# Singe Standby Generator to Two Panels?



## NoPaint (Aug 24, 2010)

I have two 200amp panels in my house.  Both are fed by a single wire each and both of those wires come from a single meter.  I would like to purchase a 30-40KW standby generator and I am trying to figure out how to attach these to feed the whole house.  Automatic transfer would be nice but manual transfer using breakers and knife switches seems more likely and just fine with me.  So what would you do?

My idea: when the power goes out I shut off the 200amp breakers at the top of each panel, then have one panel fed directly from the generator via a breaker I switch on.  Then feed the other box from the first box with another breaker I would turn on.  This would allow me to fully control the power on and power off of my generator as well as keep everything in a comfortable order.  This would work right?  How could it be done with automatic transfer switches.


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## seige101 (Aug 24, 2010)

You could get an automatic or manual transfer switch that would go between the meter socket it self and the wires going to the panels. It would have 3 positions, ON Utility Power, Off, and ON generator power.

Usually with a standby generator of that size it would come with it's own automatic transfer switch to handle the entire service.


What you are describing would technically work but would be against electrical code and could pose a serious safety hazard. There must be some form of interlock when dealing with utility power and stand by power. If you were to forget to turn off the main breaker and fired up the generator you could back feed the grid and kill a lineman working further down the street. Or if utility power mixed with generator power you will have a most impressive fireworks show.


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## NoPaint (Aug 24, 2010)

AHHHH ok.  Yeah everything must be to code and pass inspection.  Thank you.

Tell me this.  If there are two wires coming out of the meter socket how would that connect in and out of the automatic transfer switch?


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## Highbeam (Aug 24, 2010)

The transfer switch would have multiple sets of contacts. These contacts would all be switched simultaneously. Just like when you pull a plug out of the wall and there are actually three conductors being interrupted.


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## EatenByLimestone (Aug 25, 2010)

OK gotta ask something.   Why 30-40KW?  How are you planning on fueling that?  Run the fuel requirement numbers before you make the jump.  A 17kw unit can use 112 cubic ft/hr.  I think you would be looking at about $500 dollars a week in NG.  You running a major grow light operation or something?


Matt


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## NoPaint (Aug 25, 2010)

Ok so there is a transfer switch that can transfer off two inputs and fire two outputs?

I want 30-40KW for a couple reasons.  First, I have almost 9tons of cooling, 3 fridges, all electric appliances and I usually lose power over winter holidays when I have family with me.  My neighbor has an 84KW generator you can barely hear running.  It is powered by a Chevy 350.  Remember that the amount fuel used is proportional to KW drawn.  If you draw 17KW from a 17KW it will be running at the height of its capacity.  If you draw 20KW out of a 30KW (roughly what I think I will end up drawing on average and sometimes higher if more things are run at once) then you will have a smoother, cooler, and more efficient operation.  Further, it is cheaper for me to get a low hours used 30KW than a new 20KW and with the 30KW I get 4, 6, or sometimes 8 cylinders which runs INCREDIBLY quieter than air cooled engines.  I should mention that my neighbors hated my air cooled generator and so did I so I had to get rid of it.  I think 30KW will allow me to just power both of my panels comfortably and I will only be drawing tons of CNG if I am drawing tons of power; otherwise remember that its all relative - 17KW is 17KW is 17KW (just using the example of 17KW).  Remember that we are just trying to find a way to make electricity via CNG.  I doubt I will buy a 40KW but I've found a couple cheap units so I may go that route.


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## seige101 (Aug 25, 2010)

I am pretty confident there is a transfer switch made for you application, unfortunately i do not have experience with that particular application.

From what it sounds like you have a 400amp service coming in off the street split to 2 200 amp panels throughout the house. More than likely there is a combination metersocket with built in disconnect which would have 2 200 amp breakers in it. Or a disconnect right next to your meter socket, a quick pic would clear this up.

They do make a 400 amp service rated transfer switch/ disconnect. Post back with more specs on your electrical system and i can let you know what you need.


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## NoPaint (Aug 25, 2010)

Awesome thanks!  I will take a picture tomorrow but I believe you are right.  There are two huge wires coming off my meter and directly into my house where each of those huge cables feeds a 200amp box.  So essentially what I need is a way to feed both of those into a transfer switch and each back into a box.


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