Combining wires to avoid voltage drop? 12/4 cable?

I know it is unsafe to combine wires to avoid over loading a circuit; like using two #14 to carry 18a. One could come loose and the other is overloaded. But how about doing it to avoid voltage drop?
I have no power at my dock, and carrying my generator down 130 stairs isn't any fun. I have done it once, and probably never will again. It is over 120ft, so a #12 extension cord would have excessive voltage drop on a circular saw
A guy is selling a 250 roll of 12/4 wire for $50. As far as I can tell, it is something for audio hookups and has no ground. Could I treat it as 12/3 with an insulated ground, connect two of the wires together to reduce voltage drop, and leave it as a permanent extension cord? I figure that with two wires connected, the VD would be reduced to a manageable level. (yes, I realize the return is only single, but it seems okay if you average the two) There is no reason the wires should ever come undone, but if they did, the worst that could happen is burning out my saw.
Does this make sense? Is this 12/4 stuff safe for 120v?
I did the same thing when I installed my transfer switch. All I needed was 12/2, but I used 10/3 in case someone needed it in the future; since the labor was the same either way. I connected two wires together to reduce VD. A little overkill, but it was just sitting there anyhow.
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At best, you'll get something like an almost 50% cut in the voltage drop, all things assumed to be equal which is never the case; a real world figure would be in the 40-45% range at a nominal current, and possibly much less at higher currents.
So, uhh, why not do it right, use the correct derating factors for that length run, and work accordingly. Most any wire has the specs you need to be sure you won't hit the brownout margin for your saw. Use > 106Vac min and = 120Vac nominal for your calcs and you'll be fine, and using resistive calcs (E=IR) will put you in the ballpark for this; don't sweat the small stuff of inductance and all that for this kind of calcs. I don't subscribe to the "fix it later if it's a problem" when it can be done right the first time and not have to be bothered with again.
HTH,
:I know it is unsafe to combine wires to avoid over loading a circuit; like : using two #14 to carry 18a. One could come loose and the other is : overloaded. : But how about doing it to avoid voltage drop? : : I have no power at my dock, and carrying my generator down 130 stairs isn't : any fun. I have done it once, and probably never will again. : It is over 120ft, so a #12 extension cord would have excessive voltage drop : on a circular saw : : A guy is selling a 250 roll of 12/4 wire for $50. As far as I can tell, it : is something for audio hookups and has no ground. Could I treat it as 12/3 : with an insulated ground, connect two of the wires together to reduce : voltage drop, and leave it as a permanent extension cord? I figure that : with two wires connected, the VD would be reduced to a manageable level. : (yes, I realize the return is only single, but it seems okay if you average : the two) There is no reason the wires should ever come undone, but if they : did, the worst that could happen is burning out my saw. : : Does this make sense? : Is this 12/4 stuff safe for 120v? : : I did the same thing when I installed my transfer switch. All I needed was : 12/2, but I used 10/3 in case someone needed it in the future; since the : labor was the same either way. I connected two wires together to reduce VD. : A little overkill, but it was just sitting there anyhow. : :
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It's not safe for use outdoors, where exposure to moisture and UV are factors.
Captain Joe Redcloud
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moisture. Oh well. Thanks to all.
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Oh, that's right. I missed that. The 12-4 is probably not UF.
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Christopher A. Young
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Unless it's clearly marked for high voltage use, I would not use it.

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Especially in a marine environment, I'd suggest that you focus on doing it right (including safely) rather than on saving a few $. Not meaning to be cute, but one ER trip or casket purchase can really tip the accounting against you.
One possible alternative is a battery-powered saw. True, less powerful than 120v, and more expensive, but much less likely to zap you when wet. With gen at the head of the pier, you could take the batteries there for charging.
HTH, J
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sloppy (the first sign of problem would probably be either the cord or saw frying, depending on the currents involved).
As to the specifics of using audio wire for this application, that sounds like bad mojo. Insulation most likely not rated for the voltage, nor the moisture, nor the UV exposure.
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the NEC is pretty specific about paralleling conductors. You need to have at least 1/0 awg before paralleling.
http://www.electrician.com/vd_calculator.html
Is this 12/4 audio cord even insulated for 300v? Lowest rating of most extension cords.
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cords" (other than the requirement that extension cords are not to be used for permanent wiring)? Seems like more of a UL or OSHA issue.
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Strictly speaking, this is a "c*&p, my circular saw caught fire" issue ;-) NEC doesn't cover this sort of wiring per-se, and "officially" this is a UL (or CSA or CE or...) issue. However, this isn't an anal safety rule sort of thing, more of a "it _will_ bite you"/"laws of physics" sort of thing.
[The NEC does have some stuff to say about temporary wiring. Ie: temporary wiring in many cases _is_ covered by NEC, ie: "event" temporary wiring.]
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Might want to check Home Depot on their price for 250 feet of 10-2 WG. Might be close to same price. Sounds like false economy. If it's exposed to sunlight, go with UF.
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As mentioned, this isn't rated for 120V, and probably won't stand up to weathering/exterior use either. It'd become lethal within a year of exposure (if not immediately).
If it's solid conductor, even worse.
Price out 10/2 (with ground) SO (preferably SOW) (stranded/flexible heavy duty exterior extension cord), and compare with a "contractor's extension cord" (_fat_ brightly coloured extension cords) in #10. [These are SOW, but preassembled with plugs/sockets, and are often somewhat cheaper than "off the roll" wire.]
Chances are you could do it for roughly $75-100. Not cheap, but the only thing that'll stand up to any extended period of deployment.
That said:
Ignore the next two paragraphs if this is for more than one project ;-)
I have been known to run a 12A chainsaw on the end of almost 200' of linked together extension cords (about half #12, rest #14). It didn't work great, and bogged down quite easily. But, with a gentle touch, I managed to do what I needed to without blowing anything up or producing any smoke.
What I'm trying to say is that you _could_ use your circular saw on the end of a #12 extension cord if you were careful to not jam the thing (back off at the slightest sign of slowing down), went very slow, and didn't make a career out of it. Do most of your cutting _before_ you take the lumber to the dock...
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