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on the chart of allowable ampacities of conducters what determines which column you use? i live in south alabama and am getting conflicting reports on whether to use the 75 or 90 degree celcius column.
This throws another wrench into it. Conductor sizing for a residential service is also different. It does not use the same chart as feeders or branch circuits.thanks guys. i will use the 75 degree column. as for what i'm sizing up, it is a 400 amp ext panel with blade disconnect feeding two 200 amp interior panels. i will need to use 3-0 copper.
That refers to the temperature that wire/cable might be exposed to. For example an attic possibly might get very hot in your region. Or in a factory the temperature conditions could be very hot where the wire is being run.thanks so much. i understand a little better now but am still confused about the temp of the environment part.
Just did a similar installation back in April, I used two 4/0 conductor per leg, but mine was 3 phase. There are some pictures here:thanks guys. i will use the 75 degree column. as for what i'm sizing up, it is a 400 amp ext panel with blade disconnect feeding two 200 amp interior panels. i will need to use 3-0 copper.