Jury-rigging shore power at the house

[TG Twinkie]

A 50 amp to 30 amp adaptor will solve your current problem. The 50 amp service and RV receptacle will be a 4 wire system. The 50 to 30 amp adaptor will only use 3 of the 4 wires; one hot, one neutral and the ground.
So go ahead and install the 50 amp RV receptacle which will match your future needs. Pick up a 50 amp to 30 amp adaptor at most RV suppliers or maybe even Wal-Mart and you are good to go.

[ijustlee]

Hey Belegedhel exactly what are the wires that enter the garage and are they in a junction box where they enter the garage? Are they buried in the ground or in the wall and you just see the lights and outlets in the garage? Is the garage attached to the house? Why not go with your original idea as a temporary thing and take a chance it will be OK until you change it back? Maybe replace the 2 breakers with 1 GFIC so that you are doubling the wire cross section and hopefully preventing a child from being electrocuted by touching the live prongs of the unplugged cheater cord. This should be safe enough for practical purposes though it sure is not code or insurance safe. Don't do anything unless you know where the electricity could go under any circumstances. It's America after all! Signed Rube Goldberg. *I know Rube well and his Airstream is always powered up...

[JimGolden]

$1000? It shouldn't cost $100 to do this with two slimline breakers, one 30amp breaker, and some 10 gauge wire for a 30amp outlet. If it's a long run, you might go to 8 gauge wire.

If you want to do a 50amp, you should use minimum 8 gauge wire but I'd probably go 6 gauge to be safe. There are charts with temperatures, drops, etc. that show that 8 will work in a lot of cases but you need 6 in some. Just use six.

Even so, it shouldn't be anywhere near $1000. If you're worried about it not being a "professional install", do like one other guy said on here and do all the running of the wire and setting of the box yourself, so that all the electrician has to do is make the connections at each end and switch it on.

As to the main service having enough juice, you have that same problem if you wire a sub panel into the main. So you will need to check your rating on the main panel to make sure you have the capacity to add this.

I installed a 30amp outlet at each end of my garage. I run 50amp on the trailer but use a 30 to 50 pigtail and just don't turn on everything. Works fine. I got by in the trailer for the first five years with 30amp, but eventually replaced the power center with a Progressive Dynamics unit and upgraded to 50amp. It's a nice conversion.

Best of luck,

[TG Twinkie]

If the new wire to the garage is buried or in conduit it must be derated.
Do it right.

[Belegedhel]

There has been some discussion on this thread about the damage that could/will happen to an AC that is run on too thin of a line. I expect this is due to running at too low of voltage due to trying to pull too much amperage through too small of a line. Can any of you tell me what the maximum allowable loss is? For example, if I plug my multimeter into an outlet with nothing running, I see 119 volts. If I plug my Airstream into that socket using an adapter and run the AC, the voltage drops to around 112. Is this too much drop, or is it about normal?

[HowieE]

Generally anything above 110 is OK

[TG Twinkie]

Ideally there should be no measurable voltage drop.
Most quality equipment is designed for a + or - 10% range. You are pushing the boundaries with what you are reading. The question is: how far does the voltage drop when the compressor kicks in?. And how long does it last? Your meters refresh time is too infrequent to give an accurate reading of that voltage drop. The lower voltage the higher the current to maintain the power requirement. Higher current = more heat.
Contrary to popular belief the electrons do not travel thru the wire, they travel on the surface. The larger the wire the greater the surface area.

[J. Morgan]

Fwiw, in 73 the air conditioner was likely built to run on 110 or 115 volts....

I have researched this some and there is a strong contingency that claims that a about a 10% variance at point of use is ok.

Fwiw, my 72 Armstrong has been running on about 109 volts during peak heat for six weeks this summer, and the same for the two summers prior.

http://www.pge.com/includes/docs/pdf..._tolerance.pdf

Gradiens super tenui glacie.

[ROBERTSUNRUS]

Hi, house hold voltages have been stated as 110, 115, 117, and 120 volts. take your pick. Appliances have been rated at all of these voltages.

[Zil]

Except with some very high frequencies. In household power, and low voltage applications, electrons travel through the whole wire, not just on the surface. Else, why don't our wires would look like water pipe?