I've searched deep still: Can a 3phase & Split Phase service bond neutrals???

[paulsonsmithfamily]

Fire Department: 200A split phase (single phase) and a 200A 120v 3-phase service.

Fire department want both to run off same generator as currently they have 2 but one always causes issues.


??? Not worrying about the load; if one connects both transfer switches to one generator, could the neutrals of both services be bonded or would one end need a transfer switch that switches the neutrals from it's service to the generator's???

I would say not, in that service neutrals must remain separate. If you ever lost one neutral on the service it would overload the other. This could also be a hazard to linemen.

Any idea on NEC? :?

 

[ActionDave]

How are the transfer switches set up now? If each is non SDS and the generator is wired properly then there would be no problem using one generator.

 

[ggunn]

How are you getting split phase and three phase 208/120V from the same generator? Two phases of 208/120V do not make split phase; you have 120V to neutral, but phase to phase is only 208V, not 240V.

 

[JFletcher]

How are you getting split phase and three phase 208/120V from the same generator? Two phases of 208/120V do not make split phase; you have 120V to neutral, but phase to phase is only 208V, not 240V.

My question as well.

 

[beanland]

120/208V network plus 208Y/120V 3-phase

120/208V network plus 208Y/120V 3-phase

You can run a 120/208V network service and a 208Y/120V 3-phase service on the same 208Y/120V generator. You may have some unbalance issues and need to derate the generator. It is very common for utilities to use a 208Y/120V 3-phase transformer to serve a large apartment building where each unit is fed 120/208V service.

 

[kwired]

You can run a 120/208V network service and a 208Y/120V 3-phase service on the same 208Y/120V generator. You may have some unbalance issues and need to derate the generator. It is very common for utilities to use a 208Y/120V 3-phase transformer to serve a large apartment building where each unit is fed 120/208V service.

But where they will be backing up 120/240 single phase service with 120/208 generator - any 240 volt loads will only see 208 volts when running on the generator. Also will be more current on neutrals when running on the generator, though probably not too big of an issue is still something to think about. One also needs to understand that when only feeding single phase like that from a three phase source if the source is rated say 45 kVA you won't be able to run 45 kVA of loads on a single phase circuit supplied by that source.