I just bought an under-the-cabinet fluorescent light fixture to replace the one that broke. The cord on this new one is FIVE FEET LONG, about 2 feet longer than the old fixture. This means I'm going to have to coil up some of the wire.... does a coiled-up wire use more electricity than one that is straightened out?
I checked with my buddy's father-in-law who is an electrician, and the current runs the same distance whether the cord is coiled or not. So the voltage and/or wattage used is the same.
But isn't there 2 feet of resistance in the wire that wasn't there before? What about the electromagnetic field that surrounds the wire when current is flowing through? Heck, what about the potential emf should a coil find itself wrapped around the wire without it being plugged in? I need to read some Daniel Fleisch.
No extra power usage or loss of power. A coiled electrical wire will create a magnetic field (I think this is called “inductance” but it’s been a few decades since I did my physics O level) but it will be infinitesimal so you won’t need to worry about flying cutlery etc.
I don’t suppose you would do this but don’t knot the cable to shorten it. I’ve seen knotted cables overheat and burn down factories. Coiling is a much better idea.
But isn't there 2 feet of resistance in the wire that wasn't there before? What about the electromagnetic field that surrounds the wire when current is flowing through? Heck, what about the potential emf should a coil find itself wrapped around the wire without it being plugged in? I need to read some Daniel Fleisch.
Blimey, stuff down in the brain attic in unused boxes labelled 'school'. D'you remember Maxwell's left and right hand grip rules? One was for solenoids and one for motors. But which? And there was a corkscrew rule ... all lying dormant ...
Hey, it's good somebody asks stuff like this. We take a lot of our gizmos for granted. Most of what we use is safe, but we never ask.
I don’t suppose you would do this but don’t knot the cable to shorten it. I’ve seen knotted cables overheat and burn down factories. Coiling is a much better idea.
In the old sane days, plugs just had screws and a rubber keeper strip. You could just cut the cable and separate out the wires if things needed shortened. For decades now they've used those daft variegated plastic affairs at the junctions with the plug, that're supposed to stop the wires getting bent and breaking. They're the silliest nonsense to ever get a patent. The breaks just happen further up! And more often! And are hard to replace.
USB cables are offenders. The neck where the cable joins the connector itself is the first thing to go. The outer insulator separates, exposing the bundled wiring underneath. From that point onwards it's a losing battle. The general strain of wear and tear on those wires accumulates and they'll suffer fatigue, or something. Then, it's on to the next cable, etc, etc, etc.
There is a miniscule amount of resistance in the extra three feet of lamp cord. But at these voltages and such, it's absolutely negligible. Neatly coil the extra cable and secure it with a cable tie, you'll be fine
If you're really concerned about the extra 2 feet of wire, play it safe and snip it out between light fixture and cable plug and duct tape those together. Use the extra wire for your next pool party.
