Can I get away with an interlock kit? I have two panels

[EV Engineer]

I have been reading up extensively on the GFCI issues with the Pro-Power onboard.

I am looking to soon have an electrician install a 220V EVSE.
I would like at the same time to get my house ready for back-up power using Pro Power Onboard.

Looking at my system I have 2 panels of 200 amps. I assume the previous owners did this to 'super' proof the house after the last rebuild.
Attached are photos:

The outside panel only has 4 loads as shown: AC, dryer, Oven, second AC.

My question is - Does this mean the second panel is acting as a "sub panel"?

If so could I get away with an interlock kit rather than the Gen 6852 transfer Switch?

I want to be compliant with code but obviously an interlock kit would be cheaper and more robust than the Transfer switch and limited circuits.

Thanks in advance.

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[digitaldad]

Is there a main breaker on that second, inside panel? I'm not seeing it...also, not seeing any open breaker slots. You stated two-200s... it looks like a 110 sub-panel while all the 220 are on outside.

Based on the aerial wire shown, I think you may only have a 200 amp main and if no breaker on that inside panel, they may have lugged it in on that ouside panel (hence why so few breaker slots/less breaker bus bars)...or is there another aerial or underground to the house besides the one shown?

Is that inside panel reight behind the wall of the outside panel?

I am not a master electrician but my dad is, so I know more than some, less than others. In either case, not having any open breaker positions warrants an electrician's site visit (my 2 cents).

 

[Runaway Tractor]

Unless there is another disconnect somewhere not pictured... It appears that outside panel is your main panel and first means of disconnect from outside service. I can only assume the feed to the inside panel is fed from the sub lugs on the outside panel rather than having its own breaker in the outside panel. It's not wrong as long as the wiring to the inside panel is sized for 200 amps since that's the main breaker outside. These are assumptions based on photos.

IF you can find an interlock kit for the outside panel make/model, you would put it where the "oven" breaker is now. Probably move the oven circuit over to the old oven spot I guess? That would let you power up everything.

IF there is no interlock kit for the outside panel, you will have to do some more work. You cannot put and interlock on the inside panel since there is no main to interlock with. You would need to put a 200 amp manual transfer switch on the feed from the outside panel to the inside panel. One side of the MTS would be the power from the outside panel. The other side would be your generator inlet. This would power up your inside panel, not the outside panel.

 

[EV Engineer]

Unless there is another disconnect somewhere not pictured... It appears that outside panel is your main panel and first means of disconnect from outside service. I can only assume the feed to the inside panel is fed from the sub lugs on the outside panel rather than having its own breaker in the outside panel. It's not wrong as long as the wiring to the inside panel is sized for 200 amps since that's the main breaker outside. These are assumptions based on photos.

IF you can find an interlock kit for the outside panel make/model, you would put it where the "oven" breaker is now. Probably move the oven circuit over to the old oven spot I guess? That would let you power up everything.

IF there is no interlock kit for the outside panel, you will have to do some more work. You cannot put and interlock on the inside panel since there is no main to interlock with. You would need to put a 200 amp manual transfer switch on the feed from the outside panel to the inside panel. One side of the MTS would be the power from the outside panel. The other side would be your generator inlet. This would power up your inside panel, not the outside panel.

I belive y'all are correct yes. Makes more sense. A single 200 amp panel and then a sub panel.

So you're saying a 200 amp transfer switch on the feed from the outside panel to the inside panel? That seems expensive and overengineered for what the lightning or a home generator could do? I guess that would power the entire house on the inside subpanel if I was able to input enough Amps.


Hmm....What would be the most affordable and reasonable way to get some of these inside house loads onto the Pro Power Onboard then?

 

[EV Engineer]

And unfortunately this subpanel is about 3 rooms away. I cannot find the conduit so it must be well done in the wall. House was redone about 8 years ago after a storm.

P.S. I 100 % plan on getting an electrician. I understand this stuff just enough to know the basics.

I'm just trying to understand what I "can" do before I can an electrician so we can get the best option.

 

[EV Engineer]

Unless there is another disconnect somewhere not pictured... It appears that outside panel is your main panel and first means of disconnect from outside service. I can only assume the feed to the inside panel is fed from the sub lugs on the outside panel rather than having its own breaker in the outside panel. It's not wrong as long as the wiring to the inside panel is sized for 200 amps since that's the main breaker outside. These are assumptions based on photos.

IF you can find an interlock kit for the outside panel make/model, you would put it where the "oven" breaker is now. Probably move the oven circuit over to the old oven spot I guess? That would let you power up everything.

IF there is no interlock kit for the outside panel, you will have to do some more work. You cannot put and interlock on the inside panel since there is no main to interlock with. You would need to put a 200 amp manual transfer switch on the feed from the outside panel to the inside panel. One side of the MTS would be the power from the outside panel. The other side would be your generator inlet. This would power up your inside panel, not the outside panel.

If you were to install a 200amp manual transfer switch.

Why not do it Before the outside panel? That way you could 'theoretically' have access to both panels if you somehow could input enough amperes.

