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

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 2

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 3

A GFCI breaker compares the current flow between the hot and common wires. The ground wire is there for added safety, but is not necessary for proper operation of the GFCI function. In fact, adding a GFCI receptacle is accepted practice by the electrical code to provide shock protection in older 2-wire systems not having a ground wire. Ultimately the common and ground wires are tied together in the breaker panel on the common and ground bus bars (could be a combined common/ground bus bar and assuming you don't have a separate common feed to your house). If the GFCI breaker is wired correctly then the common wire will go through it before it goes to the bus bar so that the breaker can compare the current in the hot and common legs of the circuit. Assuming the GFCI breaker is not bad, if the GFCI trips when the ground wire is connected then you have a fault between the ground and the hot or common wires. A little bit of the current that should be in either the hot or common leg is flowing in the ground leg and causing the GFCI to see a difference between the hot and common current. If it doesn't trip until the ground is connected to the light fixture then it would appear that the light fixture has a fault in it's wiring and should be replaced or repaired. With the light fixture removed and without any light bulbs, use a volt/ohm meter to check to make sure that the hot, common and ground are not connected inside the fixture. If you measure continuity between any of these three wires then you should get a new fixture or fix the one you have. This would be the first thing I would check. There is also the possibility that as you connect the ground wire to the mounting bracket that you move the wires around and allow the ground wire to contact the hot or common wires or even allow the hot and common wires to contact each other. There may be a break in the insulation on the hot and/or common wires. You can check for continuity between these wires with the ground wire attached and the fixture installed, but you should switch off the breaker and disconnect the common wire from the the common/ground bus bar in the breaker panel to completely isolate the three legs. Then if there is continuity between any of them you can start checking along the circuit run to isolate the location. If it just started when you began working on this light fixture then most likely it's in the fixture box wiring or the fixture itself. WARNING: Working in the breaker panel can be deadly if not done right so depending on your knowledge of and comfort level with working in the breaker panel you can either check this out yourself or call an electrician to check it out.

Answer 4

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.

Answer 5

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 6

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 7

Techno really has this.