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Old 07-07-2012, 12:41 AM   #1
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onan bfa wiring questions

Can you guys school me on my options for wiring up my Onan bfa? I am really a novice when it comes to 120 volt and wiring outlets, etc.

Basically what I have is one 15 amp outlet wired up to the M1 and M2 outputs via a 30 amp circuit breaker. Since my unit is a 33 amp generator, is it possible to wire up a second 15 amp outlet. Giving me 2 separate outlets and the possibility of running the battery charger on one circuit and the vacuum or microwave on the second circuit. Does that make sense? Am I thinking about this correctly? Any advice?

Another question... I've noticed both the starting battery ground and the ground on the AC side are attached to the mounting plate of the generator. I've placed the generator in one of the underbelly storage compartments and it is sitting on a sheet of plywood. Should I run a ground strap from the generator to the frame of the bus?

Thanks for the help.
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Old 07-07-2012, 04:00 AM   #2
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Re: Onan BFA wiring questions

Yes, you can run another 15 amps from the generator. But you should consider the 30 amp breaker on the unit like the main disconnect on a house, and not as the protection for your branch circuits. You should have separate 15 amp breakers on the two circuits.

If you are not installing a full wiring panel, the most inexpensive way to do that would be to get a duplex outlet with an internal 15 amp GFCI ground fault interrupter/circuit breaker for each circuit. They can also protect added conventional outlets downstream, but both the hot and neutral of additional protected outlets MUST go through the GFCI outlet connected to the load side. The grounds can be tied together.

As for grounding the generator, generally yes, but it depends. The wiring diagram for a 4 kW BFA shows the M2 (neutral) to be grounded internally on the genset. When running on the genset, the genset is the power source, and the neutral should be grounded for safety, BUT . .

If you will also be on shoreline, the connection between ground and neutral must be made in the electrical service feeding the bus, and there should be no connection between the shoreline neutral and ground on the bus. If the bus neutral is grounded, and you plug the shoreline into a GFCI-protected outlet, it WILL trip off.

As long as your connection arrangement never connects generator neutral with shoreline neutral (using a double-pole transfer switch or disconnect plugs), go ahead and put a ground strap on the genny. The two AC sources should never be wired together, anyway.
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Old 07-07-2012, 11:27 AM   #3
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Re: onan bfa wiring questions

do as redbear suggested.
the ground on the onan bfa is normally attached to the lower steel plate under the generator... why i dont know, as it gets cruddy there, and that isnt a good place for a good connection. I changed mine to the generator case itself. I also used very large welding wire for ship docks to hook my batteries up to the generator as the batteries are 30' away from the gen set.
you should put a automatic transfer switch between the gen set and your converter/110v stuff, as this gen is a 110v only genset. they cost like $80 or so on eBay.
i changed out my 15amp circuit breakers to 20 amp as the air condioners sometimes trip the 15 amp upon start up.
i also have ground strap from gen base to bus chassis, and mine is mounted in steel enclosure.
be sure to allow for airflow for the bfa. most of the ones i have seen vent the air out the bottom underneith the flywheel and take air across the motor from the gen side of the unit, so that should have a screen to allow air in.
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Old 07-08-2012, 01:30 AM   #4
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Re: onan bfa wiring questions

Great info guys. Really appreciate the help.

Let me give a little more background to my setup and maybe you guys can recommend a route to go....

First and foremost I wanna keep things real simple and economical.

currently:
Battery house bank to 1500 watt msw inverter. (inverter chassis ground is floating)
house bank to 12 volt blue sea distribution panel. all 15 amp circuits.
Charge wizard 4 stage charger to house bank. (charger chassis ground is floating)

onan bfa 4k to a single 15 amp outlet.

one 15 amp "extension cord" can power all my 110 stuff minus the battery charger.
2 - 15 amp extension cords can run everything with room to spare.

generator and shore line can not physically be connected at the same time. So I'm thinking right now I will keep it simple and move the battery charger from generator to shore power and vice versa manually.

with all the being said.... I think going with two 15 amp gfci is my best bet at this point. What do you think?

Really appreciate the help.
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Old 07-08-2012, 01:33 AM   #5
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Re: onan bfa wiring questions

chev, to your point about airflow... yes I've cut a square hold in the floorboard directly below the cooling intake/exhaust area. I'm also going to be putting a few "suicide" vents in the bay doors.
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Old 07-08-2012, 10:56 AM   #6
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Re: onan bfa wiring questions

if you would buy the automatic gen/110v switch, you can just run your 110v stuff off of wiring that goes down each side of the bus. besides that you never have to do any manual unplugging..
you can also buy the heavy duty multiple end cords for computers, etc if you want to have more than one plug in on each side of the bus, or to get good ones, go to lowes and get the contractor ones.
If you use mr16 base 12v bulbs in bus, that are 3w, the battery bank will take forever to drain.
Depending on what all you are running, a minimum battery bank should be at least 400 amp hrs.

I imagine that it is best to have all circuits on gfi, but i found when i did that on my last bus, that occasionally one would trip like when the gen set started.
History on that for me. My first 2 busses had no gfi as that was like 30 yrs ago. The next one had none, and the 4th had two until i unhooked them. This bus i have now only has them next to kitchen sink as i only run 12v in bathroom. I have never had a problem, and i also check to make sure the chassis isnt "live" to ground after connecting to a new shore power. Had that happen once at one campground 15 or so yrs ago...
I put in somewhere around 8 of the multiple computer end plug in's and hard wired them along with some normal 2 plug in's in the wall. Reason i did this is that i have found out over the years that it is far easier to put in more than you need, and you never need to use extension cords in the bus. I also have a raceway strip with plug ins in it behind the wood stove and water cooler section. That way i can plug in stuff close to the dinette, a fan for the stove, the water cooler, and bath hair dryer, etc.
computer type plug in's can easily be screwed into the walls if you buy all the same type and take one apart so that you can see where to drill the holes that are completely away from the wiring and screw it to the wall with drywall screws. you only need to take one apart to check as long as you buy all the same kind at the same time.

I have my genset in the front door opening, and i had an extra rv door with a glass that slides up, so normally i keep the glass partly up and the genset runs very cool that way. Dont normally run it with window closed, but it runs fine that way for campground boondock if necessary..
I also run synthetic oil with zmax in it in the genset. The rv door opens for very easy gen set service.

hope this helps.
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Old 07-10-2012, 08:27 PM   #7
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Re: onan bfa wiring questions

Thanks for the input Chev.....

I ended up scrapping the BFA genny for our application. It does not play well with the 3 stage battery charger. Oh well... going with the honda eu2000 like originally planned. I've lost two days labor and I'm upside down about $400 but the BFA is headed to craigslist so hopefully it will bring a little money.

Need a spare bfa?
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