Impact of Floating Neutral in Power Distribution


  • If The Neutral Conductor opens, Break or Loose at either its source side (Distribution Transformer, Generator or at Load side (Distribution Panel of Consumer), the distribution system’s neutral conductor will “float” or lose its reference ground Point. The floating neutral condition can cause voltages to float to a maximum of its Phase volts RMS relative to ground, subjecting to its unbalancing load Condition.
  •  Floating Neutral conditions in the power network have different impact depending on the type of Supply, Type of installation and Load balancing in the Distribution. Broken Neutral or Loose Neutral would damage to the connected Load or Create hazardous Touch Voltage at equipment body. Here We are trying to understand the Floating Neutral Condition in T-T distribution System.

What is Floating Neutral?

  • If the Star Point of Unbalanced Load is not joined to the Star Point of its  Power Source (Distribution Transformer or Generator) then Phase voltage do not remain same across each phase but its vary according to the Unbalanced of the load.
  • As the Potential of such an isolated Star Point or Neutral Point is always changing and not fixed so it’s called Floating Neutral.

Normal Power Condition & Floating Neutral Condition

             Normal Power Condition:

  • On 3-phase systems there is a tendency for the star-point and Phases to want to ‘balance out’ based on the ratio of leakage on each Phase to Earth. The star-point will remain close to 0V depending on the distribution of the load and subsequent leakage (higher load on a phase usually means higher leakage).
  • Three phase systems may or may not have a neutral wire. A neutral wire allows the three phase system to use a higher voltage while still supporting lower voltage single phase appliances. In high voltage distribution situations it is common not to have a neutral wire as the loads can simply be connected between phases (phase-phase connection).

  • 3 Phase 3 Wire System:
  • Three phases has properties that make it very desirable in electric power systems. Firstly the phase currents tend to cancel one another (summing to zero in the case of a linear balanced load). This makes it possible to eliminate the neutral conductor on some lines. Secondly power transfer into a linear balanced load is constant.
  • 3 Phase 4 Wire System for Mix Load:
  • Most domestic loads are single phase. Generally three phase power either does not enter domestic houses or it is split out at the main distribution board.
  • Kirchhoff’s Current Law states that the signed sum of the currents entering a node is zero. If the neutral point is the node, then, in a balanced system, one phase matches the other two phases, resulting in no current through neutral. Any imbalance of Load will result in a current flow on neutral, so that the sum of zero is maintained.
  • For instance, in a balanced system, current entering the neutral node from one Phase side is considered positive, and the current entering (actually leaving) the neutral node from the other side is considered negative.
  • This gets more complicated in three phase power, because now we have to consider phase angle, but the concept is exactly the same. If we are connected in Star connection with a neutral, then the neutral conductor will have zero current on it only if the three phases have the same current on each. If we do vector analysis on this, adding up sin(x), sin(x+120), and sin(x+240), we get zero.
  • The same thing happens when we are delta connected, without a neutral, but then the imbalance occurs out in the distribution system, beyond the service transformers, because the distribution system is generally a Star Connected.
  • The neutral should never be connected to a ground except at the point at the service where the neutral is initially grounded (At Distribution Transformer). This can set up the ground as a path for current to travel back to the service. Any break in the ground path would then expose a voltage potential. Grounding the neutral in a 3 phase system helps stabilize phase voltages. A non-grounded neutral is sometimes referred to as a “floating neutral” and has a few limited applications.

          Floating Neutral Condition:

  • Power flows in and out of customers’ premises from the distribution network, entering via the Phase and leaving via the neutral. If there is a break in the neutral return path electricity may then travel by a different path. Power flow entering in one Phase returns through remaining two phases. Neutral Point is not at ground Level but it Float up to Line Voltage. This situation can be very dangerous and customers may suffer serious electric shocks if they touch something where electricity is present.

  • Broken neutrals can be difficult to detect and in some instances may not be easily identified. Sometimes broken neutrals can be indicated by flickering lights or tingling taps. If you have flickering lights or tingly taps in your home, you may be at risk of serious injury or even death.

Voltage Measurement between Neutral to Ground:

  • A rule-of-thumb used by many in the industry is that Neutral to ground voltage of 2V or less at the receptacle is okay, while a few volts or more indicates overloading; 5V is seen as the upper limit.
  • Low Reading: If Neutral to ground voltage is low at the receptacle than system is healthy, If It is high, then you still have to determine if the problem is mainly at the branch circuit level, or mainly at the panel level.
  • Neutral to ground voltage exists because of the IR drop of the current traveling through the neutral back to the Neutral to ground bond. If the system is correctly wired, there should be no Neutral to Ground bond except at the source transformer (at what the NEC calls the source of the Separately Derived System, or SDS, which is usually a transformer). Under this situation, the ground conductor should have virtually no current and therefore no IR drop on it. In effect, the ground wire is available as a long test lead back to the Neutral to ground bond.
  • High Reading: A high reading could indicate a shared branch neutral, i.e., a neutral shared between more than one branch circuits. This shared neutral simply increases the opportunities for overloading as well as for one circuit to affect another.
  • Zero Reading: A certain amount of Neutral to ground voltage is normal in a loaded circuit. If the reading is stable at close to 0V. There is a suspect an illegal Neutral to ground bond in the receptacle (often due to lose strands of the neutral touching some ground point) or at the subpanel. Any Neutral to ground bonds other than those at the transformer source (and/or main panel) should be removed to prevent return currents flowing through the ground conductors.

