#6 NM wire in 1/2" hole?

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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! Regards, Theodore.
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snipped-for-privacy@yahoo.com wrote in

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"?
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Doug Miller wrote:

Hi. The length of cable must be long, otherwise wouldn't 8-3 do? Enlarging hole is easy using rimmer, cabinet is not really heavy gauge steel.
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On Monday, July 21, 2014 7:17:12 PM UTC-4, Doug Miller wrote:

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.
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On Mon, 21 Jul 2014 15:30:28 -0700 (PDT), snipped-for-privacy@yahoo.com wrote:

Get one of these
http://www.harborfreight.com/knockout-punch-kit-91201.html
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On 07/21/2014 06:43 PM, snipped-for-privacy@aol.com wrote:

I agree, I'd punch it out.
(sorry if you got an email, I hit the wrong button)
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On Mon, 21 Jul 2014 15:30:28 -0700 (PDT), snipped-for-privacy@yahoo.com wrote:

Can you get the 6-3 cable through the required cable connector, is the big question. If you can fit the 6-3 into the connector that threads into the 1/2" knockout, you are gold. If not you will need a knockout punch to enlarge the hole to 3/4" size (Greenlee punch)
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Another option would be to find a smaller cable going through a concentric KO with a 3/4" ring, swap that to the 1/2" only KO and use the larger one with the concentric ring poked out..
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wrote:

I assume you mean a reamer - which leaves all kinds of conductive swarf all through the panel. The only RIGHT way to do it is with a "knoclut punch" - aften referred to by the most common brand - a "greenlee punch" Any electrician worth his salt will have one. All you get that way is a metal ring.
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On 7/21/2014 8:31 PM, snipped-for-privacy@snyder.on.ca wrote:

HF sells step bits which can be used to enlarge the hole. Of course, you need a shopvac in action at the same time to catch the chips.
Instead of a rimmer, use a knoclut punch. Amazing, one good misssspelled word desserves anothher.
. Christopher A. Young Learn about Jesus www.lds.org .
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On Mon, 21 Jul 2014 19:43:33 -0400, snipped-for-privacy@aol.com wrote:

That will do the job. Wouldn't want to make my living with it, but it will make a few holes, for sure. A lot cheaper than Greenlee
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Conductor size is determined by amperage, not by length.

LMAO! The tool he needs is a *reamer*. A "rimmer" is something altogether different.
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Whether he needs AWG-6 or AWG-8 is not really relevant -- neither one is listed for use with any Romex connector or clamp that I'm aware of which will fit in a 1/2" knockout.
Another question for the OP: do you really need 6-3 (or 8-3, as the case may be) for an air conditioner? If it's central AC, it's almost surely a pure 240V load, and 2-conductor cable will do -- and if it's a window AC, 10-3 is almost surely sufficient.
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snipped-for-privacy@snyder.on.ca wrote in wrote:

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?

WRONG. The big question is whether the required cable connector is listed for use with 6-3 cable. If the connector is not listed for use with 6-3 cable, it's a Code violation to use it for that, whether the cable fits or not.
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On 07/21/2014 06:30 PM, snipped-for-privacy@yahoo.com wrote:

That must be one bad ass air conditioner. Wouldn't want your electric bill.
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On Tue, 22 Jul 2014 01:10:49 +0000 (UTC), Doug Miller

Wire size is PRIMARILY dictated by load, but cable length comes into play due to excessive voltage drop. You can never go wrong going one size oversized.
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On Tue, 22 Jul 2014 01:14:05 +0000 (UTC), Doug Miller

Well, you show me a romex connector that will take a 6/3 cable that isn't listed for use with 6/3 and you may have a point. The POINT is, there is no romex connector that WILL accept a 6/3 - listed or not..
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On Mon, 21 Jul 2014 22:19:30 -0400, snipped-for-privacy@snyder.on.ca wrote: I missed the 1/2" requirement in my last reply - this is the corrected reply.

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Hi, I'm the OP. Yes, the mini split a/c system specs explicitly call for a 50amp breaker and #6 AWG (although I shudder to think that it'll actually use that much, with a 16 SEER).
I think I answered my own question by finding several "conduit fill charts" online that say 1/2" conduit can only have 2 #6 wires, so rules are there to keep me safe and I'm fine with that.
I also failed to notice one last 3/4" knock-out, so I'll be using that one. Many thanks to all the good technical solutions and suggestions! Regards, Theodore.
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On 7/21/2014 11:43 PM, snipped-for-privacy@yahoo.com wrote:

So, what's the tons or BTU that needs such a big wire?
. Christopher A. Young Learn about Jesus www.lds.org .
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