# 14awg on a 20amp



## thegoldenboy (Aug 15, 2010)

Absolutely not.

Assuming your 14 is *not *part of the original factory wiring, and it *is* fused onto the 20A circuit and *not* just passing through the fixture on a separate circuit.


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## thegoldenboy (Aug 15, 2010)

*240.4 Protection of Conductors.* Conductors, other than
flexible cords, flexible cables, and fixture wires, shall be
protected against overcurrent in accordance with their ampacities
specified in 310.15, unless otherwise permitted or
required in 240.4(A) through (G).

(*A) Power Loss Hazard. *Conductor overload protection
shall not be required where the interruption of the circuit
would create a hazard, such as in a material-handling magnet
circuit or fire pump circuit. Short-circuit protection
shall be provided.

FPN: See NFPA 20-2007, Standard for the Installation of
Stationary Pumps for Fire Protection.

*(B) Devices Rated 800 Amperes or Less.* The next higher
standard overcurrent device rating (above the ampacity of
the conductors being protected) shall be permitted to be
used, provided all of the following conditions are met:

*(1)* The conductors being protected are not part of a multioutlet
branch circuit supplying receptacles for cordand-
plug-connected portable loads.

*(2) *The ampacity of the conductors does not correspond
with the standard ampere rating of a fuse or a circuit
breaker without overload trip adjustments above its rating
(but that shall be permitted to have other trip or
rating adjustments).

*(3)* The next higher standard rating selected does not exceed
800 amperes.

*(C) Devices Rated over 800 Amperes.* Where the overcurrent
device is rated over 800 amperes, the ampacity of
the conductors it protects shall be equal to or greater than
the rating of the overcurrent

*(D) Small Conductors.* Unless specifically permitted in
240.4(E) or (G), the overcurrent protection shall not exceed
that required by (D)(1) through (D)(7) after any correction
factors for ambient temperature and number of conductors
have been applied.

*(1) 18 AWG Copper.* 7 amperes, provided all the following
conditions are met:

*(1)* Continuous loads do not exceed 5.6 amperes.

*(2)* Overcurrent protection is provided by one of the following:
*a.* Branch-circuit-rated circuit breakers listed and
marked for use with 18 AWG copper wire
*b.* Branch-circuit-rated fuses listed and marked for use
with 18 AWG copper wire
*c.* Class CC, Class J, or Class T fuses

*(2) 16 AWG Copper.* 10 amperes, provided all the following
conditions are met:

*(1)* Continuous loads do not exceed 8 amperes.

*(2)* Overcurrent protection is provided by one of the following:
*a.* Branch-circuit-rated circuit breakers listed and
marked for use with 16 AWG copper wire
*b.* Branch-circuit-rated fuses listed and marked for use
with 16 AWG copper wire
*c. *Class CC, Class J, or Class T fuses

*(3) 14 AWG Copper.* 15 amperes* <- Here*

*(4) 12 AWG Aluminum and Copper-Clad Aluminum.*
15 amperes

*(5) 12 AWG Copper.* 20 amperes

*(6) 10 AWG Aluminum and Copper-Clad Aluminum.*
25 amperes

*(7) 10 AWG Copper.* 30 amperes

*(E) Tap Conductors.* Tap conductors shall be permitted
to be protected against overcurrent in accordance with
the following:

*(1)* 210.19(A)(3) and (A)(4), Household Ranges and Cooking
Appliances and Other Loads
*(2)* 240.5(B)(2), Fixture Wire
*(3)* 240.21, Location in Circuit
*(4)* 368.17(B), Reduction in Ampacity Size of Busway
*(5)* 368.17(C), Feeder or Branch Circuits (busway taps)
*(6)* 430.53(D), Single Motor Taps

*(F) Transformer Secondary Conductors. *Single-phase
(other than 2-wire) and multiphase (other than delta-delta,
3-wire) transformer secondary conductors shall not be considered
to be protected by the primary overcurrent protective
device. Conductors supplied by the secondary side of a
single-phase transformer having a 2-wire (single-voltage)
secondary, or a three-phase, delta-delta connected transformer
having a 3-wire (single-voltage) secondary, shall be
permitted to be protected by overcurrent protection provided
on the primary (supply) side of the transformer, provided
this protection is in accordance with 450.3 and
does not exceed the value determined by multiplying the device defined in 240.6.

*(G) Overcurrent Protection for Specific Conductor Applications.*
Overcurrent protection for the specific conductors
shall be permitted to be provided as referenced in Table
240.4(G)


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## Mr. Sparkle (Jan 27, 2009)

Wow, strange timing for this thread....

Just the other day I was having a talk with a carpenter who had asked me if it is true that you can use 14awg on a 20a ckt as long as the 14awg is only used on the load side of the switch.

He believed that you could do that for years, old wise tale from an old boss.

Go figure......


