code question-wiring limits?

Reply

  #1  
Old 05-28-10, 07:31 AM
W
Member
Thread Starter
Join Date: Nov 2008
Location: tennessee
Posts: 18
Received 0 Votes on 0 Posts
code question-wiring limits?

In a new construction home with a basement, have gotten some conflicting help on my wiring. Had an electrician tell me it would be best to run our wiring in our floor joists as many wires per 3/4 inch hole as possible to avoid having to drill too many holes, which would understandably weaken the floor joists. Makes sense not to drill an individual hole for each and every wire, that would have the joists looking like swiss cheese in some places and also leave the wiring likely more messy/cluttered looking with having to space out all the holes that would be needed.

Had an industrial electrician we know come by yesterday to kind of look things over and he pointed that out and said while it is not a code issue the woman inspector where he does most of his work would not let that go as it is. She is not the inspector we get here, but this kinda has me concerned and I really don't want to ask/raise questions on this with our inspector. He also pointed out my use of staples, having wires doubled up in some 3/4 inch staples and then using the large gray staples for multiple wires in places. The work is neat and for the most part clean looking, but kind of concerned about having to pull wire back out since I already stripped the wires down into my panel. If I have to pull them back out and drill more sets of holes then so be it, but really not seeing the point in it if it is not against code.

Hoping to get past our rough in this coming Wednesday. If the use of staples and the multiple wiring in the holes are not against the 2008 nec, what are the chances our local inspector is going to have a problem with it and require that to have to be changed?

Any insight would be appreciated.
 
Sponsored Links
  #2  
Old 05-28-10, 08:17 AM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 13,660
Received 218 Votes on 193 Posts
Drilling multiple 3/4" holes in joists will not weaken a joist significantly. There are rules on drilling joists that can be found here: How To Drill Through Floor Joists | thefamilyhandyman.com | DIY Projects | Reader's Digest and How Joists Work: How Joists Works | Reader's Digest
Bundling many cables for for longer then 24" must be derated. Most times when they are just pulled through the holes it is not an issue but if they are tightly bundled you inspector might have issues with it. But to be clear it is not an issue to run more than one cable through a hole. Most times I limit it to 3 cables.

Staples have a rating on the package of what and how many cables are allowed to be used with the staple. I suspect the big gray ones are not listed to be used on #14 or #12 romex. I suggest fixing that one. Also remember not to lay the flat cables on edge.
 
  #3  
Old 05-28-10, 09:36 AM
I
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,943
Received 43 Votes on 41 Posts
I generally limit it to 3 cables in a 7/8" hole. The inspectors around here enforce an upper limit of 4 cables per hole when dealing with #12 and #14. Larger cables should be one-per-hole.
 
  #4  
Old 05-28-10, 11:22 AM
W
Member
Thread Starter
Join Date: Nov 2008
Location: tennessee
Posts: 18
Received 0 Votes on 0 Posts
Originally Posted by ibpooks View Post
I generally limit it to 3 cables in a 7/8" hole. The inspectors around here enforce an upper limit of 4 cables per hole when dealing with #12 and #14. Larger cables should be one-per-hole.
Thanks for the replies.

Have 3 runs of 3/4 inch holes where there was the concern, each with 4 wires,(12's and 14's). From this I think I will be best off to drill one more set and remove one cable from each. May only have to go back about a dozen joists.

Staples I used for the 14 and 12 are the ideal branded staples and say they are rated for up to 10/3, does not specify one or two wires. Those 3/4 inch staples 2 14/2's will fit side by side laying flat with a little slack. The gray staples I mentioned are similar to those sold at lowes for large wire up to 6/3.
 

Last edited by william; 05-28-10 at 12:19 PM.
  #5  
Old 05-28-10, 05:48 PM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: United States
Posts: 10,696
Received 91 Votes on 81 Posts
Some areas don't have an issue with more than one cable per hole and some do. It's best to find out what your inspector wants and follow that. As far as multiple cables under one staple, I think the issue is that most staples are only U.L. listed for one cable. The ratings on the box should be in accordance with their U.L. listings.
 
  #6  
Old 05-29-10, 12:27 AM
F
Member
Join Date: Mar 2006
Location: NE Wis / Paris France{ In France for now }
Posts: 4,807
Received 0 Votes on 0 Posts
most case the 2.5 or 4.0mm˛'s { 14 or 12 AWG } NM cable I useally limted to 3 per hole no bigger than 7/8" hole but for larger cable like for stove or dryer or cable run to subpanel etc., single cable to single hole in the joist but just becarefull where you bore it.

Merci,Marc
 
  #7  
Old 06-04-10, 05:44 AM
W
Member
Thread Starter
Join Date: Nov 2008
Location: tennessee
Posts: 18
Received 0 Votes on 0 Posts
Thanks again for the replies. Passed with no problems. Inspector did not mention the staples or the holes at all.
 
Reply
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: