GFCI Breaker and Florescent

I recently went through a GFI problem. GFI breakers are notorious for going bad.

Have you tried hooking up to an alternate GFI breaker to find out if it's not the breaker itself.

There are good answers on the thread you mention also. It is not recommended to run lighting through GFIs.

Yes, the GFCI was replaced with a regular breaker and it works fine now. It is sure that the problem is with the GFCI.

What if your fluorescent fixture or wiring actually has a ground fault in it? What makes you so sure?

This happens for all florescent lamps (at least 15 lamps). We again replaced with new one and got the same problem. When the GFCI are replaced with regular breaker, problem went away.

I'm sorry, but that does not answer the question.

How?

The only way to know one way or the other is to measure ohms between the circuit conductors and earth/ground with the supply cable disconnected from the breaker. If this hasn't been done, then there might still be a fault either with the light fitting(s) or the cables between the breaker ands the fitting.

• The fault here turned out to be a brass woodscrew attaching the earthed fitting to the wall, that has just kissed the neutral conductor of an incorrectly installed cable buried in the wall when the fitting was put up. The symptom was that every time the cooker went up to Warp Factor 3, the whole-house GFCI/RCCB tripped! Since the problem has been sorted, the trip hasn't operated.

The insulation has been tested and it is good.

Consult a qualified local Electrician, then.

No code says to use GFCI beaker for lighting circuit protection.

Circuit breakers protect wires and electrical equipment where as GFCIs protect peoples

GFCIs sense the electricity being supplied to a branch circuit through the hot wire AND the electricity coming back through the neutral wire. If there is a difference in the outgoing and back-coming current, the GFCI will sense that a hazardous ground fault may be occurring. If there is even 5mAmps difference, the GFCI will interrupt the flow of electricity.

NEC-USA article 210-8 says GFCI shall be used to protect the 15Amps and 20Amps receptacle (outlet) connected circuit in the following locations:

1. Bathrooms, 2. Garages, 3.Basement, 4.Kitchens, and 5.Wet bar sink. In these areas, human being resistance to current will be low due to wet human being body.

All the discharge Lamps including Fluorescent lamps (Ballasts), computers, converter and inverters are all non-linear loads that create third (3) harmonics and other Odd-order harmonics.

3-Phase and 4wire system, all 3-phases are equally loaded with fluorescent fixtures then neutral is supposed to have zero current but it will be carrying current that is sum(added) of all the 3 phases' 3^rd harmonics and other odd harmonics currents which will be equal to phase current as per NEC.

We have used in our many projects GFCI for outlets (receptacle) protection as per NEC code. One thing you have to be very careful that neutral current shall not be shared with equipment grounding wire otherwise it will trip.

Now to solve your problem, please follow a few steps below mentioned:

1. Use with GFCI breaker only two wires that is hot wire (RED) and neutral wire(Black) and connect parallel 5 number of 100watts Incandescent lamps as a load to the circuit. The GFCI CB should not trip, if connected properly.

2. Now replace the 5 number of Incandescent by 5 number of 2x40watts Fluorescent fixtures (lamps). Observe the following:

A. If GFCI CB does not trip that indicates 3^rd harmonics and other odd harmonics together with phase current in hot wire and neutral wire get cancelled and no difference (unbalanced) of current flows in GFCI.

B. If GFCI does not trip means there is some problem of wiring in your installation that a portion of neutral current is diverted through other path such as grounding wire.

Please post your findings so all of us will share results

Mushtaq Hussain-INDIA

Thanks Mushtaq. I got the answer in your comment.