Electrical resistance of flattened (smashed) wire?

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SUMMARY

The electrical resistance of solid copper wire, specifically #4 gauge (approximately 0.21 inches in diameter), does not significantly change when flattened with a hammer. The application discussed involves using this wire in a homemade spot welder, where the wire is inserted into a 1 3/8-inch diameter copper pipe to maximize contact area. The goal is to achieve minimal resistance for a current of 1.2 volts at 1500 amps. While some participants noted that work hardening may slightly increase resistance, it is generally accepted that the overall area of contact remains the primary factor influencing resistance.

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tinkeringone
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Can anyone tell me what happens to the electrical resistance of solid copper wire, i.e. #4 gauge, (about .21" in diameter) uninsulated solid copper wire when you flatten it, i.e. with a hammer?

I'm going to insert that wire inside a piece 1 3/8" diameter copper pipe, and smash the pipe over the wire to try to spread out the mutual contact area as much as possible. The application (a homemade spot welder) requires as close to zero resistance as possible between that very short length of #4 wire and the 1 3/8" diameter pipe. (It's for 1.2 volts at about 1500 amps. The unsmashed end of the solid wire will be the electrode tip, and the 1 3/8" diameter pipe will be the electrical tong it connects to.)

I just can't seem to figure out if the resistance of a copper conductor would increase or decrease when you mash it.

Thanks
 
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#4 wire can carry 1500 amps? You sure about that?

As far as smashing it, I don't think it would lesser or increase resistance.

Area is area...in my opinion.
 
Even if workhardening copper does increase its resistance a tad, I reckon it will get well annealed during welding operations! :smile:
 

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