NM bundling
- Thread starter gimpyfac
- Start date
- Status
- Location
- Massachusetts
Re: NM bundling
Here in MA any inspector I know would call that bundling.
You have 50 current carrying conductors minimum run together.
That is a 35% adjustment.
Here in MA any inspector I know would call that bundling.
You have 50 current carrying conductors minimum run together.
That is a 35% adjustment.
pierre
Senior Member
- Location
- Westchester County, New York
Re: NM bundling
That is a lot of cables through one hole. Why did you run all of those cables through just one hole?
I would have concerns about the bundling issue with this as well.
Pierre
That is a lot of cables through one hole. Why did you run all of those cables through just one hole?
I would have concerns about the bundling issue with this as well.
Pierre
jimport
Senior Member
- Location
- Outside Baltimore Maryland
- Occupation
- Master Electrician
Re: NM bundling
What size was the joist that you could afford to make a 2 1'2" hole in it?
Several smaller holes would have done less structural damage than that one monster hole.
What size was the joist that you could afford to make a 2 1'2" hole in it?
Several smaller holes would have done less structural damage than that one monster hole.
richwaskowitz
Senior Member
- Location
- Shelby Twp. MI, near Detroit
Re: NM bundling
I agree with the other guys. As slick as a trick you may have thought that was, one big hole is not the way to go. I saw that done once on a job and the inspector made the guys re-do it.
I agree with the other guys. As slick as a trick you may have thought that was, one big hole is not the way to go. I saw that done once on a job and the inspector made the guys re-do it.
Re: NM bundling
We looked at a job last year, where the guy drilled 2-1/2" holes across the basement, and ran bundled cable, they had the family moved out of the home until the damage was replaced. The owners were calling contractors, to get a quote to do the job right. 2X10's were drilled.
We looked at a job last year, where the guy drilled 2-1/2" holes across the basement, and ran bundled cable, they had the family moved out of the home until the damage was replaced. The owners were calling contractors, to get a quote to do the job right. 2X10's were drilled.
luke warmwater
Senior Member
Re: NM bundling
You can drill a 2 1/2" hole as long as it is in the center 1/3rd of the joist.
Also, if you drill (2) 2 1/2" holes, there must be 2 1/2" between the edges of the holes.
(6) 12/2, (5) 14/2, (1) 10/3, (1) 6/3 through each set of 2 1/2" holes the whole distance of the house?
I would be more concerned with the friction of pulling wires ontop of wires as the insulation on NM is easily burned through.
You can drill a 2 1/2" hole as long as it is in the center 1/3rd of the joist.
Also, if you drill (2) 2 1/2" holes, there must be 2 1/2" between the edges of the holes.
(6) 12/2, (5) 14/2, (1) 10/3, (1) 6/3 through each set of 2 1/2" holes the whole distance of the house?
I would be more concerned with the friction of pulling wires ontop of wires as the insulation on NM is easily burned through.
david
Senior Member
- Location
- Pennsylvania
Re: NM bundling
?You can drill a 2 1/2" hole as long as it is in the center 1/3rd of the joist.
Also, if you drill (2) 2 1/2" holes, there must be 2 1/2" between the edges of the holes.?
Her in Pa we are new the International Buildings codes, but doesn?t R502.8.1 ( IRC 2000 ) say you are not allowed to drill the middle third section of a joist?
?You can drill a 2 1/2" hole as long as it is in the center 1/3rd of the joist.
Also, if you drill (2) 2 1/2" holes, there must be 2 1/2" between the edges of the holes.?
Her in Pa we are new the International Buildings codes, but doesn?t R502.8.1 ( IRC 2000 ) say you are not allowed to drill the middle third section of a joist?
curt swartz
Electrical Contractor - San Jose, CA
- Location
- San Jose, CA
- Occupation
- Electrical Contractor
Re: NM bundling
A long time ago I remember being told never to drill the center 1/3 of a joist. Over the years I have talked to several structural engineers about this and they have always said never drill the end third of a joist or beam. If it?s a very small hole it is ok but always do the majority of the drilling in the center third of the member. The specs for glue lams, TGIs and Microlams all seem to support this since they require most drilling in the center third but not the end thirds.
A long time ago I remember being told never to drill the center 1/3 of a joist. Over the years I have talked to several structural engineers about this and they have always said never drill the end third of a joist or beam. If it?s a very small hole it is ok but always do the majority of the drilling in the center third of the member. The specs for glue lams, TGIs and Microlams all seem to support this since they require most drilling in the center third but not the end thirds.
Re: NM bundling
curt,
I think you are right, the house where they moved everyone out, had engineers do a report on the damage, i am not sure what standard they used, but i do remember, they had to replace every joist, they were 2x10's with 2-1/2 holes.
