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Why is it dangerous to chain power dividers? (sopuli.xyz)

submitted 6 months ago by [email protected] to c/[email protected]

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Besides putting too many devices on a single wall socket, that draw too much power, what is supposed to happen?

Like say I chain ten dividers and put a single vacuum cleaner at the end. Is that more dangerous than plugging it directly into the wall?

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[–] [email protected] 17 points 6 months ago (1 children)

Short answer, it's actually not.

The actual danger is overloading a socket. This is significantly easier with a chain of extensions.

Resistance on the individual plugs shouldn't be an actual issue. The only way it might come into play is if you are using a switch mode power supply at the end. This would adjust its current draw to account the reduced voltage. This would increase the current draw at the plug.

E.g. a PSU trying to draw 1000W. At 120V this would be 8.33A. If you drop 30V, then the supply would draw 11.1A. The intermediate plugs would dissipate 333W. You would be drawing 1333W from the wall.

In countries with low AC voltages, and a lack of fused plugs, this could overload a socket and cause a fire.

It's also worth noting that long extensions have the same issue though it's less. They also have a far lower rating when coiled than when uncoiled. E.g. I have a 13A extension that can only provide 4A when fully cooled.

[–] [email protected] 5 points 6 months ago (1 children)

They also have a far lower rating when coiled than when uncoiled. E.g. I have a 13A extension that can only provide 4A when fully cooled.

Do yours stop providing amperage when coiled? Or do they just get really hot? Because that's what happens when you overdraw.

Divisors can be quite dangerous for this reason IF they don't have a fuse. Some cheap dividers have a switch but don't actually have a fuse or breaker in them so they can be overloaded and set fires.

That extension cord you mentioned is also a huge problem because you can easily get past 13A from a divider and cause the extension cord to become a liability. Whenever you get long extension cords, especially if they are general use or for high-powered devices, ensure they are rated for 15-20A, 14 or 12 gauge.

Here's more info from Technology Connections: https://www.youtube.com/watch?v=K_q-xnYRugQ

[–] [email protected] 7 points 6 months ago

I'm UK based, so all our plugs are fused. We also work at 240VAC.

As for my extension, it has no limiter on current, other than the 13A fuse. It does have a thermal cutoff built into it's reel however. It might not be enough to stop the cable getting melty, but it should stop it catching fire. It would require a very high load, for a long time to reach that point however.

As I said, multi adapters aren't inherently dangerous. They just make it easier to create a dangerous situation, if used inappropriately.