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RVluvin · 03-14-2011, 08:36 AM

I installed an Onan 4000, 30 amp (3 wires) onto my 5th wheel in the campartment pre-wired for a generator. The trailer is 30/50 amp. The transformer is set up to accept 4 wires, 2 hot, 1 ground, and 1 nuetral. My generator only has one hot. I've tried spliting the hot using 2 breaker switches. I tried wiring the transformer with just 1 hot, and the other not connected to anything. When the generator is runing, the transformer will not recognize it and switch over. For now, my generator is connect just with an outlet, and I have to use my shore line cord. Any one know of another way I could do this?

Wizard · 03-14-2011, 09:18 AM

Not really sure what you are trying to do but transformers convert voltage, not amps. You can never get 50 amps out of a 30 amp generator.

What kind of transformer are you using and are you trying to split the 30 amp generator to two circuits.

RVluvin · 03-14-2011, 11:20 AM

When I say transformer, I'm talking about the device that automatically switch from either 12 volt, to 110 volt. I can be on 12 volt power supply, then fire up the generator and the transformer will not switch over. But, If I plug in the shore line into the generator, no problem, now I'm on 110 current. My transformer is designed to accept 50amp supply with 2 hots. My generator only supplyes 30 amp, 1 hot wire. Is there any way to make this system work like it should without having to pull out the shore line. That what I'm trying to accomplish. Thanks, for the interest.

Wizard · 03-14-2011, 11:44 AM

The answer is yes.

What you are referring to is the transfer switch. You should be able to install the hot wire from the generator to one of the hot terminals on the transfer switch and then jumper to the other. The green wire should go to the ground terminal and the white wire to the neutral terminal.

Most RV generators have 2 separate circuits and I have Winnebago wiring diagrams for that but don't know if it would help. What type transfer switch do you have, I may have a drawing for it.

With the trailer cord disconnected, the transfer switch should switch over. I personally had a bad transfer switch recently and had to replace it.

Bug512 · 03-14-2011, 11:45 AM

I do not think you can "split" the one hot leg into two...

If you connect to a 50 amp receptacle the two hot legs will be phased 180 degrees opposite of one another.

If you "split" one 30 they will not be..

I will wait until the professionals chime in..

wa8yxm · 03-14-2011, 03:58 PM

Quote:

Originally Posted by Bug512

I do not think you can "split" the one hot leg into two...

If you connect to a 50 amp receptacle the two hot legs will be phased 180 degrees opposite of one another.

If you "split" one 30 they will not be..

I will wait until the professionals chime in..

That is what you get for thinking.. The standard 50 amp service is 240 volt SPLIT phase,

However you can indeed split 1 hot into two hots, I'm doing it as I type. my generator does it as well.

The only requirements are as follows.

1: NOTHING, and I mean NOTHING in the RV requires 240 volt, it's all 120 volt (or battery powered)

2: Your neutral line can carry the FULL output of the generator or at least sixty amps if on shore power. Mine can.

The only problem with this is if you have a EMS (Energy Management System) it will sense the "Split" hot lead as 30 amps, never 50, only 30, however if you have a "Generator override" it will still allow everything to work on the genset.

Loren B. · 05-11-2011, 08:36 PM

Quote:

Originally Posted by RVluvin

Any one know of another way I could do this?

The short answer is "No, you cannot do what you want to do with that generator."

wa8yxm obviously understands electricity and could probably wire your trailer for you, but if you don’t THOROUGHLY understand what he said and why it will work, don’t attempt to do this yourself.

My answer is that you can’t do it, because a 50 amp service is 220 volts and your generator produces only 110 volts.

As you have already discovered, your generator has a single hot lead that measures 110 volts from that lead to ground (or to the neutral wire). 220 volt service uses two hot wires that are phased 120 degrees apart. Voltage between the two hot wires is 220 volts. Voltage between either hot wire and ground is 110 volts. Your generator cannot produce 220 volts because it has only a single hot wire.

As wa8yxm states, if you are a whiz-bang electrician who really knows his stuff you can get your set-up to work IF, as he said, your trailer has ABSOLUTELY nothing that requires 220 volts. If you have to ask this question, then you can’t.

I suspect that there are lots of electricians wiring houses who wouldn’t know how to do this either, so don’t feel bad.

If you get a 220 volt generator you’ll get the power you need.

– Loren

wa8yxm · 05-12-2011, 07:22 AM

Loren, thank you for the complement (You said I understand electricity,, I'm a Certified Electronics Technician)

Actually, as I read the O/P's post for the 3rd or 4th time I find the following

He made one mistake.. He typed TRANSFORMER when he should have typed TRANSFER SWITCH.

