Single Phase Backup Generator to Three Phase Mains Supply?

[chriscapetown]

I have a 6.5kw 220v single phase generator that I want to wire up to supply backup supply to a couple of offices in my house. The mains supply in the house is three phase 220v... Is there a way to wire this up? Something like an isolator/generator switch on one of the phases (as long as the offices are on the same phase)? I don't want to go to the additional expense of purchasing a 3 phase generator or a single to three phase converter but would like backup power into the office circuits. I'm not too concerned about have the entire house on the generator but do need the offices.... Thanks

[RBM]

You are not going to have a 6.5 kw generator transfer switch connected to the entire building. You're going to have some type of transfer switch or switches connected to specific loads in you main panel or you're going to have a generator controlled sub panel, and the loads needed to be controlled will be removed from the main panel and run into the generator panel. There is certainly nothing unusual in what you want to do. The only thing you won't be able to do is connect any three phase equipment

[Bill]

It is rare that a house would have 3 phase which would have 4 wires to the main service panel. But there are some very large homes, so sometimes.

Anyway outside of air-conditioning and elevators (things with very large electric motors), everything in an office would be single phase.

So just a matter of installing a transfer switch. It would be easy if there was one separate main line going to the offices and the offices had one subpanel for power to both offices. Then just install a transfer switch ahead of that subpanel.

BUT!!! How much wattage do both offices draw? Don't want to overload the generator. If too much total wattage, then might need to do a bit of re-wiring for things which will have backup power. May need to move these things to a new separate subpanel. Then only circuits on that subpanel would get backup power.

Also generators provide "dirty" "rough" electricity. This can damage electronic stuff like computers, phones, etc. So best to also have a power line conditioner between anything electronic and the generator.

[Stormin Mormon]

I suspect you're mixing up some terms, here.

In any case, best bet going is to call an electrician. Get a transfer switch installed, and get it done right. There are a lot of mickey mouse ways to get power into a panel box, but I don't reccomend them.

[Stormin Mormon]

Probably is single phase supply.

He's gonna be amazed how much gas that thing uses. Figure a galon to galon and a half an hour, wide open full load.

[Beachcomber]

First questions to ask:

Are you absolutely sure that you do, in fact, have 220V 3-phase service?

If yes, what 3 phase loads do you think need to be powered during emergencies? Unless its an elevator, fire pump, or critical water pump, then most likely you can do without the 3 phase during an outage.