Explaining Splices in Panels

[FONT=Times New Roman][size=3]Hey Guys,
Just had someone e-mail me and ask me to explain this so I figured what better way than on the board to help educate others as well. Fellow electricians please feel FREE to chime in.
The question was…Can you have splices in a panel enclosure…that contains Switches and OCPD devices?
Well…if you take the surface of the NEC ruling which is this:
[FONT=Times-Bold]312.8 Enclosures for Switches or Overcurrent Devices**. **[/FONT]
[FONT=Times New Roman]Enclosures for switches or overcurrent devices shall not be [/FONT]
[FONT=Times New Roman]used as junction boxes, auxiliary gutters, or raceways for[/FONT]
[FONT=Times New Roman]conductors feeding through or tapping off to other switches[/FONT]
[FONT=Times-Roman]or overcurrent devices, unless adequate space for this purpose[/FONT]
[FONT=Times New Roman]is provided. The conductors shall not fill the wiring[/FONT]
[FONT=Times New Roman]space at any cross section to more than 40 percent of the[/FONT]
[FONT=Times New Roman]cross-sectional area of the space, and the conductors,[/FONT]
[FONT=Times New Roman]splices, and taps shall not fill the wiring space at any cross[/FONT]
[FONT=Times-Roman]section to more than 75 percent of the cross-sectional area[/FONT]
[FONT=Times-Roman]of that space.[/FONT]
[FONT=Times New Roman]Now remember service conductors and feeder conductors are permitted in the same enclosure ( see 230.7 )[/FONT]
[FONT=Times New Roman]Ok…Basically splices are allowed as long as they do not fill up the 75% of the wiring space…Now I wont go into the math on that…if you would to view it…check out 312.8 of the NEC Handbook for more details.[/FONT]
[FONT=Times New Roman]Basically…just wanted to explain why splices are allowed in panel enclosures…[/FONT]
[FONT=Times New Roman]This post was for Educational Purposes Only - Paulright Protected[/FONT]
[FONT=Times New Roman](Edited: used the term ART for 230.7 and not Sec. for 230.7…I violated the NEC society handbook…sorry )[/FONT]


If the splice is in the conductor going directly to a breaker (extending a short wire) it is not counted at all. Wirenuts have no “fill” count. The wire count in the box has not changed. Where you might have to count an extra couple wires is if 2 cables entered the enclosure destined for one breaker (via a splice) where the panel was at it’s maximum breaker count with the maximum number of wires on each breaker. You can safely say a panel is designed to have a wire in every breaker terminal location (2 where permitted). I suppose that is why a twin breaker only supports one conductor in most lines.


If the enclosure is being used for a TAP and Splice for lets say multiple receptacles…then it would apply as this wiring would be subject to the 75% factor.

I guess the main point is…and you may agree…very hard to disallow this splice or tap…and proving the doing so of the wires and additional conductors exceed the 75%…without doing the math involved.

I also see it alot where people do not think service conductors to (1) 200A panel can cross thru to another 200A of a 400A setup…and wanted to explain a bit on the allowance of splices and feeding through is allowed.

Define adequate space?

Note: See the NEC Style Manual search for it at: www.nfpa.org look in Table 3.2.1 for Possibly Unenforceable and Vague Terms

PS: Also, see the correct way to address a Section in the NEC when in an Article, it is not correct to say: Article 110.3 but instead we should say: Section 110.3, if the Section number is used alone, that’s OK too, but never use the word Article to identify a section.

People who have been associated with the NEC for more that just two or three cycles have been aware of this for a very long time, so the issue is not one that should be questioned or argued by anyone.

The NEPA has prepared the NEC Style manual so that the members of the NEC committee and public will learn how to use the correct rterminology when writing rules.

If you need further clarification call 617-770-3000 and ask for the Electrical Departjment to ask them.



I see you are into playing again it seem Joe…lol…Art…Section…I see thinks like that really matter to you on a message board.:roll:

Anyway…I think the guys get the point…anyway I will make sure I check all posts for “Correctness”…would hate for any of my information to drive them insane…like using Article when they should have said Section…oh thats right…they should not quote code…I forgot !

Originally I was only going to post Art. 230…then decided to add the .7 to the post…forgive me for my inferior knowledge…I again appologize.

Read the NEC Style manual, nothing toward you, just the facts!

Do you want to accept that and not be so sensitive!

I have nothing against your comments and posts when I do read them, I only want the rest of the world to be made aware of the correct terminology when discussing the NEC.

Don’t always be so defensive!

Also, I pointed out a well known fact about a word: “adequate” and even have had proposals accepted to remove the word from some sections in the code.

Calm down!

Can someone please help everyone to understand what I am trying to present in the interest of using correct language, and help for those who are interested, download the NEC Style Manual here, read it and tell us what it says when the subject of the language associated with the comments I made here are considered:

**See Section Subdivision Example.



I am calm Joe…lol…playing a fight that Article can’t be used in defining code terms is nonsense…I have used Article, Section and unit before when typing examples on here…I happen to use Section alot in my classes…

( Edited : just not worth it…)

I hardly think saying Section 310.16 is any less directive as saying Article 310.16…which is a secion of Article 300…but I think they get the point…

Very Transparent…Got WORK?