It appears he is feeding each leg (L-1, L-2) via it's own breaker off the generator, EXACTLY as my coach is wired.. In short, he did it right.

Oh, for the O/P. My Onan 5500 came with dual 30 amp breakers, One feeds L-1, the other L-2 (The two hot wires) However when running off the generator it might be more proper to call them L-1a and L-1b since they are being fed in parallel, (that is the voltage across them is zero instead of 240)

But in re-reading your post.. sounds like you are doing it right.

I do wish, on occasion, that my generator was 120/240 volt, but that's only when I'm using it as an emergency power for a house.

RVluvin · 05-13-2011, 11:38 PM

Thanks everyone for trying to explain. Loren B. short answer confirmed what I suspected. I understand the problem is with only 1 hot and the whole 120/240 volts, but still don't understand why the transfer switch will work using the shore line cord but will not switch with the generator connected directly to the transfer switch even if it is only 120 volts. But that ok, I'll just have to use the shore line cord, It's not that often I use the generator anyhow. I got a really great buy on this generator from a budy losing his toy hauler, otherwise I would have purchased a larger generator.

Maharbinski · 06-02-2011, 08:28 PM

Hi
A 220 120 single phase @3650 to 4000 watts has only half power
In each l1 l2 leg to neutral.
A/c will draw most of 14 amps fan +compressor, not much left for rv.
Must use all of both legs 15+15 amps to start a/c.
U can do by 4lead 1 2 3 4 coming out be generator head being tied for
2wire 120 volt output.
U can also use 5000 or 6000 watt transformer w ct to isolate ur
Generator from the rv that is grounded with a pole in wet earth.
Cheers

RJay · 06-02-2011, 08:58 PM

RVluvin,
I copied this from my Iota 50 amp transfer switch manual. Sorry, but I can't get the diagram to print. There should be a diagram on the inside of the cover.

INSTALLATION BETWEEN POWERCORD AND GENERATOR
(CONFIGURATION A)
The ITS-50R is designed with an easy-to wire bridge. Refer to
Diagram 1 for wiring lug designations. Connect the powercord neutral
to the powercord lug labeled NEUTRAL WHT. Connect
powercord hot 1 and hot 2 to powercord lugs HOT 1 BLK and HOT
2 RED. Connect the generator neutral(s) to generator lug labeled
NEUTRAL WHT. Connect generator hot 1 and hot 2 to generator
lugs HOT 1 BLK and HOT 2 RED. Connect output to panel or other
destination to the applicable “panel” lugs. The bypass switch should
be in the “off” position (marked “1”).

wa8yxm · 06-03-2011, 08:44 AM

One thing.. He also said in the original post that the rig was wired for 30/50 amps

on a 30 amp RV, the transfer switch is kind of .. strange.. compared to a 50 amp.

Having the install manual on board I can explain the differece if needed but basically one "leg" on a 30 amp transfer switch works quite a bit different. It runs one A/C only.

BigV · 06-03-2011, 09:19 AM

It would also help to know what transfer switch he has.

A 30A Iota has one double pole relay. Most 50a switches use 4 relays. How they connect can be somewhat different.

I just replaced my 50a relay and it came with a jumper specifically for connecting a 30a generator to the 50a service.

All of those 50a to 30a adapter plugs do is bridge the two input legs. As was stated before there is nothing in an RV that requires 2 phase power. It is all 110 devices. The reason they are wired for 2 phase plugs is to load balance, nothing more.

Maharbinski · 06-04-2011, 06:43 PM

Hi
Is ur onan a old emerald plus?
If so, the 60cycle version had 120 v only on many models.
I would luv to have 240 at 16 amps for ac, but i'm stuck
With the same 120 v at 30 amp genset.
I think the microlite is 2 pole 3600 rpm for the same juice out.
My old emerald has no control board or voltage regulator.
It uses a 120 v test that sends 12 to 18 dc to the exciter rings from the inside cabin batteries 120 v to 12 vdc power supply once the generator puts out ac.
I removed all that onan electronic 15 hrs ago, the old 2 cyl runs fine at 1800 rpm. It is a heavy turd, tho for an old guy to fiddle with.
I looked at the stator coils years ago, the 4 pole arcs put out 30 v ea for 120 v total sum, there is a b set that is identical for another 120v,
The ac can have it's compressor at 120 or 240
My problem is shore power is 120 and most campsites are 120, some
Offer 120/240, but I wd have to chg my plug and cord for what is there.

I have rewired the coils for 120/240 when the genset is used to construct buildings where there is no power, then I put it back like it was.
Cheers