20A circuit wired with 14 gauge?

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Old 07-02-17, 07:43 PM
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20A circuit wired with 14 gauge?

In my house I have an outlet that I ran 14 gauge wire to a new outlet for a garbage disposal and dishwasher. I thought it was a 15 amp circuit. When I took a closer look at my electrical box I saw that it was a 20 amp.

At first I panicked because I used 14 gauge. But then I remembered when I wired them together that the old wires were the same size and the sheath was white and not yellow. So it should be obvious if one wire is 12 gauge vs 14 right?

Did the electrician put in a 20 amp circuit breaker but use 14 gauge wire? I don't remember ordering an extra 20 amp outlet when it was built so maybe the electrician just used a spare 20 amp? I live in Chandler Arizona and I'm not sure if this is allowed or not.

If it's not allowed is there anything to worry about? The garbage disposal and dishwasher if running at the same time should only take up 12.3 amps. And there is the 20 amp circuit breaker, should I put a note somewhere to indicate 14 gauge wiring. Or should I have someone change it to a 15 amp circuit breaker?

Thanks!
 

Last edited by Monsterdaddy; 07-02-17 at 08:01 PM.
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Old 07-02-17, 08:39 PM
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You need to investigate further. #14 wiring cannot be used on a 20A breaker.
Look at the jacket of the cable for size ID. It may be easier to see at the panel end.
That should be a 20A circuit and if an electrician installed it... it should be right.

I believe the color coded NM-b cable started around 2001. I also believe there is no place in the code that says the colored NM-b must be used but inspectors do like to see it..... and the inspector is always right.
 
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Old 07-02-17, 08:45 PM
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Thanks, I'm actually hoping my eyes were wrong and it was a 12 gauge. Simple fix to undo the 14 and get some 12. Obviously, I would rather have a 20 amp for a garbage disposal and dishwasher. I will look tonight.
 
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Old 07-02-17, 08:48 PM
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14 AWG cable should not be on 20A breaker. There are some exceptions, but not in this case.

the sheath was white and not yellow.
Older NM-b cables did not have color coding on the sheath. Both 14 and 12 AWG had white sheathing. (Or some other color depending on the manufacturer)
If exiting cable has same size wire and 14 AWG you installed, then it is 14 AWG and should not be on 20A breaker. You should change the breaker to 15A. It is very easy to replace unless you have some discontinued breakers. It is probably easier than installing a switch or outlet since wiring is already done.

Disposal and dishwasher should not be on the same circuit by code, but will not be a hazard if you replace the breaker with 15A.
 
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Old 07-02-17, 09:00 PM
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Disposal and dishwasher should not be on the same circuit by code, but will not be a hazard if you replace the breaker with 15A.
A gray area. The code doesn't preclude those two on the same circuit but some inspectors want to see two circuits.

I have been combining them on one 20A circuit with no concern from the inspector.
However... the same is not true on a 15A circuit. That would be considered undersized for the two units.
 
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Old 07-02-17, 09:07 PM
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I've been looking specifically at low amp garbage disposals and dishwashers. I found an inexpensive 4.5 amp gd and a 7.8 amp dw for a total of 12.3 amps because I thought it was just a 15 amp circuit originally. But probably good to stick with the low amps anyway.

The only other thing that may run off this is a TV if I decide to mount but I think I have a lot of cushion for that.
 
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Old 07-02-17, 09:30 PM
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7.8 amp dw
The 50/50 rule states that if a fixed in place appliance exceeds 50% of the total circuit amps there can be nothing else on the circuit. Technically you are .2 amps over. [QUOTE]
 
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Old 07-02-17, 09:43 PM
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BTW why does every new dishwasher instructions ask for a dedicated circuit??? I found that 7.8 amp (and another 7.1 amp) DW require that. Of course, it's seems to be the same boilerplate I read on every mfg pdf so maybe they just specify that no matter what.
 
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Old 07-02-17, 09:47 PM
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Does the 50/50 rule apply nationwide? I wonder how would it be applied since clueless consumers probably don't know this and buy DW without checking the amps.

BTW, is that why microwaves seem to all top off at 1200 watts (which I assume is 10 amps)?

I guess I better hope it really is a 20 amp circuit (or buy the 7.1 amp DW).
 
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Old 07-02-17, 11:14 PM
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Does the 50/50 rule apply nationwide?
It is part of the NEC but all codes are local and may or may not conform to the various sections of the NEC.
BTW, is that why microwaves seem to all top off at 1200 watts
The rule does not apply to countertop MWOs if that's the kind you mean. Insead that is probably so it will work on a common 15 amp circuit. It does apply to ones fastened in place over stoves.
 
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Old 07-03-17, 01:26 PM
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Thanks all, it looks like it was a 12 gauge wire and spray paint had made it's sheath look white. So I rewired it all with 12 gauge.
 
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