110 Wire Guage question

[Midniteoyl]

You need to upgrade the wire.. Doubling the wires will NOT equal double the gauge, more like a third more. Voltage drop should be less, however, but only on that doubled leg. Your small neutral will still be a limiting factor.

I would upgrade to at least 10ga (8ga is better since you have such a drop), but keep the breaker(s) at 20amp.

 

[CliffordK]

I'm going to reverse my position on this and say to go ahead, it should be fine, although your building inspector would have a cow if he saw it.

PROVIDED BOTH WIRES ARE CONNECTED TO THE SAME BREAKER (which is discouraged). Perhaps you could do it with a pigtail and wire nut.

Anyway...
Say you have a single 20A breaker.
Then the whole circuit will be limited to 20A, independent of the wire configuration, and no individual wire would get over 20A.

Now, with the data you've given.
About a 40V voltage drop at 10A (assuming 120V at source).

V=IR
And your resistance is about 4 Ohms over the circuit.
That means that each leg has a resistance of about 2 Ohms.

Now, if you double the wires on the "Hot" leg, then you halve the resistance on that leg, to give you about
1 Ohm on the hot leg, and 2 Ohms on the neutral leg.

Add it together, and your circuit resistance should be about 3 Ohms, and your voltage drop would be 30V rather than 40V, giving you a final voltage for the circuit at about 90V at 10A.

You're still running 10A on all the legs, well, actually, the Neutral leg still gets the 10A, the "hot legs" would get half that, or 5A on each one.

You just couldn't install a larger breaker than the 15A or 20A breaker.

Even if the circuit was a mile long, as long as you're feeding less than the 15A or 20A into it, you should be fine, although some of your devices might compensate for the voltage drop by sucking more power.

If you doubled the neutral too, then your resistance would be halved on both legs, and your voltage drop would only be 20V rather than 40V, giving you about 100V final voltage at 10A.

Is any of this in conduit that would be easy to pull the old wire and put in new?

Also, keep in mind that only about 2/3 of the power that you're paying for is getting to the destination. If used lightly, that wouldn't be an issue, but if used continuously, then the cost of the power loss could add up.

Anyway, it is up to you. As long as you don't oversize the breakers, you should be reasonably safe, but certainly not considered Kosher.

 

[Midniteoyl]

Resistance is not halved by doubling the wire in AC circuits..


http://daycounter.com/Calculators/SkinEffect/Skin-Effect-Calculator.phtml

http://www.daycounter.com/Calculators/AWG.phtml

 

[mcandrew]

Id say its at least pretty close. There shouldn't be any skin effect at 60hz, and if its stranded wire, theres a lot more skin.

 

[SPYDERLK]

Id say its at least pretty close. There shouldn't be any skin effect at 60hz, and if its stranded wire, theres a lot more skin.

There ya go. ... Not sure stranded will be analogous to multiple single conductors tho. - Not that this is an issue here.
larry

 

[woody]

wow, this is interesting but what if he doubled the hot wires say tie the red and black together double the neutral and ground tie them together and then drive a ground rod in at the old well site giving him a path to ground? would this get him by until he could do better with larger wire?

 

[SPYDERLK]

.,,Yes.

 

[FourSonsFarm]

The National Electrical Code (NEC Article 310.4) states that for wires to be run in parallel that they must be of size 1/0 or larger. Granted no one will be coming behind you to inspect the work. One thing to keep in mind. As the load on the circuit goes up the voltage will go down, inversely proportional. Also not a good idea to place a second grounding rod at the old well pump site. If for some reason the path to ground is of less resistance to the new rod than the old one, then the whole house would start grounding to the rod at the old well pump site. The two number 12s or 10s in parallel would hardly be enough. All that being said, it should work for light loads, but keep an eye on things. Definitely not the best long term solution. Just my 2

 

[hosspuller]

Another reason to pull new wires. A supply voltage of 80 - 90 volts is bad for refrig compressors. The lowered voltages produces heat in the compressor windings. The added heat shortens the life.

 

[woodlandfarms]

Well, I went to HD today to do some research. I have 14-3 for the well wire (what a friggin joke, can't believe it is what they used, even if the pump is only 1/2HP).

I think I would need 10-3 to make the 300 foot run. It is $4.09 per foot. As this outlet is seldom used (too much in my opinion as it provide electricity to the inlaws camper if you get my subtle dig) - I am not going to run new wire at this point. Not worth it Financially.