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Question: 14 on 20 AMP with one foot run.

4K views 29 replies 13 participants last post by  electures 
#1 ·
Here is the Issue: I installed an outlet in a closet on the opposite side of the wall of an existing outlet. And wired it with 14. This run is around a foot. The outlet I ran it from has an 15 AMP outlet but the wire feeding it is 12 and is on a 20 AMP breaker. I didn't notice this until I was done wiring it. Is this unsafe should I bother rewiring it? Someone already told me that on this short of run it doesn't matter.
 
#7 ·
Just to be clear about the part you asked about but which nobody else actually adressed directly... The 15 amp receptacle is allowable on a 20 amp circuit.

20 amp circuit can not have 14 ga. wire.
 
#13 · (Edited)
The tap rule (I forget chapter and verse in the NEC) allows the little (16-18 gauge) wires, called taps, in a light fixture to connect to a 15 or 20 amp circuit. This rule specifies the maximum length of such smaller wires, it is something like 14 inches, preventing 14 gauge wires from the wall switch all the way up to the ceilint light in a 20 amp circuit.

Now there are bathroom lights with a shaver receptacle (labeled max X watts) that have <14 gauge wires to connect to the power source. Perhaps something like this gave someone the idea that running a foot of 14 gauge on a 20 amp circuit was okay. Except that if run to a duplex receptacle, there could be two things plugged in drawing a total of more than 15 amps.

You can have single (non-duplex) 15 amp receptacles on a 20 amp circuit provided there are at least two receptacles altogether.

Heating of the wire due to larger current draw produces just as many BTU of heat at any spot in a 1 foot segment as in a 10 yard segment. It is the spot BTU, not the BTU over the leng6th of the entire wire, that presents a hazard.

OT: Meanwhile the voltage drop in each foot of a piece of wire, with a given load in amperes, is the same. It is the cumulative voltage drop over the entire length of the wire (round trip; hot and neutral for 120 volt circuits) that you are interested in.
 
#14 ·
When someone says “The outlet I ran it from has an 15 AMP outlet but the wire feeding it is 12 and is on a 20 AMP breaker” the first thing that comes to mind is kitchen SABC, laundry or bath receptacles, none of which are allowed to be ‘tapped’ to feed ‘an outlet in a closet’ (in general). Anyone else catch that?
 
#15 ·
I think everyone picked up on the incorrect mixing of the wire sizes and may not have thought about the source of the circuit or its possible restrictions.
 
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