manual transfer switch tripping generator breaker

[LouisianaApprentice]

The original thread was because the GFI on the generator was tripping, assuming the generator has GFI protection on the 30amp TL output...OK feeding a main breaker type load panel and a generator load panel that does not separate the grounds and neutrals the GFI senses the current flow through the bonding jumper ground loop thus created and trips. But why was the circuit breaker tripping? That happens when the generator connection cord or the generator inlet is wired improperly or an undiagnosed short down line. As I read it the generator has to be wired as a separately derived system if the ground and neutral are bonded in the standby power system. The short is a separate issue.

Sorry I don't mean to revive a dead thread but this was an interesting one. I have a question about this. This problem comes from the transfer switch being bonded to a bonded service panel which bonds the neutrals to earth right? Couldn't this problem be fixed by driving a ground rod by where the portable generator will be used in this application and connecting equipment ground to it. Wouldn't this stop the GFCI tripping issue and the GFCI would still trip from a ground fault..... since the GFCI is the first point of service entry it should be bonded there right and not at the transfer switch back to the load center? You would then just have to unbond the main panel Everytime there was a power outage correct? I'm trying to picture this in my head as most transfer switches I remember have their own neutrals and grounds and a load center with breakers but this I'm reading only switches hots and neutral is bonded.

 

[kwired]

Sorry I don't mean to revive a dead thread but this was an interesting one. I have a question about this. This problem comes from the transfer switch being bonded to a bonded service panel which bonds the neutrals to earth right? Couldn't this problem be fixed by driving a ground rod by where the portable generator will be used in this application and connecting equipment ground to it. Wouldn't this stop the GFCI tripping issue and the GFCI would still trip from a ground fault..... since the GFCI is the first point of service entry it should be bonded there right and not at the transfer switch back to the load center? You would then just have to unbond the main panel Everytime there was a power outage correct? I'm trying to picture this in my head as most transfer switches I remember have their own neutrals and grounds and a load center with breakers but this I'm reading only switches hots and neutral is bonded.

If "normal power" is via a service, you created multiple grounding conductor pathways by grounding/bonding again to the grounded conductor. Separately derived system you can more easily isolate any upstream bonding but with service - POCO already has bonding/grounding at the source.

 

[LouisianaApprentice]

If "normal power" is via a service, you created multiple grounding conductor pathways by grounding/bonding again to the grounded conductor. Separately derived system you can more easily isolate any upstream bonding but with service - POCO already has bonding/grounding at the source.

I meant to treat the generator as it's own "service" when in use. Normally even if it's a bonded panel our company will separate grounds and nuetrals then bond with the bondig screw if this is the case. Everytime the owner had to use his generator he could simply take out the ground screw then his nuetrals would be isolated but he would still have a path to ground through the ground rod at the generator and the neutral would be bonded there. And the GFCI would trip normally. Unless if I'm wrong which I generally am was just wondering if that would work.

 

[LouisianaApprentice]

Oh sorry now I get it it would still trip because the nuetrals is bonded at the service drop.

 

[kwired]

I meant to treat the generator as it's own "service" when in use. Normally even if it's a bonded panel our company will separate grounds and nuetrals then bond with the bondig screw if this is the case. Everytime the owner had to use his generator he could simply take out the ground screw then his nuetrals would be isolated but he would still have a path to ground through the ground rod at the generator and the neutral would be bonded there. And the GFCI would trip normally. Unless if I'm wrong which I generally am was just wondering if that would work.

Oh sorry now I get it it would still trip because the nuetrals is bonded at the service drop.

"Service" as used in NEC is when your source comes from the utility company. Your generator is not "service" though it can be connected as "separately derived" or "not separately derived". One method requires grounding/bonding at the source and switching the grounded conductor in the transfer equipment, the other requires grounding/bonding at the service equipment and separate grounded and equipment grounding conductor to the generator - the generator frame is still bonded to grounded conductor, but bond is at the service equipment and not at the generator.

 

[allison2]

I mostly do commercial/industrial and in those the transfer switches that are open transition only have mechanical and electrical interlocks that prevent a closed transition. If that coil wire is busted and there's no protection you could be closing into the utility with the generator.