“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
To clarify a bit, the benefit of the UK system isn’t the end device having a fuse, but the cable itself having a fuse.
In the US the setup would be something like
In the UK the 10A extension cord will have its own 10A fuse in the plug. So when you turn on the two 10A devices the fuse in the extension cord will blow and prevent the extension cord from overheating.
Bold of you to assume that the wall outlet would have a 20a breaker. Most don’t, unless they’re in a kitchen.
But you’re right about the resistance. Also, most extension cords are undersized for the loads they pull, they’re commonly made with 16 or even 18awg wire, further increasing resistance (which translates to heat).
Source: am electrician in US
The circuit power doesn’t matter for the example. I was just picking easy numbers. You can have the same problem as long as the rating of the extension cord is less than the circuit breaker. (And as you pointed that out this is a very common case due to the frequently low rating of extension cords.)