What's the utility of a generator panel?

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marmathsen

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Seattle, Washington ...ish
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Electrical Contractor
In a residence, if someone is opting for a manual startup generator and manual transfer switching, why would they opt for a generator subpanel (with feeder) or the kind with the individual circuit transfer switches (what do you call that?) as oposed to a backfed breaker with an approved interlock kit?

I have always been of the option that feeding into the main panel and installing an interlock kit is better because then you have the ability to power anything in the house (assuming only one panel). Obviously the onus is on the homeowner to manage the load so as not to overload the generator.

I'm surprised how often I see generator panels though. Doesn't that seem like an inferior installation because you have to predict ahead of time what circuits you want to be able to run in a power outage? Plus the fact that it's more labor and materials to install? I know dedicated generator panels have ammeters but so does the generator.

Maybe I'm missing something (hopefully nothing too big, I've installed a number of interlock kits). Which do you install most often and why?
 
I think we used to install them more under the premiss that we would tell a customer that X size of generator will run these certain circuits in a generator designated panel. And yes, interlocks of the kind that attach to the main of the service panel either were not readily known of or available as the simple butterfly style of interconnects which was a quick easy way to switch between utility/generator breakers.
 
They've been around longer, and seem like more of a DIYer's installation.

However, I certainly agree with you.
 
marmathsen said:
I have always been of the option that feeding into the main panel and installing an interlock kit is better because then you have the ability to power anything in the house (assuming only one panel). Obviously the onus is on the homeowner to manage the load so as not to overload the generator.

Maybe I'm missing something (hopefully nothing too big, I've installed a number of interlock kits). Which do you install most often and why?
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IMO there is almost never a good reason to install a generator panel. If someone is capable of plugging in the generator, starting it, and switching over an interlock they can figure out which CB's to turn on and off. An interlock is a much better option.
 
In my opinion, it depends on the size of the generator. If small compared to potential load, I think it might be a good idea to limit what can be put on it. There are a lot of people who can start a generator and throw the main transfer switch, but then trying to judge which breakers have to be on and which off can be a problem. Then teenager comes along and turns on everything as they don't want to be inconvenienced.

Also, with a generator panel, you can leave something turned on which isn't on the generator panel, but when it comes to life, you know you can turn off the generator.
 
Some AHJs do not accept breaker interlocks as they are listed as breaker interlocks and not "transfer equipment" The language in 702.5 requires the use of transfer equipment.
 
A generator panel could provide an opportunity to expand the number of branch circuits just as a subpanel normally does. But I don't know how big of a factor that is in choosing the approach for a generator installation.
 
don_resqcapt19 said:
Some AHJs do not accept breaker interlocks as they are listed as breaker interlocks and not "transfer equipment" The language in 702.5 requires the use of transfer equipment.
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No one around here has that interpretation as long as the interlock is listed for the panel.
 
If bonded generators that cant be unbonded become prevalent, then you will have to go with a transfer switch that switches the neutral.

I just installed a transfer panel the feeds a 32/64 panel. I left the big upstream circuits in the upstream panel for things i never really plan to use on generator like a car charger and the air conditioner that would be a tough start for the genny.

I really dont like the interlock looks or the little Gentran boxes. But it is nice to feed the main panel and be able to choose anything you want to run.
 
It depends highly upon the homeowner whether leaving everything in their hands is a superior or inferior option. (This is all the more true for the battery systems I design than it is for fossil fuel backup generators, but still true nonetheless. )
 
infinity said:
IMO there is almost never a good reason to install a generator panel. If someone is capable of plugging in the generator, starting it, and switching over an interlock they can figure out which CB's to turn on and off. An interlock is a much better option.
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And the generator will let you know when you turned on to much.
 
Your assuming the homeowner knows enough to turn on only certain loads. Even if you label them, no guarantee. Then too, they are homeowners that don’t want to bother with turning circuits off and on. There is also the instant notification the power is back on when other loads start back up that were not on the generator panel.
 
Barbqranch said:
Also, with a generator panel, you can leave something turned on which isn't on the generator panel, but when it comes to life, you know you can turn off the generator.
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This is what we do. No neighbors around to know power is back on. But if the circuits not on the generator panel come alive, time to shut the generator down.

synchro said:
A generator panel could provide an opportunity to expand the number of branch circuits just as a subpanel normally does. But I don't know how big of a factor that is in choosing the approach for a generator installation.
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Not if using the old Generac type panel, as you still need a real breaker to feed the circuit. Now, if installing a new sub panel to be fed from a generator, YES.

I put in a Generac type panel years ago in my home, as Chinese puzzle interlocks were not common, and the little generator could not handle the 400 amp service. :LOL:
 
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