5 ms·
Why would 2x20A wires use less copper than a 40A one? Current capacity is a function of the cross-sectional area. Or did you mean that you only need to run one
by lutorm 16y ago
Why would 2x20A wires use less copper than a 40A one? Current capacity is a function of the cross-sectional area.
Or did you mean that you only need to run one set of wire instead of multiple ones to multiple outlets?
- ramchip 16y agoAccording to (http://www.faqs.org/faqs/electrical-wiring/part1/section-20.html http://www.faqs.org/faqs/electrical-wiring/part1/section-20....) and to the wiki article on wire gauges, 40A requires 8-gauge wire, which is 3.264mm in diameter, while 20A is 12-gauge, which is 2.054mm. The ratio of their cross-sectional area is 2.53; this justifies that the 40A wire conducts twice as much as the 20A but has 2.53 as much area, thus being more costly. I'm not sure why. Is the skin effect sufficient to explain this?
- mturmon 16y agoSkin effect is not a factor in 12AWG wire at 60Hz. It takes much higher gauges and/or higher frequencies.
- regularfry 16y agoI doubt it's skin effect. More likely to be a safety margin so that it doesn't risk overheating.
- kjuhygtfrde 16y agoYes, a ring circuit you run a single wire around the room and back to the fuseboard. With a spur circuit you run a single wire to the furthest plug. In a typical room going back to the fuseboard isn't much further so it's not twice as much wire - more like 10% more
- castis 16y agoIts my understanding that their electrical outlets are designed similar to a token ring network setup. That uses way less cabling than any other network.