ryan_618
Senior Member
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- Salt Lake City, Utah
Don: I don't think we need to 210.19 to change the OCP provisions. 240.21(A) already nullifies the provision of 240.4.
14 ga. on 20 or 30 a circuit
- Thread starter realolman
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Twoskinsoneman
Senior Member
- Location
- West Virginia, USA NEC: 2020
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- Facility Senior Electrician
Ryan, here is the problem I keep running into. 240.21(A) says taps need to have OCPD IAW 210.20. And then 210.20(B) says conductors need OCPD IAW with 240.4......
So how did 240.21(A) nullify 240.4?
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Don: I don't think we need to 210.19 to change the OCP provisions. 240.21(A) already nullifies the provision of 240.4.
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
I should have said nullifies 240.4(D). 210.19 says I have to size the conductor with sufficient ampacity, which 14 AWG satisfies. 210.20 says I have to follow 240.4. 240.4(E) gets me out of the 15A limitation by calling the conductors a tap, which they can be called by definition.
I understand your point but can't agree. The logic of titles and provisions of 210.20, 210.24, 240.4, 240.21 that send one to 210.19 says it is valid.
- Location
- Illinois
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- retired electrician
Ryan,
I still don't see it. The only part of 240.4(E) that would apply to the original question is 240.4(E)(1) and that references 210.19(A)(4). The only part of 210.19(A)(4) that changes the permitted overcurrent protection for a #14 is the exception and the exception does not apply to conductors that feed receptacle outlets.
I still don't see it. The only part of 240.4(E) that would apply to the original question is 240.4(E)(1) and that references 210.19(A)(4). The only part of 210.19(A)(4) that changes the permitted overcurrent protection for a #14 is the exception and the exception does not apply to conductors that feed receptacle outlets.
The very fact that you are qualifying the tap conductor size and ampacity under 210.19(A)(4) relinquishes the overcurrent protection requirement of 240.4(D)(3)... but only for the tap conductor (i.e. not the branch circuit conductor ahead of the tap conductor). Now if a tap conductor don't meet the size and ampacity requirement of 210.19(A)(4), then 240.4(D)(3) requirement is reinstated.
Now, where does it say that a tap conductor can only qualify as tap conductor under 210.19(A)(4) Exception No. 1???
Twoskinsoneman
Senior Member
- Location
- West Virginia, USA NEC: 2020
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- Facility Senior Electrician
240.4(E)(3) certainly seems to apply.
- Location
- Illinois
- Occupation
- retired electrician
That just sends us right back to 210.19.
- Location
- Illinois
- Occupation
- retired electrician
I just do not read it that way. The section only tells me what size conductor I can use and in no way changes the permitted overcurrent protective device size. The only thing in the section that does that is the exception to (A)(4) and that does not apply to a receptacle circuit. If the general part of (A)(4) releases the OCPD sizing, there is no need for the exception.
I think we just have to disagree on this.
You are looking at 210.19(A)(4) to have some provision to change the permitted maximum for the tap conductor. You are looking in the wrong place.
The provision that changes it is in 240.4(E) where it says, "Tap conductors shall be permitted to be protected against overcurrent in accordance with the following:..."
Upon satisfying the "in accordance" mentioned, the overcurrent maximum imposed by 240.4(D)(3) is rendered void by its very own condition, "...specifically permitted in 240.4(E)..."
The only requirement of 210.19(A)(4) that needs to be "in accordance" is the tap conductor "shall have an ampacity sufficient for the loads served and shall not be smaller than 14 AWG."
- Location
- Illinois
- Occupation
- retired electrician
There is no specific provison for overcurrent protecion in 210.19 that applies to the conductor in question.
The fact that the section specifies the minimum ampacity of the conductor does not have anything to do with the size of the OCPD. This is just like 240.4(B) that permits an oversized OCPD, but does not change the permitted ampacity of the conductor.
But why are you resorting to the Exception?
The exception is only there to permit compliance for an installation which otherwise does not comply with the main provision. Same as for Exception No. 2. But more specifically for this Exception, it is to permit yet limit installations where the size is less than 14 AWG or a 20A-rated conductor. This is not the case as is being discussed, so resorting to the Exception is neither necessary nor does it apply.