[ February 29, 2004, 10:23 PM: Message edited by: satcom ]
curt,
I think you are right, the house where they moved everyone out, had engineers do a report on the damage, i am not sure what standard they used, but i do remember, they had to replace every joist, they were 2x10's with 2-1/2 holes.
[ February 29, 2004, 10:23 PM: Message edited by: satcom ]
Re: NM bundling
I have the "frameworks building system" booklet in front of me now, it comes on the TJI joists in a plastic bag attatched to the joists, one of the builders gave me it this summer after talking about drilling holes in the joists came up.
It has all the specs. for allowable holes.
Allowable holes -Beams,Headers and wall studs.
There is a table that had the minimum distance from inside face of any support to nearest edge of hole.
John
I have the "frameworks building system" booklet in front of me now, it comes on the TJI joists in a plastic bag attatched to the joists, one of the builders gave me it this summer after talking about drilling holes in the joists came up.
It has all the specs. for allowable holes.
Allowable holes -Beams,Headers and wall studs.
There is a table that had the minimum distance from inside face of any support to nearest edge of hole.
John
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: NM bundling
WoW seem's to me the center of a span would be the weakest place to drill a hole. as it seems like the joist would be weakened less if the holes were drilled closest to where the joist is supported? But I too have seen where HVAC guys would bucher joist and TGI's and the inspector would just say it's allowed.
WoW seem's to me the center of a span would be the weakest place to drill a hole. as it seems like the joist would be weakened less if the holes were drilled closest to where the joist is supported? But I too have seen where HVAC guys would bucher joist and TGI's and the inspector would just say it's allowed.
Re: NM bundling
On page 1 on the Framers pocket guide to the "frameworks building system"
On a 9 1/2" joist depth TJI 100Ts the minimun distance from inside face of any support to nearest edge of hole (Example 4" hole) would be 2' 6".
The tables give 4 different joists depths...9 1/2" thru 16"
19 types or rating of joists.......
And round hole sizes from 2" thru 12".
************
Page 2 Allowable Holes - Beams, headers and wall studs.
It shows what I would call a pre-lam.
Notes are as follows.
For uniformly loaded beams only.
Rectangular holes are not allowed.
Holes in canterlievers require additional analysis.
On this page it also shows a ALLOWED HOLE ZONE which is the center 1/3 of the span.
The round hole chart is as follows for what I am calling the pre-lam. beam.
BEAM DEPTH 4 3/8" MAX.ROUND HOLE SIZE = 1"
BEAM DEPTH 5 1/2" MAX. ROUND HOLE SIZE =1 3/4"
BEAM DEPTH 7 1/4" thru 20" MAX. ROUND HOLE SIZE = 2"
John, Edited to clarify .
[ February 29, 2004, 11:49 PM: Message edited by: drg ]
On page 1 on the Framers pocket guide to the "frameworks building system"
On a 9 1/2" joist depth TJI 100Ts the minimun distance from inside face of any support to nearest edge of hole (Example 4" hole) would be 2' 6".
The tables give 4 different joists depths...9 1/2" thru 16"
19 types or rating of joists.......
And round hole sizes from 2" thru 12".
************
Page 2 Allowable Holes - Beams, headers and wall studs.
It shows what I would call a pre-lam.
Notes are as follows.
For uniformly loaded beams only.
Rectangular holes are not allowed.
Holes in canterlievers require additional analysis.
On this page it also shows a ALLOWED HOLE ZONE which is the center 1/3 of the span.
The round hole chart is as follows for what I am calling the pre-lam. beam.
BEAM DEPTH 4 3/8" MAX.ROUND HOLE SIZE = 1"
BEAM DEPTH 5 1/2" MAX. ROUND HOLE SIZE =1 3/4"
BEAM DEPTH 7 1/4" thru 20" MAX. ROUND HOLE SIZE = 2"
John, Edited to clarify .
[ February 29, 2004, 11:49 PM: Message edited by: drg ]
david
Senior Member
- Location
- Pennsylvania
Re: NM bundling
I went and looked it up in the 2000 International residential building code section R502.8 Drilling and notching and I was wrong though R502.8 deals with bored holes and notches only notches are prohibited in the middle third of a joist span.
Bored or cut holes are only limited in size and spacing they cannot have a diameter greater than one- third the depth of the joist and they cannot be any closer than two inches to any other hole or notch. The hole has to be two inches from the top and two inches from the bottom of the joist.
I went and looked it up in the 2000 International residential building code section R502.8 Drilling and notching and I was wrong though R502.8 deals with bored holes and notches only notches are prohibited in the middle third of a joist span.
Bored or cut holes are only limited in size and spacing they cannot have a diameter greater than one- third the depth of the joist and they cannot be any closer than two inches to any other hole or notch. The hole has to be two inches from the top and two inches from the bottom of the joist.
luke warmwater
Senior Member
Re: NM bundling
David, thank-you, thank-you.