I am humbled in the fact I know nothing…I beg your forgiveness as my knowledge is sub-par and I should not be helping others…I have done the cardinal sin…I have used Article in place of Section…I am so embarassed…I should be locked away for the mistake…:slight_smile:

Here’s the page from the Official NEC Style Manual that covers the subject.


Why dont you just cut and paste the topic…can’t get the PDF to load…and besides…I would not want to instruct anyone wrong on here again and have them KILL themselves…because they stuck a fork in a LIVE article…:slight_smile:

What is amazing to me is…I used the term ART in a quick abbreviation to direct someone to section 230.7…and you found it a perfect time to berate me in your own way…nothing in that educational post refers to Article…except that small () excert which was added…and it warrants THIS?

Here is another post I did…same time…http://www.nachi.org/forum/showpost.php?p=137415&postcount=1

Hmmm…I dont see any use of Article or Section within it…so the short Art. is really going to SCREW up the learning terminology Joe…get real…you are not trying to educate me…this was a learning post and a good reply by Greg…you turned it into a chance to PISS on me…same old JOE…no need to calm down…I know how you work fella…I am COOL with it…:slight_smile:

Transparent and quite whinner also to higher ups when you feel your livelyhood is in question…yeah…I know about the calls JoeBu…:slight_smile:

OK, here’s the file as a word document!

H A P P Y N E W Y E A R !

Chapter — **Chapter 2 Wiring and Protection **

Article — **Article 250 — Grounding **

Part — II Conductors

Section — 250.121 Identification and Size of Equipment Grounding Conductors. Unless otherwise required in this *Code, *equipment grounding conductors shall be permitted to be bare, covered, or insulated.

Level 1 — (A) Identification of Conductors. An insulated or covered conductor larger than No. 6 copper or aluminum shall be permitted to be identified, at the time of installation, by one of the following means:

List item — (1) Stripping the insulation or covering from the entire exposed length.
List item — (2) Coloring the exposed insulation or covering green.
List item — (3) Marking the exposed insulation or covering with green tape or green adhesive labels.

Level 1 — (B) Size of Conductors.

Level 2 — (1) General. Copper, aluminum, or copper-clad aluminum equipment grounding conductors of the wire type shall not be smaller than shown in Table 250.122.

Level 2 — (2) Adjustment for Voltage Drop. If conductors are adjusted to compensate for voltage drop, equipment grounding conductors shall be adjusted according to circular mil area.

Level 2 — (3) Conductors in Parallel. If conductors are run in parallel, the equipment grounding conductors shall be sized by either of the following methods.

Level 3 — (a) Each parallel equipment grounding conductor shall be sized on the
basis of the ampere rating of the overcurrent protective device. If
ground-fault protection for equipment is installed, each parallel equipment
grounding conductor run in a raceway shall be to be sized in accordance with
Table 250.122.

Level 3 — (b) Parallel equipment grounding conductors in multiconductor cables
shall be permitted to be sized in accordance with the Table 250.122
on the basis of the trip rating of the ground-fault protection if the
following conditions are met:

List item — (1) Only qualified persons will service the installation.
List item — (2) The trip rating is not greater than the ampacity of a single conductor.
List item — (3) The ground-fault protection is listed for the purpose.

For THOSE who can’t download the PDF…and would like this article…I mean Reference material…:slight_smile:

Freakin Petty…Same Ole’ Same Ole’ :roll:

Paul…I hope you can appreciate, as many of us do, the availability of multiple sources for information in the technical areas of our message board. I think that having a code expert reviewing your posts for accuracy is good for all of us and what is derived from them can be more useful.

Joe knows (and grumbles at) the HI’s reluctance to refer to code, but I think he is correct to insist that when it actually is referred to, it is referred to correctly.

I don’t think his post was mean spirited or intended to do anything other than ensure that the correct information was being communicated.

Thanks, Joe.

lol…now I expected that…:)…sorry the abbreviation ART caused such a stir…I will leave the posting to the experts…:slight_smile:

It’s feeding time…come on…where are others:)

You are 100% correct JB…I agree totally…

On SECOND THOUGHT…The NACHI guys can’t get RID of me that easy…you have FAILED at making a mountain out of a MOLE hill…thehehhe…lol…lol…lol

My last order of duty will be to recommend Mr. Tedesco for the Educational Com…oh wait…I must be on CRACK…never mind…remove that recommendation…thehehe


But what about the other question relative to your post and the section you referred to? What actually is “adequate space” as it applies to these splices? Anyone?

Thanks Jim, coming from you I am now relieved and appreciate your comments.

I always try to help HI’s and those who are following giving presentations.

I will look forward to assisting anyone who has just started to teach the NEC nationwide, as I have been for over 35 years.

Let’s have a Marathon on the Use and Understanding of the NEC between the NEC enthusiasts?

lol…man I read that and died laughing…sorry !