4/0 cable into the back of a 3 1/2 inch deep panel

[ronaldrc]

Re: 4/0 cable into the back of a 3 1/2 inch deep panel

Don

I agree with Jil this is a bending distance between entry and the terminal or lug.

If this is true why do we have the 2" and 2-1/2" kos in the back I know there not there for 2" inch nipples for #12 or branch circuits.

And if this is true 75 percent of the home services in my area of the country are wrong.

Ronald

[ March 05, 2004, 09:02 PM: Message edited by: ronaldrc ]

 

[websparky]

Re: 4/0 cable into the back of a 3 1/2 inch deep panel

Hi Ronald,

Please consider this exception as it quotes 312.6(A)for a reference.

314.28 (A)(2) Angle or U Pulls.
Exception: Where a raceway or cable entry is in the wall of a box or conduit body opposite a removable cover, the distance from that wall to the cover shall be permitted to comply with the distance required for one wire per terminal in Table 312.6(A).

 

[luke warmwater]

Re: 4/0 cable into the back of a 3 1/2 inch deep panel

After re-reading all posts in this thread, it appears that everyone involved is starting at article 312. (with the possible exception of Jii)

I submit that this is wrong, on the basis that we are talking about a panelboard.

Therefore, I submit that the pertaining article is 408.

So, in 408, we go to 408.35.

Now in 408.35, it references TABLE 312.6(A) and TABLE 312.6(B), so none of the wording in ARTICLE 312.6(A), (B)(1),(2), and (C) apply.

The first part of 408.35 states that "the enclosure for a panelboard shall have the top and bottom wire-bending space sized in accordance with TABLE 312.6(B) for the largest conductor entering or leaving the enclosure". So, as long as (for 4/0 AL) there is 6" from the terminal to the top(or bottom) of the can we're good, so far.

408.35 goes on, "Side wire-bending space shall be in accordance with TABLE 312.6(A) for the largest conductor to be terminated in that space". So, as long as (for 4/0 AL) there is 4" from the terminal to the side of the enclosure (read the Note under the table, we're good.

What is everybody's take on that approach???

 

[pierre]

Re: 4/0 cable into the back of a 3 1/2 inch deep panel

It is amazing how much interest this thread is receiving ), the answer is no.

As far as past practice is concerned, we have all installed something not to code and maybe not realized it. Now we know a little more and will not do it again

Pierre

 

[iwire]

Re: 4/0 cable into the back of a 3 1/2 inch deep panel

Pierre thank you for pursuing this with Square D, I knew you would present the info without a predetermined agenda, and also that you would report your findings back whatever the outcome.

Everyone,.. first we are not talking about distances to terminals, we are taking about the bending space between the back and front of a 3.5" deep enclosure, call it a panel, gutter conduit body, whatever you want but it must comply with Table 312.6(A) Minimum Wire-Bending Space at Terminals and Minimum Width of Wiring Gutters

Take a look at 314.28(A)(2) (posted below) to see an example of this for LBs and would apply to the panel as the panel front is removable.

The space from the terminals is determined as a separate issue.

I still do not understand a couple of the augments presented here that are in support of allowing 4/0 in the back of a 3.5" deep box.

1)They would not put a 2" KO in the back if it was against code to use it.

Say what? :roll:

2)LBs or conduit bodies if you want.

As I pointed out earlier.

They are stamped with the max conductor size and quantity, this amount will be less than what the raceway they are connected to can accommodate.

And the code Don was kind enough to point out.

314.28(A)(2) Angle or U Pulls. Where splices or where angle or U pulls are made, the distance between each raceway entry inside the box and the opposite wall of the box shall not be less than six times the metric designator (trade size) of the largest raceway in a row. This distance shall be increased for additional entries by the amount of the sum of the diameters of all other raceway entries in the same row on the same wall of the box. Each row shall be calculated individually, and the single row that provides the maximum distance shall be used.

Exception: Where a raceway or cable entry is in the wall of a box or conduit body opposite a removable cover, the distance from that wall to the cover shall be permitted to comply with the distance required for one wire per terminal in Table 312.6(A).

Our we all yet in agreement that there is not sufficient space to enter 4/0 conductors in a enclosure that the opposing wall of is less than 4" away?

[ March 06, 2004, 09:06 AM: Message edited by: iwire ]

 

[ronaldrc]

Re: 4/0 cable into the back of a 3 1/2 inch deep panel

Hi everyone

I agree with everyone on here about the clearance and it being a code violation, if enforced.

But don't most agree that this is just a oversight of the NEC board and not being coordinated with the panel manufacturers and a exception needs to to made in this also?

Whats the difference between a panel and an LB. fitting? Do they think your going to wear the insulation off the conductor taking the cover off so much or what?

Are we going to have to start using a lot of extra fittings and wire just to comply to this oversight? And also make a sloppy installation.

When most electricians in this area build a 200 amp. residential service through the wall all you see outside is a meter base and a 2-1/2" stinger.Do you really want to use extra fittings wire which is unprotected to compensate for this not me?

This is not the only contradiction in the code no ones perfect we don't live in a perfect world.

Ronald

 

[iwire]

Re: 4/0 cable into the back of a 3 1/2 inch deep panel

Use 2/0 copper for the 200 amp service as allowed by Table 310.15(B)(6) and you will be in compliance even when coming into the back of a 3.5" deep panel.

 

[don_resqcapt19]

Re: 4/0 cable into the back of a 3 1/2 inch deep panel

Ron,

Whats the difference between a panel and an LB. fitting?

There is no difference. Both require a 4" depth for 4/0 conductors.
Don

 

[pierre]

Re: 4/0 cable into the back of a 3 1/2 inch deep panel

Engineering an installation to meet code is the engineer/installer's responsibility. The manufacturer may make the KOs available, but the use can be compliant with other than 4/0 conductors, such as branch circuits, etc...

