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Todays Email, How to wire a Generator Head for RV use.

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DIYer RV Wiring

You’ll notice I didn’t put up an April Fools Joke on April 1, sorry, I wasn’t thinking, but the article I put up about the page is an everyday joke, read that.

So it’s April 2nd, and my Grandson Zach who’s not three yet is waiting for his Sister to Arrive this month, being fascinated by all things Garbage or Recycle, he’s picked out a     name for her, “Trash”.

Today’s Email:

Name: Dan B

Subject: Generator

Message: Hi, I was hoping I might ask a bit of advice if you have time? I read your posting about rewiring the generator head to get full power on 11o volts. When I bought my generator it said the front plug would provide 30amp service, so with an adapter for my RV plug I thought I would be all set. Turns out they meant 30amp at 22o only.

15amps will not run my RV. My question is, rather than taking the generator all apart, do you think it might be possible that I could get a twist-lock plug for the 240 twist lock socket and combine the wiring at that point into a small fuse box with an RV socket coming out of that. My goal would be that I could easily return the generator to normal function when others barrow it or if I were to sell it. Any advice you can give me on the subject is greatly appreciated as my wife is ready to go spend thousands on a bigger unit if I can’t get this one to handle the job. I should mention it is a 5000 watt unit.

Thanks, Dan

As I sit here, I attempt to frame the question, and look at the data provided.

30 amps at 220 volts = 6600 watts,  so if his generator manufacturer says it’s a 5000 watt generator, how they do that?

I’m totally  ignorant of how many ways RVs are wired to accept 120 VAC, and Dan’s statement that 15 amps doesn’t do it raises questions.  The first question is what is the typical source of AC power used to power an RV? At least a good percentage of the supply comes from a KOA campground plug, or one from the home.

In most new houses, the wiring is now 14 gauge, and they are often fitted with 15 amp breakers. With the understanding that breakers are only rated to carry 80% of the rating on the face of the breaker on a continuous basis, so we know that figure is 12 amps we might be able to pull without blowing the breaker.

If we are lucky, we might find a dedicated  120 VAC plug-in the garage that’s fed by a 20 amp breaker, but we have another safety concern, and that is the rating of the wall plug itself,many are not rated for a full 20 amps if you could carry it,  and we should note our 20 amp breaker is only rated to carry 16 amps continuous without tripping. Yes, your 20 amp breaker might trip closer to 20 amps, BUT the manufacturer is allowed a little leeway so he doesn’t have to sell you a precision breaker at high dollars to you.

For those following along, I’m thinking  out loud here, we need study the entire path of current flow from the typical power supply to the RV.  And one place I see real trouble is extension cords, some people want to set up their generator in the next zip code over, and run it to the camp site, so the noise is

a lot lower. We need be VERY careful to note the size of the wire (gauge) and know that a cheap cord of small gauge (higher numerical number) is a BAD idea. you’ll need a good cord, and if it’s any length, you should consider 10 gauge, and even a moderate cord in length should be 12 gauge by my measure WHEN you think you are pulling near the limits of a (typical) 120VAC circuit.

So how do we answer Dan’s question? I was ready to show him how to install a switch to go from 120VAC only, at full Amperage, but perhaps all we do is set him up to start a fire in the RV wiring as we deliver more current through a box or plug not rated to carry it.

There’s an additional question, and that’s the real capacity of this generator, many are rated 6600 watts peak, and 5000 continuous. if this is the case, the unit should deliver 20 amps per stator winding 20 amps at 120 VAC, per side. If this is the case, we have the an outlet from the generator at 120VAC that will carry as much current as what we find in any standard home outlet.

So before we proceed with a solution, we need to hear from the RV experts that visit utterpower, I know there are several who know far more than I do about how they are wired. We also need to know what is drawing all this current? Perhaps it’s the fridge that runs on either propane or electric, and we can just make sure we are on propane? Perhaps a switch to isolate that one load that draws so much, and run a second extension cord to run it directly?

And Dan, at this point, you are using half the power your generator can deliver, you wife needs to know a bigger generator may not deliver any more current at 120 VAC than your present one.  A complete schematic of the RV wiring would be helpful, if the RV typically needs more than 15 real amps, I’d expect it to be wired different, but then again, it’s not clear that your wife’s adornments aren’t pulling 12 amps all by themselves

So as not to frustrate Dan too much, I’ll anser this much. It’s not often the generator manufacturer makes it easy to run in the 120VAC only mode, and as we touch on above, it would require a plug rated to carry the current that would be delivered in that situation (on the generator).  Some Honda generators I’ve seen have a switch to go from 120 only to 120/240VAC,  it’s easy to wire that in on many generators if you have access to both ends of the two stator windings.  When we create a special non standard situation, we can catch things on fire, and create a liability for ourselves. RVs are dangerous enough without our help in increasing those dangers. I remember a Racer Friend of mine getting ready to go to a race in another state, the motor home and race trailer were in the drive, and at about 4AM the morning they were to leave, a loud explosion, and the back yard filled with burning rubble.  I saw it on the morning news on a Seattle TV station.

DIYers. Scroll down to comments help me! let us know what you’d do, Dan, try and identify why you need this much juice. what circuits pull this kind of current?

Added  Comment 4/3/12 :

I forgot we had so much info on this page, thanks for the reminder Mike L.

Category: Forex

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