Bundling question

Two cables zip ties together are bundled. As Augie stated after 4 cables the derating will lower the 20 amp rating associated with #12 AWG.
 
Just a quick note that the previous answers assume a 30C or less ambient temperature. If bundling occurs in a higher ambient temperature (say a typical unconditioned residential attic), then bundling can cause significant derating with fewer than (5) 12-2 cables.

Cheers, Wayne
 
Because that is 10 CCC'S which requires a derating to 50%.

30*50%=15 amps no good for 20 amps.

9 CCC'S would be 30*70%=21 amps good for a 20 amp circuit.
I see that now. I didn't understand Gus' reply at first. my initial thought was what you said in your post. Two cables would be bundling as you would have (4) CCC
 
I see that now. I didn't understand Gus' reply at first. my initial thought was what you said in your post. Two cables would be bundling as you would have (4) CCC
Yeah Gus just gave us a shortcut to the no more than 9 CCC'S rule of thumb for #12 NM cables.
 
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