Yes Ronald, you will have to design/engineer a different method of installation to be compliant. It may cost more, you or your customer may not like the appearance, but it will be compliant.

Redheads/antishort bushings are installed to be compliant with the code. I have heard guys say 'look no redhead, wow can you believe that guy'.
One of the reasons so many will comply with the redhead requirement is it cost almost nothing and is easy to install.
As soon as the requirements become harder, require more knowledge or cost more money, we hear more arguments as to the validity.

Pierre

Pierre

 

[stew]

Re: 4/0 cable into the back of a 3 1/2 inch deep panel

are the carpenters gonna have to furr out all there 2/4s in the area where thees new 4 inch panels go? Websparkey I do not see anywhere in the article where the dimension is referenced from irts"point of entry".
I also hope someone gets to ronald reed at Square D as he is one the code writing paanel for this subject. Or maybe the chairperson?

Luke warmwaters take is also I think valid. If you read the rest of the exceptions specifically #3 in 408.35 it even describes the 90 degree bend we all us to make this install!!

And Im goona start using 2/0 cooper too just so some cunfused inspector doesnt start this argument all over again!!

[ March 06, 2004, 12:44 PM: Message edited by: stew ]

 

[iwire]

Re: 4/0 cable into the back of a 3 1/2 inch deep panel

Stew one suggestion I have is to use 2/0 copper from the meter to the panel, 2/0 would meet the wire bending space.

You could still use 4/0 AL from the meter to the POCO.

The panels I use are 6.75 deep so I am all set.

Bob

 

[ronaldrc]

Re: 4/0 cable into the back of a 3 1/2 inch deep panel

Ah what the heck most the panels anymore are 4" anyway.

 

[iwire]

Re: 4/0 cable into the back of a 3 1/2 inch deep panel

Ronald I was wondering if anyone was going to pick up on that.

3.5" studs + 1/2" rock sounds like 4" to me.

 

[ronaldrc]

Re: 4/0 cable into the back of a 3 1/2 inch deep panel

Bob

If I remember right some of the old panels had a separate dead man cover that recessed back in the can making it less than 4" now most are just the one cover and are recessed back only around the breakers.


Thanks and have a good one.

Ronald

 

[richwaskowitz]

Re: 4/0 cable into the back of a 3 1/2 inch deep panel

OK. Here's the poop from Sq-D.

Just got off the phone with Allan Manche of Sq-D. He was very knowledgeabe on the matter and spoke with authority and confidence. Sitting on code committees and having the authority of Sq-D behind him, he seemed to be qualified to address my question and he did answer my question.

In his opinion, the intent of 312.6 is to ensure there is sufficient space available for one to bend and manipulate conductors around within the confines of enclosures and addresses those confines in two dimensions, in other words on a vertical plane only. The "opposite wall" mentioned means the top of the enclosure in the case of a breaker panel where the main lugs are pointing stright up. "Not leaving opposite wall" refers to the side walls of the panel, not the rear. Therefore 312.6(B)1 would apply where a conductor enters the side of the panel, but not the rear.

It is his opinion that it is the intention of this rule to give us room to work, NOT to limit the radius that a conductor may be deflected. He cited UL 83 (standard for bending thermoplastic conductors) where for example a 4/0 conductor may be bent at a radius much tighter than that restricted by the 4 inches in table 312.6(A).

As for me, I will adopt his interpretation and agree that it is OK TO RUN 4/0 INTO THE REAR OF THE ENCLOSURE AND THIS IS NOT A VIOLATION. The instructor that informed me to the contrary will consequently be lowered ever so slightly from the high pedestal on which I placed him, but he is still up there.

I want to thank everyone for their contributions and I hope we all learned something. I sure did.

 

[jibber]

Re: 4/0 cable into the back of a 3 1/2 inch deep panel

Rich, Thanks for your effort in following up the matter. I really never even gave the "problem" a thought.ignorance is truly bliss. Think about the ones who never log on to this forum, they never new there was a question....

Good detective work!

 

[iwire]

Re: 4/0 cable into the back of a 3 1/2 inch deep panel

I remain unconvinced, I do not have faith in the engineers at any manufacturer to know the codes as well as some of the people here.

This is nothing against engineers but who works with the NEC more?

 

[don_resqcapt19]

Re: 4/0 cable into the back of a 3 1/2 inch deep panel

Guys,
Just remember that Allen's answer is just an opinion and not the official NFPA position on this issue. His opinion is no more valid than the opinion of Rick's instructor who said it is a violation. All answers are opinions unless you have a formal NFPA interpretation.
Don

 

[iwire]

Re: 4/0 cable into the back of a 3 1/2 inch deep panel

Alan Manche is an Alternate on CMP-No 8

That CMP deals with articles 342 through 392.

He should have told you just what Don pointed out that his opinion is not an NFPA interpretation.

 

[websparky]

Re: 4/0 cable into the back of a 3 1/2 inch deep panel

Stew,

Websparkey I do not see anywhere in the article where the dimension is referenced from irts"point of entry".

This is were it is referenced;

Exception: Where a raceway or cable entry is in the wall of a box or conduit body opposite a removable cover, the distance from that wall to the cover shall be permitted to comply with the distance required for one wire per terminal in Table 312.6(A).

and

(1) Conductors Not Entering or Leaving Opposite Wall. Table 312.6(A) shall apply where the conductor does not enter or leave the enclosure through the wall opposite its terminal.

Oh, and one more;

408.35 Wire-Bending Space in Panelboards.

[ March 08, 2004, 05:17 PM: Message edited by: websparky ]