Generator switch for house with two 200 amp load centers / panels

[joe_pinehill1]

Hi, looking for advice on options for back up power in our new house. I have two side by side 200 amp panels. Loads I want to back up are split between the two panels. We have a heat pump for heat, and we're in Northern VA. I don't plan to back up the heat, we have a gas fireplace for back up heat. I would like to back up 110 loads like freezer, septic pump, sump pump, lights, so a 5KW generator should be more than enough. Can one transfer switch be wired to two panels?

Our last house was easy, one 200 amp panel, and I wired one switch.

 

[mike93lx]

Simplest way? Move some stuff around, then put an interlock in one panel. I did this for my dual 200's.

If you want a single input, you'll need to rewire the whole thing through a transfer switch. That will be way more complicated.

I had an idea to have an interlock in panel 2 that is fed from a 30a breaker in panel 1, but that felt way more complicated than it was worth

 

[joe_pinehill1]

I thought of that. The panels are side by side in the garage, sheet rocked, three studs between them. It would take a lot of surgery in sheet rock and holes in framing.

 

[larry4406]

Hi, looking for advice on options for back up power in our new house. I have two side by side 200 amp panels. Loads I want to back up are split between the two panels. We have a heat pump for heat, and we're in Northern VA. I don't plan to back up the heat, we have a gas fireplace for back up heat. I would like to back up 110 loads like freezer, septic pump, sump pump, lights, so a 5KW generator should be more than enough. Can one transfer switch be wired to two panels?

Our last house was easy, one 200 amp panel, and I wired one switch.

Sounds like you have 400A service which is quite common on homes here in northern VA.

I am no sparky, but see the following options:

• 400A transfer switch and generator to match. Will power both panels. $$$$$
• 200A transfer switch and generator to match. Move all critical circuits to the single 200A panel which is now a sub-panel served by the transfer switch. This is what we do on new construction homes and the customer is guided on the selection of which loads are critical. Less $$$$
• Move critical circuits all to one of the 200A panels. Install a generator interlock, backfeed breaker, and generator inlet. Manage your loads by killing all non-critical circuits that happen to remain in this panel. Sounds like this is similar to your last home.
• Install a generator transfer panel with generator inlet and move the critical circuits to that panel.

Drywall repairs are quite easy to perform to accomplish any of the above.

 

[mike93lx]

Drywall work is easy. You could cut out everything within a foot of the panels and then patch it when complete for few hundred bucks if you hire it out and under a hundred if you diy

I despise drywall work and it's still the way I would go

 

[theoldwizard1]

I thought of that. The panels are side by side in the garage, sheet rocked, three studs between them. It would take a lot of surgery in sheet rock and holes in framing.

How are they feed ?

Likely, one is a sub off of the other. Most POCOs fo not allow you to double tap the meter.

 

[theoldwizard1]

• Move critical circuits all to one of the 200A panels. Install a generator interlock backfeed breaker and generator inlet. Manage your loads by killing all non-critical circuits that happen to remain in this panel. Sounds like this is similar to your last home.
• Install a generator transfer panel with generator inlet and move the critical circuits to that panel.

"Backfeed" is a dirty word around here !

I have a great disdain for generator transfer panels compared to interlocks. Someone installed one on the elderly lady next door house. They did not include any circuits in the basement ! With the interlock, you CHOOSE which circuits you want to power when the lights goes out !

 

[mike93lx]

How are they feed ?

Likely, one is a sub off of the other. Most POCOs fo not allow you to double tap the meter.

Dual 200's off a 320a meter are incredibly common. It is very likely (I dare say almost certainly) not a main and sub situation

 

[joe_pinehill1]

I know, its just sheet rock, I have no problem with sheet rock work. Moving the loads to one panel will mean a lot of wire nuts in the panel, the wires are probably not long enough. Is an interlock at the meter an option? Probably more expensive, but might be safer. A switch like this: https://www.generac.com/residential...ty-30a-generator-manual-transfer-switch-6335/

I don't know why the photo flipped 90 degrees.

 

[mike93lx]

You would need a meter/main to do an interlock.

If you get a 320a transfer switch, you can put it between the meter and panels. They then become subs and need the neutrals isolated, plus you have to rewire the feeds and add a big transfer switch on the outside of the box.

Some wire nuts and rethink on what you really need in an outage still sounds like a winner to me

You have tons of space in those panels

 

[joe_pinehill1]

Looking at the two panels more, one panel looks like it has the loads I would like to back up. Maybe the electrician thought ahead and put the critical loads on one panel. The two sump pumps, the septic pump and alarm, Kitchen 1 that has the fridge are in the same panel. My freezer is in the garage and could plug in directly into one of the 110 outlets on the generator. One transfer switch with 10 circuits should be enough. I assume if a switch is wired to one panel, the second panel main breaker should be off. Anyone know if I'm within Code to have a switch on only one panel?

