Ampacity Table, NEC 2020 - [310.15], (13min:26sec)
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- Опубликовано: 22 окт 2020
- The number of conductors in the same raceway that are carrying current can affect conductor ampacity, as can the ambient or surrounding temperature. In this video we’ll explain how to evaluate these factors to make the proper choice when sizing electrical conductors.
This video is an extract from Mike Holt’s Electrical Calculations Training Library, based on the 2020 NEC. For more information about this product visit www.MikeHolt.com/examprep or call 888.632.2633.
For over 40 years, Mike Holt Enterprises has been providing quality electrical code training to help electrical professionals learn the Code, prepare for exams, and improve their electrical knowledge. Visit www.MikeHolt.com for exam preparation tips and training, instructor and curriculum support, continuing education options, free videos and graphics, and so much more.
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excellent refresher. Ive used this proper math for a very long time........good now to VERIFY for myself and others.
thanks Mike. God bless you.
Thank you, and God Bless.
Thank you Mike, regards from honduras.
Thank you and I pray you are safe.
thanks Mike for your good help.
You are most welcome.
I know one day this channel is going to become huge.
I just want to do all I can to help the industry.
Thankyou Mr Mike
Thanks Mike
My 2014 NEC had Tables 430.247 crossed out as well as many other tables. It was purchased already high lighted wnd many tables are X-Out. Where can I find the reasoning and the new table.
Thank you for these videos, Mike!
You are most welcome.
Good day. I came across a wire gage measurement of 36557, which translated into 2/0 AWG.
What is this measurement?
when do we use table 310.17 ? can it be used for 3 single runs instead of a 3 core cable in cable tray
What if I run a 6 gauge conductor, but I want to use it at the 90 degrees ampacity, (75 Amps) if before landing my #6 conductor to the breaker, I add a small piece of 4 gauge conductor which is rated for 85 Amps at the 75 degrees. Is there a code against doing sometime like that?
Most wire will fall in the 90 degree column. But when making adjustments you have to go with the rating of the wire. I.E. if it is TW or UF it must be the 60 Degree column. Might not matter a lot in real life but could be on a test.
Excellent point!
Nope, that is not true for ampacity correction or adjustment. We use the 90C for that purpose. See 310.15.
Why do we only concern ourselves with the 90° columns in both 310.15(B)(1)(1) and 310.16 when there are other insulation types in the 60° & 75° columns?
Sir i have a question, is there a code violation in NEC if water pipe is above sa electrical pipe/conduit, and also sprinkler head near electrical busduct. Thanks hoping i will an answer
Please post your question on MikeHolt.com/Forum, and see 110.26(E).
pretty sure this info is included in the NABCEP, right?
In this video you stated the correction and adjustment factors only apply to current carrying conductors (ccc). Does a switch leg count as a ccc because the constant hot will see the same heating effects of current flow already? It seems to me that the switch leg and the constant are the same donductor. What are your thoughts?
Of course it's a current carrying conductor.
Sir why #14,#12nmd wire are restricted to 60 degree columns but other bigger size nmd wires can used for 75 degree
Loving your content, and presentation
I appreciate that!
@@MikeHoltNEC also I passed, my Michigan Masters test today! Thanks for you videos, they did help.
@@GhostofSicklesleg Yes! Contratulations.
I recommend your videos as the cherry on top prior to test. They filled in a lot of my questions and again your presentation was helpful in getting me to remember and convert old fart brain cells into a working functioning brain for that little bit of time I needed it!
@@GhostofSicklesleg Thank you for the message. Anybody that gets my Exam Prep library now can get 'digital' access to the videos as well as DVS's.
Why is NM-B ampacity rated at the 60 degrees ratings?
What about NMB do can i use the 90 degree column for correction and adjustments?
Please read 334.80 for your answer.
Mike Holt, you are a God. You’ve helped me so much
Nice presentation. Quick question. If your correction and adjustment factors make the ampacity fall below the 60C or 75C ampacity ratings, which supersedes?
