What’s the deal with bundling?

P

Pinnie

Senior Member
Location
Ohio
Occupation
Commercial Electrician
I’ve been told you can’t have more than 3 mcs under the same zip tie. I also know there’s a bundled definition but that only applies to art 520. There’s also a code rule that says something like if more than two mcs pass through the same hole with insulation or fire caulk you have to start derating.
 
The ampacity adjustment rule does not use the term "bundled" It says that ampacity adjustment is required when when more than 24" is installed "without maintaining spacing". A single tie, that lets the cables spread out would not require ampacity adjustment. Multiple ties that keep the cables together for more than 24" would require ampacity adjustment.

The passing through a hole with caulking or thermal insulation is in 330.80(C)
(C) Thermal Insulation.
Where more than two Type MC cables containing two or more current-carrying conductors in each cable are installed in contact with thermal insulation, caulk, or sealing foam without maintaining spacing between cables, the ampacity of each conductor shall be adjusted in accordance with Table 310.15(C)(1).
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don_resqcapt19 said:
The ampacity adjustment rule does not use the term "bundled" It says that ampacity adjustment is required when when more than 24" is installed "without maintaining spacing". A single tie, that lets the cables spread out would not require ampacity adjustment. Multiple ties that keep the cables together for more than 24" would require ampacity adjustment.

The passing through a hole with caulking or thermal insulation is in 330.80(C)
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So to be clear you could have as many mcs under a zip tie you want, given it’s less than 24” of no space between cables. They just need to be secured well to satisfy to supporting and securing requirement. And it would not need to be a listed zip tie unless in an environment the code requires.
 
Pinnie said:
So to be clear you could have as many mcs under a zip tie you want, given it’s less than 24” of no space between cables.
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There is also an exception for MC cable with #12 conductors where you're permitted to have up to 20 CCC's and no derating is required even when the cables are bundled for more than 24".
 
What are some violations that come to mind? I believe you could zip tie to a mini that is already supporting a conduit even though that’s hacky imo. You can strap to anything unless there is a rule against it, it seems to me. Like you can’t secure to a raceway unless you meet an exception.
 
Pinnie said:
What are some violations that come to mind? I believe you could zip tie to a mini that is already supporting a conduit even though that’s hacky imo. You can strap to anything unless there is a rule against it, it seems to me. Like you can’t secure to a raceway unless you meet an exception.
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Strapping directly to a raceway generally no. Strapping to the supports for a raceway yes.
 
Pinnie said:
They just need to be secured well to satisfy to supporting and securing requirement. And it would not need to be a listed zip tie unless in an environment the code requires.
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Starting with the 2017 code, cable ties used for securing and supporting MC cable must be listed for that purpose
 
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