Alrighty then...this question is for the voltage gurus in the crowd.
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We have completed a little shed that will be our first and only enclosed human habitat structure at our LNP project. I have the heat under control and have now moved on to the electric.
Since we have no power on the property and likely won't pull it in for a couple of years, we use a gasoline powered generator for our electicity needs. Here is the short term plan:

• Wire the entire shed and install a breaker box panel with a main lug.
• Run one dedicated line from the breaker box to an exterior 15 amp protected GFCI outlet.
• Take the wires that enter the breaker box from this dedicated line and install them into the power feed lugs...as if these wires were the incoming power source.
• Set up the rest of the internal wiring as per normal within the breaker box
• Fabricate a 25' long 12 or 10 gauge extension cord with a standard 120 V male fitting at both ends.
• When we arrive at the project, we can wheel the generator outside, fire it up, and plug in the 25' long extension cord between the gen. output and the exterior GFCI outlet.

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This should work...right? I can't see why not. Assuming the physics is reliable for this type of back-feed, will the 15 amp exterior GFCI still work in reverse? I mean, will it still pop at the 15 amp overload with the juice flowing thru it in the opposite direction? I hope so, because the outlet needs to be protected from overload and it would be a great first defense in limiting amperage...I am planning on 2 separate 15 amp circuits within the shed. I suppose that if I had to, I could put both of the HOT internal circuit wires into the same 15 amp breaker for the short term.

That will work as described. That is how I have my hunting cabin wired except I used three breakers in the breaker box. It has worked for 5 years with no trouble.

As Mr. Shock indicates, this will work.

Generator only has 110 VAC output, Brettski? Ours is 220 VAC, and I backfeed through 220VAC welder outlets with an appropriately wired pigtail (your double-male extension cord), after opening the main switch to take us off the power company supply lines.

Remember that if the pigtail comes unplugged from the shed while the generator is running, you'll have live 110 VAC on those male plugs and whatever they touch. An over-engineering guy like you might want to use a twist-lock (hubble?) outlet and plug on the shed, and then switch to a conventional outlet when permanent electricity is hooked up. You can still get GFI protection by using a GFI circuit breaker.

we used to call that one shore-power. hmmmm...

It's actually a 5 kw 110/220 unit. I based all my wiring configurations so that if the inspector should ever visit and poke around, he would only see a normally wired structure that is awaiting the introduction of the local power feed. Of course, this all goes down the drain if I am hooked up to the gen set.
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Do you s'pose I could get a female 220 socket that would readily fit and adapt to the standard exterior outlet box I already have installed? It's a thought, eh?

There is a standard 220 VAC outlet/plug configuration that is the same size as the regular 110 VAC duplex outlets in your house. The 3 prongs look the same, except one of the flat blades is turned 90 degrees, like this:

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(assume the period ["ground"] is one space to the right, centered under the two flat blades ["hot" and "neutral"])

This config plug is used for the 220 VAC output on my generator.

I went by Menards tonite to gather supplies for the on-going shed project. I spent more quality time wandering the electrical aisle, examining plugs, outlets, wire, blah blah...and price tags. I like your 220 (aka: 210, 220, whatever it takes) idea, but the upgrade would require another considerable chunk of cash. Enough $ to remind me that the power upgrade is unnecessary. What does bother me is your first point about the potential of the hot plug popping out. I can come up with a cure for that, but I'm open to plug-security creativity.
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Anyway...I wound up buying a 25 ft 12-3 contractor's extension cord ($14) and 2 separate male 110V plugs ($4). I figger that I can start with my original plan and see how it goes. If I create the M/M pigtail with 12" of wire I have in stock + the $4 worth of male 110V plugs, I can leave the new ext. cord intact with M/F (and still use it elsewhere for it's intended purpose).

** UPDATE ON THE BACKWARDS ELECTRIC SERVICE **
Well, a GFCI will not work in reverse...or, at least the GFCI outlets that I purchased don't. It was driving me nutz. I have an entire circuit wired thru the breaker box and into the interior and no juice. So, break out the wiggie and start eliminating variables. Blah, blah, blah...it was the exterior GFCI outlet. If I wire it to the normal inbound terminals, it pops when I plug in the reverse feed. If I wire it to the outbound terminals (the terminals that would normally carry GFCI protected juice further along in the the circuit), it works OK without popping, but I assume that the power is not GFCI protected. That's OK because the I am using 1 GFCI outlet as the first interior device on each circuit and feeding the balance of the devices in the circuit off the output terminals.
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So there...it don't woik.

Just wondering why you think you need a GFCI outlet. Most houses dont have them, unless there is a swimming pool. Maybe new home regulations require them under certain situations?? Like if you or a little one tries to test the outlet with a coat hanger.

Technically, this is a garage. That's the hitch. When we built our garage at our principal residence, I recall that code requires GFCI protected outlets on the walls. They weren't required for outlets in the ceiling (ie; outlets for garage door openers). Besides, it's not D-ski or me that I worry about. It's really more of a fear of the Dr Burger house calls when I feel myself slipping into Pointy Hat Syndrome. Your childhood photos still haunt you (and me).
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