Unwinding of power extension cords

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AC power cords have the Active an Neutral conductors twisted around each ot her, minimising any included loop area. Inductance at 50Hz is completely sw amped by copper resistance.

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Even running cords under thick carpet or bundled with others is a bad idea.

People's homes have burnt down because of it.

... Phil

Both!

If they are close coiled, yes, heat cannot escape. If they are close coiled, more heat is generated. A double whammy.

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When layered as well, the surface area exposed for cooling is much smaller.

The heat in Watts follows the "I squared R" rule - so as the cable rises to a higher temp than otherwise the R value rises too so the is more heat for the same load.

R increase = 1 + temp rise / 245 in degrees C

.... Phil

I was thinking more in terms of induction heating in a coil with AC currents. It isn't just the inability to cool the coil.

The cores being twisted alleviate that.

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Induction heating uses Magnetism & Eddy Currents, also absent here.

Winding a twisted pair cable on a drum adds no inductance.

..... Phil

Just for fun, I once saw a welder attempting to do some (Mig?) welding from his trailer mounted welder. (he was welding aluminum) The welder had an internal spark gap to generate High frequency to start the arc. He was having a hard time getting his welder to arc properly until he uncoiled the welding cable off the trailer. Once he did that it work great.

Three weeks ago you posted a puzzle over on SED, and then died, or that's what all your pals thought! Are you going to finish the thread?

Yes. We are waiting for you, Phil.

I am guessing that you have gone away because one of us got it right... but you have so much vial hatred for everybody so that you cannot admit that. Being that way can not be good for ones' health.

Do I need to change my name?

Surely no to Bruce!