14ga wire on a 20amp circuit?

[afazz]

I’m pretty sure what I found is not up to code, but I wanted to confirm before I swap breakers. Are there any exceptions to the code I’m not aware of? Or do 20 amp circuits always require 12ga wire?

Details:
Detached residential garage built in PA, USA in 2001. Dedicated lighting circuits with 20a breakers, 15a three way switches, 14ga neutral, 14ga travelers, 12ga power to the first switch. All THHN in PVC conduit. The total amount of lights per circuit draw less than 12 amps (80% of 15 amps), so I plan to switch out the 20a breakers for 15.

 

[pattenp]

Breaker is sized to the smallest amp rating wire used in the circuit. If 14 is used then breaker needs to be 15A.

 

[Norcal]

If it was a motor circuit, or A/C unit, it might be allowed, but for a branch circuit 14 AWG is 15A max.

 

[wyliesdiesels]

#14 is 15a max for those types of circuits

 

[TRWham]

THHN would be good for more except for limitations in 240.4(D).

 

[afazz]

Thank you all for confirming my suspicions, I'll pick up some 15 amp breakers!

 

[NUTTSGT]

20A breakers and 14ga wire sounds like job security for some of us.

 

[Norcal]

20A breakers and 14ga wire sounds like job security for some of us.

In a normal branch circuit, yes, 14 AWG should never have overcurrent protection exceeding 15 amperes.

 

[NUTTSGT]

In a normal branch circuit, yes, 14 AWG should never have overcurrent protection exceeding 15 amperes.

We see it alot and when it gets cold for a week or so around 0°F, we see it in structure fires with electric heaters, knob/tube and 30A fuses.

Why 30A fuses, because they already blew the 20A fuses 2-3 times.

 

[Metal-Marc]

We see it alot and when it gets cold for a week or so around 0°F, we see it in structure fires with electric heaters, knob/tube and 30A fuses.



Why 30A fuses, because they already blew the 20A fuses 2-3 times.

I had an electrician replace the old main fuse panel with a modern breaker panel some 20 years ago. About one third of the fuse receptacles in the old panel were half melted.

 

[Syberia]

If it's THHN in conduit, why not just replace the small amount of #14 with #12?

 

[TTTTTT]

So playing devils advocate here, if you added an led light off off a 20 amp circuit all wired with 12 gauge with a small piece of 14 gauge that would be a no no. The draw would be very small through that piece of 14. Obviously if the 14 gauge piece is in line and and continues to a 12 gauge that would a no

 

[AntonLargiader]

Probably, but it seems to me the nature of the no-no would depend on the details. If you're plugging a 14g cord for the LED into a recep, you're just building a non-listed appliance assembly which many of us do all the time. If the 14g is part of the branch circuit, that's different.

So playing devils advocate here, if you added an led light off off a 20 amp circuit all wired with 12 gauge with a small piece of 14 gauge that would be a no no. The draw would be very small through that piece of 14. Obviously if the 14 gauge piece is in line and and continues to a 12 gauge that would a no

 

[TTTTTT]

Thanks, I guess from a 20 amp 12 gauge fed junction box, you ran a single 14 /2 gauge wire to a switch to a led light from that junction box. Again a very small draw though the 14 gauge part.

Sent from my SM-T290 using Tapatalk

 

[dscheidt]

We see it alot and when it gets cold for a week or so around 0°F, we see it in structure fires with electric heaters, knob/tube and 30A fuses.

Why 30A fuses, because they already blew the 20A fuses 2-3 times.

when I bought my house, the two or three circuits supplying outlets on the main floor had been 'upgraded' to 50A breakers. 50A in 90 year old rubber covered 14AWG wire makes wire pretty crispy.