14 wire in 20amp circuit

[Solarbear]

Does code allow for using 14 awg wire in switch loops or elsewhere in a 20 amp residential lighting circuit?

 

[augie47]

Nope. 240.4 & 240.4(D)(3)
You might look at 240.5(B)(2) also

 

[Dennis Alwon]

Nope. 240.4 & 240.4(D)(3)
You might look at 240.5(B)(2) also

Gus, I am amazed at how often this question is asked. I wonder where the misconception originated. It seems like it is misconstrued across the country. Since you are the old man I thought you might know.:grin:

 

[augie47]

Age allows me the time to store such data, but it also causes me to forget it :grin: View attachment 4076
It is definitely a "practice" that hangs on. Up until a few years ago the supervising electrical inspector (now retired) for the State of Tn ruled it should be accepted.
I have found no one who can actually quote a Code that allowed the practice.

 

[raider1]

I think some of the confusion comes from a misunderstanding of what a tap is in regards to fixture wire. I have had people in the past try to argue that the switch leg is a tap and use 240.4(E) and 240.5(B)(2) as their supporting evidence.

Chris

 

[augie47]

Solarbear, I forgot to say "Welcome to the Forum"
As stated, this is an often discussed topic.
You might enjoy linking to this lengthy thread which shows one of the earlier lively discussions.

http://forums.mikeholt.com/showthread.php?t=117753&page=20&highlight="fixture+wire"

 

[Dennis Alwon]

I think some of the confusion comes from a misunderstanding of what a tap is in regards to fixture wire. I have had people in the past try to argue that the switch leg is a tap and use 240.4(E) and 240.5(B)(2) as their supporting evidence.

Chris

I bet you are correct. It seems logical in some ways.

 

[Jim W in Tampa]

If an inspector let this happen then the idea will spread fast. Usually 1 red tag is all the teaching required. Perhaps part of an inspectors job is to teach. A reinspect fee will teach a lot faster than a no charge.

 

[LarryFine]

Solar, welcome to the forum!

I wonder where the misconception originated.

I think it came from the same standard as the pull-point-every-100' rule.

 

[TOOL_5150]

I have had insectors tell me that it is ok to run #12 to the first light then #14 to the rest - KNOWING the circuit was a 20A.

Sometimes I have to ask myself if they even really read / understand the code.

~Matt

 

[Hendrix]

I have had insectors tell me that it is ok to run #12 to the first light then #14 to the rest - KNOWING the circuit was a 20A.

Sometimes I have to ask myself if they even really read / understand the code.

~Matt

Were they electrical insectors or building insectors

 

[Solarbear]

Thanks for the input everyone, this is a great forum!

 

[viclibo]

# 14 is rated for 15 amp .................if you are using a 20 amp circuit breaker than you must use # 12 through out.

 

[480sparky]

# 14 is rated for 15 amp ........

According to........?

 

[Dennis Alwon]

# 14 is rated for 15 amp .................if you are using a 20 amp circuit breaker than you must use # 12 through out.

Just to be argumentative, I will say not always. Often you may use #14 wire with a 30 amp OCP device for A/C units.

 

[flashlight]

Just to be argumentative, I will say not always. Often you may use #14 wire with a 30 amp OCP device for A/C units.

Have not encountered this--where would you do this ?

 

[Dennis Alwon]

Have not encountered this--where would you do this ?

The most common place to do this is with an a/c-- at least in my world. Look at Table 310.16 and you see that #14 is good for 20 amps. Now we all know that art. 240.4 prohibits 10, 12, & 14 from being protected at 30, 20, & 15 respectively. However look at the asterik on Table 310.16 and read below. It says to go to 240.4(D)

(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.

This bolded section refers to (G) allows a/c units as an exception to the general rule.

Say we have an a/c unit that draws 19 amps. The a/c units allow about 175% for the max. OCP. 175% of 19 is 33 amps so a 30 amp breaker is allow and in some cases higher.

The a/c has thermal protection that protects the money from overload protection. The breaker is for ground fault and short circuit protection.

 

[LarryFine]

Have not encountered this--where would you do this ?

Min ckt ampacity - 20a (or less), max OCP, 30a.

 

[jumper]

The most common place to do this is with an a/c-- at least in my world. Look at Table 310.16 and you see that #14 is good for 20 amps. Now we all know that art. 240.4 prohibits 10, 12, & 14 from being protected at 30, 20, & 15 respectively. However look at the asterik on Table 310.16 and read below. It says to go to 240.4(D)



This bolded section refers to (G) allows a/c units as an exception to the general rule.

Say we have an a/c unit that draws 19 amps. The a/c units allow about 175% for the max. OCP. 175% of 19 is 33 amps so a 30 amp breaker is allow and in some cases higher.

The a/c has thermal protection that protects the money from overload protection. The breaker is for ground fault and short circuit protection.

Min ckt ampacity - 20a (or less), max OCP, 30a.

Here is a heat pump name plate to help show what they mean:

 

[480sparky]

Have not encountered this--where would you do this ?

Motors, transformers, welders, that sort of thing is not limited to the 15a/14ga 'rule'. See 210.2 for a shopping list of circuits.

I have seen in the past a motor calculation that allows a 35-a OCPD on #14 for a motor, but I've never seen it in the field.