"Assuming all connections are up to code"

0
since you can not (per NEC) parallel anything smaller than 1/0

I should have known better than to ask a question like this here among all the "experts". I should have said all connections are tight and secure. What I wanted to know was how to answer some one that asked me this as strictly a theoretical question. There is no intent to use something like this in any building wiring of any type. No hidden meaning or plans to use this anywhere, just a simple question. If one wire will carry 20 amps, will two of the same size in parallel theoretically have double the capacity. I did not realize that I had to lower the question to a fifth grade level to get any sort of simple answer.

The current rating on wires is based on the rules involving the heat dissipation, etc... there's NO WAY to answer your question. There's no way to guarantee that small gauge NM is going to be balanced enough to support larger currents in parallel.

In an ideal situation, the resistance of paralleled conductors is halved, which means you can carry twice the current for the same voltage drop. However, there are more issues to ampacity than just DC resistance.

shadetree_bob, your second post in this thread is completely unwarranted and makes you look like a jerk.

And believe me, I know about looking like a jerk.

two 12 ga wires together does not equal 1 eight ga which you would need for 40 amp. I t equals approximately one ten ga which is only good for 30 amps

I have always wondered about this. You would need three 12g wires to equal the cross sectional area of one 10g wire. (or is it surface area, I forgot). And if this holds true, what about a section of copper pipe. Since it is a hollow conductor wouldn't it carry charge on the inside and outside surfaces?

I realize these questions have no practical value. It's just something I have always wondered about.

Pooh Bear

No! Current does not flow across the surface, it flows through the conductor material.

https://phet.colorado.edu/sims/html/resistance-in-a-wire/latest/resistance-in-a-wire_en.html

All these people pretentvyo be ecoerts but being too ignirant. We in power utility very iften run csble in paralle.

"All these people pretentvyo be ecoerts but being too ignirant. We in power utility very iften run csble in paralle. "

I bet some of you even proofread comments before you hit the "Submit" button.

It's funny how the brain can interpret such totally scrambled writing. I read and understood Victor's post and didn't even notice the errors until elltwo pointed them out!