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Generator Transfer Switch on split service

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May 28, 2013, 10:48 AM
Generator Transfer Switch on split service
I recently purchased a portable generator. I would like to install a transfer switch, but I'm running into a bit of an issue. My house has a split electrical system. The service comes in, hits my main box in the garage (which powers a number of rooms mostly upstairs and the garage) and then from there it splits to a sub that is in the basement that powers pretty well the main floor and the basement (ie, furnace and hot water).

Basically, if I install a transfer switch with the individual circuit switches, there does not seem to be a way that I can power what I need in the Main box and also what is in the Sub. I had thought I could just wire one of the 240V transfer breakers to power my sub panel in the basement, but then that circuit would have the furnace, chest freezer, sump pump, water heater (blower), and a number of rooms on it which would likely be over the 20 amp or 30 amp that breaker is meant to supply.

Any suggestions? Right now I'm thinking that I would have to basically choose a box with the most critical circuits to favor (ie, the basement sub). Then I would have to tell my wife that our bedroom will still not have power (but maybe she'll be ok with candle light ambiance). After all...heat, warm water, frozen and refrigerated food, and a dry basement are probably the most important.
May 28, 2013, 05:52 PM
that's the problem with installing subpanels instead of upgrading the main panel in the first place... your control is all over heck and gone.

any useful alternative involves a lot of rewiring, money that would be better spent consolidating all the power at a new main panel. so yeah, I'd say once you cover all the must haves off the sub, heck with the rest. unless you have a whole-home setup, you're doing that in any event, triaging what counts into a generetor isolation addition.

I finally got scared into buying enough generator for the furnace, basically, as that's about all I figured I could get forgiveness on from wifey. emergency mode is going to be flip the breaker and the service switch, disconnect the BX, put on a cord end, and through a GFI strip run it outside. after a few hours, unplug, refuel, and switch to the freezers for an hour, then back on the heat.

that's all I need. funny flicker-light LED candles and the occasional flashlight or headlamp, with the batteries we usually stock, would work for a week. cook in back on the Weber and/or the Coleman campstove. only problem is up to 4-1/2 gallons of gas every 10 hours. the cars hold 36 gallons, and the can holds 5. the snow thrower would burn up a half gallon every time we clear a foot of snow off the driveway. those are the critical numbers for a Minnesota disasster.

This message has been edited. Last edited by: swschrad,

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