If I use a 20 KW generator to power my entire home, would I just run 240 VAC into the junction box?

Question

(First through a 200 Amp Manual Transfer Switch)

Answer 1

All you need is a manual transfer switch rated for the 20KW supply, and of course an electrician to hot it up, make it legal and make it safe.

By the way it is called "backfeeding" when your generator feeds the grid.

Answer 2

If you connect a generator to your junction box during a black out you create a condition called "islanding" where your generator is trying to supply the grid with power.  You're essentially putting a lethal voltage on the utility companies equipment while they may be working on it.

Answer 3

The items in your home that you wish to be covered by the generator have to be routed from the house panel to the breakers in the transfer switch. In turn the house power has to have a main breaker supplying the transfer switch with house power under normal conditions. When the power fails the transfer switch closes the normal power and changes to the generator. This should really be done by a pro. You will also have to have a gas line ran to the unit.

**JD

Answer 4

There's a little misunderstanding here of how 120 and 240 volts are derived -- and if you have to ask, then certainly you need a pro to do the installation.

There is not a separate 120 and 240 volt line - there are 2 hot legs and a neutral - the phasing is such that there are 240 volts across the hot legs (one to the other), and 120 volts from each leg to neutral.

So running both hots and neutral from the generator, you have 240 volts AND 120.  In theory at least, you could run only one hot leg and the neutral and all you'd get is 120v, but you just wouldn't do it that way.

The safety ground is the 4th wire, but that doesn't affect the derivation of the voltages.

  

Answer 5

The service main needs also to be connected to the transfer switch so the gennie isn't connected to your service line when it's on. It's a double-pole-double-throw switch, either automatic or manual.

See more here: http://www.smps.us/transferswitch.html