I only run copper around here because the inspectors take an extra close look at any aluminum wiring that runs inside finished walls. They get out their box and start doing calculations and stuff.
If they saw 4ga on a 125 amp breaker they may not even bother to question it.
This is for a dedicated welder circuit.
NEC 630.11 I think is the one.
Because welders are intermittent variable loads, depending on the welding machines I could as much as double the breaker size over what's normally installed on a given wire size.
I could go as little as 6 gauge on a 100 amp breaker.
But I run my welding circuits to be at least 50% duty cycle for the wire size. Running my miller model 250 which is about out the size of an apartment refrigerator and weighs 360lb, at full power draws about 100 amps. 100 amps on 4 gauge wire is about a 80 or 90% duty cycle. My welder is rated for a 40% duty cycle at full power. If some how I ran the full 125 amps on that 4 gauge line it would be good for about a 60% duty cycle.
A welding machine that would draw 125 amps at a 60% duty cycle would be a machine about 2 class sizes bigger than what I have now. Those welding machines are typically used to build bridges, skyscrapers, power plants, ships, oil rigs.
When I move I will pull the 125 amp breaker off that welder circuit and put in an 80 or 90 amp breaker and relabel it "electric vehicle charger ".
|