"Surfer" writes:

I would like to test the current carrying capability of a connector that's
used in a 208VAC 3-phase circuit. I have the manufacturer's spec (10 amps at
300V) and just want to verify performance in this application. For reasons
that would take too long to explain, I want to test this connector out of
circuit. It was suggested to just use a low voltage supply, like a PC power
supply and set up a resistive load that would deliver 10 amps.

Since the formula for power, P=I^2*R doesn't include a value for voltage,
would 10 amps at 3VDC provide the same heating effect as 10 amps at 208VAC?


10 amps over the connector will heat it up exactly the same whether
you run 3V over it or 208V. The only relevant voltage is the voltage
drop across the connector, which is dependant on the resistance of the
connector and current run through it.

The R in your formula above is the R across the connector, not in the
load.

The only relevance of the 300V voltage spec is for isolation.

To compare AC with DC you need to use the RMS current of the AC.