Various Factors which cause Neutral Floating:

  • There are several factors which are identifying as the cause of neutral floating. The impact of Floating Neutral is depend on the position where Neutral is broken

1)    At The Three Phase Distribution Transformer:

  • Neutral failure at transformer is mostly failure of Neutral bushing.
  • The use of Line Tap on transformer bushing is identified as the main cause of Neutral conductor failure at transformer bushing. The Nut on Line Tap gets loose with time due to vibration and temperature difference resulting in hot connection. The conductor start melting and resulting broke off Neutral.
  • Poor workmanship of Installation and technical staff also one of the reasons of Neutral Failure.
  • A broken Neutral on Three phases Transformer will cause the voltage float up to line voltage depending upon the load balancing of the system. This type of Neutral Floating may damage the customer equipment connected to the Supply.
  • Under normal condition current flow from Phase to Load to Load to back to the source (Distribution Transformer). When Neutral is broken current from Red Phase will go back to Blue or Yellow phase resulting Line to Line voltage between Loads.
  • Some customer will experience over voltage while some will experience Low voltage.

2)    Broken Overhead Neutral conductor in LV Line:

  • The impact of broken overhead Neutral conductor at LV overhead distribution will be similar to the broken at transformer.
  • Supply voltage floating up to Line voltage instead of phase Voltage. This type of fault condition may damage customer equipment connected to the supply.

3)    Broken of Service Neutral Conductor:

  • A broken Neutral of service conductor will only result of loss of supply at the customer point. No any damages to customer equipments.

4)    High Earthing Resistance of Neutral at Distribution Transformer:

  • Good Earthing Resistance of Earth Pit of Neutral provide low resistance path for neutral current to drain in earth. High Earthing Resistance may provide high resistance Path for grounding of Neutral at Distribution Transformer.
  • Limit earth resistance sufficiently low to permit adequate fault current for the operation of protective devices in time and to reduce neutral shifting.

5)    Over Loading & Load Unbalancing:

  • Distribution Network Overloading combined with poor load distribution is one of the most reason of Neutral failure.
  • Neutral should be properly designed so that minimum current will be flow in to neutral conductor. Theoretically the current flow in the Neutral is supposed to be zero because of cancellation due to 120 degree phase displacement of phase current.
  • IN= IR<0 + IY<120 + IB<-120.
  • In Overloaded Unbalancing Network lot of current will flow in Neutral which break Neutral at its weakest Point.

6)    Shared neutrals

  • Some buildings are wired so that two or three phases share a single neutral. The original idea was to duplicate on the branch circuit level the four wire (three phases and a neutral) wiring of panel boards. Theoretically, only the unbalanced current will return on the neutral. This allows one neutral to do the work for three phases. This wiring shortcut quickly became a dead-end with the growth of single-phase non-linear loads. The problem is that zero sequence current
  • From nonlinear loads, primarily third harmonic, will add up arithmetically and return on the neutral. In addition to being a potential safety problem because of overheating of an undersized neutral, the extra neutral current creates a higher Neutral to ground voltage. This Neutral to ground voltage subtracts from the Line to Neutral voltage available to the load. If you’re starting to feel that shared neutrals are one of the worst ideas that ever got translated to copper.

7)    Poor workmanship & Maintenance :

  • Normally LV network are mostly not given attention by the Maintenance Staff. Loose or inadequate tightening of Neutral conductor will effect on continuity of Neutral which may cause floating of Neutral.

 How to detect Floating Neutral Condition in Panel:

  • Let us Take one Example to understand Neutral Floating Condition.We have a Transformer which Secondary is star connected, Phase to neutral = 240V and Phase to phase = 440V.

    Condition (1): Neutral is not Floating

  • Whether the Neutral is grounded the voltages remain the same 240V between phase & Neutral and 440V between phases. The Neutral is not Floating.