 

[Runaway Tractor]

So you're saying a 200 amp transfer switch on the feed from the outside panel to the inside panel? That seems expensive and overengineered for what the lightning or a home generator could do?

Because it has to handle the normal 200 amp feed when it is on its main power source.

Hmm....What would be the most affordable and reasonable way to get some of these inside house loads onto the Pro Power Onboard then?

A generator sub panel inside the house next to the panel.

Why not do it Before the outside panel? That way you could 'theoretically' have access to both panels if you somehow could input enough amperes.

The only way to turn off the power to do that installation is to pull the meter. More expensive, more work, and mostly pointless.

 

[K6CCC]

Like others have said, nothing really shows how the 2nd panel is fed. If it's a sub panel downstream of the outside panel, it SHOULD have a breaker in the outside panel. The sub panel also needs a main breaker (unless it's there, but out of the view of the photo. I also do not see any available breaker positions on either panel.

The only way to turn off the power to do that installation is to pull the meter. More expensive, more work, and mostly pointless.

I don't know about your utility, but for me (Southern California Edison), they are perfectly happy to do a disconnect at the meter for no charge. I have had them do that twice for me. First time about 30 years ago was to replace the main breaker that was not opening one phase. Second time was to replace the main panel, including replacing the drop in order to upgrade my service from 100 amp to 200 amp.

With that said, I agree that doing so is overkill unless you are planning on installing a generator large enough to power all the large 240V loads

 

[hturnerfamily]

your home's electrical setup is just like mine: 200amp MAIN PANEL outside, with it's own individual BREAKERS, and the home's INTERIOR 'sub-panel' for most of the home's regular needs.

It looks like someone decided to use the outside Main panel as the source for all your 240v appliances and 'high draw' needs, while the interior panel is all 120v circuits... it really doesn't matter, and there may have been reasons to do so, although my own interior panel had ALL service for 120v and 240v needs, while the outside Main Panel's breaker slots were simply for EXTERIOR needs, such as my 240v EVSE outlet(s), an outside separate 120v outlet nearby, and even a separate switched outside Flood Light with it's own GFCI outlet.

Any 'cut off' or 'interlock' goes on the outside MAIN PANEL, where the only MAIN BREAKER is located. Your interior panel has no 'main breaker' since it is served by the outside panel, and is simply a 'sub panel'... although it is directly supplied by the exterior panel typically thru the lower LUGS - so, it's 'main breaker' is actually the 200amp MAIN BREAKER, just like for the outside panel's breakers.

 

[hturnerfamily]

as to whether you can 'get away' with an interlock simply comes down to trying it, although it's unlikely... the LIGHTNING is not going to act any different for you than it does anyone else: it doesn't like the home's GROUNDED panel, the Main panel... whether you have 'two' panels, a sub-panel, or not, will likely make no difference. It did not for mine, either.

 

[Runaway Tractor]

With all that space between the meter and the outside panel, there is plenty of room to put a 3-pole MTS there. Very straight forward once the meter is pulled to cut the power. This will be the most versatile setup since you can power everything an also mitigate the GFCI issue.

 

[EV Engineer]

With all that space between the meter and the outside panel, there is plenty of room to put a 3-pole MTS there. Very straight forward once the meter is pulled to cut the power. This will be the most versatile setup since you can power everything an also mitigate the GFCI issue.

I am looking into this idea. Since I'm going to have to have a fair amount of work done regardless I kind of want the most robust system.

This will allow me to access the entire panel rather than a critical loads. So can power things as needed rather than just designating 8 things.

Also gives future potential for larger input generators (solar, Generac, whatever) if I feel the need arises.

 

[SFsparkie]

Regarding installing a 200A MTS before the outside panel. I would interpret NEC 230.83 to require an overload protection disconnect (200A breaker) between the service lateral and an ATS feeding your 200A exterior panel. You can check with your local licensed electrician or inspector.

 

[chl]

Just a comment about a GENERAC transfer switch.

Some of us, myself included, who have the GENERAC 6853 manual transfer switch wired 100% correctly (either DIY or by an licensed electrician) have had a GFCI trip in the Lightning ProPower system and a report from the Lightning of a "Ground Fault" when there is utility power present on the GENERAC switch utility input while switching from utility to the Lightning during testing (even with no load breakers on).

[Yes, we have thoroughly checked all the wiring for any mistakes - none found. One electrician put a call in to GENERAC to inquire about this issue, awaiting a reply.]

There is also a trip if switching back to utility if it is present on the transfer switch input.

Of course, if using it during an outage there would be no utility power present on the transfer switch, so it is only an issue when testing. AND I tested my system with no utility power to the transfer switch and there was no GFCI trip.

Turning off the breaker supplying utility power before switching to the Lightning does not cause a GFCI trip. Or if you experience a trip under these circumstances, just resetting the GFCI restores Lightning power.

When switching back to utility, simply turning off the Lightning ProPower first prevents the Lightning from reporting the GFCI trip as a "Ground Fault."

My best guess about why this happens is the solenoid in the transfer switch produces a spike of voltage on the generator input lines when switching (as the coil field collapses) which I observed using a voltmeter. But that is just an educated guess.

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