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## doubleoh7 (Dec 5, 2009)

Mr. Sparkle said:


> Wow, strange timing for this thread....
> 
> Just the other day I was having a talk with a carpenter who had asked me if it is true that you can use 14awg on a 20a ckt as long as the 14awg is only used on the load side of the switch.
> 
> ...


 


Tell him you believe that a roof with trusses spaced at 24" can be sheathed with 3/8 OSB.


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## Electric_Light (Apr 6, 2010)

Mr. Sparkle said:


> Wow, strange timing for this thread....
> 
> Just the other day I was having a talk with a carpenter who had asked me if it is true that you can use 14awg on a 20a ckt as long as the 14awg is only used on the load side of the switch.
> 
> ...


Practically yes, but code wise no. If it shorts out to ground on load side, the breaker will pop. Once you get inside the fixture, all the wires are 18 AWG solid.


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## 480sparky (Sep 20, 2007)

A simple perusal of T310.16 (or T310.15(B)(16) in the '11) shows #14 can even be on a* 25* amp breaker.




Mr. Sparkle said:


> .........
> He believed that you could do that for years, old wise tale from an old boss.
> 
> ......


*Wive's* tale, not wise. :whistling2:


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## MarkyMark (Jan 31, 2009)

I don't see why it is against code. The code states it's fine for "fixture wires," it doesn't say "factory installed fixture wires." We use 14 gauge light whips all the time for 2 x 4 troffers. To me, that is more of a stretch of the code than running wire through a bunch of strip lights.

240.5(B)(2) actually allows *18 gauge* wire to be protected at 20 amps for up to 50 feet when used as a fixture wire!


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## thegoldenboy (Aug 15, 2010)

480sparky said:


> A simple perusal of T310.16 (or T310.15(B)(16) in the '11) shows #14 can even be on a* 25* amp breaker.
> 
> 
> 
> ...


The * next to the 14, 12 and 10 AWG will kick you back to 240.4 (D).


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## 480sparky (Sep 20, 2007)

thegoldenboy said:


> The * next to the 14, 12 and 10 AWG will kick you back to 240.4 (D).



Which does NOT always apply. :whistling2:


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## thegoldenboy (Aug 15, 2010)

MarkyMark said:


> I don't see why it is against code. The code states it's fine for "fixture wires," it doesn't say "factory installed fixture wires." We use 14 gauge light whips all the time for 2 x 4 troffers. To me, that is more of a stretch of the code than running wire through a bunch of strip lights.
> 
> 240.5(B)(2) actually allows *18 gauge* wire to be protected at 20 amps for up to 50 feet when used as a fixture wire!


As long as it complies with T402.3.


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## thegoldenboy (Aug 15, 2010)

480sparky said:


> Which does NOT always apply. :whistling2:


Maybe I'm not seeing it Ken, 310.16 is Allowable Ampacities and 240.4 is Protection of Conductors. I understand that #14 cu is capable of withstanding a max. of 25A under the correct circumstances but 240.4 (D) does not allow us to fuse it at greater than 15A, other than the exceptions listed in 240.4 (E) & (G). 

In the OP, I'm *assuming** the conductors are THHN and not something specifically listed as fixture wires by Art. 402, so (E) does not apply and this scenario does not meet the requirements of (G).

Correct?

*Sometimes assuming can make an ass out of you and me.


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## 480sparky (Sep 20, 2007)

thegoldenboy said:


> Maybe I'm not seeing it Ken, 310.16 is Allowable Ampacities and 240.4 is Protection of Conductors. I understand that #14 cu is capable of withstanding a max. of 25A under the correct circumstances but 240.4 (D) does not allow us to fuse it at greater than 15A, other than the exceptions listed in 240.4 (E) & (G).
> 
> In the OP, I'm *assuming** the conductors are THHN and not something specifically listed as fixture wires by Art. 402, so (E) does not apply and this scenario does not meet the requirements of (G).
> 
> ...



You're looking right at it:

240.4(D) Small Conductors. *Unless specifically permitted in 240.4(E) or (G)*,............

Now go to (E) and (G) to see where the 'small conductor rule' does not apply.


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## thegoldenboy (Aug 15, 2010)

480sparky said:


> You're looking right at it:
> 
> 240.4(D) Small Conductors. *Unless specifically permitted in 240.4(E) or (G)*,............
> 
> Now go to (E) and (G) to see where the 'small conductor rule' does not apply.


Okay, we're on the same page. I thought maybe I was overlooking something. The "small conductor rule" does not apply in this instance. Your original post was in general whereas I was speaking specifically to the parameters of the OP. :thumbsup:


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## Greg (Aug 1, 2007)

It can be used on 20A OCP, when dealing with motors.


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## Mr. Sparkle (Jan 27, 2009)

Greg said:


> It can be used on 20A OCP, when dealing with motors.


Also even higher OCPD's at times.


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