General question about wiring / loads

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Old 12-03-18, 12:43 AM
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General question about wiring / loads

Theoretical question here... Let's say you have 12 gauge wiring running from the circuit breaker in line to various outlets and switches, but at some point there's a 14 gauge pigtail or line of wire that branches out from the 12 gauge outlet to an outlet and ends there. Now let's say that there's a 500 watt load being drawn from that outlet on the 14 gauge line. And let's say other lights and outlets along the 12 gauge line are drawing 1,800 watts. Is as much electrical load stress being put on the 14 gauge wire as the 12 gauge wiring, even though that little branch of the 14 gauge wiring is only running 500 watts?
 
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Old 12-03-18, 04:53 AM
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Answer is no. The current on the 14 gauge wire will be dictated by the load on that branch only. However, you would not want to wire anything this way. Not only would it be against code, it would also be a potential fire hazard because the 12 gauge cabling would be on a 20A breaker, and 14 gauge is only rated for 15A.
 
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Old 12-03-18, 02:43 PM
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Correct on the theory -- each section of wire carries only the load actually connected through it. In a controlled, engineered system where you know all the possible loads in advance, this would be no safety problem because you can size the branch wiring to the known loads. However in general premises wiring, code usually does not allow reduced gauge taps because anyone in the future could plug in different stuff or swap out lamps and overload the circuit to a dangerous level. So in virtually all circuits it is mandatory to size all wiring in the circuit to match the breaker size.
 
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