 Condition (2): Neutral is  Floating

  • All Appliances are connected: If the Neutral wire for a circuit becomes disconnected from the household’s main power supply panel while the Phase wire for the circuit still remains connected to the panel and the circuit has appliances plugged into the socket outlets. In that situation, if you put a voltage Tester with a neon lamp onto the Neutral wire it will glow just as if it was Live, because it is being fed with a very small current coming from the Phase supply via the plugged-in appliance(s) to the Neutral wire.
  • All Appliances are Disconnected: If you unplug all appliances, lights and whatever else may be connected to the circuit, the Neutral will no longer seem to be Live because there is no longer any path from it to the Phase supply.
  • Phase to Phase Voltage: The meter indicates 440V AC. (No any Effect on 3 Phase Load)
  • Phase to Neutral Voltage: The meter indicates 110V AC to 330V AC.
  • Neutral to Ground Voltage: The meter indicates 110V.
  • Phase to Ground Voltage: The meter indicates 120V.
  • This is because the neutral is “floats” above ground potential (110V + 120V = 230VAC). As a result the output is isolated from system ground and the full output of 230V is referenced between line and neutral with no ground connection.
  • If suddenly disconnect the Neutral from the transformer Neutral but kept the loading circuits as they are, Then Load side Neutral becomes Floating since the equipment that are connected between Phase to Neutral will become between Phase to Phase ( R to Y,Y to B), and since they are not of the same ratings, the artificial resulting neutral will be floating, such that the voltages present at the different equipments will no longer be 240V but somewhere between 0 (not exactly) and the 440 V (also not exactly). Meaning that on one line Phase to Phase, some will have less than 240V and some will have higher up to near 415. All depends on the impedance of each connected item.
  • In an unbalance system, if the neutral is disconnected from the source, the neutral becomes floating neutral and it is shifted to a position so that it is closer to the phase with higher loads and away from the phase with smaller load. Let us assume an unbalance 3 phase system has 3 KW load in R-phase, 2 KW load in Y-phase and 1 KW load in B-phase. If the neutral of this system is disconnected from the main, the floating neutral will be closer to R-phase and away from B-phase. So, the loads with B-phase will experience more voltage than usual, while the loads in R-phase will experience less voltage. Loads in Y-phase will experience almost same voltage. The neutral disconnect for an unbalanced system is dangerous to the loads. Because of the higher or lower voltages, the equipment is most likely to be damaged.
  • Here we observe that Neutral Floating condition does not impact on 3 Phase Load but It impacts  only 1 Phase Load only

How to Eliminate Neutral Floating:

  • There are Some Point needs to be consider to prevent of Neutral Floating.

a)    Use 4 Pole Breaker/ELCB/RCBO in Distribution Panel:

  • A floating neutral can be a serious problem. Suppose we have a breaker panel with 3 Pole Breaker for Three Phase and Bus bar for Neutral for 3 Phase inputs and a neutral (Here we have not used 4 Pole Breaker). The voltage between each Phase is 440 and the voltage between each Phase and the neutral is 230. We have single breakers feeding loads that require 230Volts. These 230Volt loads have one line fed by the breaker and a neutral.
  •  Now suppose the Neutral gets loose or oxidized or somehow disconnected in the panel or maybe even out where the power comes from. The 440Volt loads will be unaffected however the 230V loads can be in serious trouble. With this Floating neutral condition you will discover that one of the two lines will go from 230Volts up to 340 or 350 and the other line will go down to 110 or 120 volts. Half of your 230Volt equipment will go up in high due to overvoltage and the other half will not function due to a low voltage condition. So, be careful with floating neutrals.
  • Simply use ELCB, RCBO or 4 Pole Circuit Breaker as income in the 3ph supply system since if neutral opens it will trip the complete supply without damaging to the system.

b)   Using Voltage Stabilizer:

  • Whenever neutral fails in three phase system, the connected loads will get connected between phases owing to floating neutral. Hence depending on load resistance across these phases, the voltage keeps varying between 230V to 400V.A suitable servo stabilizer with wide input voltage range with high & low cutoff may help in protecting the equipments.

c)  Good workmanship & Maintenance :

  • Give higher Priority on Maintenance of  LV network  . Tight or apply adequate Torque for  tightening of Neutral conductor in LV system


  • A Floating Neutral (Disconnected Neutral) fault condition is VERY UNSAFE because If Appliance is not working  and someone who does not know about the Neutral Floating could easily touch the Neutral wire to find out why appliances does not work when they are plugged into a circuit and get a bad shock. Single phase Appliances are design to work its normal Phase Voltage when they get Line Voltage Appliances may Damage .Disconnected Neutral fault is a very unsafe condition and should be corrected at the earliest possible by troubleshooting of the exact wires to check and then connect properly.

About Jignesh.Parmar
Jignesh Parmar has completed M.Tech (Power System Control), B.E(Electrical). He is member of Institution of Engineers (MIE) and CEng,India. Membership No:M-1473586.He has more than 16 years experience in Transmission -Distribution-Electrical Energy theft detection-Electrical Maintenance-Electrical Projects (Planning-Designing-Technical Review-coordination -Execution). He is Presently associate with one of the leading business group as a Deputy Manager at Ahmedabad,India. He has published numbers of Technical Articles in “Electrical Mirror”, “Electrical India”, “Lighting India”,”Smart Energy”, “Industrial Electrix”(Australian Power Publications) Magazines. He is Freelancer Programmer of Advance Excel and design useful Excel base Electrical Programs as per IS, NEC, IEC,IEEE codes. He is Technical Blogger and Familiar with English, Hindi, Gujarati, French languages. He wants to Share his experience & Knowledge and help technical enthusiasts to find suitable solutions and updating themselves on various Engineering Topics.

131 Responses to Impact of Floating Neutral in Power Distribution

  1. shyam says:

    i am shyam kumar.k, working as sub-station in-charge in BHEL-trichy. The information provided by you is very worthy and is very useful for every electrical engineer.

    your great effort is to be definitely appreciated.

    Thanks & Regards,
    Shyam kumar.k

    • Andrew HL says:


      “How to eliminate neutral floating – Simply use ELCB, RCBO or 4 Pole Circuit Breaker as income in the 3ph supply system since if neutral opens it will trip the complete supply without damaging to the system.” – I do not see how using a 4-pole breaker will help at all, specifically, how will a “neutral open” trip the 4-pole breaker unless an overload (or short circuit) occurs as a result. I would appreciate your clarification. Best regards.