 

[mike93lx]

Skip the transfer switch and buy an interlock kit

 

[manwithtools]

How are they feed ?

Likely, one is a sub off of the other. Most POCOs fo not allow you to double tap the meter.

On the contrary, dual 200's off one 320 meter are very common.

 

[dcg9381]

Skip the transfer switch and buy an interlock kit

If you're running a 5kw generator, this is definitely what you want rather than a whole-panel transfer switch:

Generator Interlock Kits | Electrician Interlock Kits | GenInterlock

The GenInterlock.com generator interlock kit provides an economical and dependable way to meet your electrical needs.

www.geninterlock.com

I have 320A service (2 x 200A) panels. One panel is on an ATS with a 20KW generator. The other panel is on an interlock kit with a "manual" 10k generator.

 

[joe_pinehill1]

I was thinking a switch like this https://www.northerntool.com/produc...olts-50-amps-12-500-watts-model-51410c-100005

 

[billconner]

So Im probably way off, but why not parallel the generator to each panel with an interlock kit and breaker in each? Seems simplest, both least expensive and least work.

 

[larry4406]

I was thinking a switch like this https://www.northerntool.com/produc...olts-50-amps-12-500-watts-model-51410c-100005

With this you are still introducing wire nuts into your panel to splice to that switch.

If you install an interlock with back feed breaker and inlet receptacle, you don’t need to rewire any of your circuits.

 

[mike93lx]

I was thinking a switch like this https://www.northerntool.com/produc...olts-50-amps-12-500-watts-model-51410c-100005

Why? I would only use one of those when an interlock is not possible.

Its more expensive, more complicated to install plus is less useful

 

[theoldwizard1]

You would need a meter/main to do an interlock.

Concur !

OR

If you get a 320a transfer switch, you can put it between the meter and panels.

Meter/main sounds simpler and cleaner.

OR

Some wire nuts and rethink on what you really need in an outage still sounds like a winner to me

You have tons of space in those panels

Concur again !

 

[walta]

If it were my I would find the largest pair of knock outs that line up with each other and drill a hole between then. Line the hole with PVC conduit glue a collar on each end. Put all the required circuits in one panel with a transfer switch.





Walta

 

[mike93lx]

So Im probably way off, but why not parallel the generator to each panel with an interlock kit and breaker in each? Seems simplest, both least expensive and least work.

In this case, you could theoretically overload the wiring to the generator (assuming you don't use breakers in each panel rated for half the generator's output) , but the generator would trip out well before a real problem occurred, as long as you don't have one sized we'll beyond the wiring/inlet capacity (like a 12kw on a 30a/#10 inlet).

I had posed a similar suggestion/question a while back and vaguely remember a concern about the neutrals

 

[HoosierMark]

When I built my house I had a select group of breakers in one panel with a lockout. I also put a plug in by my basement garage door. I roll out my generator fire it up and plug it in. Then walk over and throw the lockout. When power come back on, I shut generator down and throw lockout the other way. Simple and easy.

 

[wyliesdiesels]

How are they feed ?

Likely, one is a sub off of the other. Most POCOs do not allow you to double tap the meter.

huh? Ive never heard of any PoCo having this restriction. It all depends on the meter pan

 

[wyliesdiesels]

I was thinking a switch like this https://www.northerntool.com/produc...olts-50-amps-12-500-watts-model-51410c-100005

that is gonna require a ton of wiring. an interlock will save you a lot of time and some money

 

[joe_pinehill1]

that is gonna require a ton of wiring. an interlock will save you a lot of time and some mo

Will an interlock basically require an interlock kit, a 30 amp breaker, and a 30 amp receptacle to plug the cord from the generator into?

The panels are near the garage door. I was thinking install the receptacle below the panel. The generator can be outside, with a 10 or 15 ft cord should be fine. If I understand correctly, the generator feeds back to panel through the 30 amp breaker.

 

[mike93lx]

Will an interlock basically require an interlock kit, a 30 amp breaker, and a 30 amp receptacle to plug the cord from the generator into?

The panels are near the garage door. I was thinking install the receptacle below the panel. The generator can be outside, with a 10 or 15 ft cord should be fine. If I understand correctly, the generator feeds back to panel through the 30 amp breaker.

Yes. 30a is common, but you can also do a 50a.

It will mean shuffling some breakers around, as the interlock breaker must be in 2 positions nearest to the main breaker

 

[joe_pinehill1]

Yes. 30a is common, but you can also do a 50a.

