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Old 06-22-2016, 07:27 PM   #15
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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
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Old 06-22-2016, 09:15 PM   #16
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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.


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Old 06-22-2016, 09:42 PM   #17
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Jury-rigging shore power at the house

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

Simple, easy, cheap, safe, DONE.


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Old 06-23-2016, 07:26 AM   #18
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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.
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Old 06-23-2016, 08:20 AM   #19
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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]
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Old 06-23-2016, 08:46 AM   #20
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I had my exterior 30 amp outlets built to code. Not worth chancing the wrath of the gods.
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Old 06-23-2016, 09:24 AM   #21
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Thanks all for your feedback. I had another look at my breaker box last night, and it turns out that both breakers for the two circuits going to the garage are located on the same breaker "block" (ie., there is a single breaker unit that has two breaker switches on it), so there should be no worries about phases, etc.. I thought it was two 15A breakers, but in fact they are 20A each. I thought about it some more, and think I have found the real danger in the plan.

As a thought experiment, lets take the jury rigged pigtail arrangement out of the equation and imagine just hard-wiring a female 30 amp plug where the two sets of wires for the two circuits enter the garage, combining the inputs as described earlier. If I plug my trailer into this plug, theoretically the two circuits will share the 30A load, roughly equally assuming wire lengths are the same and overall resistances are the same. The problem is that those circuits will continue out of the 30A plug (where they are joined), one of them supplying lights, and the other supplying outlets in the garage. If I plug my mal-functioning circular saw into an outlet and the motor windings are in a dead short, it will try and pull all the current it can through the circuit. Since the outlet circuit combines with the light circuit at the 30A plug, the breakers won't pop until they see a combined 40A load. This 40A dead-short max load will be seen by the 20A max capacity wiring that goes from the 30A plug to the outlet that the saw is plugged into, and here is where the fire danger lies, when that wiring melts. I could defeat this by installing a secondary set of breakers within the garage, in between the 30A plug and the two garage circuits, but it is still a jury rig, definitely wouldn't meet code.

Another option might be to replace my garage circuit breaker with a 50A breaker, wire that to a sub-breaker box, and then put the two 20A circuits and the 30A circuit breakers in that box. This would still require running the additional 30A wiring out to the garage, though. I guess I'll see if I can find an electrician with a more creative/cost effective solution than the first one I consulted.
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Old 06-23-2016, 09:34 AM   #22
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Thanks all for your feedback. I had another look at my breaker box last night, and it turns out that both breakers for the two circuits going to the garage are located on the same breaker "block" (ie., there is a single breaker unit that has two breaker switches on it), so there should be no worries about phases, etc.. I thought it was two 15A breakers, but in fact they are 20A each. I thought about it some more, and think I have found the real danger in the plan.

As a thought experiment, lets take the jury rigged pigtail arrangement out of the equation and imagine just hard-wiring a female 30 amp plug where the two sets of wires for the two circuits enter the garage, combining the inputs as described earlier. If I plug my trailer into this plug, theoretically the two circuits will share the 30A load, roughly equally assuming wire lengths are the same and overall resistances are the same. The problem is that those circuits will continue out of the 30A plug (where they are joined), one of them supplying lights, and the other supplying outlets in the garage. If I plug my mal-functioning circular saw into an outlet and the motor windings are in a dead short, it will try and pull all the current it can through the circuit. Since the outlet circuit combines with the light circuit at the 30A plug, the breakers won't pop until they see a combined 40A load. This 40A dead-short max load will be seen by the 20A max capacity wiring that goes from the 30A plug to the outlet that the saw is plugged into, and here is where the fire danger lies, when that wiring melts. I could defeat this by installing a secondary set of breakers within the garage, in between the 30A plug and the two garage circuits, but it is still a jury rig, definitely wouldn't meet code.

Another option might be to replace my garage circuit breaker with a 50A breaker, wire that to a sub-breaker box, and then put the two 20A circuits and the 30A circuit breakers in that box. This would still require running the additional 30A wiring out to the garage, though. I guess I'll see if I can find an electrician with a more creative/cost effective solution than the first one I consulted.
I am going to assume you are attempting to create a fictional episode for a comedy TV show here. If so please sign your comments with a disclaimer, or as Rube Goldberg, as there may be some readers that may see this as possible and follow suit.
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Old 06-23-2016, 09:41 AM   #23
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The option in your last paragraph may be feasible, but you should get an electrician to calculate the wire size for the 30a run out to the garage.
Also check with your local building inspector. You will need a permit and they will be able to tell you any local requirements and maybe a cheaper alternative.
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Old 06-23-2016, 11:29 AM   #24
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Terminology

BTW, jerry-rigging is an approach. Jury-rigging is a crime.

I'm just saying'...

Jay and Lisa
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Old 06-23-2016, 11:52 AM   #25
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I always say living in a trailer is life at the end of an extension cord. Getting enough power for me to stay comfortable is a bit of an art form as the 15A to 30A adapters melt if you look at them hard. It's hard to say much about your situation without knowing exactly what is there because details count when dealing with electricity. From what you have shared so far it seems like you have 2 hots and maybe 2 neutrals running to the garage. How do the wires enter the garage, is there a junction box that you can look into? What do you see in there? How much would you spend to have AC? Breakers are sized to protect the wires and usually 20A breakers go with # 12 wire and for a long run like you have I wouldn't try to pull more than 15A per hot wire. There is hope but meeting code could be tricky so you need an electrician that knows what they are doing. Maybe send 220 to a transformer and sub panel in the garage? A sub panel with breakers for the garage circuits? There is probably a way to get the job done safely.
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Old 06-23-2016, 11:58 AM   #26
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I had the same problem and fixed it with adjusting the breakers in the box so that I could open up 30 amp service. I had the installer put an outside 30 amp plug just below the box and then bought a 50ft male to female 30amp extension to go to my RV which has to be in the street (driveway to short). This has worked very well except for 1 day when the outside weather was at 120deg (AZ). The cord got so hot in the sun it tripped the coach breaker for the ac unit. I kill the breaker at the box when not in use (I have an outside box so it is a weather protected outlet). This was a lot cheaper than having the installer run conduit. Just a note, I also looked at trying to use something makeshift and was quickly talked out of it. If you can move some loads around in your box and not create a fire hazard I think this is a great solution.
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Old 06-23-2016, 12:07 PM   #27
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A quick wire calculation says 30 amps of single phase 120 volt AC at 150' requires 4 gauge wire.

150' seems like a long measurement, even for a long, skinny home.

Measure and make sure that the 50 yard estimate is correct. The re-arrangement of breakers and/or the addition of a sub panel are acceptable methods to add circuits.

The combining of receptacles via extension cords is not.


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Old 06-23-2016, 12:11 PM   #28
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http://www.ecmag.com/section/systems...ected-parallel


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