    • Narasimharaju says:

      hi sir am Narasimharaju am made a wiring in my home in that we are making a single phase ups input nutral and output nutral as made commen any problem in this so please assists.

      Narasimharaju RM.

    • mohanakurup g says:

      single phase voltage 240 then phase to phase 415 volt not 440 as stated in the diagram .

  2. Arun Banerjee says:

    Dear Mr Jignesh,
    All the information provided by you are extremely useful for any electrical engineer.
    I convey my heartfelt good wishes to you.
    Arun Banerjee

  3. P.Prabhakaran says:

    All the information provided by you are extremely useful for any electrical engineer.


  4. says:

    Dear Mr.Jignesh,

    Its very good information and are very much usefull.


  5. sharath says:

    nice informations .it helps to clear some doubts .what we can do if the leakage in neautral please give the informations .

  6. akash says:

    Its too good to having a all information on every point of electrical engineering weather it is a theoretical or practical ,,its really great thank you so much.

  7. Senthil says:

    Very good, relevant information

  8. Abig says:

    nice information ! thanks
    from Ethiopia

  9. callistus ozoke says:

    Dear J Parmar,
    Your entire submission on the impact of loose earthing is a master piece.How would a resident electrical engineer know when the has occurred?

  10. dear sir,
    Thanks fr the valuable data. would u provide the clearances for the power cables in trays & related standards.

  11. John says:

    Good article. Systems in the United States are typically single phase 120/240V systems with 2 energized phases and a common neutral. A classic symptom of a disconnected neutral is incandescent lights going alternately dim and bright in the home. This symptom should also be present in the system described above. Appliances operating on 110 Volts will tend to go to 220V at times when large loads on other phases operate. Ask the user if lights are going bright and then dim. If they answer “yes,” suspect a disconnected or poorly connected neutral.

    • Bill says:

      I purchased a Chinese made diesel generator; Kaiser KDE-12-STA; a 10KW unit. During a recent power outage I hooked up the unit to the house, for the first time. Started seeing strange things, random voltage both high and low and damaged several items before getting it shut down. During trouble shooting, I discovered that the 3 prong female receiver plug at the 240 volt spot ONLY had two wire feeding it, both were hot, they are 120v each. There is NO neutral wire at all, the prong is empty, no wire attached to it; Therefore I do not have a neutral feed going into my sub-panel from the generator. I have been told that this is the reason why I am getting crazy voltage readings in the house. I was also told that If I could trace the neutral wire, that is on the 120v spots, to the source and then bring a wire from the source out to the 240v spot on the generator, that this would solve the problem. Others I said that it will make no difference and that I can not use this generator to supply a house with the 120/240 supply. Your help would be much appreciated. I found you by following a thread about floating neutral problems.
      Thank you,

  12. Lala says:

    working on my masters project on London Distribution Network. been trying to figure out how the 3-phase 1-phase to neutral line works in under distribution. this is reallly useful! thanks!

    • Basavaraj A says:

      Dear Mr.Jignesh,

      Its very good information and are very much usefull.

      Basavaraj Avali

  13. YuXiang says:

    Dear Sir,
    A 600VA single phase isolation step up transformer 100V to 120V, primary side feed with 100VAC and Earth cable connected to panel chassis. The secondary side 120V is supplied to a
    controller’s L and N terminal; the E terminal of controller is tied to panel chassis earth. When i measured the L and N terminal with respect to the chassis earth, it has 75.5V and 41.5V respectively. Is it what we call floating neutral voltage? I think this not healthy to the controller and with some electrical noise will cause the controller haywire too. What’s corrective method? Please advise.

    • g.raman says:

      thanks for presenting a valuable information with illustration.we appreciate your effort .thanks

  14. kareena shah says:

    THANKS while designing these notes are really helpful

  15. Mangey ram says:

    Dear sir,
    Thanks for all useful information about the floating neutral.I am also an electrical engineer in UP state Govt. and i found a solution of my problems relatively neutral and earth, from your great experience.

    Mangey ram

  16. Hi! I understand this is sort of off-topic but I needed to ask.
    Does managing a well-established website such as yours take a
    lot of work? I am brand new to blogging however I do write in my
    diary on a daily basis. I’d like to start a blog so I will be able to share my experience and feelings online. Please let me know if you have any kind of suggestions or tips for new aspiring bloggers. Thankyou!

  17. rahul says:

    thanx a lot for this information its be benefitial for my academic

  18. Praveen says:

    Hi JP,firstly thanks for the info.we have installed ELCB/rcbo & 4P breakers even then we had an issue with the neutral,the safety devices did not trip resulting in a huge loss.
    can you suggest other measures to prevent neutral floating /Breakage/isolating.

  19. Sibaji Pattanaik says:

    It is really true and very very important to check the Neutral condition in any house hold application to avoid Electrical Hazard.

  20. yogesh Dohaiya says:

    in 3phase 4four system total load of computers coneccted in all 3phases.Fault occur in this system is neutral carry more current than phases(e.g. ph1-20A,ph2-21A,ph3-31A and N-56A why?piease give anser.

