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I have 12 gauge wires on a 20 amp breaker, and there are 3 power outlets in this circuit.

Can I create an extended outlet (just for a WIFI router about 50w) using 14/2 gauge wire on that 12 gauge circuit?

Why I am considering doing this:

  1. I have 14 gauge wires available
  2. This power outlet will only be used for the 50w WIFI router

Any safety concerns?
Thanks

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  • 1
    My suggestion is to just buy some 12 gauge wire and keep the 20 amp breaker. Wouldn't cost very much depending on the length of run and you still have use of the 20 amp outlets at full strength. Sep 27, 2023 at 12:17
  • Safety? Well, the entire world would be on fire if you couldn't put 14g on a 20. However it fails code.
    – Mazura
    Sep 28, 2023 at 0:11
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    Is your Wireless device POE capable? Then there's only cheap ultra-low voltage cable involved completely negating the need to fiddle with mains wiring.
    – Criggie
    Sep 28, 2023 at 3:22

3 Answers 3

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If you change out the breaker for a 15 amp breaker, then 14/2 wire to that receptacle is fine. Otherwise you're out of compliance with the NEC.

The safety concern with 14/2 wire on a 20 amp circuit would be an appliance at the new receptable continuously drawing 19.5 amps without tripping the breaker. The 14 gauge wire could overheat and cause a fire.

The NEC allows breaker circuits with wiring ampacities far in excess of the breaker tripping amperage, just not breaker circuits with wiring ampacities below the breaker tripping amperage.

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  • Thanks, I go replace the breaker.
    – Ming
    Sep 27, 2023 at 7:01
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    @Ming, you sure? Think of all of that 12 gauge wire already in that circuit that will go wasted. The price difference between 14 gauge romex and 12 gauge romex is about 0.15 USD per foot
    – popham
    Sep 27, 2023 at 7:37
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    @Ming I would rather just change the wire to 12 gauge. It might be different if you had buy the wire at a hundred feet, but most wire of those gauges come in useful lengths.
    – crip659
    Sep 27, 2023 at 10:17
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    You can buy 12/2 by the foot. A 15A breaker costs money too. The cost difference will be small, I think I'd try to preserve the 20A capability on this circuit by buying the cable.
    – jay613
    Sep 27, 2023 at 13:20
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    @Ming Use Yelp or whatever replaces the Yellow Pages to search for "lumber yards" and "hardware stores". You will find many businesses you never realized existed because they are not Lowes or Home Depot. Call them and ask if they sell Romex by the foot. Go and buy just the length of Romex you want. It's cheaper than small spool prices at big-box. Sep 27, 2023 at 19:11
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The likelihood of your 50W router suddenly pulling between 16A and 20A is pretty much zero. If it ever fails in an overcurrent situation, it will likely fail catastrophically (short circuit) and trip the breaker.

The problem is future owners - and even future you a few years from now when you've replaced the router and moved it to another location. And the HVAC quits, and this room is now the place you want to be warm and cozy (it might not be that room now, but room uses change over time) and you plug in a heater. Or worse, 2 heaters. And each heater draws 12A (the standard amount), for a total of 24A. Which is 20% above the rating of a 20A breaker. Which means that depending on the breaker and the trip curve, it may take a while to trip.

In fact, looking at a sample trip curve from Schneider Electric, 20% overcurrent might trip in 15 minutes or might never trip, but your 14 AWG wire could eventually overheat and start a fire. On a 15A breaker it would be 60% above the rating and trip between 2 and 15 minutes, preventing the 14 AWG wire from burning up.

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I have 12 gauge wires on a 20 amp breaker, and there are 3 power outlets in this circuit.

All wires on this circuit should be 12 gauge or thicker

Can I create an extended outlet (just for a WIFI router about 50w) using 14/2 gauge wire on that 12 gauge circuit?

No.

14 gauge wires require a circuit breaker downgrade to 15 amps first.

I have 14 gauge wires available

Mix and matching wire sizes on a single circuit goes against best practices.

Buy 12 gauge instead of creating an invisible hazard.

This power outlet will only be used for the 50w WIFI router

That's irrelevant.

There is nothing stopping a person from plugging in enough high draw appliances which exceed the 14 gauge rating.

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  • Exactly - you cannot predict what someone else will do with the power point in the future.
    – Criggie
    Sep 28, 2023 at 3:21

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