Generator question

[dwellselectric]

Can someone please explain something to me? My boss and I are working on a generator and I was wiring the disconnect for the generator outside and in the Square D plastic disconnect there is only one ground bar. My boss told me that I had to isolate the grounds and neutrals. I asked him why they had to be isolated and he said that he didn't know that was just the way to do it. But I would like to understand why you have to isolate them? Could someone please help me out?

 

[iwire]

The answer depends on the transfer switch.

If the transfer switch does not switch the neutral you do not bond at the generator as it will be bonded by the bond at the service panel. It is not considered an SDS (Separately Derived System) by the NEC.

If the transfer switch does switch the neutral you do bond at the generator as it will not be bonded by the bond at the service panel. It is considered an SDS (Separately Derived System) by the NEC.

 

[charlie b]

The answer depends on the transfer switch.

To that, I will add that it is a design choice, as to which type of transfer switch to buy (i.e., 4-pole or 3-pole, meaning switched neutral or non-switched neutral). With all else equal, I generally prefer the 4-pole. But I am guessing that you already have the ATS, and are just looking into the right wiring. That brings you back to Bob's reply.

 

[qcroanoke]

I've had a lot of experience around Gensets and transfer switches.
4 pole ATS's, seen 1 maybe 2.
But what I Used to see a lot of was bonded generators! We took a many of them loose. Not so common anymore.
I'm with the others,depends on what the switch is. 4 pole or 3 pole.

 

[jrclen]

Can the main bonding jumper and grounding electrode conductor be in the transfer switch enclosure? With a four wire feeder from the generator (no bonding), and another 4 wire feeder to the service panel, which would then become a sub panel? Is the transfer switch between the meter/generator and the panel the first disconnect in the service?

 

[Oakey]

The answer depends on the transfer switch.

If the transfer switch does not switch the neutral you do not bond at the generator as it will be bonded by the bond at the service panel. It is not considered an SDS (Separately Derived System) by the NEC.

If the transfer switch does switch the neutral you do bond at the generator as it will not be bonded by the bond at the service panel. It is considered an SDS (Separately Derived System) by the NEC.

Iwire that is the best/easiest way of explaining that issue I have ever read. I actually understand this now...thx