    • sanjay kulshreshtha says:

      as computor are non linear load ,in such case calculation of size of neutral conductor is different,other wise it overloaded fault will develop.

    • sanjay kulshreshtha says:

      earthing of 3phase ups transformer need to check also

  21. website says:

    Thank you, I have recently been looking for information about this subject for a long
    time and yours is the greatest I’ve found out so far. But, what in regards to the bottom line? Are you sure in regards to the source?

  22. Gaurav Goyal says:

    Very nice info, recently I had a neutral disconnected situation at my home and a few equipments like both microwaves and a tablet charger broke. Still do not understand why there were isolated incidents as there were several things plugged in.

  23. Rama says:

    Thank you sir ,very interesting, and useful information, thanks

  24. this is really very informative. can u pls suggest me some book on improving my understanding on power quality specially the problem of voltage between neutral and Ground.

  25. Hafiz says:

    Thanks for the lengthy explanation. My system 33 & 11kV with Neutral Earthing Resistance network. Can I use a Neutral Displacement \ Voltage Displacement relay to detect missing neutral?

  26. ishtiyaq ahmed says:

    can u plz post a note on testing of electrical equipments like trnsfrmr, HT/LT switchgear, motor, breaker, CT and VT.

  27. Shaun thomas says:

    Great information even though I deal with theses issues on a daily bases. One question on a 3 phase+neutral system: if the phases are imbalanced and a high current occurs on the neutral, will this have any implication on the electrical running costs?
    Shaun T

  28. Mahaveer Bhandari says:

    Good information even for new graduates.
    One observation- A similar neutral break contion occurs, when the ground buried supply cable develops a fault (insulation failure or any short between RYBN and shield of the armoured cable. This has been noticed by me on several occassions when severe unbalance conditions of volatage occur at the user end and damage the equipment. The 4 wire ELCB at the entry point of utility is a good suggestion to protect the connected load.

  29. Miller the Killer says:

    What damage will a floating neutral do to 120V appliances and/or 240V appliances (AC units, hot water heaters,etc.)? What about any wire damage or long term effects on household appliances? I had a floating natural for several months in a vacant house that was being renovated and the contractor burned up some tools and the power bills were over $500 per month. One leg at the meter was reading +/- 120V, but the other one was spiking to over 175V. The neutral/ground on all the outlets, the water hose bibs outside, etc. were spiking to over 70V. The lights in the house were literally going up and down all night. The power company already changed out the transformer that submerged last year under salt water, but that did not fix the problem. They are coming back tomorrow and the electrician has determined it is an outside problem (“floating neutral”) and assumes it is a problem with the burred wires. Thank you.

  30. steven says:

    first, thanks for your valuable teaching, will buy you a drink next time we meet..
    you said in Condition (2): Neutral is Floating, Phase to Ground Voltage: The meter indicates 120V (at the consumer power socket). But I understand that in TT distribution System, the ground at the consumer power socket is the one go down directly to the earth mass by grounding rod, which also located at consumer end. If the ground line at the supply transformer end is in proper order condition (not broken ) and both the earth electrodes resistance are good, then I think the phase to ground voltage measured at consumer socket should be near to 230V..

  31. anthony says:

    at the gererating plant, how you test the neutral braided bus bar ?

  32. Mukesh Tyagi says:

    Thanx a lot ,it very usefull.Looking for more usefull knowledge.

  33. lupupa peria says:

    mine its nt a comment bt a question,wat happens to a domestic house which has a floasting neutral and at the same time it has good earthing system? Wil it have impact on neutral?

  34. Miller the Killer says:

    The readings on one leg at the bus bar was ranging between 40V to over 170V depending on the power load. The house at night looked like someone was getting electrocuted as the lights were going up and down all night until the problem was fixed.

  35. Smith says:

    Thanks a lot for Useful Information

  36. prasada says:

    hi sir thanks for your valuable information
    i have doubt regarding “PT” secondary voltage is fluctuating at 11 kv phase to neutral side.we are getting 1.7v difference in the single phase.even though the earth resistance is 0.1 ohms.why it is getting like that can u explain me please

  37. M.K.Madhavan says:

    Dear Sir,
    Your explanation regarding Floating Neutral turns my attention towards the reasons why the voltage variation in each phase to neutral is happening. Thanks.

  38. Teguh says:

    Appreciated so much, thank you for your sharing. very helpful

  39. shivaraj says:

    Dear Mr.Jignesh,

    Its very good information and are very much usefull. for me i am very small home electrical technician
    i am seen neutral floating problem iam still can’t salved can you help me to solve this problem
    and how remove the short between neutral phase (like that i put the tester neutral and phase both line are showing live and any one line removed from the circuit than showing ok ) and some time when swithed the light bulb bulb liting dimly i checked voltage that time showing 120v neutral to phase and that line one bulb liting normaly and one bulb liting dimly any help for this solve this problem


    shivaraj from Bangalore

  40. K.V.RAO says:

    Nice write up on floating neutral. My sincere appreciation to Mr. Jignesh

  41. Richard Keakantse says:

    Richard says
    Ah! first thanks for giving out that knowledge. But still i don’t see how a four pole breaker will help during neutral floating problem . Could you explain more.


