Is there an electrician in the house?

[Kevin Hooks]

I have an issue. About a year ago I started thinking about dropping a new sub-panel in my basement shop. I bought the panel and on eBay I found a lot of 25 amp breakers, not realizing that I was creating an issue for myself at the time. So I guess I am now between wire gauges Ie. 20amp breakers protect 12awg wire. My largest loads are the 3hp machines (Unisaw, planer, bandsaw). I would like to run the 12awg wire if possible just because it is easier to work with. My question: is it against code to run 12awg via 25amp breaker for non continuous duty electric motors? I've seem some mention that there are special tables in the NEC but I don't have access to a book. Or, should I be running 10awg regardless? Or should I put the 25amp breakers back on eBay and buy 20 amp breakers?

[Logan William]

Your breaker capacity is determined by your wire size, 12 gauge wire is rated for 20 amps, so you have to protect it by 20 amp or lower breakers. You shouldn't have a problem running any of those machines off a 20 amp circuit assuming you have them wired for 220V. If they're on 110 I would suggest changing them to 220 then you won't have any problems running 12 gauge for outlets.

[Carroll Courtney]

Google ampacity charts and you will fine all the capacitys of different wire sizes----Carroll

[Myk Rian]

Use 10 g wire and there will be no problems with the 25a breakers.

[Jason Rutkowski]

I second the 10g wire suggestion. I wired my whole house with 10g to go along with my 400 amp service, but im an extremist.

[Alan Tolchinsky]

I'm not an electrician but have done a lot of wiring. I would not want to work with #10 wire as #12 is hard enough to work with. And I don't think most outlets will work with it. To me #12 wire with 20 amp breakers would be best. Good luck.

[Myk Rian]

10g is barely stiffer than 12. He already has a bunch of 25a breakers. No sense buying 20a now.
It would also be an easy switch to 240v if needed.

[John Terefenko]

25 amp breakers??/ No wonder they were selling them. Not much use for 25 amp breakers in homes. If you are going to use them then you need to jump up to a #10 wire. To me it might be alot cheaper buying the breakers than the wire today. Price of copper is up there.

[Bob Glenn]

Don't even think about using 10g wire in regular boxes. Its almost impossible to wire up the recepticals because the wire is so stiff.

[John McClanahan]

25 amp breakers are rather uncommon. Can you get more breakers (of any size) to fit the panel, if needed? Wall outlets and switches will be over protected with 25 amp breakers. Also, the quick connect feature, that's the hole you just push the wire into, cannot be used with 10 ga. wire. You will have to use the screw terminals. 10 ga. wire will cost more per foot.

John

[Glen Butler]

To me it might be alot cheaper buying the breakers than the wire today. Price of copper is up there.

+1 This was my thought while reading through the posts. A 20 amp breaker is $5.50 jumping up a wire guage I would think is a lot more. But at least you will never have to worry whether you have the draw capabilities on a 120v circuit.

[Glen Butler]

25 amp breakers are rather uncommon. Can you get more breakers (of any size) to fit the panel, if needed? Wall outlets and switches will be over protected with 25 amp breakers. Also, the quick connect feature, that's the hole you just push the wire into, cannot be used with 10 ga. wire. You will have to use the screw terminals. 10 ga. wire will cost more per foot.

John

I don't believe you can use the quick connect for 12ga either. They are only available for 14ga. So moot point really.

[Kevin Hooks]

I can definately get new breakers, this is a standard Cutler Hammer box. I should have clarified a bit. I will be running my 120v circuits using 20a breakers and 12awg. The 25 amp breakers are all two pole for my 240v circuits (3hp machines - planer, Unisaw, Bandsaw, Cyclone). I think 3hp calls for 10awg anyway doesn't it?

[Myk Rian]

I think 3hp calls for 10awg anyway doesn't it?

Yes it does.

[Rod Sheridan]

Yes it does.

Not necessarily.

A high quality 3 HP motor will be under 14 amperes, so #12 wire and a 20 ampere breaker is all that's required.

Once you get into low power factor, low efficiency motors, the current can rise into the 18 to 19 ampere region.

Circuit requirements are not based upon horsepower, they're based upon current.

Always check the motor nameplate for full load current ratings.

Regards, Rod.