DIYbanter - View Single Post - can't figure correct resistance for teflon coated copper wire

Ralph Mowery

In article ,
says...

Hmmmm... If it is sufficiently important to know the precise and accurate resistance of a given (and very short) length of wire, then that method will not work very well. I have never, ever come across a factory-sealed spool of electrical wire that is within even 1% of the nominal length, with the tendency to run a bit long
rather than short. And even shop-cut lengths tend to have a bit added for waste and crimps.

And here is another issue: I keep a pretty good Fluke meter which gives a resolution of +/-0.5% in ohms in ranges above 32 ohms, and +/- 2% at the lowest range. Which may not be good enough in this application.

Again, if it is sufficiently important, then the correct instrumentation and the calibration and set-up of same is critical.

For most at home the best way for very low resistance is to have an
ampmeter and voltmeter and varitable power supply. Put as much current
as you can through the wire and measure the voltage across it and ohm
law the resistance.