I have a food trailer i’m Building, and am now at the testing and set up stage, and am having problems with my panels. I have a 20kw generator built in, feeding a main panel on one side, and a sub-panel on the other. Both bonding screws are removed from the panels. Every outlet has it’s own circuit and 15A gfci breaker. The 2 coffee machines are on 30a gfci breakers. The smoke detector is on its own CAFI breaker. The panels are Schneider Homeline Square D push on neutral.
When I energize the panels the cafi breaker is fine, the 2 30a gfci breakers are fine, but when I turn on anything on the other circuits, they trip.

Thanks for your help. kurt.

  • 1
    Does the generator have its own neutral-ground bond? Mar 28, 2019 at 2:19
  • I’m not sure, i’ll Have to check tomorrow at the generator. If I do need to remove a neutral ground bond at the generator, How can the 2 poles work and the single poles trip the way it is now. I have a 6000 watt brewer plugged in and running on the 30a gfci
    – kurt s
    Mar 28, 2019 at 2:42
  • I don't get it. Where is neutral and ground bonded in this system??? Anyway I don't think that's the cause. It seems like a downline wiring problem of some sort. Mar 28, 2019 at 3:45
  • I think neutral and ground are bonded in the main disconnect box where the 80 a breaker on the generator is
    – kurt s
    Mar 28, 2019 at 3:59
  • A shot of what's going on inside the panel would be helpful. You can edit it into your post by clickng edit. On the tripping GFCI breakers, how many wires are connected to each? Also can we see a shot of your wiring at the socket? Mar 28, 2019 at 14:19

2 Answers 2


My idea is that you connected them badly: neureal from RCD-protected circuit must go TROUGH the breaker, I think you have all the 'whites' connected together on the neutral-bar, you should have 'protected' circuits connected to the neutral coming out from RCD breaker.

A photo of your panels may help

  • Or, since he mentioned 15A to each outlet, maybe OP put each duplex outlet on an MWBC. Just the kind of thing a clever person might do. Would not play well with single-pole GFCIs. Mar 28, 2019 at 14:26
  • 1
    It's easy to find out: if with one breaker on it stays (and all appliances connected to that leg work) on and when second is turned on (and one appliance 'sharing' the neutral is turned on) both trip it's a shared neutral
    – DDS
    Mar 28, 2019 at 14:28
  • I could be wrong but I think modern GFCIs do a power-on self-test where they check for improper neutrals. Hmm, does a GFCI breaker interrupt neutral? I'm not sure they do. Mar 28, 2019 at 14:31
  • Usually they do, at least here in EU: I've never seen an RCD/RCBO, not breaking both phase(s) and neutral. But I must admit I've never seen 'electronic' US-Style RCD, only european purely electro-mechanical as mandated by code of most EU countries. Anyway: is RCBO the correct termo for magneto-thermal-differential breaker (MTD in Italian)? Magneto -> short-circuit, Thermal -> Overload, Differential -> ground-fault
    – DDS
    Mar 29, 2019 at 9:44

We can't guess. It's something to do with your neutral hygiene. You have circuit neutrals that are interacting with other neutrals. We would need photos of all the wiring in all the boxes associated with any one failing circuit, which in your case is pretty easy since your circuits are so somple: the wiring at any failing outlet, and the panel itself. I bet we could get to the bottom of it right quick.

Also, make a mental note. Next time you're building a panel in a vehicle, "plug-on neutral" is not a feature you want. "Plug-on anything" is not a feature you want. Next time go to the Siemens, Square D or Eaton dealer and get their panel series that use bolt-down breakers. Normally those are used in factories where they don't want line workers tampering with the panel (the bolts are energized at all times). That's wrong for a homeowner, but the generator makes that not a problem. You want it because it's a vehicle and stuff vibrates out. You'll have less trouble with that.

  • Or well, anybody really -- SqD NQ, Eaton PRL1, or Siemens P1 would all be cromulent choices here Mar 28, 2019 at 4:31

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