When you size a wire, you need to know the ampacity. This has nothing to do with 60C or 75C terminals. Example, if you calculate the ampacity of a 90C wire and it's 70A, but it's only 100A at 75C, then of course the ampacity is 70A.
Must the conductor Ampacity tables in the code always be use, or can a wire manufacturer’s own tables supersede the code?
Please give me a link to a manufacturer ampacity table. I never hear of any such thing.
@@MikeHoltNEC My bad. I looked closer and it was stated that the Ampacity table was taken from NEC.www.cerrowire.com
Where can I find the part of you guys talking about not counting the neutral as a current carrying conductor? This was mentioned at 8:54
Two wire 120V circuit, one hot and one neutral, the neutral is a current carrying conductor. This is in accordance with 1 in that it doesn't carry only the unbalanced current of other conductorS of the same circuit; it carries all the current of the sole ungrounded conductor in the circuit. So a neutral is considered a ccc quite often.
mike, when i have a 3Fases circuit with 2 o more conductors per fase in a one conduit, it must be apliied the group factor?
I don't understand your question. The grouping factor is applied as shown in the video. Watch it again.
Am I only allowed to use this chart for air conditioning and motors? Or is 12 gauge wire always 30 amps
Please review 240.4 in it's entirity.
I understand it now thank you. There is also stars next to 14 through 10 bringing it to that code
Mike, great video! question, when would table 310.15 (b) (2) be used for adjustment?
When the temperature is over 86F.
Im having a hard time understanding when to use 310.15 (B) (1) and 310.15 (B) (2). For example if ambient temperature is 44 Deg C. Both tables provide 41-45 Deg C range . Mike says to use 310.15 (B) (2) when its is above 30 Deg C (86 deg F). A couple of questions. If the table is intended for that.
Why state that is based on 40 Deg C? Why does 310.15 (B) (1) have ranges above 30 Deg C?
Hi What does the code say about Electrical Shower Head? Is it allowed?
Is there such a UL listed product? Get me information, Mike@MikeHolt.com.
Mr Holt, Right at 7.59 minute mark you said we adjusting the ampacity of conductor based on the 90 degree C Column. where in the code state based on 90 dgree Column ? I could not find that, thank you for your time
See 310.15 , it states "The temperature correction and adjustment factors shall be permitted to be applied to the ampacity for the temperature rating of the conductor, if the corrected and adjusted ampacity does not exceed the ampacity for the temperature rating of the
termination in accordance with the provisions of 110.14(C)."
I was looking at this section today, and it occurred to me this code section should be re-written, to say "not less than" instead of "does not exceed" the ampacity for the temperature rating of 110.14 (C). We can always use a conductor that exceeds ampacity requirements, but never less than. @@MikeHoltNEC
When do you use Table 310.15(B)(2) versus Table 310.15(B)(1)?
(B)(1), because Table 310.16 is based on 30C.
Mr. Holt, If your OCPD is rated for 75 degree C wiring but your wire is rated for higher temperature such as 90 degree C (or in the case of transit Exane wire 110 degree C) do we size our wiring ampacity according to the 75 degree column? Furthermore, do we do our ambient and bundling adjustments using the wire's actual temp rating (in this case 90 or 110 degree C)? This is a little confusing. Thank you so much! :)
Watch ruclips.net/video/k7d03Tic6LE/видео.html and ruclips.net/video/OLIHEiiY_Rs/видео.html
@@MikeHoltNEC Thank you!! :)
Mike: I have taken several practice questions and when talking about current caring conductors the neutral is always counted. In this video you said you do not count the neutral as a CCC. I have also been taught to count the neutral as a CCC. How and when do you not count it????
The answer is contained in 310.15(E).
