Generator With Bonded Neutral.....

[Seven-Delta-FortyOne]

It's my understanding/interpretation of the Code that if a portable generator has a bonded neutral, the transfer equipment needs to be installed as a Separately Derived System, otherwise you would end up with 2 points where the neutral is bonded.

Additionally, the only way that I am familiar with doing a transfer switch like that, would be with a 3-pole, double-throw switch. Mechanical interlocks on the breakers are out.



What do you all think?

 

[ActionDave]

If you are talking about a small portable generator for a house then yes, you would need a transfer switch that breaks the neutral along with the hots. That's not your only choice though. The bonded neutral on a portable generator is a UL requirement but there is no requirement that generators be UL listed so you can still get an unlisted generator without a bonded neutral or remove the bond and then you can use a breaker interlock.

 

[Seven-Delta-FortyOne]

Most of the transfer equipment I install is for floating neutral generators. It's just an easier and cheaper installation.

But every once in a while, a HO will pick out a cheaper unit with a bonded neutral.

I have call in to the manufacturer, to find out if the generator is field modifiable, to convert to floating neutral. I seen conflicting information on whether this is possible.

Otherwise, the customer is going to have to find another unit, or pay about twice as much for a transfer switch, sub-panel, and possibly a new main.

 

[infinity]

Most of the transfer equipment I install is for floating neutral generators. It's just an easier and cheaper installation.

But every once in a while, a HO will pick out a cheaper unit with a bonded neutral.

I have call in to the manufacturer, to find out if the generator is field modifiable, to convert to floating neutral. I seen conflicting information on whether this is possible.

Otherwise, the customer is going to have to find another unit, or pay about twice as much for a transfer switch, sub-panel, and possibly a new main.

For my Generac portable generator it was just a matter of removing three neutral conductors from under bolt and connecting them together to un-bond the neutral (about a 5 minute job). Using an un-bonded neutral generator with an interlock and an inlet is the way to go.