20 amp duplex and 15 am duplex on the same circut

[brad_casie]

i want to know if it is ok to wire a 20 amp duplex in series with 15 amp duplex recepticles, it is in the garage on a 30 amp breaker? i just got a bandsaw from grizzly and says in runs 20 amps on 110. i dont have any 220 in the garage right now. How do i wire the new 20a duplex, there is only 2 brass screws and one for the ground? Do i just use one terminal for black and the other for white?

Thanks

brad

 

[Charles (in GA)]

Seriously, sounds like an accident (or fire) looking for a place to happen. What size is the wire in the circuit. 15 amp and 20 amp 120v receptacles are not OK on a circuit protected by a 30 amp breaker. I'll bet its only 12 gauge wire too!!!!!

If you have a 20 amp circuit breaker and 12 gauge wire, its OK to have 20 amp receptacles, or 15 amp receptacles on the circuit, code makes the exception for the 15 amp rated receptacle on the 20 amp circuit, but on a 30 amp CB, no.

If you don't know for sure how to wire it, find someone who does, and have them show you and do it with you, so you can learn.

Charles

 

[brad_casie]

it is only 12g wire, i can add another breaker but i thought it would be easier to just add another duplex, if i changed the 30 amp breaker to a 20 then can i add the 20 amp duplex in with the 15's?

 

[Gary S]

No, you absolutely cannot put a 30amp breaker on #12 wire. #12 can handle only 20amps. If you try to draw 30amps on #12, you can expect to burn your garage down.
If you need a 30 amp circuit, you need to run a 30 amp circuit using #10 wire all the way from your breaker box.

 

[Charles (in GA)]

it is only 12g wire, i can add another breaker but i thought it would be easier to just add another duplex, if i changed the 30 amp breaker to a 20 then can i add the 20 amp duplex in with the 15's?

Yes you can. NEC 210.21(B)(3) permits this.

Charles

 

[Charles (in GA)]

No, you absolutely cannot put a 30amp breaker on #12 wire. #12 can handle only 20amps. If you try to draw 30amps on #12, you can expect to burn your garage down.
If you need a 30 amp circuit, you need to run a 30 amp circuit using #10 wire all the way from your breaker box.

While the above is certainly good general advise and rule to follow (especially in this case), realize that there are exceptions that come to mind (240.4(D)). Depending on the type of insulation used, the type of wire (THHN for instance) the #12 wire may be rated well above 20 amps, but for general residential use a #12 wire should be protected by not greater than a 20amp breaker.

Situations such as a dedicated compressor circuit might dictate (and be allowed by code) to have breakers as much as 250% greater than needed by the compressor during normal running, to prevent tripping of the breaker during startup.

Charles

 

[sberry]

Good thread, to add a bit, its highly unlikely the 30 would cause a problem with fire in the building wiring but the devices connected to these circuits are designed to be connected to breakers no larger than 20A, as Charles pointed out there are exceptions but they are for dedicated circuits, not for general use where anything may be connected.