When it's an individual circuit, one hot paired with one neutral, regardless of voltage or system type, the neutral carries the full current of the hot and is always counted. Usually when the neutral is shared by multiple hots, it's not counted. However, if it's a 3-wire or 4-wire circuit of a wye system, 310.15(E)(2) or (3) apply.
PLEASE HELP- I have read all of 310.15 there is NO reference of 90 degree column anywhere (that I can find) I was under the understanding you are to use the HIGHEST rating for that insulation... Example RHW, THHW, THW - Etc all fall in the 75 degree columnn (to my understanding th -2 indicates upgraded insulation) So what do I do - and can you or somenone please tell me where the 90 degree referance is? Thanks!
310.15(B) states that we use the temperature ampacity correction [310.15(B)(1)] and adjustment ampacity factors [310.15(C)(1)] are applied to the ampacities listed in Table 310.16, based on the conductor’s insulation temperature rating. We typically use THWN-2, which is 90C.
@@MikeHoltNEC Thats what I thougt / could ascertain from the code - If I am understanding this (to paraphrase) "Use the highest degree column based on insulation type and disregard termination"
Watch the video again, 90C is only used when you are required to apply conductor ampacity adjustments and corrections in accordance with 310.15, this has nothing to do with sizing a conductor to terminals per 110.14(C)(1), 210.19(A)(1), and 215.2(A)(1).
@@MikeHoltNEC I guess I meant not sizing to terminals... but terminal temperature rating 😉
on a side note: is this Mike Holt? if so I am very flattered that the "The Man, The Myth, The Legend" took time to respond...That is awesome .. If not it's it's still awesome that someone took the time to respond!
So much of electrical training, if you don't already understand it. It's hard to relate it to your actual work. This took me 10 years in the trade to really come to terms with.
After 50 years, I'm still learning... it never ends.
Buenos dias. Sera posible informasion en idioma español. Gracias..
No, I'm sorry. My work is for the US, and you need speak and read English.
So the purpose of 90 deg c column is to down size the wire to fit in with terminals without compromising on the ampacity. If its not necessary to derate the wire so there's no need to go to 90 c . Great help :3
Not really. Wires are to be sized to the load in accordance with 210.19 and 215.3. The 90C rating is only used for conductor ampacity adjustment. Please watch the video again.
What about table 310.15 b 2 b
2017 nec
This table is not used because the conductors are rated 30C, not 40C.
First here
Lol
Mike & Brian are incorrect. You count the neutral conductors quite often.
NEC 310.15(E) Neutral Conductor: "Neutral conductors shall be considered current carrying in accordance with the following:
(1) Carries only the unbalanced current.
(2) When the neutral "carries approximately the same current as the line-to-neutral load currents".
(3) When "the major portion of the load consists of nonlinear loads, harmonic currents are present in the neutral".
(1) is NOT considered current carrying (2) is a 3 wire circuit on a 3PZ wye system using two of the three phase conductors and sharing a neutral. What are the examples where this is done often? (3) Is a 4 wire circuit using a neutral where the majority is non- linear. Again what are your example of where this is done often? - Brian
@@MikeHoltNEC Ah! I see I was wrong. I didn't read 310.15(E) all the way through. It says,
"Neutral conductors shall be considered current carrying in accordance with any of the following:
(1) A neutral conductor that carries only the unbalanced current from other conductors of the same circuit shall NOT be required to be counted when applying the provisions of 310.15(C)(1).
Regarding 2 & 3, 310.15(E) states,
"(2) In a 3-wire circuit consisting of two phase conductors and the neutral conductor of a 4-wire, 3-phase, wye-connected system, a common conductor carries approximately the same current as the line-to-neutral load currents of the other conductors and shall be counted when applying the provisions of 310.15(C)(1).
(3) On a 4-wire, 3-phase wye circuit where the major portion of the load consists of nonlinear loads, harmonic currents are present in the neutral conductor; the neutral conductor shall therefore be considered a current-carrying conductor."
I don't need examples Brian. I am simply quoting the code. Are you saying the code in (2) & (3) is incorrect?
