Neutral Bonded Generator with Meter Mounted Transfer Switch

[spicywire]

Hi everyone, formerly low voltage/digital design guy looking for some insight. I have a question related to connecting a neutral bonded generator with GFCI to a meter mounted transfer switch.

The generator I have is configured to be a separately derived system in order to be OSHA compliant. I would like to use this same generator as a backup power source for my home in the event of power outages. However, my transfer switch is meter mounted, and has the neutral and ground connections from the generator bonded. This transfer switch does not switch neutral.

I see that in this situation, the neutral to frame connection must be removed at the generator in order to prevent creating a parallel path for neutral current to flow. Additionally, since the generator is connected to preexisting wiring, it would utilize the neutral/ground bond and EGC of the home's wiring. Under normal circumstances, disconnecting the neutral bond within the generator would be the easy and typically recommended solution. Unfortunately, I cannot modify this generator's neutral bond. Additionally, the generator has a GFCI, making it unusable with my transfer switch with its current wiring setup.

In this situation, would it be possible to remove the ground connection between the generator and transfer switch and still have a code compliant and safe system?
I am trying to work my way through relevant codes/standards (NEC, UL), as well as normal operational and fault conditions, but am a little uncertain of how viable/safe this solution would be.

Under normal operating conditions, I believe this would function properly. Line 1, line 2, and neutral are connected between the generator and transfer switch. Neutral and ground (generator chassis) are bonded internally. The chassis would be at the same potential as neutral.
However, fault conditions have me concerned. In a line to chassis fault, there would be the possibility of current flowing between line, chassis, and back to neutral for an undetermined amount of time. Ideally, any internal current limiting protections would trip, but I do not know specifically how long this would take to trigger.

Looking forward to any advice on this situation. Thanks!

Summary:
Generator configured as neutral bonded and has GFCI.
Transfer switch is meter mounted and has neutral and ground from generator inlet bonded, as it is the first means of disconnect.
Unable to modify generator or transfer switch.
Looking to modify connection between generator and transfer switch to allow for proper operation as home backup system.

 

[ActionDave]

Unless you unbond the neutral on the generator or set up your transfer switch as a separately derived system you are always going to trip the generator GFCI. The simple solution is to use a couple of extension cords for the refrigerator and a lamp out to the generator and wait for the power to come back on.

 

[spicywire]

Unless you unbond the neutral on the generator or set up your transfer switch as a separately derived system you are always going to trip the generator GFCI. The simple solution is to use a couple of extension cords for the refrigerator and a lamp out to the generator and wait for the power to come back on.

How would the GFCI be tripped if the ground connection from the generator to the transfer switch was removed? The issue, at least from what I can tell, in the original setup is that there is a parallel path back to the generator neutral through the neutral wire and the parallel ground wire from the TS to the generator ground, then back to neutral through the internal bonding. If the ground wire was disconnected from the cable between the generator and transfer switch only, wouldn't this remove the parallel path, making it so all current flowing out from L1 and L2 return through neutral?

 

[pipe_bender]

I have seen a generator on a welder's truck with a switch added for the neutral bond, I think it was for this purpose.