“never plug extension cords into extension cords” is probably the most common piece of electrical related advice I’ve ever heard. But if you have, say, 2 x 2m long extension cords, and you plug one into the other, why is that considered a lot more unsafe than just using a single 4 or 5 meter cord?
Does it just boil down to that extra connection creating another opportunity for the prongs to slip out and cause a spark or short circuit? Or is there something else happening there?
For that matter - why aren’t super long extension cords (50 or more meters) considered unsafe? Does that also just come down to a matter of only having 2 connections versus 4 or more on a daisy chained cord?
Followup stupid question: is whatever causes piggybacked extension cords to be considered unsafe actually that dangerous, or is it the sort of thing that gets parroted around and misconstrued/blown out of proportion? On a scale from “smoking 20 packs of cigarettes a day” to “stubbing your toe on a really heavy piece of furniture”, how dangerous would you subjectively rate daisy chaining extension cords, assuming it was only 1 hop (2 extension cords, no more), and was kept under 5 or 10 metres?
I’m sure there’s probably somebody bashing their head against a wall at these questions, but I’m not trying to be ignorant, I’m just curious. Thank you for tolerating my stupid questions
Same reason power cables outside are fucking huge and the cord to your TV is tiny.
Electrical loss generates heat, so the longer the cable, the thicker it needs to be before that heat is too much.
Don’t forget a filament in an old school light bulb is just really thin wite. The thinner it is the less energy required to make it glow, which is why there’s like a 200 year old light bulb still going, it’s just a thick filament and very inefficient
So I’d never plug two of those rinky dink indoor extension cords together, it doesn’t take much length before it starts “glowing” like a light bulb filament, which happens at the plug and can burn a house down.
But…
Growing up doing rural construction with heavy gauge extension cords we never thought twice about hooking multiples up as long as it was just something quick for a few minutes at a time. Then never left it plugged into the source when not in use. You’d never do it for like a radio even because eventually it’s gonna heat up back at the aource.
Someone else already mentioned not pulling it right, we’d “doughnut” the connection so that if it did get yanked accidentally it wouldn’t unplug, but obviously it can’t be under constant stress even like that.
So many people here talk about the thickness needed of else it heats up. That is simply wrong. The heat is the same per length and is dissipated the same way with twice the length aka the temperature is the same*. The issue is that the short circuit current could drop below the value needed to actually pop the breaker, allowing for a ton of heat to be generated where it shouldn’t be. The same way a light bulb glows bright hot but does not trip the breaker etc., now just imagine the cable to be the glowing part.
*There is another issue if you do not lay them out, that the heat has nowhere to go. Causing coiled wires to have a far lower rating compared to when they are fully extended.