# Electrical question

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• posted on March 18, 2007, 10:30 am

True, but you failed to consider that romex might be appropriate when you proposed a #10 cordset as the "lowest cost solution available".

OK, but when the cost of #14 goes up, so does the cost of #10.

Maybe where you live, but I pay \$0.087/KWH. My estimate of \$0.10/KWH for a national average wasn't pulled out of the air. Here's a couple of links. http://www.entergy-mississippi.com/content/price/bills/Ms-bill.pdf http://www.eia.doe.gov/cneaf/electricity/epm/epm_sum.html

Sorry Lew, but I just don't trust you <G>. While your line-loss argument is valid for a conductor that is marginal or undersized for the load, the law of diminishing returns catches up pretty quick. I simply don't accept your assertion that an 11 amp load heats #14 wire enough to degrade the insulation. The wire length required to get a 2% voltage drop on #14 wire at 10 amps is 90 feet. At 30 feet of total wire length (15 ft x 2), voltage drop and heat simply won't be a big factor in this application. #14 is adequate. #12 is what I would use. #10 won't hurt anything.
My whole point is this. After your wire size is adequate for the task, you can't just arbitrarily jump up a couple of sizes and say, "Oh well, the electricity savings will pay for it." In an industrial application where the wire you install powers a motor that runs 24/7 at full load, maybe; but in a home shop environment, we may not live long enough to see the payback.
I think we done beat this horse to death. You have a nice day.
DonkeyHody "In theory, theory and practice are the same, but in practice, they are not."
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<%-name%>
• posted on March 18, 2007, 5:37 pm

Agreed. With a caveat.

Don't assume that your 14 ga conductor from an off-shore source has Cu purity levels for them to play by North American charts. Same thing for their insulation standards. Also, thermal increases along the length due to resistance is not linear with conductor length. Add to that, that inductive loads on a partially coiled 14 ga wire with an 11 amp load can geberate localized heat, and the whole 'perfect' argument goes out the window.
I have seen, with my own eyes, that 50' cords from off-shore suppliers (which means most cords) rated at 14 gauge AWG shrivel up into snake- mottling-like messes by ordinary uses on jobsites. And we're not talking about tables-saws or compressors either.

The argument you make about pay-back makes sense.... from 12 gauge on up.

You said it.
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<%-name%>
• posted on March 18, 2007, 8:42 pm
DonkeyHody wrote:

If you need a cord, buying a molded cord set will be lowest cost solution.

Sounds like a personal problem to me<G>.
Everything, including man, starts the inevitable march to the junk yard, the day it is put in service.
An 11A load on a #14AWG wire, produces heat.
Heat is the enemy of insulation.
Sooner or later it bites you.
> The wire

SFWIW, what some often forget in these discussions is the 80% rule.
The full load continuous current permitted by a molded case circuit such as found in the typical load center or panelboard is 80% of the nameplate value as defined by NEC.
Thus a 15A C'Bkr, used for #14AWG conductor protection, will allow 12A (15x80%) on a continuous basis.
Above 12A, you are operating on the time derate curve of the C'Bkr.
Your choice of #12AWG for this application is an improvement over #14AWG, and is economically a good one.
Many years ago, I decided not to worry about wire size and standardized on #10AWG for all cordage applications in my shop.
Strictly a personal choice.
I have found that with a little patience and making purchases when you are not under the gun, you often find sales on things including #10AWG cord sets, which is when I buy them; however, even at full price, the difference between #12AWG and #10AWG, 25 ft molded cord sets rarely exceeds the cost of a decent 12 pack.

As indicated, power savings alone is not the total answer. It is a combination of power savings and insulation life of not only the conductors, but also the power consuming device.
Trying to calculate the cost of reduced insulation life is an exercise I leave to others.
> In an industrial

Actually, in an industrial application, the payback period rarely exceeds 2 years, thus they tend not to have much spare capacity in their designs.

OK.
One final thought.
If this discussion has raised the awareness of the group to the fallacy of trying to use relatively small conductor size extension cords for relatively long applications, it will have served it's purpose.
Lew
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<%-name%>
• posted on March 19, 2007, 1:33 pm

Oh, you mean other people besides me and you are still following this tread?
And a fine and pleasant discussion it's been too.
But I still don't trust you. <G>
DonkeyHody "We should be careful to get out of an experience only the wisdom that is in it - and stop there; lest we be like the cat that sits down on a hot stove-lid. She will never sit down on a hot stove-lid again---and that is well; but also she will never sit down on a cold one anymore." - Mark Twain