Jury-rigging shore power at the house

[Belegedhel]

My Airstream (with 30A plug) sits in the driveway near my garage. Power in my garage is limited to two 15A circuits that power the lights and 110v outlets. I would like to plug the trailer in and run the 13500 btu air conditioner. If I use an adapter to plug into one of the 15A circuits, it won't run long before the adapter warms up and the breaker trips. I have looked into just running a 30A circuit out to the garage, but my breaker box is already full, allowing no room for expansion, so in addition to running the line, I would have to replace and rewire my entire breaker box, which gets expensive.

So what I had in mind was to build a jury-rigged pig-tail which would essentially be two extension cords, the male ends of which would each plug into the two separate 15A circuits that are presently in my garage. The female ends would then be spliced together (in a parallel circuit) in a 30A female receptacle, achieving a combined 30 amp capacity.

Anyone see a problem with this? Am I risking breaking laws, burning down my garage, or cooking myself?

Thanks in advance!

[Zil]

That is right up there with the most stupid idea this month.
Sorry. You can take a 30 amp circuit out of your existing panel. Move something else to share a different breaker and then install a 30 amp breaker. Use heavy enough wire from the panel to the garage outlet, or you may fry the AC with low voltage.

[Aerowood]

What size is your current box and where is it located. You may or may not be able to put in a sub panel. If you could put in a sub panel in your garage you could move the garage circuits to the sub panel thus opening up space on the main panel to put in a breaker for the sub panel. Then put in the 30 Amp 110 service for your trailer. A 50 amp sub panel would be more then enough

[HowieE]

If you take other the Aerowood's approach make sure the fire insurance is paid in full.

[markdoane]

Originally Posted by Zil

That is right up there with the most stupid idea this month.
Sorry. You can take a 30 amp circuit out of your existing panel. Move something else to share a different breaker and then install a 30 amp breaker. Use heavy enough wire from the panel to the garage outlet, or you may fry the AC with low voltage.

I guess I would rate this the #1 idea of the month. At least OP asked the question.

Use Aerowood's method.

[mojo]

Originally Posted by Belegedhel

Anyone see a problem with this? Am I risking breaking laws, burning down my garage, or cooking myself?

Yes, call an electrician.

[Belegedhel]

Originally Posted by Aerowood

What size is your current box and where is it located. You may or may not be able to put in a sub panel. If you could put in a sub panel in your garage you could move the garage circuits to the sub panel thus opening up space on the main panel to put in a breaker for the sub panel. Then put in the 30 Amp 110 service for your trailer. A 50 amp sub panel would be more then enough

I appreciate the constructive response. My house sits on a long skinny lot. The house is in the front, and the main breaker box is near the front corner of the house (can't tell you the size off the top of my head). The garage sits in the very back of the lot, so there is roughly 50 yards between the breaker box in the front and the garage itself.

I did start this consideration by calling an electrician. His recommendation, which I would imagine may be the "best" way to do the job (though not the mmost affordable) was to replace the entire breaker box with one that has greater capacity, and then to run the additional 30A circuit back to the garage and so on. The cost of the job was well over $1000 with other potential inflation involved in hiring out the necessary trenching associated with running the 30A circuit.

This led me to consider a way to use the existing circuits and electrical lines to accomplish a temporary (as I never know how long I am going to be at this residence), yet hopefully safe, configuration. Yes, I know it sounds sketchy--this is why I used the term "jury-rig" as opposed to "DIY-Genius solution" in the title.

[TG Twinkie]

Just because you have 2 outlets doesn't mean you have twice the capacity. They are more than likely wired in parallel and fed by one breaker at the house.

Chances are if you only have lights and a couple of outlets in the garage the wire between the house is WAY too small to run a 30 amp circuit.
For that distance you would probably need #4 or maybe #2 wire to provide what you need because of the voltage drop between the house and garage.
It's better and SAFER to do the job right. Make sure if you hire an electrician he knows the trailer requires 120 volts not 240 volts.

[kscherzi]

Let's imagine one breaker serves the two outlets and the other breaker serves the lights. This means you'll have to wire in a third outlet drawing from the lights circuit. With lights out you might theoretically have 30 amps at your disposal. However with a jury rigged cord combining the two there's no way to meter the draw between the circuits to ensure its 50/50. So if for watever reason one circuit happens to be asked to supply 65% of the current it will quickly trip leaving the other circuit at 100% and tripping it too.

I wouldn't do it.

