fitting on the attached ladder.
  • Fitting must also be supported at the radius center point on both sides of the fitting as per below:
  • At the midpoint (45°) of the arc for a 90° elbow.
  • At the midpoint (30°) of the arc for a 60° elbow.
  • At the midpoint (22.5°) of the arc for a 45° elbow, excluded are 305 mm (12″) radius fittings.
  • At the midpoint (15°) of the arc for a 30° elbow, excluded are 305 mm (12″) radius fittings.

Method for Installation of HVAC System (Part-4)


HVAC Refrigerant  Pipe Testing:

(A) Refrigerant Piping (Leak Check) by Pressure Testing:

  •  Pressure testing helps ensure a leak free system, a critical component to a successful installation.
  • Max PSI and duration of pressure tests can vary between manufacturers and should be reviewed in the installation manual.
  • All VRV systems should be pressure tested to 550 PSIG and held for 24 hours.
  • Pressure testing process: Tighten down stop valves before any pressure testing to prevent nitrogen
  • From leaking back through condenser and contaminating refrigerant.
  • Pressure testing shall be done in three (3) steps.
  • Step 1 – Leak check 3 minutes at 150 PSI
  • Step 2 – Leak check after 5 minutes at 325 PSI
  • Step 3 – Leak check after 24 hours at 550 PSI (450 psi for systems with vertical Air Handlers)
  • After the gauge reading reaches 550 psig, isolate the system by first closing the gauge manifold, then close the nitrogen cylinder valve.
  • Check the flared and brazed connec­tions for leaks by applying a bubble solution to all joints.
  • The bubble solution must be a solution designed for refrigerant leak testing. Common soap solution must never be used on refrigerant piping as those contain chemicals that could corrode copper and brass, and cause product malfunction.
  • If the pressure does NOT drop for 24 hours, the system passes the test.
  • In this case, the pressure drop of 9.5 psig was due to temperature differences, therefore, there is no leak in the refrigerant piping system.
  • If the pressure drops and it is not due to ambient conditions, there is a leak and it must be found. Remove the bubble solution with a clean cloth, repair the leak(s), and perform the leak / pressure check again.
  • After the system has been thoroughly tested and no leaks are found, depressurize by loosening the charging hose connector at the nitro­gen cylinder regulator. When system pressure returns to normal, completely disconnect the charging hose from the cylinder, and release the nitrogen charge from all refrigerant piping. Wipe off any remaining bubble solution with a clean cloth.
  • Ambient Conditions and the Leak / Pressure Check
  • If the ambient temperature changed between the times when pressure was applied and when the pressure drop was checked, adjust results by factoring in approximately 0.79 psi for each 1°F / 1°C of temperature difference.
  • Correction formula: (°F / °C Temperature when pressure was applied – °F / °C Temperature when pressure drop was checked) x 0.79.
  • Example: When pressure (550 psig) was applied, temperature was 80°F / °C; 24 hours later when pressure drop (540 psig) was checked, temperature was 68°F / °C.
  • Thus, (80°F / °C – 68°F / °C) x 0.79 = 9.5 psig.

(B) Triple Evacuation (Vacuum)

  •  Why is a triple evacuation so important instead of a deep vacuum? Because the relationship between pressure and temperature with water.
  • When the first vacuum is pulled, some of the moisture in the lines boils and evaporates.
  • However, once it reaches a certain pressure the water will actually freeze and leave small ice crystals in the system. This is why a single deep vacuum is insufficient.
  • A triple evacuation of all piping should be performed to eliminate moisture in the system:
  • Do NOT open service valves until the deep vacuum of 500 microns or below has been achieved and the additional charge has been added
  • If Heat Recovery System connect to all three main refrigeration stop valves at outdoor unit.
  • Verify that the micron gauge is connected at a point where it can read the system’s pressure at all times during this process, even when the vacuum pump is not running during the hold test.
  • Evacuation procedures: Evacuation procedures shall be performed as follows:
  • Step 1- Operate the vacuum pump and evacuate the system to the 2,000 micron level.
  • Isolate the pump by closing the manifold gauges and the vacuum pump valve, and then watch the micron level. Micron level may rise a bit, but MUST eventually stop rising for fifteen (15) minutes.
  • If the micron level DOES NOT stop rising, there is a leak, and the leak test must be performed again. If the micron level DOES rise above 2,000 micron, re-open the manifold gauges and the vacuum pump valve and continue evacuation back down to 2,000 micron level.
  • If the micron level holds at 2,000 micron, Break the vacuum with dry nitrogen to a pressure of 2-3 PSI and hold for 15 minutes (this is to “sweep” moisture from piping).
  • Step 2- Evacuate to 1,000 micron level.
  • Isolate the pump by closing the manifold gauges and the vacuum pump valve, and then watch the micron level. Micron level may rise a bit, but MUST eventually stop rising for fifteen (15) minutes.
  • If the micron level DOES NOT stop rising, there is a leak, and the leak test must be performed again.
  • If the micron level DOES rise above 1,000 micron, re-open the manifold gauges and the vacuum pump valve, and continue evacuation back down to 1,000 micron level. If the micron level holds at 1,000 micron, Break the vacuum with dry nitrogen to a pressure of 2-3 PSI and hold for 15 minutes (this is to “sweep” moisture from piping).
  • Step3- Evacuate to static micron level ≤500.
  • Micron level must remain ≤500 for 24 hours. If the vacuum gauge rises and stops, the system may contain moisture, therefore, it will be necessary to repeat the steps of vacuum break and drying.
  • After maintaining the system in vacuum for 24 hours, check if the vacuum gauge rises or not. If it doesn’t rise, then the system is properly evacuated.
  • Close manifold gauges.
  • Shut the valve before turning off the vacuum pump.

