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Drilling in truss system

M

mjf

Member
Joined
Mar 24, 2013
Messages
24
Location
New York's Hudson Valley area
Have a 1960's or 70's gutted house I am re-wiring and the ceiling joist/roof rafters are a 2 x 4 truss system. What are the codes regarding drilling through these 2 x 4 ceiling joist?

Thanks in advance,

Mike
 
mjf said:
Have a 1960's or 70's gutted house I am re-wiring and the ceiling joist/roof rafters are a 2 x 4 truss system. What are the codes regarding drilling through these 2 x 4 ceiling joist?Thanks in advance,

Mike
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Take a look at 802.10.4 pretty much a no no
 
Gregg Harris said:
Take a look at 802.10.4 pretty much a no no
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R802.10.4 Alterations to trusses. Truss members shall not

be cut, notched, drilled, spliced or otherwise altered in any

way without the approval of a registered design professional.
 
mark handler said:
R802.10.4 Alterations to trusses. Truss members shall notbe cut, notched, drilled, spliced or otherwise altered in any

way without the approval of a registered design professional.
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Thank you very much. Guess I'll be putting running boards in the "attic" to support my wires. Much easier when it was originally built and you could just lay wires on top of joist!
 
Running boards are not required by code for "support" in an attic but are for protection if the cable is within 6' of an access scuttle.

Just be sure to staple it <=4.5' OC.
 
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ICE said:
Running boards are not required by code for "support" in an attic but are for protection if the cable is within 6' of an access scuttle.Just be sure to staple it <=4.5' OC.
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Thought that code changed at the same time we were no longer allowed to affix wiring to the underside of joists in unfinished basements. I'm planning to put a call in to the AHJ in the AM. Thanks.
 
We don't do basements here so I wouldn't know when that came into the code but the attic wiring has been done the same way for a long time.
 
mjf,

Also, welcome to the Building Codes Forum!

Article 334.23 refers back to Article 320.23, which refers to Type AC cable assemblies.

Are you installing this type of conductor assembly in your referenced attic space?

Also, has your AHJ actually adopted the NEC versus the IRC for electrical applications?

Some AHJ's have not adopted the NEC for use!

.
 
mjf said:
Thanks for the welcome! I agree with you all also....found the code ( 334.23 ) allowing it in my 2008 NEC
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If your attic is not permanently accessible by stairs or ladder, protection for conductors is only required within 6 feet of scuttle access
 
globe trekker said:
mjf,Also, welcome to the Building Codes Forum!

Article 334.23 refers back to Article 320.23, which refers to Type AC cable assemblies.

Are you installing this type of conductor assembly in your referenced attic space?

Also, has your AHJ actually adopted the NEC versus the IRC for electrical applications?

Some AHJ's have not adopted the NEC for use!

.
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The protection requirements are the same for AC or NM

320.23 In Accessible Attics. Type AC cables in accessible attics or roof spaces shall be installed as specified in 320.23(A) and (B).

(A) Cables Run Across the Top of Floor Joists. Where run across the top of floor joists, or within 2.1 m (7 ft) of the floor or floor joists across the face of rafters or studding, the cable shall be protected by substantial guard strips that are at least as high as the cable. Where this space is not accessible by permanent stairs or ladders, protection shall only be required within 1.8 m (6 ft) of the nearest edge of the scuttle hole or attic entrance.

(B) Cable Installed Parallel to Framing Members. Where the cable is installed parallel to the sides of rafters, 70-186studs, or ceiling or floor joists, neither guard strips nor running boards shall be required, and the installation shall also comply with 300.4(D).
 
The OP was about boring holes in a "2 X 4 truss" system, that is what I was addressing. See R502.11.3.

So is it an "engineered", manufactured truss system, if so, we need to find out what an engineer thinks about boring holes in the ceiling cord. I had one once where there were 7-8 one inch in a row inch apart, basically they rebuilt the truss.

If this is a a plain ceiling joist, follow the requirements of R502.8.
 
fatboy said:
The OP was about boring holes in a "2 X 4 truss" system, that is what I was addressing. See R502.11.3. So is it an "engineered", manufactured truss system, if so, we need to find out what an engineer thinks about boring holes in the ceiling cord. I had one once where there were 7-8 one inch in a row inch apart, basically they rebuilt the truss.

If this is a a plain ceiling joist, follow the requirements of R502.8.
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Wouldn't 502.8 be addressing floor joists and 802.7.1 fit the criteria for 2/4 trusses?
 
2006IRC R802.7.2, engineered wood products, holes bored or notches are prohibited unless permitted by the manufacturer's recommendations or considered in the design of the membber by the RDP.

If it's engineered, it's like dating the farmers daughter, "Don't do without permission!"

pc1
 
"Wouldn't 502.8 be addressing floor joists and 802.7.1 fit the criteria for 2/4 trusses?"

Text of R802.7.1 refers you back to the requirements of R502.8.1
 
Gregg Harris said:
It appears that I am not the only one to visit the barn! Unless I miss construed your "now you tell me"
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I visited plenty "barns" I don't understand the "shadow the blame".
 
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