Perhaps some electricians, electrical engineers, or physicists can chime in on this one…
I recently installed my window A/C unit to combat the sweltering heat. I was just wondering if it’s necessary to untie the bundled power cord (by bundled, I mean the power cord is still wound into a small, tight ball with the twist-tie holding it together, just like how it came from the factory). Is there any danger in running an appliance such as an A/C unit for long periods of time with the power cord still bundled? Do the twists/turns/curves in the bundled cord pose any danger of starting an electrical fire, overload, or any other hazard? :eek:
And yes, before you suggest, “Why don’t you just simply unbundle the power cord?”, I would prefer not to (if I don’t have to), because I already have a jumble of other wires strewn about in my bedroom, and if possible, I’d like to keep the power cord on the A/C bundled together to keep it separate from the other cables.
You shouldn’t have any problem doing this. As long as the cord is intact, then the hot and neutral wires are side by side and their magnetic fields from current flow are effectively self canceling. If you were to split the hot and neutral and run them separately, you could have a problem, but only if the wires were coiled, When bundled, with the cord folded back and forth, the magnetic field from current running up one leg is cancelled out by the current running down the adjacent leg of the bundle.
It is not recommended to run ANY (ac or dc) current through a bundled extension cord, for example. The wire needs ambient air flow to allow heat to dissipate. Overheating increases resistance and this only serevs to exacerbate the situation… - Jinx
All conductors carrying current have some resistance, very small but still there.
Its the resistance that causes the cable to warm up, when its coiled its possible that there might be some self induction, but the main problem here is likely to be airflow.
The heat generated may be quite small, but if the wire is tightly bundled, then it can’t release that heat into the air.
If its likely to draw around 10 amps or more, then yes, I would definately unwind it, if 5 amps or less, you’ll probably be ok, in between is anyones guess, lots of dust and crap stuck behind something may add to any warming up, if the bundle is hidden out of sight.
The only time the NEC mentions bundling (which I’ve found) is in Article 334 regarding nonmetallic sheathed cable, e.g. Romex. 334.80 Ampacity addresses multiple NM cables passing through wood framing. Nothing in Article 400 which covers flexible cords speaks of bundling.
Would I personally do it? No. I tend to be cautious, sometimes overly-so. YMMV
YMMV