# Switch box knockouts



## gstull (Oct 8, 2007)

I have a gangable 1 1/2" deep switch box that has 1/2" knockouts. The contractor has knocked out these and installed 3/4" conduit. Is this up to NEC code, what about UL listing?


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## 14awg.com (May 1, 2008)

As long as the contractor used reducing rings then it should be up to code.


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## raider1 (Jan 22, 2007)

14awg.com said:


> As long as the contractor used reducing rings then it should be up to code.


I believe that the Op was talking about using a KO set and punching the 1/2 kos out to 3/4 kos so you wouldn't need to use reducing washers, but I could be mistaken.

I don't think that punching out a 1/2" knockout to a 3/4" size would violate the listing of the box. As long as you don't exceed the box fill I would say that you are OK.

Chris


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## 480sparky (Sep 20, 2007)

I sure hope using a KO set doesn't make me loose the listing on my boxes..... every commercial panel I install I order without KOs and I punch my own in exactly where I want them.


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## HighWirey (Sep 17, 2007)

480sparky said:


> I sure hope using a KO set doesn't make me loose the listing on my boxes..... every commercial panel I install I order without KOs and I punch my own in exactly where I want them.


Exactly, never had many factory KOs that worked in my favor.

Best Wishes Everyone


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## DCsparks (Apr 17, 2008)

You could use a unibit and drill out the 1/2" KOs. As far as I know its not a violation, but of course...I don't know.


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## micromind (Aug 11, 2007)

If this is indeed a violation, I might as well just go down to the Sheriffs office and ask to be locked up forever. I don't know how many thousands of times I've enlarged or made new knockouts in boxes, gutters, cans, and panels. 

Like alot of others, I always get commercial/industrial panels with no knockouts, and make my own where I need them.

Rob


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## 14awg.com (May 1, 2008)

It is not a violation to enlarge a ½ KO to ¾ KO so long as the box fill stays within regulations. A unibit will work if you have one large enough, I use a hole punch kit it will make a perfect circle in sizes 1/2" to 2"; although, a unibit would work better for a gangable box as the punch kit probably would not fit... anyways it is not a violation:thumbup:


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## 480sparky (Sep 20, 2007)

The only 'violation' I can think of is if you try to take a box that has ½" KOs spaced so close together that you cannot punch them out to ¾" and get the ¾" fittings/locknuts on.


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## macmikeman (Jan 23, 2007)

If it has gotten to the point where we are worrying about listing violations if we use a knock out set to enlarge a 1/2" ko to a 3/4" ko , its time for me to hang up my hat. You could probably get about 6 or 7 pages out of this over at MH.


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## randomkiller (Sep 28, 2007)

If this were illegal I am sure we would have all be sited for it. I always punch my own or enlarge holes.


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## HighWirey (Sep 17, 2007)

macmikeman said:


> If it has gotten to the point where we are worrying about listing violations if we use a knock out set to enlarge a 1/2" ko to a 3/4" ko , its time for me to hang up my hat. You could probably get about 6 or 7 pages out of this over at MH.


Mac,

You just hit me funny, MH does seem to get more MMP (miles per post).

Work'in For That Free Tee . . .


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## matthewryandohm (4 mo ago)

CHECK THIS OUT! This is the easiest/quickest/cleanest method i have found for enlarging 1/2” KO’s to 3/4” KO’s. _This method also works for 3/4” KO’s to 1” KO’s_ And the best part about it… all you will need are a few basic tools you probably already have in your toolbox. For 1/2” to 3/4”…. (1) Take your standard 1-1/8” Hole saw and screw it onto your arbor. (2) Loosen the set screw on the side of the arbor with an allen key and remove the 1/4” pilot drill bit. (3) Grab your standard 5/8” chrome socket and wrap some electrical tape, like 6-8 wraps, around the base of the socket. (4) Push the taped end of the socket inside your 1-1/8” metal hole saw. It should be very snug. Take your hammer and tap it down until its about halfway in the hole saw. (5) Put this state of the art technology into your drill and start turning 1/2” holes into 3/4” holes. When you see how well this works, you will cream in your pants. And for turning 3/4” KO’s to 1” KO”s Same exact method. Only youll use your 1-3/8” hole saw and a 13/16” Chrome Socket. You’re welcome. Enjoy!


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## wiz1997 (Mar 30, 2021)

matthewryandohm said:


> CHECK THIS OUT! This is the easiest/quickest/cleanest method i have found for enlarging 1/2” KO’s to 3/4” KO’s. _This method also works for 3/4” KO’s to 1” KO’s_ And the best part about it… all you will need are a few basic tools you probably already have in your toolbox. For 1/2” to 3/4”…. (1) Take your standard 1-1/8” Hole saw and screw it onto your arbor. (2) Loosen the set screw on the side of the arbor with an allen key and remove the 1/4” pilot drill bit. (3) Grab your standard 5/8” chrome socket and wrap some electrical tape, like 6-8 wraps, around the base of the socket. (4) Push the taped end of the socket inside your 1-1/8” metal hole saw. It should be very snug. Take your hammer and tap it down until its about halfway in the hole saw. (5) Put this state of the art technology into your drill and start turning 1/2” holes into 3/4” holes. When you see how well this works, you will cream in your pants. And for turning 3/4” KO’s to 1” KO”s Same exact method. Only youll use your 1-3/8” hole saw and a 13/16” Chrome Socket. You’re welcome. Enjoy!


I already have the proper tool for the job in my tool box.

No need to rig something.

How often do you need to change the tape as it melts and makes a gunky mess.


