Bonded or Not Bonded. That's the Question.

[ruko]

Hello
I know you will not give advice on DIY stuff. How about just hypothetically or theoretically should a generator be bonded or not bonded when connecting to a house electrical system using proper safe and legal connection methods? Like panel interlocks and/or transfer switches. When I talk to people supposedly in the know I get different answers.
Thank you,
Russ

 

[infinity]

He's my setup for a portable generator. Neutral in generator is not bonded. 4-wire to inlet, sign above inlet, interlock at panel. Not sure why anyone would want to use the generator as an SDS.

 

[retirede]

Not sure why anyone would want to use the generator as an SDS.

Some are internally bonded with no provision to change it.

 

[retirede]

Hello
I know you will not give advice on DIY stuff. How about just hypothetically or theoretically should a generator be bonded or not bonded when connecting to a house electrical system using proper safe and legal connection methods? Like panel interlocks and/or transfer switches. When I talk to people supposedly in the know I get different answers.
Thank you,
Russ

There’s a proper way to use either, but like Infinity said, it’s most straightforward when the generator isn’t bonded.

 

[infinity]

Some are internally bonded with no provision to change it

Remove the cover, remove the bond to the chassis, reinstall cover. 10 minute job.

 

[ruko]

He's my setup for a portable generator. Neutral in generator is not bonded. 4-wire to inlet, sign above inlet, interlock at panel. Not sure why anyone would want to use the generator as an SDS.

I'm confused. Isn't your setup a separately derived system? I guess I don't understand what SDS really means.

 

[xformer]

I'm confused. Isn't your setup a separately derived system? I guess I don't understand what SDS really means.

it means just that... A separately derived system from an existing service or other system. It usually starts with a transformer.
one can create a 24V system by installing a 120V / 24V transformer.

 

[xformer]

He's my setup for a portable generator. Neutral in generator is not bonded. 4-wire to inlet, sign above inlet, interlock at panel. Not sure why anyone would want to use the generator as an SDS.

Dont care about the rest of the house, but the deer freezer, kegerator, and man cave in the detached garage better be working.

 

[augie47]

Very few transfer switches or other standby power switching means actually switch the neutral therefore the systems are no SDS and the neutral should not be bonded at the genset.

 

[infinity]

Very few transfer switches or other standby power switching means actually switch the neutral therefore the systems are no SDS and the neutral should not be bonded at the genset.

That's how mine is set up. The house already has a completely robust GES so there is no reason to set up the generator as an SDS and have to switch the neutral.

 

[Sea Nile]

Watch this video starting at 4 hours and 9 minutes into the video.

I actually watched the whole thing because I'm just crazy like that, but do yourself a favor and start at 4:09:00

 

[retirede]

Remove the cover, remove the bond to the chassis, reinstall cover. 10 minute job.

I don’t think that’s possible to do with an F150 Pro Power source.

 

[winnie]

Your electrical system should have a single bond between ground and neutral. This bond happens in your electrical service.

If the generator has a ground to neutral bond, then you need a transfer switch which switches the neutral, essentially selecting between the two available ground-neutral bonds.

If the generator doesn't have the ground to neutral bond, then you don't switch the neutral, and the system uses the ground-neutral bond built into the service.

The latter approach is much more common, but either are compliant if installed correctly.

Jon

 

[Jpflex]

Hello
I know you will not give advice on DIY stuff. How about just hypothetically or theoretically should a generator be bonded or not bonded when connecting to a house electrical system using proper safe and legal connection methods? Like panel interlocks and/or transfer switches. When I talk to people supposedly in the know I get different answers.
Thank you,
Russ

From what I’ve been reading, a permanently installed generator has its frame bonded with the premises grounding electrode system (connects to, bonds to and shares the same building electrode).

Also the generator has its system neutral and frame, EGC all bonded together

 

[augie47]

Also the generator has its system neutral and frame, EGC all bonded together

If it does then the neutral needs to be switched by the T/S. If the T/S does nor switch the neutral then the neutral should not be bonded at rhe generator,. (See winnie's post #13)
For standby power, the determination of a gnerator being a SDS is based on the transfer switch.

 

[suemarkp]

As said above, there isn't a right or wrong answer, but it is a circular one as the components need to be correct for the approach chosen. I'd start with looking at transfer switches. Do you want a simple interlock? Those can't switch the neutral. Most transfer switches don't switch the neutral, but if you want one that does they cost more.

Next, look at generators. If you picked a transfer switch that is solid neutral, you need to find a generator that is unbonded or can be unbonded. GFCI outlets on the generator could also be an issue, so hopefully it has a non-GFCI one (and I think those are better with floating neutral if you have them). I also thought UL was starting to demand more portable generators (under 15 KW) be solid neutral because of wanting to ground worksite generators. So if you end up only able to get a bonded generator, then you need to revisit the transfer switch decision and find one that switches the neutral.