  42. Tofiq Azad says:

    The contents of the article are very useful for electrical engineers.

  43. How to decrease the Neutral to earth voltage in a distribution system.

    • Tauseef says:

      i think,1st you have to balance your load on 3 phases,and 2nd you should ground your neutral near to distribution transformer..

  44. Dear Mr.Jignesh,

    Hi sir thanks for your valuable informatio Its very good information and are very much usefull i am Asst Executive Engineer in PWD Andhra Pradesh.I am facing floating neutral problem in some of our Govt Buildings in those building when we measure voltage between Neutral to Earth it is nearly 15v. So how to decrease the voltage between neutral to earth so kindly give solution for this problem.


    shivaraj from Bangalore

    • Tauseef says:

      i think your neutral is grounded too far and facing resistance in neutral conductor.,and these 15v are subtracting from phases.your load is also imbalanced..

  45. Dionne says:

    Thanks for sharing your knollege

  46. Tauseef says:

    Dear Mr jignesh!
    aslam o alaekm!

    the info provided by you is very good and usefull,i m electrical superviser in a local organization….i was very confused about neutral and i m cleared about it..thanks for ur great information.
    may God bless you,

  47. Jay Kulkarni says:

    Dear Mr. Jignesh,

    Thank you very much for the information.

    Pl tell me why neutral CT is required at distribution transformer?

    Kindly clarify it to me.


    Jay Kulkarni

  48. Sharron says:

    Hello, all is going fine here and ofcourse every
    one is sharing data, that’s really fine, keep up writing.

  49. Vinod says:

    Mr. Jignesh
    I am Vinod Shimpi working as Asistant Engineer (Testing) MSEDCL, Maharashtra ,. Thank you very very much for your valuable and noble help / service to all electrical engineers It’s a very collective information very useful to any Electrical Engineer.
    Once again Thanks for your efforts and sharing the knowledge to everybody…
    Very Nice job and keep it up…………..
    Thanks & Regards
    Vinod Shimpi

  50. osanyingbemi sunday says:

    Nice explanation

  51. Hello Jignesh, I am J. J. Trivedi owner of Aksis Electronic Systems – Industrial Electronic Repair Specialist, Mumbai, India.

    The information provided by you is very useful for Electronic Engineer working on three phase power.

    Thank you.

  52. Hemant Arora says:

    Hi Jignesh

    Explanation by you was a good read….In most of the cases 3P + Bolted Neutral are used except for double source supplies and switch-gear application in Explosive environment.

    For a particular case of mixed balanced & imbalance load, is there a way to calculate Voltage between neutral and ground in TT system??

  53. dharmaraj perumal eo says:

    hello sir gd mrg ur information most of helps me thaks ur serv cont…………
    best regrads

  54. Charles jones says:

    Just installed a water filtration system for a hospital and the manufacturer asked to have a floating neutral. Why I asked and they haven’t answered me .maybe someone can answer this before my meeting tomorrow.

  55. VIpul Chaudhari says:

    Very useful information for distribution engineer…actually i am suffering from this problem.. thank you very much

  56. MOURAD says:

    Dear sir, i am doutful that an ELCB will trip and save the customer load as because the ELCB will detect the leakage current to earth only, which is not the case here. I have done an research and my experiment proofed that an ELCB is not a protection system suitable for Neutral break. Only a 4pole UVR will solve the problem if installed at the main DB of customer. It will detect the low voltage between each phase and neutral. and trips when the neutral floats.

  57. Hemant Arora says:

    Mr. Murad
    You are absolutely correct… ELCB (RCD) does not trip on Neutral Float. We actually did an experiment where in voltage increase on one of the phases was experienced but RCD did not trip.

  58. givenson says:

    thanks for this useful information

  59. Ali says:

    Very useful info. I came across this as I had a broken neutral in the main DB of the building. Fried my equipment, and it actually fried my RCD. However, anything on phase R wasn’t affected, S & T phases got fried. The neutral broke due to poor workmanship by the electricity supplier company who connected the cables to the building. I will opt with the 4P MCB.

  60. Defrea says:

    Dear Sir,

    Thanks for such useful information. Am an electrical engineer here in S.A but i have a problem with a floating neutral on a generator. Checking from the mains supply the neutral is okay but once the DG is on am getting voltage from neutral to earth up the ranges of 330v.

    Checked the whole DG panel everything looks normal,please help.



  61. Vinayak says:

    Hi Jignesh,
    Thanks for giving practical examples of this situation. I think I faced a similar problem and despite repeated trying to fiddle around with just switching appliances on/off , mcb on/off and meter reading it was not solved. I thought our meter was running fast , but that was just a side effect of a geyser being running while floating neutral existed. Somebody else seems to have fixed the problem , but definately after reading your article I can connect the dots. I should keep practicing the basics I think as by education I too am an electrical engineer :).

    Thanks for your detailed article with example diagrams.


