Comment on Home renovations

• GreenKnight23@lemmy.world ⁨7⁩ ⁨hours⁩ ago

  I didn’t know I was talking to a professional here!

  what would be the resistance of a plate of 16 gauge aluminum over 9 feet long?

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  • merc@sh.itjust.works ⁨6⁩ ⁨hours⁩ ago

    I’ll answer that for you, but first tell me what the (typical, average, ballpark) resistance of a human body is.

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    • GreenKnight23@lemmy.world ⁨6⁩ ⁨hours⁩ ago

      totally depends on conditions.

      for a typical dry adult hand with a moderate to heavy amount of calloused skin, it’s around 100k Ω. add any type of moisture or water like sweat it will be far less.

      btw did you know the skin is the primary conduit of electrical conductively? only HV is a real danger to your organs because it permeates through all tissue.

      side note. the internal resistance of the human body sits around 200-400 Ω.

      so, what’s the resistance of a 16 gauge plate of aluminum that’s 9 feet long? in all honesty it’s probably more likely to be 22 gauge though. which one would have the lower resistance?

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      • merc@sh.itjust.works ⁨5⁩ ⁨hours⁩ ago

        So, a fair estimate for a human body’s resistance is about 1000 Ω. That’s a case when the hands are sweaty, or there’s an open wound, or other cases where the skin isn’t acting as a massive resistor and blocking any current from flowing.

        According to this chart, a 16 gauge sheet of metal is about 1.5 mm thick. A 22 gauge is about 0.76 mm thick. I’m going to go in metric since everything is so much more straightforward.

        So, 9 feet long is about 3m long. Apparently stripper poles typically come in 38, 45 and 50mm diameters, so, let’s go for the smallest one to have the highest possible resistance. So, 38mm diameter means a circumference of 0.038 * Pi = 0.12m. So, the area of the pole is its circumference multiplied by its thickness, or about 0.12 * 0.00076 = approx 0.00009 m^2 (9*10^-5 m^2).

        To calculate the resistance of something you need its resistivity. This table gives resistivities for common materials. Aluminum is listed at 2.82×10−8 Ωm. To calculate the resistance given the resistivity, cross-sectional area and length you plug the values into:

        R = ρL / A

        R = 3E-8Ωm * 3m / 0.00009m^2 = 3E-8 * 3 / 9E-5 = 0.333 E-3 = 3E-4Ω

        Or, about 0.3 milliohms, or 300 microohms.

        As a check, you can compare it to the resistance of a wire. Another chart gives the resistance of wires of various gauges at 1000 ft, or approx 300m. So, a 3m length of wire is going to be roughly 1/100th of that resistance. The values in the chart are on the order of 1 ohm at 300m, so 0.01 ohms (10 milliohms) at 3m. Of course, wires are much thinner than a whole pole, but wires are also designed to be good conductors, but 0.3 milliohms vs. 10 milliohms seems like we’re in the right ballpark. So, even if the neighbour was dangling from a length of AWG 14 wire, and it was somehow not breaking, even then she’d be in no danger of electrocution.

        This is all just back of the envelope estimation, but we’re talking 6 orders of magnitude difference in resistance. No matter what the pole is made of, or how thin it is, it’s still metal, and metal has much lower resistance than flesh. The current is going to stay in the pole, and the pole dancer is in no danger.

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