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## matthewdohm9 (4 mo ago)

.


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## emtnut (Mar 1, 2015)

matthewdohm9 said:


> ….about as often as you leave douchey comments on the internet to people who are only trying to offer some helpful advice. Anyone asking how to enlarge a knockout clearly doesnt own a knockout set. Moron.


Well, it was back in 2008 ... so glad you came on here to help him out.

Lotsa Matt's showing up here with only 1 post, are they all a bit stunned ? 😂


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## matthewdohm9 (4 mo ago)

Put that vienna sausage back in the can.


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## wiz1997 (Mar 30, 2021)

matthewdohm9 said:


> ….about as often as you leave douchey comments on the internet to people who are only trying to offer some helpful advice. Anyone asking how to enlarge a knockout clearly doesnt own a knockout set. Moron.


Anyone posting on this site is suppose to be a professional electrician, who more than likely have the proper tools they need to do the job.

What a Maroon.


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## matthewdohm9 (4 mo ago)

It achieves the same result, my guy. All I am doing is offering an alternative to people who either dont have or cant justify buying a knockout tool. All you are doing is being a negative asshole.


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## splatz (May 23, 2015)

matthewdohm9 said:


> It achieves the same result, my guy. All I am doing is offering an alternative to people who either dont have or cant justify buying a knockout tool. All you are doing is being a negative asshole.


A knockout would work but it's a lot of trash to drag around for this simple everyday task. A step bit. That's what everyone uses for this.

In a pinch, you can enlarge a hole with a hole saw, but your fakakta setup with a socket built up with tape is not something I'd try. If it's ever used on wood in the future, I bet it will be a real treat getting the slug out with the tape residue in there after this. 

A well known improvisation is to thread the larger hole saw on the arbor first, then thread on the smaller hole saw. The smaller hole saw acts as a pilot for the larger. There's even a special pilot you can buy just for this










Wouldn't it be great if there was a tool you had with you that made something the right diameter to use as a pilot for the smaller hole? How about the smaller hole saw? You can just run the smaller hole saw through a 2x4, then slide the slug over the pilot bit with the larger hole saw. You'll actually need one and a half slugs so it sticks out past the teeth. It will be slightly undersized, by the thickness of the kerf. If you have a hole saw the next size up you could try that but most electrician sets only include the KO sizes. But it will work fine a little loose if you think a bit.

Another thing you can do is make a jig to guide the larger hole saw. All you need is something with a hole in it the size of the larger knockout, and since you have the hole saw, you can definitely make that. You can just cut a hole in a box cover, scrap of wood (whatever is handy) and clamp that onto the box and use that as a jig. 

So the rube goldberg sticky tape mess that you made is the worst method I have ever heard to accomplish this task, but you do get a point for finding a way, even if it isn't the best way, or a top ten way, to get the job done. Unfortunately you lose points for being a complete douchebag at the slightest criticism and with only one pity-point for your idea, that puts you in negative points territory.

I think the universe might want you to be a drywaller, or maybe drive for Uber. If that is the case please abide by the universe's wishes, sooner than later, and before making a sticky mess of any more innocent hardworking tools, it's hard to watch.


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## macmikeman (Jan 23, 2007)

I have used my Spyder hole saw kit to stack 2 sizes of hole saw cutters before. I put a Lennox 6" behind the Spyder 4" hole bit because of customer's wanting to upsize some 4" wafer lights to six inch wafer lights in drywall ceilings. The Spyder's have a deeper cup which makes this thing work. The sliding mandrel could use another 1/4" of threads to make it a perfect tool for this , but it functioned , just barely due to only grabbing a minuscule bit of thread for the inner hole saw onto the mandrel. Anyway, it did center the 6" cuts exactly in the same place as the original 4" hole's were located at. The Spyder hole saw kits are pretty cool , especially when you swap out the Spyder cutter bits with conventional ones and use the long bit and mandrel with them instead of those Spyder bits.


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## Wirenuting (Sep 12, 2010)

matthewryandohm said:


> CHECK THIS OUT!
> all you will need are a few basic tools you probably already have in your toolbox.
> You’re welcome. Enjoy!


A standard KO set is already a basic tool in the tool box. 

Your welcome.


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## wiz1997 (Mar 30, 2021)

Wirenuting said:


> A standard KO set is already a basic tool in the tool box.
> 
> Your welcome.


A majority of the jobs I've been on as a journeyman electrician, required the standard KO handset on the mandatory tool list, even though there was usually a hydraulic set in the company's gang box.

Apprentices were not required to have a KO set.


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## readydave8 (Sep 20, 2009)

matthewdohm9 said:


> ….about as often as you leave douchey comments on the internet to people who are only trying to offer some helpful advice. Anyone asking how to enlarge a knockout clearly doesnt own a knockout set. Moron.


your posts were mildly interesting until you started calling people morons

your method is brilliant if it was improvising when stuck somewhere without proper tools, otherwise not so much


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## macmikeman (Jan 23, 2007)

My good old Greenlee 7906SB compact KO hand pump recently gave up the ghost. It served me well for decades, I miss it greatly. Please excuse me for the following bit........


Waaaaaaaaaaaaaa. 😢😭


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## LGLS (Nov 10, 2007)

wiz1997 said:


> A majority of the jobs I've been on as a journeyman electrician, required the standard KO handset on the mandatory tool list, even though *there was usually a hydraulic set in the company's gang box.*
> 
> Apprentices were not required to have a KO set.


Just wait for it... it'll get there eventually.


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