[mrsmith]

“power cables supporting streetcars in Portland were stretched to the extreme, melting in some areas.”

Something wrong here.
Power cables are not insulated, and aluminum or copper doesn’t melt at these temps.

[Quality_Not_Quantity]

Power cables are not insulated, and aluminum or copper doesn’t melt at these temps.

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Not insulated? If you’re referring to the ones up on the power lines, that’s true. These are the ones feeding the overhead trolley wire that power the street cars. Those are insulated - that one looks like it was abraded and shorted out.

As far as not melting, what happens is that they do elongate as they get hot, so any combination of ambient heat and internal heat generated by an increase in current will cause the overhead wires to sag on hot days and/or days with big loads on the supply grid.

[ifinnegan]

Something wrong here.
Power cables are not insulated, and aluminum or copper doesn’t melt at these temps.

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Exactly.

[cva66snipe]

Something wrong here. Power cables are not insulated, and aluminum or copper doesn’t melt at these temps.

Partially true. The Primary side of the power grid running on power poles up to the power pole for a structure are not insulated. Those are about 7600 volts give or take some. The cables feeding off the transformers on the pole going to a structure as service drops for or underground are insulated and a much loser voltage. Also cables in extreme heat will expand and sag some.

[EEGator]

It would be from the increased amperage running through them due to the heat. (AC units cranking, etc.)