that is not what i said though chris. i said i always put a 15 amp breaker on a 20 amp circuit.

by doing it this way, the breaker will trip before you can stress the circuit.

 

Are you installing a 15amp breaker on a circuit with 12ga wire and 20amp receptacles?

 

yes. a full 20 amp circuit, but i only put in a 15 amp breaker. the local building inspectors love to see my work, cause they know there will never be a problem with the electrical.

my garage has 6 gauge wire to the compressor and plasma cutter outlets, but i only have 40 amp breakers on those lines. i always use 1 size smaller breaker than the wiring is designed for.

 

That is not a problem using wire one size larger. The only problem is using a 20amp outlet on a circuit with a 15amp breaker.

 

I quite understand what the rules say, and don't have a problem with that. What I don't understand is why you say the 20 Amp receptacle is going to cause an overload on a circuit with a 15 amp breaker. No matter what load is plugged into the 20 amp receptacle, it can never draw more than 15 amps before the breaker trips. Actual performance will be the same as a 15 amp receptacle.

 

A 20amp receptacle allows you to use an appliance/tool/whatever that is rated for more than 15amps on the circuit which will overload the circuit.

 

But if the circuit is otherwise correct, it cannot overload - the 15 amp breaker will protect it. No different than plugging a toaster and an iron into a 15 amp receptacle at the same time -

 

I had done the same thing in my house. My entire house is wired with 12ga. For what little extra it cost me for the wire, I have peace of mind, also if I have to add a higher draw item. It's as simple as changing the breaker instead of running a whole new line.

 

I have to disagree with this. Putting a 20amp outlet on a 15amp circuit is the same as increasing the size of your wire. on the other hand, You should not put a 15amp outlet on a 20amp circuit. That is where the meltdown would occur.

 

Frank,

The NEC excerpt posted above specifically prohibits that first condition while specifically permitting the second in your statement.

See my post above for the link to the NEMA diagrams. A 15A receptacle will only permit a 15A rated plug to be installed. A 20A NEMA receptacle will permit either a 15A or a 20A plug to be inserted. A 20A NEMA receptacle can be identified by looking at the neutral slot. It will have a "T" shaped opening (sideways). A 20A rated NEMA plug has the neutral spade perpendicular to the hot spade. It can only be inserted into a 20A NEMA receptacle but not a 15A receptacle. A 15A rated NEMA plug can be inserted into either a 15A or a 20A NEMA receptacle which is still a safe condition. Therefore, a 15A receptacle will ONLY allow a 15A plug to be inserted, not a 20A plug.

20A receptacles should be used when a 20A load is anticipated. Since the load is anticipated, the rest of the branch circuit should be installed to accommodate it. That means at least 12 ga wiring and a 20A CPD. If a 20A receptacle is NOT required, then the 15A receptacles should be used.

The plugs and receptacles are specifically designed to allow only correctly rated loads to be connected.

Chances are, most homeowners have never even seen nor will ever own an appliance or other device that REQUIRES and has a 20A NEMA plug on it. I've only owned one, an early 80s gas range that featured a microwave convection oven.

As far as installing a lower rated breaker onto an otherwise larger branch circuit, this is permitted and indeed does build in an extra margin of safety.

Steve

 

The outlets in my house are rated at 20amps/comercial grade. They are designed to except a 15amp or a 20amp plug (-l l) Now I am confused. Also why do the sell a 20amp gfci that only excepts a 15amp plug?

 

If someone is selling a "20A" GFCI outlet that accepts only a 15A plug, I'd bet they're cheating and you're probably buying knockoff imports. Chances are, you actually seeing 15A GFCI receptacles but not realizing it. Otherwise, that "20A" rating might be for the pass-thru only portion of the circuit.

Check out Leviton's site. They're a reliable manufacturer and properly comply with the NEMA receptacle ratings.

Steve

 

I see what you mean, but it still is not the correct way of doing things and should NOT be done since you are inviting an overloaded circuit.

Why someone wouldn't just install a 20amp breaker if you have it wired correctly for it is beyond me

 

A 15amp outlet is perfectly fine on a 20amp circuit PROVIDED that it is not the ONLY outlet on that circuit.

 

Quote:
<TABLE cellSpacing=0 cellPadding=4 width="100%" border=0><TBODY><TR><TD class=alt2 style="BORDER-RIGHT: 1px inset; BORDER-TOP: 1px inset; BORDER-LEFT: 1px inset; BORDER-BOTTOM: 1px inset">Originally Posted by tewferford

I have to disagree with this. Putting a 20amp outlet on a 15amp circuit is the same as increasing the size of your wire. on the other hand, You should not put a 15amp outlet on a 20amp circuit. That is where the meltdown would occur.

</TD></TR></TBODY></TABLE>

Wow, all this discussion -- looks like common sense is getting in the way of the code book...................or vice-versa.......