Another Generator 115/230v Question

[Beachfinn]

Got to wiring my 10kw Onan yesterday. after I finally got into the wiring box on top, I found all wires just cut here and there. After consulting the wiring diagram and various bits of wiring found my 4 main leads T1-4. I was originally going to wire it as 115v and run #2 wire. However this generator has a two pole 45A breaker, that is also the connection block for everything (and a ground bolt). As my head hurt already after this, I wired it with #6 for 230/115, with L1 & 2, neutral and ground bonded at the ground lug. I was not sure about the two (S1& S2) wires so those were left out. After reading through I found those to be the regulator wires, that should be connected to L1 & N, in 230 setup. Anyways, made the connections at the panel, fired up the genset, put one 20A and outlet and all is beautiful 

NOW: if I wanted to go back to 115, would I just jump the 45A on the supply side from the one hot lead coming from the generator? If so, the neutlral would be undersized in 115 setup, how would in the 115 setup the two separate bus bars at the panel be tied together? Another Issue here is making the connections with #2 in the very limited space. What is the correct way of doing the connections? Get a 90A single pole that fits in the place of dual 45A and connect the two T wires at terminal and go out with #2? Then bond the other T wires ar the ground lug?

I like the idea of 230, since 50A shore hook up would be simple and I would have an option for 230v outlet if needed. Obviously I would have to worry about balancing:
- L1 two rooftops, backup water heater
- L2 one rooftop and 2800w inverter loads
About balancing; how picky are the modern Onan  Gensets about balancing?

[DoubleEagle]

I am not an electrician, but to quote George Myers, who is, "In coach wiring, the neutrals and the safety grounds are never connected". There is a potential electrocution hazard if you do. As far as switching back and forth between 115 & 230, I am not sure how that goes correctly, it would be best to check with an electrician who is familiar with RV's and Coaches (not an electrician who works on homes only, unless he has a bus).

[TomC]

Need to make sure your generator is capable of full power straight 120vac. Usually they are if the generator is a 4 wire. On mine, instead of using line one and common one, line two and common two, you connect line one to common two, and line two to common one. But-please don't take my word for it. Good Luck, TomC

[scanzel]

Make sure you get a qualified person to do the electrical otherwise one could screw up and make the exterior shell of your coach electrified and if one comes up to it and touches it or the door it could be the last time. On  my coach I left my Kohler 9kw at 220 and put in a Square D QO 100 amp breaker panel with a 50 amp main breaker. I have a 150 amp rotary switch that gives me shore/invertor/generator/off so I can select which power source I need.  My incoming shore ac has a surge device that senses the power and only connects me to shore if it detects that everything is ok before it comes on line. It has a small meter that shows LI/volts/amps, L2/volts/amps. I put all my electrical panels in the bedroom in a cabinet so I can check everything at any time and do not have to go out into a bay to investigate an issue. In also have at 12v and 24v panel for my dc devices. Almost all of my lighting is led either 12v or 24v dc. My invertor is a Magnum 4024, 4000 watts with an 8 AGM battery bank giving me 400 amp hours.v The batteries were free so that is why 8. To answer one of your questions if you stay with 220ac then you will need to balance your ac loads as best as you can. Good Luck and be Carefull.

[Beachfinn]

Yes the genset is capable of 115v output only (T1 & T3 together and T2 & T4 together). If wired this way i'd had to change the wiring from the generator to the panel to appropriate size.

On bonding; im not sure I follow the logic. If Neutral is not bonded anywhere in the coach and left floating (lets assume there is no shoreline or transfer switch, as there are none right now), how would that prevent shock hazard if a wire is frayed and contacts the bus body? I have always been under the impression that when a generator is hardwired to a system with outlets and appliances Neutral is always bonded at the source (generator)? This bond is broken when outside power is brought in and the bonding is done at the source of that power.

[buswarrior]

Beachfinn, you've got it right.

The neutral/ground bond should be switched so that it is only bonded at the source being used.

There is a TON of material in the archives of both Boards on this topic, it can get quite complex if automating.

A simple way is to have the same plug for the generator as you use at the campground.

The coach is on the end of the cable, plug in to the source you want, as soon as you unplug from the generator, that bond is broken.

happy coaching!
buswarrior

[jackhanow]

My bus is set up with a generator outlet and a shore out let and I plug the coach into which ever one I'm using. Works good. The auto boxes get hot and come with a lot of problems. Just saw one melted in a pretty high dollar rv last week.

[gumpy]

Neutral / ground bond at the source.

Generator - Bonded at the generator.
Inverter - Bonded at the inverter.
Shore - Bonded in the shore source. Not bonded anywhere in the coach.

[Beachfinn]

Thank you Gentlemen !
Yes as much as I like technology I am starting to lean towards the plug method.

I spend last night staring at the generator end box and while the wiring for 115V is dead set simple, I just cant see how to do it simply. Im sure that the folks at Onan know what they are doing and im just not getting the full logic on how they set the wiring and breaker up. Here's the only way i can see it happening with the existing hardware: the 4 main wires coming out are all various lengths, two of them cut by previous owner. the only connection point is the two pole 45A breaker with 1/4" terminals and 1/4" ground bolt. Now, this is where it gets tricky, I could run T1 to one side of the breaker T3 to the other pole, run a jumper between (on the generator side). Then run two #6 wires to my main square D panel upstairs, one wire per busbar? Should it be jumped again at the panel, between the two separate wire carrying L1? Then change the current #6 Neutral to #2 from the generator to the panel. Would this be kosher?

Attached is the genset wiring diagram for those interested