Issue with a GFCI breaker and in a metal building. ?

Question

I've recently built a 30 x 40 metal building and to pass inspection I installed 2 lights and 3 plugs. Everything is has it's own breaker running though conduit from the breaker box to the plugs and light. My reason behind this was so that there would be less to inspect. After the inspector did is thing I was going to install more plugs. They require that I have the 120v plugs on a GFCI and my lights on an Arc Fault breaker. My plugs work fine when I replace the breakers with standard breakers. You can plug anything in and it will run fine. I can run my welder or plasma cutter off the 220v plug without a problem. When I install the GFCI breaker it doesn't matter what you plug in it trips the breaker. I can't figure out what it is, if it's a problem with the ground or what. Is it possible that I've gotten a faulty GFCI breaker? Three in a row seems unlikely. I'm just stumped on this problem.

Answer 1

The problem is that you installed (expensive) GFCI breakers instead of installing (cheaper) GFCI outlets and you have a metal building.  GFCI's are so sensitive that long runs of wiring after a GFCI will cause the GFCI's to trip if there is capacitive coupling to produce loses great enough to trip the GFCI.

I installed GFCI outlets in feedthrough mode at the beginning of long runs of wire that included buried outdoor cable.  I had consistant problems with them tripping with changes in soil moisture.  I think you are getting losses that are low enough when nothing is plugged in, but increase above the limit when current is running.

  I would suggest abandoning the (expensive) breakers and put GFCI outlets at the location you want the outlets. If you buy several at one time or wait for a sale, it is fairly easy to get them under $10, so you can get 4 or more for the price of one breaker the last time I priced them. This is also more convenient as you can reset the GFCI for just the problem, if it occurs, not all the outlets on the breaker.

I strongly support the safety of GFCI's as I have experienced the slight jolt on gets before tripping several times and the baseball bat crunch of a full electrical shock once.

Answer 2

Techno really has this.  

Answer 3

For each of your GFCI breakers, you need a separate neutral run in the circuit.  There is a chance that one or more of the neutrals or lines is grounding out. Check the circuit for line neutral reversal and be certain you have a good separate neutral.  Good luck.

Answer 4

Are you obtaining the 240v for the welder from two separate GFCI breakers that feed the 120v recepts? If so, that is your problem.

A single pole GFCI breaker has both a hot and neutral connection to supply the circuit. These connections can not be intermingled with any other connections or the GFCI will trip, doing exactly what it is supposed to do.

The 240v circuit should not be obtained by connecting across two 120v circuits. A separate 240v circuit should be run from the panel. A two-pole gfi breaker could be used if GFCI protection required but for a dedicated welder recept it may not be necessary.

Answer 5

GFCI outlets is a good solution, for the reasons mentioned and the fact that you can have inductance from circuits running parallel(especially with a metal building.  Get the outlets and replace the breakers.

Answer 6

It sounds like one your ground wires and a neutral wire are touching some where in one of the boxes, that is why the GFCI is tripping and the regular breaker is not, if it where a direct short hot to ground the regular break would trip right away and make sure in the panel that the right neutral is on the GFI breaker that will cause the same issue.