Generator To Power My House?

[gmoreno]

Hi everyone:

I have 5.5 KW Onan generator in my 35' Damon Daybreak MH ( I think this is a 50 amp unit). I'm exploring the possibility of hiring an electrician to see if he can wire this unit to a transfer switch so that the generator can provide us back-up power in the house. Transfer switch would be a 10 circuit.

Secondly, I also have a stand-alone 5.5 KW Generac generator, 30 amp. Would also like the electrician to wire this unit to provide power to the house. Both the MH and the stand-alone generator would hopefully work in tandem to power the house. Transfer switch would be a 6 circuit.

My needs are:

1. Well pump for water.

2. Septic pump ejector.

2. Water heater for forced hot water heat in the house

3. Two household Fridges.

4. Some lighting throughout the house.

5. A TV or two for the kiddos.

We were out of power in the North shore area of Boston with a recent freak winter storm just before Halloween and we were out of power for 4 days.

Reason number 16,523 to own your own rig...we lived in the unit for four days!!

Any advice? Thanks!

Robert

[wolfe10]

Robert,

Yes, a licensed electrician can wire a transfer switch such that you can run your home from either power company or generator. And, it is critical that only one source be used at a time, AND that there is no way for the generator to "back feed" the power company grid. Back feeding can easily kill a lineman working on repairing the grid.

Now, using two different generators at the same time is a lot more complex. You would need to split your loads into two sub-panels with each generator supplying only those circuits on its sub-panel. Said another way, there is no way that the HZ of two generators (there are exceptions, but not the units you have) can be synchronized. So in essence each generator would supply a unique set of circuits. This means not only separating the hots, but also the neutrals as you divide the loads into the two sub-panels.

Not sure what you mean by a 50 and 30 amp 5.5KW generator. 5.5 KW= 45.8 amps @ 120 VAC. And, that will be a single hot (i.e. not 120/240 like a 50 amp RV outlet). 240 VAC generators are very rare, as the voltage regulator can regulate ONE leg/hot. If the other leg/hot has a substantially different load, it's voltage will be substantially different-- NOT GOOD. So most are wired as 120 VAC only.

Brett

[gmoreno]

Thanks Brett.

I'm certain when the electrician arrives, we'll make a better decision about which generator has what for amperage. I know the stand alone has a label that reads "30A" on the outside of the gas tank. With respect to the MH, I don't have it here with me to verify amperage, but when I pick it up from repairs, I'll be sure to further investigate.

Thanks,

Robert

[deenad]

Brett is right with the generator output. A "true" 50 amp RV circuit has 12,000 watts on two legs (50 amps X 120 volts x 2) = 12,000 watts.

A 30 amp circtuit is 3,600 watts (30 amps X 120 volts) = 3,600. Since it's one leg than that's all there is.

That's the reason 50 amp circuits can power so much more.

[gmoreno]

UP-date on generator install:

My electrician STRONGLY ADVISED me not trying to use two generators at the same time. Something about each generator giving off different sine waves and not synching. Maybe because I had a hair-brained idea that we could hook both protable and MH generator in "parallel" so that I could power more stuff in my house; effectively achieving 10kw. In sum, he installed an interlock switch on my home panel, labeled the really important stuff, and just told me to be VERY CAREFUL which breaker switches to turn off and on during an outage...especially if I keep my well pump water breaker switch in the on position indefinetly.

Though Bretts idea was a very good one about having two sub-panels, I still wouldn't have the flexibility of flipping whatever breaker switches I wanted to the "on" position at a moments notice. Also, I could eventually purchase a larger, more powerful generator and not worry about the seperate panels. Also, interlock switch was about $150....a heck of a lot cheaper than two sub-panels.

[Cruzer]

Actually, you can synchronize two generators. I learned that when I took the factory certified service tech school at Kohler's generator plant. They need to be fed through a load matching transformer and each one will lock onto the waveform in the transformer so that they sync up. You wind up with two input windings and one common output winding. It's a load matching transforner, not a step up or step down. The problem is that these aren't on your average electrical supply house shelf and they will be pricey. They do it all the time in large applications but it's pricey for 60KW and under.

Frankly, I don't care for the split neutrals either. If it was me I'd just get a 120/240 split phase generator rather than a straight phase 120-only unit to run things.