Are the feeders for a subpanel sized at the table 316.10 size because the wires are considered branch circuits coming from the main panel?
Example: 200A main panel single phase 100A subpanel 75 degree rated lugs SER from main panel to sub panel Given the loads for the sub panel are an unknown mix of continuous and non continuous I would suppose sizing at 100% continuous. Am I correct the cable would need to be #1 copper or 2/0 aluminum because 125% of 100A puts me there or am I oversizing?
Second: 200A breaker in 1600A main switchgear three phase 120/208 200A subpanel three phase Conduit run to subpanel Again unsure of continuous vs non-continuous I assume needing to size at 100% continuous Would I need 250kcmil copper, or could I go smaller because I thought there was a three phase multiplier to reduce the needed amperage size. Or again am I missing something and oversizing?
The breaker is sized to protect the wire is a a good way to look at it. How did you come about for #1 wire for an 100 amp panel? on a 100 amp panel a #3 usually is required. #1 is for 125 amp panel I do believe without looking at 316.
Mic Short answer ... no. This is a feeder. 310.16 is fine at 100% and you could even use the round up rule (240.4(B)). #3 is 100a so it is a perfect fit on a 100a feeder (no rounding). As a design issue you might not want to "round up" but generally you have pretty good diversity in residential feeders.
3 #3s and 1 #8. Four wire feeder. Seperate grounds and neutrals. Bond ground bus to electrodes and metal piping if available. If this is unattached you need a main breaker in the sub. If attached you can use a lug panel.