Portable Generator, Floating Neutral

[jazer]

For the first time ever, I'm dealing with a portable generator that has a floating neutral and it's not modifiable. It's a small Honda with an inverter so I do not want to mess with the internal components. Home owner wants it for a single circuit to run a sump pump and maybe their furnace in an emergency if need be. I'm thinking of using a single pole, double throw toggle switch to control the dedicated outlet in the basement near the sump between the house/utility power and the generator. My concern comes in with bonding and connecting the generator neutral to the house/utility neutral. I feel like the generator floating neutral would send 60-65 volts (my meter reading from both hot and neutral to the unconnected ground prong on the generator) onto the house neutral and wreak havoc on everything else in the house. I understand this is how a floating neutral on a separately derived system should be bonded in order to provide a safe fault current path but I guess I've never actually come across it in the field and thinking through it has me concerned. Any advice or correction to my understanding? Thanks

 

[LarryFine]

Simply connect the generator cord's EGC to the EGC of whatever it lands in. You're not switching the neutral, so the bond in the panel will do the bonding.

 

[jazer]

ah, that makes sense. But I would still need to connect the generator neutral and the house neutral together in the box with the double throw switch, therefore sending voltage from the generator back onto the house circuit neutral/system, no?

 

[LarryFine]

ah, that makes sense. But I would still need to connect the generator neutral and the house neutral together in the box with the double throw switch, therefore sending voltage from the generator back onto the house circuit neutral/system, no?

No. SINGLE-pole/double-throw. Only switch the hots. Wirenut the neutrals together.

I'm sorry, I re-read your question.

Yes, the neutrals will all be tied together, just like with almost every home generator installation, whether manual or automatic.

No, tying the neutrals together will not send current into the panel.

 

[jazer]

here's what I'm thinking. The neutral connection is what concerns me.

 

[jazer]

Thanks Larry. Appreciate your help.

 

[LarryFine]

here's what I'm thinking. The neutral connection is what concerns me.

Again, perfectly okay. As long as the two source hots are never connected, your wiring arrangement will never send any current between sources.

Added: In fact, your floating neutral prevents neutral current on the EGC. With a bonded-neutral generator, how would you prevent it?

 

[jazer]

On a bonded system, a DOUBLE throw, double pole switch would work. The second pole switching the neutrals. That's how every generator I've ever worked on was arranged. This one just threw me for a loop for a minute. Thanks again for your help.

 

[LarryFine]

On a bonded system, a DOUBLE throw, double pole switch would work. The second pole switching the neutrals.

Exactamundo.