John, TGI's and laminated beams are different than dimentional lumber.
Satcom, I don't know all of the details of the job that you describe, but if the holes were indeed too close together, or in the wrong location, it may have been permissible for them to 'sister' the joists?
Ryan J, where do you stand on this type of installation???
David, thank-you, thank-you.
John, TGI's and laminated beams are different than dimentional lumber.
Satcom, I don't know all of the details of the job that you describe, but if the holes were indeed too close together, or in the wrong location, it may have been permissible for them to 'sister' the joists?
Ryan J, where do you stand on this type of installation???
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: NM bundling
1) If the wood is dimensional lumber, you must not drill in the middle 1/2 of the span, nor can you drill in the top or bottom 2 inches of the member.
2) If the wood is an engineered product (such as an I-joist), you can drill in the outer third of the span, but not very large (about 1 1/2"). If you drill in the center 1/3 of the span, you can drill a huge hole (up to about 8") and not hurt anything.
Now, as far as bundling goes, if the bundling occurs for more than 24", I would have a problem with it and require de-rating.
If you are asking me about drilling the wood, there are two VERY different things to consider with the type of material being drilled.
1) If the wood is dimensional lumber, you must not drill in the middle 1/2 of the span, nor can you drill in the top or bottom 2 inches of the member.
2) If the wood is an engineered product (such as an I-joist), you can drill in the outer third of the span, but not very large (about 1 1/2"). If you drill in the center 1/3 of the span, you can drill a huge hole (up to about 8") and not hurt anything.
Now, as far as bundling goes, if the bundling occurs for more than 24", I would have a problem with it and require de-rating.
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: NM bundling
Let me elaborate on my last response.
Here is what the code says:From the 2000 International Residential Code, Section R502.8.1
Sawn Lumber. Notches in soliod lumber joists, rafters and beams shall not exceed one-sixth if the depth of the member, shall not be longer than one-third of the depth of the member and shall not be located in the middle one-third of the span. Notches at the ends of the member shall not exceed one-fourth the depth of the member. The tension side of members 4 inches or greater in nominal thickness shall not be notched except at the ends of the members. The diameter of holes bored or cut into members shall not exceed one-third the depth of the member. Holes shall not be closer than 2 inches to the top or bottom of the member, or to any other hole located in the member. Where the member is also notched, the hole shall not be closer than 2 inches to the notch.
And here is what a popular manufacturer says about wood I-joists:
Let me elaborate on my last response.
Here is what the code says:From the 2000 International Residential Code, Section R502.8.1
Sawn Lumber. Notches in soliod lumber joists, rafters and beams shall not exceed one-sixth if the depth of the member, shall not be longer than one-third of the depth of the member and shall not be located in the middle one-third of the span. Notches at the ends of the member shall not exceed one-fourth the depth of the member. The tension side of members 4 inches or greater in nominal thickness shall not be notched except at the ends of the members. The diameter of holes bored or cut into members shall not exceed one-third the depth of the member. Holes shall not be closer than 2 inches to the top or bottom of the member, or to any other hole located in the member. Where the member is also notched, the hole shall not be closer than 2 inches to the notch.
And here is what a popular manufacturer says about wood I-joists:
david
Senior Member
- Location
- Pennsylvania
Re: NM bundling
Ryan
Since electricians bore a lot of holes and our state has now adopted the 2000 IRC and if I think the issue is relevant to a discussion in an electrical forum. I will also be responsible for giving electricians the correct guidance in this area I fill its important for me to understand where in IRC 2000 section 502.8.1 does it address holes being prohibited in the center third section of a joist.
I can clearly see that it addresses this with notches but I am not seeing the same thing you are with bored or cut holes
Ryan
Since electricians bore a lot of holes and our state has now adopted the 2000 IRC and if I think the issue is relevant to a discussion in an electrical forum. I will also be responsible for giving electricians the correct guidance in this area I fill its important for me to understand where in IRC 2000 section 502.8.1 does it address holes being prohibited in the center third section of a joist.
I can clearly see that it addresses this with notches but I am not seeing the same thing you are with bored or cut holes
- Location
- Massachusetts
Re: NM bundling
Once you get to more than 3 current carrying conductors you need to look at 310.15(B)(2)(a).
In general if you are dealing with NM once you exceed 9 current carrying conductors you will not be able to use a 20 amp breaker with 12 AWG or a 15 amp breaker with 14 AWG.
You should take a look at 310.15(B)(2)(a) yourself to see how it is worded.
It is not how many cables, it is how many current carrying conductors.
Once you get to more than 3 current carrying conductors you need to look at 310.15(B)(2)(a).
In general if you are dealing with NM once you exceed 9 current carrying conductors you will not be able to use a 20 amp breaker with 12 AWG or a 15 amp breaker with 14 AWG.
You should take a look at 310.15(B)(2)(a) yourself to see how it is worded.
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