  62. subrata choudhury says:

    Respectable Sir,
    I have single phase 230 v line. The problem is electricity is leaking from neutral. I have separate earthing for my computer. Unfortunately when I touch my tongue to computer case I feel the electricity leakage.
    Whether rccb/elcb is the solution for the problem?
    Please advise what to do?
    Yours sincerely
    subrata choudhury

  63. dayananda naik says:

    I have one problem recently 30 led street light conncted 15 is working 15 is not working but supply are coming frome 2 transformer but all street lights are gud but street light works from 50volts to 300voolts what is the solution

  64. satsheel raut says:


    Thanks for information.i am facing floating neutral problem at my house.the supply boards people are unable to solve the problem. I had made seperate earthing pit and connected neutral to it but the problem is not solved.please advice me at my mail id

  65. Saleh says:

    I am doing transmission and distribution work. But at the moment I am to save cost on the installation of underground distribution system. So instead of using 300 mm2 4 core copper cable with xlpe insulation I wanna use 300 mm2 3 core copper with same insulation. I intend to installed this 3 core cable directly from substation to the residential building and than install a separated neutral and earthing measured at 1 mega ohm.

    What is the possibility?

  66. mimi says:

    Sir, Thank you so much for your good information.

  67. Rahul kumar says:

    I have to face the blue phase low problem . Sir please tell me how can i solve this this problem

  68. Adeboye Kayode Ismaill says:

    Good reports, very educative and useful for all Electrical supervisor. From Lagos, Nigeria

  69. Nick says:

    Will a surge protective device fitted down stream of the failed neutral circuit protect the load from damage?

  70. sachin says:

    Dear Sir,
    Can u please explain the impact on the system , if the neutral is connected to the transformer star point and the transformer neutral is not connected to earth.

  71. Berhanu says:

    i am working on 110/6,6KV substation it is using for cement Factory.The star point of the power transformer according their design is not connected to the ground.Just they left open .Do you think thatthis is possible to leave open.Please can you give me an explanation for this case.

  72. mudadi fred says:

    the topic is eductive

  73. i too faced this problem in my home so i’m designing a voltage stabilizer…..should i measure voltage between line and neutral which should be bet (210-240)v or between two phases

  74. RK SRIRANGA says:

    Hello Mr. Jignesh Parmar,

    I have a question regarding earthing the neutral line.

    I work for a company that supplies remote monitoring and control system to various telecom tower sites and we measure the voltage and current on supply line as well as load line and these measuring instruments along with the data transmitter is housed in a metal panel, which is connected to the common ground in the site. We often face a very high voltage, say 30-60 VAC across Neutral and Earth and because of this some of the sensitive electronic components are going faulty. However it is a challenge to convince the tower owner about the fault at site. Hence, is it safe or acceptable if we connect the neutral line to ground inside our panel. I will be grateful if I can get your valuable advise.

    Thank you,


  75. Amadi says:

    Thanks a million for clearing my doubts on floating neutral. I will go through the write up over and over until it becomes part of me. God bless you richly in Jesus Name.

  76. RSS says:

    Pls guide us how to calculate the neutral busbar size( for solid connection) for transformer neutral earthing ? If transformer rating 2 MVA ,33/0.433 kV.50 Hz,

  77. hanh says:

    Dear sir,

    The high pressure sodium lighting lamp of lighting system system in my workshop has just been burnt out, I suspect that maybe overvoltage due to unbalance phase had made that damage. Please give me your opinion on that problem.

    Thanks in advance!

  78. SANTOSH K SINGH says:






  79. Krishnan S says:

    can you please clarify in applications of UPS system the problem of floating neutrals

  80. Girish says:

    Dear Sir,

    This was the most lucid info I have ever gone through.


  81. chetan says:

    sir ji
    i read ur neutral condr broken tips.

    but i have one question that in three phase 4 wire system if neutral broken current comes in neutral condr.
    then why current r not come in every electric pole where neutral condr r connectrd.
    if neutral condr r broken

  82. Pingback: Floating Neutral Impacts in Power Distribution | EEP

  83. james githinji says:

    a 17kva genset is reading 236v phase-neutral and 116v neutral earth and 110 on earth neutral. I think the neutral is floating.

  84. akmal says:

    A lighting panel board 3 phase 230 volts feeding to 220 volts ligth fitting having all 20A 2 POLE MCB . THEN HOW THE UNBALNCE CURRENT FLOW THROUGH NEUTRAL SINCE IT IS NOT CONNECTED

    • akmal says:

      For 2 pole mcb 2 hot wire are connected and earth cable is connected and neutral is not since 2 pole mcb is out of phase so in 2 hot wire 1 wire will act as retrun path but when system is unstable where this unbalance current flow since neutral not connected

  85. Jelil says:

    Please are want to no the installation for 3phase generators.

  86. Swapan says:

    Dear Sir, Please advice. I found out that my father’s house built in early 90s has no earthing system which has a 3 phase connection. Can we have a RCCB or 4pole MCB installed in the main board to protect against neutral failure in the absence of any earthing? Please help.

  87. parthasharathi says:

    Dear sir,
    one one transformer 444/230v its output connect connected to another transformer 230/24v but we measured output between PN 24V but N to G 44V, how can it possible

  88. umair ali says:

    Dear Sir,

    We have 12 LV generators operating in parallel & on 4 wire system, we have to install one more generator so can I install this generator without neutral means 3 wire system because we have circulating current in neutral. Also, explain that we have unbalancing of 5% if we isolate the neutral so what will be the side effect of this???

