Whole House Transfer Switches

solarix · February 2015

Could anyone explain how a whole house automatic transfer switch is properly wired?
I'm talking about a 200A combo service panel and a 20kW, 75A generator.
Not talking about the transfer panels that just move a number of branch circuits or manual switches.
How do you tap into the feeders between the meter and main breaker without violating the listing of the combo panel?

oil pan 4 · February 2015

I would just wire the generator into an appropriate sized breaker on the main panel, so long as your main panel has a shut off. Then I would add some provisions for a lock to out the generator so no one can apply power to it accidently and lock out the main breaker switch.
Since the generator is over 15kw it will need its own disconnect.

What are you going to run that needs 75 amps?
That is going to be about a 20kw generator and will suck fuel like no tomorrow.

Ethan Brush · February 2015

solarix wrote: »

Could anyone explain how a whole house automatic transfer switch is properly wired?
I'm talking about a 200A combo service panel and a 20kW, 75A generator.
Not talking about the transfer panels that just move a number of branch circuits or manual switches.
How do you tap into the feeders between the meter and main breaker without violating the listing of the combo panel?

Is the transfer switch service rated? Do you have a meter and main disconnect combo? If so I would just install it after the meter/main. Unless I'm misunderstanding, seems like you are wanting to put the transfer switch in between the meter and main disconnect of the combo unit?

solarix · February 2015

No, can't do just a simple backfed breaker, cause (as I said) this is to be automatic - not manual.
Yes, the transfer switch is service rated and needs to switch power to the main panel (thus making the existing main panel really a sub-panel).
I know back east the meter box and main panel are usually separate, but around here the panels are usually outside and are combo panels with the meter built in.
How do you get the transfer switch in between the main disconnect and the breaker bus? Only thing I can see is to wire the transfer switch to the breaker bus with 3/0 and move all the circuits to a subpanel off the transfer switch. But is there a way to not have to move all the circuits by getting in between the main disconnect and the breaker buss?
Why is this much backup power needed? I guess when the shtf, some people can afford to not give up any comforts....

Ethan Brush · February 2015

solarix wrote: »

No, can't do just a simple backfed breaker, cause (as I said) this is to be automatic - not manual.
Yes, the transfer switch is service rated and needs to switch power to the main panel (thus making the existing main panel really a sub-panel).
I know back east the meter box and main panel are usually separate, but around here the panels are usually outside and are combo panels with the meter built in.
How do you get the transfer switch in between the main disconnect and the breaker bus? Only thing I can see is to wire the transfer switch to the breaker bus with 3/0 and move all the circuits to a subpanel off the transfer switch. But is there a way to not have to move all the circuits by getting in between the main disconnect and the breaker buss?
Why is this much backup power needed? I guess when the shtf, some people can afford to not give up any comforts....

Yes there are some utilities that have real annoying and silly requirements. Do you think you can add a stand alone meter socket, put the transfer switch between that and the existing combo, and put a bypass plate over the combo meter socket?

Or many of those combos have a piece of regular conductor connecting the meter to the panel bus. Could you remove that and run new conductors to your transfer switch? I see no a issue if listed lugs and conductors are used.

techntrek · February 2015

solarix wrote: »

...
Why is this much backup power needed? I guess when the shtf, some people can afford to not give up any comforts....

You can keep all the comforts with a much smaller fuel consumption. 20 kw will be 4 gallons of LP per hour even with no load. If you need the capacity in order to run 1 or 2 whole-house A/Cs (just guessing) consider adding a much smaller genset for your baseline loads. Then you have the bonus of having an N + 1 backup. Small one goes down, you have the big one.

oil pan 4 · February 2015

Unless you live in the middle of no where, if its obvious you still "have all the comforts" when SHTF expect some one to try and take it.
Even my little 7kw which is rated to consume a disastrous .77 gallons of fuel at half load can run my entire house with ease. Only thing it wont run is my stick welder at full power or my plasma cutter at full power.
Why not save thousands upon thousands of dollars, do a manual transfer and get a reasonable sized generator?
If you cant pull off a manual transfer on your own when SHTF then I only expect you to last as long as your fuel supply, if that.

solarpat · February 2015

You could talk to the utility and ask them if you can put the transfer switch before your meter-main, or like one guy said stick a meter first then transfer switch, that way you are on the customer side of the demarcation point. Another option though not as favorable is transfer switch after meter-main but then you would need another panel. Why don't you check with Siemens, I know they make an automatic transfer switch that installs in one of there newer 200 amp panels and it switches the whole thing. They might make one that could install into your meter-main but most likely you would have to upgrade your meter-main.

oil pan 4 · February 2015

Just remove your KWH meter to disconnect from the power grid.
It works, its fool proof and its free.
But I guess some people just like throwing away money.

BB. · February 2015

I am not sure that I would do the meter removal very often... The utility has to come out and inspect/re-seal the meter. The utility would probably not be happy if they had to do this very often or for very many people.

There is meter base automatic transfer switch:

GenerLink.com

Attachment not found.

-Bill

oil pan 4 · February 2015

I cut the tag and pulled my meter so I could rewire my house. The power company didn't bother to come out and reseal it for almost 2 years. Even then the only reason they resealed it was because they installed a new digital meter.
I noticed "Generlink.com" didn't have a price posted for their product. And that tells me if you have to ask how much it is, you cant afford it or you wont want to spend that much on it.
I am sure you could have a electrician put in a sub panel, to install a generator feed and you could pull your power meter to grid disconnect all for a fraction of the price of that what that "Generlink" costs.
Heck, you might even be able to buy a 7 to 10kw generator, hire an electrician to put in a sub panel and set up your generator back feed for less than what that generlink costs.

BB. · February 2015

You are probably correct.

-Bill

solarix · February 2015

Around here, the utility will not reconnect your meter unless the local AHJ has green tagged it which means getting a permit from them and paying the fees etc. Cutting off your meter seal is a big hassle.
The Generlink is only for smaller generators.

oil pan 4 · February 2015

If you call them and ask, of course they are going to make it into a big hassle, just so they can wring more money out of you.

Whole House Transfer Switches

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