Refrigerant Charging:

  • Weigh in additional refrigerant with digital scales. Calculate charge based on total line length plus lb/ft of diameter. Check with each unit model for correct multiplier.
  • After the amount of refrigerant to be added is determined write it down on the label on the back side of the front cover. After the vacuum/drying is complete, charge the additional refrigerant in its liquid state through the liquid stop valve service port.
  • Make sure to use installation tools you exclusively use on R410A installations to withstand the pressure and to prevent foreign material from mixing into the system.

Gas Pressure For any Ton Capacity

Refrigerant Suction Pressure (PSI) Discharge Pressure (PSI) Standing Pressure (PSI)
M/C ON M/C ON M/C OFF
R 22 60 To 70 250To 300 156
R 32 120 490 260
R 134A 35 158 To 199 95
R 290 65 275 To 300 125
R 404A 87 270 To 356 190
R 407C 63 247 To 307 153
R 410A 110 To 120 400 To 500 250
R 417A 65 261 140

Refrigerant Piping –Additional Refrigerant Charge:

  • Do NOT open unit service valves until additional refrigerant charge has been calculated, added and recorded.
  • Calculates the additional refrigerant charge based on the refrigerant piping layout. If at any time there is a change in the actual piping installation from the design layout, it must be reported back to the designer for verification.
  • Enter additional refrigerant charge amount -R410A.Lbs.
  • Record additional charge amount inside the outdoor unit using a permanent marker.

Additional Refrigerant Charged Volume

Liquid pipe Size R410A (kg/m)
6.4 mm 0.022
9.5 mm 0.057
12.7 mm 0.11
15.9 mm 0.18
19.1 mm 0.26
22.2 mm 0.37
25.4 mm 0.45

Split AC Copper Pipe Additional Refrigerant Charge

Total Pipe Length 50 Meter 60 Meter 70 Meter
Additional Refrigerant None 250 gm (25gm/Meter) 500 gm (25gm/Meter)

Electrical Connections:

  • Make all electrical connections in accordance with electrical codes and ordinances.
  • Multi-pole circuit breaker or disconnect is required to fully isolate the unit from all power.
  • Install circuit breakers/disconnects in accordance with local and national codes.
  • Select the power cable in accordance with relevant local and national regulations.
  • Unbalanced power must be maintained within 10% of supply rating among all indoor units or the unit will stop and an error code will be generated. (Significantly unbalanced power may shorten the life of the system.)
  • Ground the unit at an exclusive grounding terminal, at the electrical panel
  • The communication cable between single-phase outdoor units and between indoor and outdoor units has no polarity.

Testing of the System:

(A) Indoor Unit Cooling Measurement:

  • Measure Indoor unit Return Air Temperature or Room Temperature.
  • Measure Indoor Unit Grill Temperature.
  • Grill Temperature should be 10⁰C to 13⁰C less than Room Temperature in 10 to 15 min.

(B) Outdoor Unit Hot Air Measurement:

  • Measure Outdoor Atmosphere Air Temperature near Out Door Unit (Fan inlet Temperature).
  • Measure Outdoor Unit Fan Discharge Temperature.
  • Outdoor Unit Fan Discharge Temperature should be 11⁰C to 14⁰C higher Out Door Unit Fan inlet Temperature.

(C) Measure Suction Pressure and Discharge Press of System

  • Suction and Discharge Pressure should be according to Refrigerant Type.

(D)Measure Cuurent drawn by Compressor.

  • Ampere drawn by should be as per Manufacture recommended Current Rating.

(E) Fell Cooling of Discharge Line (Liquid Line)

  • Discharge line should be cool enough after starting of Compressor.

(F) System Cooling Problems

  1. Less or No cooling even though No Leakage in Refrigerant Pipe & Suction Pressure is OK.
  • Low Discharge Pressure
  • Weak Compressor.
  1. Ice accumulation on Discharge Line (Liquid Line / Small Line)
  • Less Gas Pressure
  • Capillary Problem.
  1. Ice accumulation on Suction Line (Gas Line / Big Line)
  • Less Gas Pressure
  • Indoor Air Filter chock up, Blower Not running, indoor unit cooling coil problem.
  • Outdoor unit Fan speed is too low, Capacitor Discharge, Refrigerant Pipe Bend or punch
  1. Ice accumulation on both Suction & Discharge Line
  • Not Cut Off Compressor,
  • Electrical Contactor stuck , Electrical Contactor coil not working
  • Problem in Sensor, Thermostats.
  • Machine is continuous working 

System Problems

System Problem Discharge Line Pressure Suction Line Pressure Suction Line Temperature Compressor Amp
Over Gas Charge High High Low (Ice on Suction Pipe) High
Under Gas Charge Low Low High Low
Capillary Block Low Low High Low
Less Air Flow on Evaporator (Indoor Unit) Low Low Low Low
Less Air Flow on Condenser (Outdoor Unit) High High High High
Dirty Condenser (Outdoor Unit) High High High High
Low Ambient Temperature Low Low Low Low
High Ambient Temperature High High High High
In sufficient Compressor Low High High Low

HVAC System installation & Testing Flow Chart

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