  89. rajneesh says:

    Dear Sir,
    I have one query, suppose for 3CX11 kV HT cable only one of the core gets damaged, then whether straight through jointing shall be done for one core or for all three cores.
    with regards

  90. JN GHOSH says:

    It is very good information, I request you to share this knowledge with photograph of power system.Can you send one ppt regarding power flow from service line to consumer branch circuit and up to any switch board.

  91. kalicharan undamatla says:

    Hi,thanks for the information and it solution provided by you that is use of MCB,ELCB,RCBO not tripped the circuit in absence of neutral failure.Tried it practically .But use of contactor was worked in this case

  92. naveen says:

    1-phase 230volts y 3-phase has 440

  93. Vimal Negi says:

    Thanks! nice information.

  94. nice info …I want to know what will be impact of floating neutral on three phase equipments ?? pls clarify

  95. pollen barua says:

    Hi….if neutral of wye configuration is earthed will triple n harmonics will find a path to flow?

  96. Sam says:

    thank your for your simple and comprehensive explanation

  97. shekhar says:

    Sir,… I have a three phase connection in my house and earth pit is not there. For last six month our meter is running very faster, earlier it was normal. Is this due to earth break.

  98. powerworxaus says:

    I have a situation where when I disconnect a customers load neutral from the protected neutral bar the RCD trips and wont reset. Any suggestions? Mixed neutral?

  99. Riyasmon abdul rahim says:

    Sir, i have a 3phase panel board and so many lights cinnected to this panel board.i removed the main neutral from the neutral link in the panel biard, but the lights are working.why? As per my information , lamps required phase and neutral now there is no any neutral

  100. praveen says:

    if due to some fault phase current flows through neutral and all the equipment which are connected but swichedoff burnt due to heavy current. ..what the safety device we can use.
    pl suggest.

  101. dhilip says:

    please advise

    01. ATS provided with Main power supply, DG power supply, and Load power supply indication on ATS panel Door. We found when we are switching off Main power supply completely indication will be Go-off.
    But when we fail one phase ( R) then Main power supply R phase indication will glow,
    the same will happen in (B) phase also,

    only (Y) phase when we switch off power the y phase indication will go-off,

  102. Stalin S says:

    My problem is with normal load like light and fan all the phases show 230V. When Motor or A/C is switched on, the particular phase voltage reduces and another phase the voltage adds up. How will I know where the problem lies, like house/house to Pole/EB Transformer. pls advise

  103. mytrafo says:

    Nice Content Sir.
    Site on Power Distribution

  104. Vusi Silubane says:

    Your information helped a lot, as we speak now I’m seating in the dark due to neutral shortage on my power, when using a tester it shows me 330volts

  105. thousif says:

    hello everyone how can a surge voltage be protected in a system,the voltage between neutral to ground shows for 30 to 40 seconds & again it goes off how to rectify?


  106. Ashutosh says:

    Hi…if the neutral is missing in single phase power supply then is it possible that it can damage PLCs or Inverters(AC Drives) etc….??

  107. Anand says:

    In my Home we have taken 3 phase service and sourcing the power from (service pole to Busbar panel and MCB). I have faced neutral floating problem recently resulted in 3 LED bulbs are fused. please advise how to protect neutral loss. please do the needful

  108. Elangovan M says:

    Thank you for such a nice basic theory. Please help to get the answer for below query. in Aircraft three phase system, we are measuring the current through 3 phases using current transformer. Each phase 2 wire in the CT secondary will go to opamp signal conditioning circuit. if any one wire is open, i can consider my opamp input is open. please correct me if my understanding is wrong

  109. B Blakely says:

    Interesting article. My “usage” of electric power has increased by about 25% over comparable periods in the past. At about the same time, I lost voltage and had the electric company out; it was discovered I have a weak / defective neutral line. They are going to repair. Does the failure or weakening of a neutral line cause an INCREASE in electricity use??? In other words, is electric energy lost due to neutral issue??

  110. shailesh says:

    If three phase supply given for domestic use in residence & current passing through 3P+N.which rating of MCCB is used to protect home appliances in case of neutral open.

  111. Sudhir Patne says:

    Problem of neutral getting current at 3phase inverter output of 20 kw solar power plant

  112. Er. Shaurav says:

    Plz provide note on combined CTPT related to its internal connection of CT & pt

  113. Vivek says:

    Good evening Jignesh,
    Last Sunday that had a neutral failure (due to MSEB cable fault) that fried 3-4 of my gadgets and scaring me and my family to look at such threats/risks very seriously.
    I am interested in protecting my home circuit (single phase) and avoid such risks in future? Any help/guidance from you will be appreciated.


  114. Anjeswarachary says:

    Dear sir

    In our Industry Control Supply 6 Amps MCB in DOL Feeder is tripping suddenly at motor Running condition.we checked the Current of control circuit is less than 1 amps.

    we made Fuse instead of MCB another feeder Control MCB Is tripping.

    Please suggest me sir.

  115. Usman Jillani says:

    Jignesh.Parmar Sir can i have your email?

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: