On Monday, July 21, 2014 7:17:12 PM UTC-4, Doug Miller wrote:
wrote in

:



Hi,

I'm running a 6-3 Romex NM-B with ground for my new air

conditioner system. My main panel doesn't seem to have any spare

(unoccupied) 3/4" size punch outs left; but there is a 1/2"

punch out. It is possible for me to fit this 6-3 with ground in

there, but does anyone know whether this is prohibited by the

NEC? All advice (and NEC references) appreciated!



I doubt very much that this would meet Code. First of all, you can't just pass the cable

through the knockout hole -- for the protection of the cable and the connections, Code

requires some sort of fitting on the hole (e.g. a cable clamp aka "Romex connector") which

secures the cable to the box. And I can't imagine that any fitting which would fit a 1/2"

knockout is listed for use with anything as large as 6-3; for example, the Romex connectors

used with 1/2" knockouts are listed for 14-2 through 10-3.



Does the panel have any vacant 1" knockouts? Or can you ream the 1/2" hole to 3/4"?

Aside from that, does he really need #6 for an AC? Presumbably a home AC?
I have a 5 ton, which I believe is the largest made and it's rated for #8. I
wonder if he's sizing based on breaker, instead of sizing based on the
install instructions and eqpt rating. Meaning I have a 50 amp breaker on
my 8 gauge, 5 ton and it's to code because it's a motor load, not an oven.