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Joined: Sep 2002
Posts: 25
R
Randy Offline OP
Member
is it legal to use a 14-2 for a switch leg only on a 20 amp circuit?

2017 / 2014 NEC & Related Books and Study Guides
Joined: Aug 2003
Posts: 1,374
R
Moderator
NO!

It is an illegal branch circuit tap. Fixture wires are one of the few legal branch circuit taps. These are discussed in sections 402.10 and 402.11. You have a branch circuit, not fixture wires.


Ryan Jackson,
Salt Lake City
Joined: Oct 2001
Posts: 172
W
Member
What about a switch that controls a motor with thermal overload protection? [Linked Image]

Joined: Aug 2003
Posts: 1,374
R
Moderator
Bob (Iwire) is right...this is a tough crowd! Watthead: I would agree with you on that one.


Ryan Jackson,
Salt Lake City
Joined: Jan 2003
Posts: 4,391
I
Moderator
Yes the members here are on top of things.

That's good. [Linked Image] it forces me to look things up like I should be anyway [Linked Image]

Bob

I agree, no on the 14 AWG with the 20 amp lighting circuit.


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Joined: Apr 2002
Posts: 7,274
Likes: 2
Member
Reminds me of a thread a while back....some adamant discussions on a tap rule for #14 from #12 (20 amp circ OCP.

That thread had a lot of action....time permitting I'll have to look for it.

#14 switch leg off of a #12 20 amp, you get a red sticker!

As to Watthead's comment, yes thats allowable, but the original ?? seemed to lean toward a resi situation.

John


John
Joined: Sep 2002
Posts: 25
R
Randy Offline OP
Member
when or is a #14 wire allowed on a 20 amp circuit ?

Joined: Feb 2002
Posts: 840
C
Member
Randy,

Circuits supplying motors and air conditioning equipment.

Case in point: The AC units at my house are ultra high efficiency.

Nameplate says:
Min circuit ampacity: 11 amps.
Min fuse/breaker: 15 amps
Max fuse/breaker: 30 amps

So the feed could be #14 protected by a 30 amp breaker.

Peter

[This message has been edited by CTwireman (edited 04-02-2004).]


Peter
Joined: Jan 2003
Posts: 4,391
I
Moderator
By Randy.
Quote
when or is a #14 wire allowed on a 20 amp circuit ?

14 AWG is rated 20 amps @ 60 C & 75 C, even 25 amps @ 90 C which helps when needing to derate.

The only thing that normally keeps 14 AWG on a 15 amp breaker is 240.4(D)

Quote
240.4(D) Small Conductors. Unless specifically permitted in 240.4(E) through (G), the overcurrent protection shall not exceed 15 amperes for 14 AWG, 20 amperes for 12 AWG, and 30 amperes for 10 AWG copper; or 15 amperes for 12 AWG and 25 amperes for 10 AWG aluminum and copper-clad aluminum after any correction factors for ambient temperature and number of conductors have been applied.

Notice the first part of that says:

"Unless specifically permitted in 240.4(E) through (G)"

(E) Tap Conductors.

(F) Transformer Secondary Conductors.

(G) Overcurrent Protection for Specific Conductor Applications

(G) has a table that lists about 10 applications that may allow 14 AWG on a breaker larger than 15 amps.

As Peter (CTwireman) pointed out HVAC equipment is one of those times, so are motors.

With the following nameplate data 14 AWG would be fine on a 30 amp breaker

Nameplate says:
Min circuit ampacity: 19 amps.
Max fuse/breaker: 30 amps

Bob


Bob Badger
Construction & Maintenance Electrician
Massachusetts

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