Wiring a Generator for 120v

[Ericbsc]

I read the post about gen loading. I have a 10k Onan quiet diesel in the bus. I just have it sitting and hooked to fuel lines. I wired a temp panel for load testing. The plate inside the gen shows to wire it with two legs @ 120v, netural & ground. I ran two roof ubits on one side and one on the other. Ran fine for over 8 hrs. I asked the Onan service about wiring to st 120 and he said that was not needed. His view was that if I run that way and put the extra load on the leg with one ac it would handle it fine. I have no 220v need the water is 120v with a heat exchanger thru the proheat & engine. Ref is a 120v Summit with 3 amp draw. I also have a Heart 4500 inverter. What to do? Seems to work fine? P.S. He did not think the gen could be wired st 120?

[TomC]

Typically- to have a 120/240vac gen reconnectable to straight 120vac, it needs to be a 4 wire gen-2 hot, and 2 common.  When wired for 120/240vac, you have the two legs of hot and then the common connected together.  When wiring for straight 120vac, one leg is wired normally and the second leg is reversed so polarity is the same on both sides to create only 120vac.  When wired this way you need to have two hot and two commons going to the breaker box.  Good Luck, TomC

[Airbag]

Eric can I piggy back on this thread?


Tom
Can one still keep their 50 amp park plug and transfer switch? I have an electric water heater but not sure what voltage it runs. The switch for the water heater is in the closet mid ship. I am starting to see the advantage to power management panels with all the switching / volt / amp meters in one place.

Onward and upward

[Sean]

... I have a 10k Onan quiet diesel in the bus. I just have it sitting and hooked to fuel lines..... What to do? Seems to work fine?

I see no advantage to rewiring for 120, and several disadvantages.  Do the best you can to balance the loads between legs instead.  If you were to rewire for 120, you'd need to go to an 80-amp breaker, and upsize the feeders to accommodate it.

P.S. He did not think the gen could be wired st 120?

I think he's wrong, but I don't have the prints, either.  You might have to open up the wiring box for the head, though, if the unit was not made at the factory to be easily convertible.

Can one still keep their 50 amp park plug and transfer switch? ...

Probably not, again because you have 50-amp transfer gear, and if you have, say, a 10 or 12k genny, you'd need to upsize everything to 80 or 100 amps.

-Sean
http://OurOdyssey.BlogSpot.com

[Airbag]

If I can't keep my 50 amp gear then That clinches it I will stay with what I've got. I have an 8KW gen that does not like two AC's on one leg.

[Sean]

If I can't keep my 50 amp gear then That clinches it I will stay with what I've got. I have an 8KW gen that does not like two AC's on one leg.

You could rewire for 120 if you installed an intermediate panel between the genny and the transfer switch, and then fed the transfer switch from a 50-amp single-pole breaker in this panel.  That would give you a 50-amp, 120-volt system, and you could feed both hot legs of your current setup with this (but could only use 50 amps total between the two legs).  That would let you run two A/C's, and use 6kW of your 8k genny as-is.

Instead of leaving the other 17 amps (2kW) on the table, you could wire some items directly to this intermediate panel.  These items, of course, would then only run on the generator and not on shore power.  For example, if you have electric fans cooling your genny, wire them here instead of to the main panel.

FWIW.

-Sean
http://OurOdyssey.BlogSpot.com