310.15(B)(2) add Exception 6.

[hurk27]

Re: 310.15(B)(2) add Exception 6.

I feel like I am really belaboring the process. What do you think about this?

Hey Charlie other than boring the other people here who cars? Besides that, we have a year.

(2) where these cables are not larger that No. 12 Cu. or No. 10 Al.

I just changed it the post before yours. It must have been that "copy and paste thing" LOL
Should we try to incorporate it back in?

This Exception shall not apply where more than two NM cables containing two or more current carrying conductors are bundled together and pass through wood framing that is to be fire- or draft stopped using thermal insulation or sealing foam, as required in 334.80

Or would there be a better way of wording this?
Boy this isn't easy, But a lot of fun and a good learning experience.

Sorry Wayne, every time I look at this I see something else.

Keep seeing, Keep seeing LOL

P.S. Thank's Charlie for all the help.
You too Bob. And all the rest.

 

[charlie]

Re: 310.15(B)(2) add Exception 6.

I will have to give that some thought. I think it is important to deal with open (not insulated) spaces if we are going to bundle the whole world together (OK, just the 15 and 20 ampere world).

 

[mulllet]

Re: 310.15(B)(2) add Exception 6.

IT only works if I use the number keys on the right side of the keyboard not the ones up top.
? ? ? Cool.

 

[physis]

Re: 310.15(B)(2) add Exception 6.

Well, since this topic emerged on my monitor again.

Have you submitted a proposal yet Wayne?

 

[hurk27]

Re: 310.15(B)(2) add Exception 6.

Not yet as I have been real busy lately But maybe Charlie has some new ideas to throw out here?
I just don't see the bundling issue that allot of inspectors do. and with a code change will stop some of the rules like that was posted in another thread saying that some areas only allow one cable to a hole. :roll:

 

[charlie]

Re: 310.15(B)(2) add Exception 6.

Sam, I would wait until the first of September to do any submittals. This gives plenty of time to let them move around in your mind. Also, more general discussion will have been done in the forum that may influence your proposal. The deadline is not until November 4th @ 5:00 PM EST so September up to mid-October is a good time to send in the proposals.

 

[physis]

Re: 310.15(B)(2) add Exception 6.

That's a good point Charlie. I presume you guys wont start on them until "Proposal Season" anyhow.

 

[heco]

Re: 310.15(B)(2) add Exception 6.

Well I be durn........that is Awsummmm

 

[George Stolz]

Re: 310.15(B)(2) add Exception 6.

Originally posted by hurk27:
[QB]the dwelling unit load is so diverse and that those circuits are almost totally for convenience; therefore, the need for derating is not required as circuits will be used minimally and in small groups. The heaviest loaded circuits would likely be one or two small appliance branch circuits, a bathroom receptacle circuit, and a laundry circuit. Those circuits, mixed in with the other circuits, would not require derating.

Given this good point, would it make sense to create a different section for dwelling units, and have the existing section deal with "other than dwelling units"? Might add clarity.

Then this could be knocked down to:

This Exception shall not apply to NM cables bundled as described in 334.80

 

[slk]

Re: 310.15(B)(2) add Exception 6.

I am betting that the code panel will disaprove this change due to the FPN to table 310.15(B)(2)(a). The FPN allows for load diversity to increase the derating capacity to 70% for up to 24 conductors (etc. per the table). Load diversity is present nowhere if not in a residence. I have used this table with approval (inspector not engineer) in my neck of the woods for residential applications, never tried for commercial...

 

[charlie]

Re: 310.15(B)(2) add Exception 6.

SLK, read the substantiation on the first post in this thread. I really do think it has a fighting chance.

 

[physis]

Re: 310.15(B)(2) add Exception 6.

Do you the CMP or Wayne Charlie?

 

[slk]

Re: 310.15(B)(2) add Exception 6.

I am not an engineer, nor do I play one on TV, but it seems to me that the original proposal (first post) wants to eliminate derating factors entirely in the situations described due to load diversity. I am saying that these situations have already been looked into by the code panel and they have come up with the limitations that the load diversity table provides. For this reason I think the proposal may be doomed to failure.

Using the load diversity table that I mentioned, you can run 12 12/2 NMB cables in the same bundle for longer than 24 inches and still maintain a 20 amp breaker on the conductors. You could run 21 14/2 NMB cables in the same bundle for more than 24 inches and still maintain a 15 amp breaker on the conductors. Do these limitations need to be exceeded very often in the field?

I think I understand that we are trying to eliminate the interpretation by some inspectors of bored holes fitting into the definition of bundling, thereby requiring derating. I just see a possibility of the code panel rejecting this approach due to the load diversity table already being in the code (the load diversity issue has already been looked into with the previously mentioned limitations).

Please note that I am not intending to shut down anyone's good idea, just trying to contribute to the thread in a way that I haven't seen anyone mention yet. I also could be missing something; I was perfect once, and then I was born...

 

[physis]

Re: 310.15(B)(2) add Exception 6.

If I remember right the impetus behind the proposal was inspectors calling cables ran through bored holes bundled.

 

[George Stolz]

Re: 310.15(B)(2) add Exception 6.

Load diversity is pretty involved stuff. This proposal would provide a clearer means of relief from the problem, IMO.

 

[hurk27]

Re: 310.15(B)(2) add Exception 6.

Time to get this rolling again, as I'll be leaving for Hot Springs Ak. next weekend for Western Section then off to Florida for a couple weeks:
Any more Idea's?

1.) NEC Section/Paragraph: 310.15(B)(2) add Exception 6.

2.) Proposal Recommends: [new text]

Exception No. 6: derating factors shall not apply to cables run in bored holes, or cut notches in joists or interior walls in dwellings under the following conditions:

(1) Where these cables are run in bored holes in a wall, floor, or ceiling space, and where the ambient temperature will not exceed 30?C in normal use and.

(2)Where the ambient temperature will not exceed 30?C in normal use

(3) Where these cables Are not larger than No. 12 Cu. or No. 10 Al.

(4) This Exception shall not apply where more than two NM cables containing two or more current carrying conductors are bundled together and pass through wood framing that is to be fire- or draft stopped using thermal insulation or sealing foam, as required in 334.80

4. Statement of Problem and Substantiation for Proposal.
Where there are cables run in bored holes in joists with spacing between each joist, the maximum load on these cables, will most likely never be used because of the load profiles in dwelling units. The temperature rise of these cables is minimal under these conditions. By limiting this exception to 15 and 20 ampere circuits, the range, dryer, electric furnace, etc. are excluded and the likelihood of more than one or two heavily loaded circuits are eliminated.

The code now requires multiple holes to be bored in floor joists to accommodate the runs and building regulations limit the amount of these holes that can be safely bored into floor joist. This places an undue burden on the electrician to find exit routing from panelboards. This proposal will provide some relief from the stringent requirements.
And that the dwelling unit load is so diverse and that those circuits are almost totally for convenience; therefore, the need for derating is not required as circuits will be used minimally and in small groups. The heaviest loaded circuits would likely be one or two small appliance branch circuits, a bathroom receptacle circuit, and a laundry circuit. Those circuits, mixed in with the other circuits, would not require derating.

[ September 17, 2005, 03:33 PM: Message edited by: hurk27 ]