It will mean shuffling some breakers around, as the interlock breaker must be in 2 positions nearest to the main breaker

I'm new to VA, is an interlock within Code in VA?

 

[mike93lx]

I'm new to VA, is an interlock within Code in VA?

I am not aware of any special restrictions here

 

[Chuckster in NJ]

Good selection of manufacturers and I have purchased from: www.geninterlock.com

 

[wyliesdiesels]

Will an interlock basically require an interlock kit, a 30 amp breaker, and a 30 amp receptacle to plug the cord from the generator into?

You need an inlet not an outlet (receptacle)

 

[joe_pinehill1]

You need an inlet not an outlet (receptacle)

Isnt the R side on the generator cable (so you don't hand someone a hot pronged cord), and the P side would be on the interlocked feed? I may have mixed terms

 

[mike93lx]

Isnt the R side on the generator cable (so you don't hand someone a hot pronged cord), and the P side would be on the interlocked feed? I may have mixed terms

Yes. You have it right. Buy a Reliance Controls inlet box and you'll be good to go.

The heavy gauge cord going into the top right slot of the right panel may be a problem. I believe that's where the interlock breaker will go and it doesn't appear that there is enough slack to move that down

 

[wyliesdiesels]

Isnt the R side on the generator cable (so you don't hand someone a hot pronged cord), and the P side would be on the interlocked feed? I may have mixed terms

yes correct. an inlet looks like a recessed plug....

previously you said receptacle which would mean you need a plug on both ends of the generator cord, which is called a suicide cord.

 

[Innovate1]

How are they feed ?

Likely, one is a sub off of the other. Most POCOs fo not allow you to double tap the meter.

What are you basing that on? Mine is exactly that - two panels fed from the meter base. The POCO suggested it and it's the way many homes are done here. It wouldn't make much sense to feed one 200A panel from a 200A panel unless you just wanted more breaker spaces - you would still be limited to 200A.

I moved a couple circuits and put a breaker interlock on one panel.

 

[mike93lx]

What are you basing that on? Mine is exactly that - two panels fed from the meter base. The POCO suggested it and it's the way many homes are done here. It wouldn't make much sense to feed one 200A panel from a 200A panel unless you just wanted more breaker spaces - you would still be limited to 200A.

I moved a couple circuits and put a breaker interlock on one panel.

As typical, made up ****, called out by several people and ignored.

 

[dcg9381]

It wouldn't make much sense to feed one 200A panel from a 200A panel unless you just wanted more breaker spaces - you would still be limited to 200A.

It makes sense in many situations, especially when the "main" 200A panel is pretty far away from the structure. It's all about where you distribute the wire. You're basically saying "sub panels don't make sense".

There are two of us with 320A service serving 2 x 200A panels. That math is even worse.

 

[mike93lx]

It makes sense in many situations, especially when the "main" 200A panel is pretty far away from the structure. It's all about where you distribute the wire. You're basically saying "sub panels don't make sense".

There are two of us with 320A service serving 2 x 200A panels. That math is even worse.

I'm sure there are more than two of us with 320A service here. I bet there may even be four

 

[joe_pinehill1]

I'm sure there are more than two of us with 320A service here. I bet there may even be four

Our panels have separate feeds from the meter. Our neighbor also has two panels like our house. A couple months after moving in, he didn't realize he had lost power to one panel until he found the basement waste water pump wasn't working. The Utility Company had to come out, open the utility trench and resplice one of the feeds to his house.

 

[larry4406]

Our panels have separate feeds from the meter. Our neighbor also has two panels like our house. A couple months after moving in, he didn't realize he had lost power to one panel until he found the basement waste water pump wasn't working. The Utility Company had to come out, open the utility trench and resplice one of the feeds to his house.

You have a typical "400A" service" as done here in Northern VA. Pictures below showing a typical "400A meter can" with SER running to the separate 200A panels (others here on the forum I believe are referring to this as a 320A meter can).

This is standard on all of our new homes here. These are pictures of a Dominion power meter can. Depending on where you are in northern VA, you might have NOVEC as your power provider but their meter cans and wiring are near identical.

You can see from the meter can lugs that the panels each get L1, L2, and neutral. Dominion has not yet run the secondary to this can.

 

[mike93lx]

Our panels have separate feeds from the meter. Our neighbor also has two panels like our house. A couple months after moving in, he didn't realize he had lost power to one panel until he found the basement waste water pump wasn't working. The Utility Company had to come out, open the utility trench and resplice one of the feeds to his house.

If one of the legs dropped, he would have lost half the circuits in both panels plus all 240v circuits , not one whole panel. The panels are paralleled off a single feeder from the poco, so to lose a panel, both hots feeding it would have to fall out of the lugs in the meter can.

My setup is the same as yours