[Chae]

As others have said, you can't. It's likely the outlets lead back to the same breaker in the panel. You can't look at the number of outlets and just add up the amps. It's like plugging in a 6 outlet surge protector and saying you have 90 amps.

[AnnArborBob]

It's good that you asked about this before you tried it. My advice to you is simply that you contact a qualified electrician in your area and explore your options with him/her. This is too dangerous to try on your own with advice from the Forum.

If cost is a factor (and it appears that it may be based on a subsequent post) my advice would be to consider how badly you really need to run the AC when the trailer is at your house.

[beachbouy]

Sounds like a garage fire waiting to happen.

[SteveSueMac]

Originally Posted by Belegedhel

My Airstream (with 30A plug) sits in the driveway near my garage. Power in my garage is limited to two 15A circuits that power the lights and 110v outlets. I would like to plug the trailer in and run the 13500 btu air conditioner. If I use an adapter to plug into one of the 15A circuits, it won't run long before the adapter warms up and the breaker trips. I have looked into just running a 30A circuit out to the garage, but my breaker box is already full, allowing no room for expansion, so in addition to running the line, I would have to replace and rewire my entire breaker box, which gets expensive.



So what I had in mind was to build a jury-rigged pig-tail which would essentially be two extension cords, the male ends of which would each plug into the two separate 15A circuits that are presently in my garage. The female ends would then be spliced together (in a parallel circuit) in a 30A female receptacle, achieving a combined 30 amp capacity.



Anyone see a problem with this? Am I risking breaking laws, burning down my garage, or cooking myself?



Thanks in advance!

Well, I think you've found several folks do indeed have a problem with this - some expressed that concern in more dulcet tones than others...

I notice from your profile you're in TX so I can see why you want to run the AC. I would imagine if you shopped around, you could find a qualified electrician to do the work for less than $1K but honestly, that would be a good price to pay to have the peace of mind that it was done right and in essence, "cheap" insurance against a possible catastrophic fire.

Electricity is just one of those things I never want to mess with.

Good luck!


By the way (on edit) this site has a diagram of how it must be wired (some electricians mistakenly set it up like a washing machine outlet...). http://www.myrv.us/Imgs/PDF/30-amp%20Service.pdf

[kokopat]

Have you utility company put in another service with meter at the garage. I'm sure they want it done correctly.

[Al and Missy]

Another consideration that no one has mentioned is, assuming you actually do have two outlets on two separate breakers in the garage, they may be on different legs of the 120/240 service. Are the breakers in the same vertical row in the breaker box? If not they are different phases and connecting them together will short your 240 volts and blow both breakers (if you are lucky).

While what you have suggested is unconventional, and may violate the building code, I'm not sure there is any particular risk. This is not unlike connecting the output of two Honda (or Yamaha) generators in parallel to get twice the capacity. Each generator has an output breaker, connecting the two in parallel gives twice the capacity. The special circuitry in the generators synchronizes the two, but that is not required in this case because the two breaker outputs are in phase (if they are on the same side of the breaker panel as mentioned above). The only problem is that the two circuits may not equally share the load and you could pop the breaker in the circuit that is carrying more load and then guarantee that the other breaker would pop.

That said, your safest option is to have a licensed electrician hook up something for you. The suggestion to add a sub-panel would be the least expensive. You could save some more money by renting a trencher and digging the ditch for burial of the cable yourself.

Al

[rmkrum]

When it's electrical power, it's far safer to do it right. Jury-rigging stuff with AC power can bite hard, or burn your house down.

Better to bite the bullet and do it right.


Sent from my pocket Internet using Airstream Forums

[J. Morgan]

The sub panel idea mentioned above is what I would do.

Simple, easy, cheap, safe, DONE.


Superat stultitia.

[Zil]

Originally Posted by markdoane

I guess I would rate this the #1 idea of the month. At least OP asked the question.

Use Aerowood's method.

A sub panel would be next best to larger main panel. How ever, in my service, I have three light circuits that could be safely combined. In any case, a knowledge of electricity is required. Ask another electrician about your case.

[ROBERTSUNRUS]

Originally Posted by kokopat

Have you utility company put in another service with meter at the garage. I'm sure they want it done correctly.

Hi, in the long run this would be the best idea. At 50 yards, that's just too much wire for a heavy load. [move the garage closer to the house]

[AWCHIEF]

I had my exterior 30 amp outlets built to code. Not worth chancing the wrath of the gods.