However, please note that for those excepted installations, it does permit a minimum tap conductor ampacity of 15A on a less-than 40A rated circuit, and 20A on a 40A- or 50A-rated branch circuit. This follows the concept of a branch-circuit tap conductor having an ampacity less than the overcurrent protective device rating for the branch circuit of which it is part of, and it has no additional overcrrent protection other than its own ampacity and the normal current draw of the load served.
240.4(E)(1), or '(3) via 240.21(A) do not specify any change or additional overcurrent protection device as being required. Overcurrent protection of the tap conductor(s) is afforded by proper sizing of the tap conductor. See below...
But sized to have sufficent ampacity for the load served is the overcurrent protection for the tap conductor. There is no device associated with that protection other than the branch circuit OCPD ahead of the tap conductor and the load(s) it serves or may serve. This is the main difference between feeder and branch circuit tap conductors. Feeder taps always require an additional overcurrent protective device... branch circuit tap conductors never do. If they did, the circuit conductors ahead of them would no longer be branch circuits, would they?
Twoskinsoneman
Senior Member
- Location
- West Virginia, USA NEC: 2020
- Occupation
- Facility Senior Electrician
Yeah this is the way I read it also. I think.
- Location
- Illinois
- Occupation
- retired electrician
I don't see it that way. A code rule that tells me how to size a conductor is not a code rule that tells me how the overcurrent protection for that conductor is sized. The two issues are independent. In the absense of specific wording that tells me I can protect the #15 "tap" conductor with a 20 amp OCPD, I can't do it. There is no specific provision that says a #14 tap conductor can be protected by a 20 amp device. 210.19, in general, only tells me the minimum size of the conductor, it does not address the OCPD.
- Location
- Illinois
- Occupation
- retired electrician
How does the exception not require compliance with the main provision? They both require that the conductor have an "ampacity sufficient for the loads served". The main rule says the conductor cannot be smaller than #14 and the exception says it must have an ampacity of not less than 15 amps. Using the ampacities in the NEC, there is not a conductor smaller than #14 that has an ampacity of 15 amps. Using your logic there would be no need for the exception.
I said the exception permits compliance for an installation which otherwise would not be compliant under the main provision. Regardless, what I meant was, "...exceptions shall convey alternatives or differences to a basic code rule." ...and you can likely presume where that was copied from.
Agreed.
Agreed ...but it also exemplifies the circuit rating can be in excess of the tap conductors ampacity rating which you are reluctant to elicit from the basic code rule in conjunction with 240(E) and/or 240.21(A).
First off, it says an ampacity of not less than 15.
Second, what about a #16, 90?C Cu conductor? It is NEC rated at 18A per Table 310.16. As long as it is terminated using 90?C connections and not directly connected to anything having a lower temperature rating, it can maintain that 18A rating and even have a little room for ampacity correction.
...And if you try to say one cannot use such as sized and connected tap conductor, it would be your logic saying there is no need for the exception
I cannot fathom how you perceive that my logic would have such an implication. But then again, I can tell from your comments that your logic is on some different level.
Set the NEC aside for a second, and reason using only basic electrical principles for the following. What provides overcurrent protection for the 18 AWG "zip cord" of a cord-and-plug-connected utilization equipment that is powered via a 15A-rated receptacle on a 20A-rated branch circuit? When you answer this question as posed, you will have the answer to the "riddle" at hand. :smile:
- Location
- Illinois
- Occupation
- retired electrician
There is very few if any uses for a 90C rated conductor, so lets leave that out.
As is yours:-?:-?:-?But then again, I can tell from your comments that your logic is on some different level.
There is no riddle at hand...there is a specific code rule that says you can use the #18 zip cord on that circuit. We are talking code rules here and in the absence of a very specific rule that gives a higher overcurrent protection for the #14, you can't use it on a 20 amp circuit. There are a number of specific rules that permit that...there just isn't one for the case in this thread.
I am sure your not going to change you position and neither will I so, I think it is time to just let this drop.
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