Comment on Why is daisychaining multiple extension cords considered unsafe, even if only done to the length of a standard cable?

BillibusMaximus@sh.itjust.works ⁨2⁩ ⁨weeks⁩ ago

• scarabic@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

  It’s not just the minimum materials in order to be cheap, period. They are given the minimum copper and shielding they need for the length they are made.

  As soon as you plug two together, you’re operating at greater resistance than either one was made for, and relying on the margin of error.

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  • Lanthanae@lemmy.blahaj.zone ⁨2⁩ ⁨weeks⁩ ago

    I’ve run a full DJ setup with speakers, a mixer, soundboard, laptop, etc. off a single line of 6-8 daisy-chained extension cords more times than I can count.

    …uh…how have I never learned of this.

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    • misterdoctor@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

      DJ’s really will find any excuse to tell you they’re a DJ

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    • bdonvr@thelemmy.club ⁨2⁩ ⁨weeks⁩ ago

      Honestly that’s probably not a huge electrical load.

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    • Mr_Blott@feddit.uk ⁨2⁩ ⁨weeks⁩ ago

      Because you ain’t loud enough lol

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• kevincox@lemmy.ml ⁨2⁩ ⁨weeks⁩ ago

  But unless coiled up on the ground the longer cable also has more area to dissipate heat, so the longer cable doesn’t change anything here. The heat output will be consistent for any section of the cable no matter how much more cable there is on easier side of it.

  The only think that the different resistance would affect is the voltage drop to the end device. But voltage drop varies wildly so you are unlikely to have a meaningful difference caused by a few extension cords (unless maybe you are already a bad case like an apartment building to start).

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  • Xtallll@lemmy.blahaj.zone ⁨2⁩ ⁨weeks⁩ ago

    Resistance of a cable is (resistivity x Length)/(πr^2) so the residence increases with length, which is why longer extension cords are designed thicker to reduce resistance. Power grids are voltage stabilized so the voltage drop will be negligible but it will take more power to get down the daisy chain, producing more heat.

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    • uis@lemm.ee ⁨2⁩ ⁨weeks⁩ ago

      And temperature difference to ambient temperature is thermal resistivity * dissipated power / (2\*π\*radius\*length). If you will plug dissipated power = resistance * current^2 and resistance into it, you will see, that temperature difference is invariant of length.

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  • HeckGazer@programming.dev ⁨2⁩ ⁨weeks⁩ ago

    The longer wire (being also thicker) has less resistance and is therefore wasting less power as heat, that’s where the Voltage drop is going.

    Sure, most of the time it’s fine if you know what you’re doing, but that’s why it’s general wisdom and not a hard rule, like “don’t put metal in the microwave”, it’s said to protect those that have no idea what they’re doing/why the saying exists

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• fine_sandy_bottom@lemmy.federate.cc ⁨2⁩ ⁨weeks⁩ ago

  I have no idea whether this really is the answer but it seems like the most plausible answer.

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• douglasg14b@lemmy.world ⁨1⁩ ⁨week⁩ ago

  Distance by itself would be no different than a single cord of the same length.

  However, connection points are areas of localized resistance where connectors meet. This can introduce dangerous areas.

  The practical, human, problem here is important. Connectors come loose, which makes them dangerous. The majority of this thread is treating this question like a paper test problem, when in reality there are other factors that outweigh the “under ideal circumstances” problem.

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• uis@lemm.ee ⁨2⁩ ⁨weeks⁩ ago

  The longer the wire, the more heat it can dissipate, so no, you don’t need wire to be thicker.

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  • gazter@aussie.zone ⁨1⁩ ⁨week⁩ ago

    Not sure if you’ve ever used fuse wire before. It’s what was used before capsule fuses and breakers. Essentially, if too much current goes through it, it will melt, breaking the circuit as protection. The thicker the fuse wire, the more current it can pass through without melting. The length of the wire doesn’t come into it. 1cm of 10 amp fuse wire will melt at the same current as 1 meter of 10 amp fuse wire.

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    • uis@lemm.ee ⁨1⁩ ⁨week⁩ ago

      Yes, maximum carried current is indeed invariant of length. I explained math behind it in lemm.ee/comment/17115060

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      • gazter@aussie.zone ⁨1⁩ ⁨week⁩ ago

        We may be discussing slightly different things here, I’m not sure if I follow the application of your math in this context.

        My point is that a thinner wire will get much hotter than a thicker wire, given the same amount of current. Is this not the case?

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