Why are the power lines on the poles so small in gauge but for example my 200 amp service has a much thicker wire going into the panel. ?
In: Engineering
People have discussed distribution voltages and Ohm’s law at length already, which is all true, but there are 2 other things that are missing from the conversation.
First, the wires on the pole are larger than you think. They tend to be uninsulated aluminum with a steel core for strength. Between not being insulated and being quite high, they look smaller than they really are.
Second thing is that because they’re uninsulated and because they’re out in free air, the utilities are allow much higher current than you are for a given cable gauge. That’s because electrical insulation also acts as thermal insulation, greatly reducing heat dissipation, and the codes for house wiring make additional conservative assumptions that this cabling may be stuffed into a conduit or grouped with a bunch of other wires in a confined space that further reduces heat dissipation. Thus the allowances for your house are very conservative, while the utility’s bare wires in the open air have excellent heat dissipation, even if it’s hot and sunny outside.
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