@@icevariable9600 Two wire 120V circuit, one hot and one neutral, the neutral is a current carrying conductor. This is in accordance with 1 in that it doesn't carry only the unbalanced current of other conductorS of the same circuit; it carries all the current of the sole ungrounded conductor in the circuit. So a neutral is considered a ccc quite often.
I don't see any reason why artificial intelligence can't completely codify the NEC
If you understand AI and the Code development process, you'll understand why we still need 'humans.'
I very much understand why we need humans, I just fell that if I can say ‘I’m installing a 3 phase motor 100 feet from my disconnect rated at such and such amps at such and such temperature , what size wire will I need? The AI element should be able to digest the NEC code requirements and spit out an answer. Of course as the human doing the install I would have to check to make sure the AI is correct, but it’s all code…it’s not that hard.
@@Mrlostinterest MHE is extensively involved with AI and its application with the electrical industry. I can't image who would invest hundreds of thousands of dollars to create any such an AI platform. Did you know that some states are on the 2008, 2011, 2014, 2017, 2020, and 2023 NEC. Also many states have local amendments, and sometimes we have county amendments, and city amendments.
How anybody could gather all of that information to get an accurate answer is beyond me. Let me know when you find a platform that answers the question you presented.
AI is not exactly what people think it is (yet).
Why is everyone wearing a tie? Are they going to a funeral afterwards?
Because we are professionals when we teach.
@@MikeHoltNEC Sorry, but a tie does not make you a professional! Relax, a tie is like a collar!
@@Adi-S You are correct, a tie does not make one a professional. However a professional like myself wears a tie, and I insist that all of my video team members wear ties. It makes us feel positive and in a position of leadership.
@@MikeHoltNEC There is nothing wrong with that, it should be up to everyone to decide. ✅
@@Adi-S it would probably benefit you more to focus on the subject matter material, than to concern yourself with the panel members attire.
@8:47. In almost all cases, don't count the neutral. 🤥 Most cases are not multiwire branch circuits. Please let brian correct you, you could tell he wanted to but bit his tounge. (5) Neutral Conductor. (a) A neutral conductor that carries only the unbalanced current from other conductors of the same circuit shall not be required to be counted when applying the provisions of 310.15(B)(3)(a).
Your comment doesn't make sense, this video was not about determining if the neutral conductor was a current carrying conductor. That is a separate rule 310.15(E).
@@MikeHoltNEC Two wire 120V circuit, one hot and one neutral, the neutral is a current carrying conductor. This is in accordance with 1 in that it doesn't carry only the unbalanced current of other conductorS of the same circuit. So a neutral is considered a ccc quite often.
@@pld8993Please watch the video again, it has nothing to do with the fact that the neutral conductor carries current. It's related to 310.15(C) rule when counting the number current-carrying conductors for ampacity adjustment.
@@MikeHoltNEC The video says that in almost all cases the neutral is not counted. That is only true when we are talking about a neutral with multiple ungrounded conductors sharing it. When the neutral is the "return" path in an individual circuit (one hot paired with one neutral), it always carries current and it is always counted as a ccc. The video only talks about shared neutrals and never discusses individual circuits. One could try to make the argument that in an individual circuit, one hot and one neutral, what we are calling the neutral is technically not neutral and is more appropriately identified as the grounded conductor, in which case 310.15(E) would not even apply and it would definitely be counted as a ccc. If we are going to apply 310.15(E) to an individual circuit, one hot and one neutral, because the neutral is NOT carrying ONLY the unbalanced current from other conductorS (plural) in the circuit, counting it as a ccc is fully in accordance with 310.15(E)(1). If it's carrying only unbalanced current it's not counted, therefore if it's carrying current that's not unbalanced current it's counted.
@@pld8993 sorry for making this 'general' statement in this video. Thanks for the feedback. I'll try to be more careful.
The ocp is the bottom line this conversation is a waste.