I came across a situation today ...
Double (220v) 25amp breaker but with a wire only connected to one of the breakers. Now the wire was 12awg which I know is undersized for 25 amps, but other than that is this a legal and safe way to use a double pole breaker?
Secondly, this circuit is powering a swimming pool pump and I would think that it should be a GFI breaker (it's not). Is that a requirement?
Thanks, Stephen
There are a lot of things going on there. Normally you can't protect a
12ga wire with anything larger than a 20a breaker but since this is a dedicated motor load you can go to 250% of the FLA of the motor.It is not strictly legal to use a 2 pole breaker on a single pole load (mfg instruction thing) but it is not dangerous.
Yes you should have this on a GFCI breaker.
Thanks for your help.
I've read about the 125% rule which I think means that the
25amp breaker is OK in this situation with 12 awg wire.How is the 250% rule applied?
240.4(D) says you can only use 20a max breaker on a 12 ga wire but there are exceptions and one is on a dedicated motor circuit.
In the motor articles, using the FLA on the motor plate,
430.52 says if the motor has internal overload protection you can use an inverse time breaker that is 250% of FLA430.122 says you size the wire to 125% of the FLA, using 310.16 (25ga = 25a)
These are rules best implemented by electricians and engineers who understand all the other issues. For most people, you just put the 12 ga on a 20a breaker and avoid all the confusion. You really should be using a GFCI on the pool pump.
680.22(B) GFCI Protection. Outlets supplying pool pump motors from branch circuits with short-circuit and ground-fault protection rated 15 or 20 amperes, 125 volt or 240 volt, single phase, whether by receptacle or direct connection, shall be provided with ground-fault circuit-interrupter protection for personnel.
Thanks again for your help.
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