Knockout hole sizing - where am I going wrong?

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Old 08-23-20, 10:58 AM
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Red face Knockout hole sizing - where am I going wrong?

Having some trouble with the knockout hole on a Reliance inlet box. I must be missing something; hopefully someone here knows where I'm going wrong. This is the Reliance PBN30 non-metallic inlet box: https://www.homedepot.com/p/Reliance...BN30/205337808

Per the instructions ( https://images.homedepot-static.com/...262b218f93.pdf),
REMOVE KNOCKOUT FROM THE INSIDE OF THE ENCLOSURE USING A SCREWDRIVER INSERTED INTO THE SLOT IN THE KNOCKOUT AND STRIKE GENTLY WITH A HAMMER. 3/4-inch fittings can be installed directly into the knockout holes. To use 1/2-inch fittings, insert the knockout washer (provided) into the open hole, and then install the fitting.

I don't see how a 3/4" connector fitting will fit this hole. It's only 0.875" diameter, which looks to be the same diameter of the 1/2" KO holes on my main panel. Here are pics of the hole from the outside of the inlet box, with 3/4" NM button push-in connector, 3/4" NM clamp connector and 1/2" NM button push-in connector. No way those 3/4" connectors will fit this hole. The 3/4" NM button connector has a diameter of 1.16" (the part that is supposed to fit through the KO), and the 3/4" NM clamp has a diameter of 1.0" at the threads.
https://imgur.com/S2k6Rsc
https://imgur.com/ZSUCfzk

Here's a pic from the inside of the box, again with 3/4" connectors.
https://imgur.com/PD6Pnwx

Here's a pic with the "knockout washer" inserted for use with 1/2" fittings - you can see that this washer has the same inner diameter as the inlet box hole.
https://imgur.com/RcydALK

So unless I'm missing something, I need to enlarge this hole to use 3/4" fittings. I figure I must be overlooking something because none of the reviews on Amazon or Home Depot mention any issues with the KO holes. Please help!

 

Last edited by PJmax; 08-23-20 at 11:07 AM. Reason: added pic fron link with arrow
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Old 08-23-20, 11:07 AM
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I added an arrow to the picture. Isn't that a 3/4" KO ?
 
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Old 08-23-20, 11:21 AM
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You've got eagle eyes, but no, that's not a KO. Here's a pic showing the inlet box with the popped out KO piece. The red circled area shows the inside of the box around the round mark you saw on the outside. In this pic you can see the other 2 KOs - there are a total of 3 KOs - one on the back (the one I popped out) and one on each side of the box.
https://imgur.com/nYvjAFX

Also, the faint circled area you noticed would be blocked off by the inlet, as shown below.
https://imgur.com/PtlDEEI
 
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Old 08-23-20, 11:25 AM
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In that same picture...... where you knocked the KO out..... that ring looks like it comes out.
Possibly using a screwdriver to pry it out or needle nose to grab it.
 
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Old 08-23-20, 11:46 AM
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The popout piece is just cut this way so that it can be stuffed back into place if you don't want to use that KO hole. Tried to take a side view pic so you can see how both the popout and the hole are cut so that you can stick the KO back in to seal up the hole.
https://imgur.com/nU5yt7v

And here's a pic with it fully reinserted.
https://imgur.com/LX6iG3g

The paper instructions (which uses slightly different wording than the online pdf) refers to this as a POP-FAST reusable knockout.
https://imgur.com/Ggr4NkC

These reusable KOs don't require a screwdriver and hammer to remove. They can be pressed out with a thumb. I pushed out one of the side KOs - it's exactly the same size as the rear KO piece.
 

Last edited by cartman; 08-23-20 at 12:11 PM.
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Old 08-23-20, 12:19 PM
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Unfortunately..... those instructions may not have been for that exact box.
They change manufacturers constantly.
Do you have a unibit..... just drill it out to the size you need. It's only plastic.
 
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Old 08-23-20, 05:17 PM
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Yeah, that makes sense. Strange that no one mentioned it in the recent reviews. Maybe people were stuffing 10/3 cable through a 1/2" KO NM clamp.

Good call on the unibit. I was originally thinking of enlarging the hole with a hole saw bit, but the step bit is a much better choice for this task.

Got 'er done, thanks PJ.
 
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Old 08-24-20, 07:52 AM
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I just checked the PBN50 I was getting ready to install.... same thing!!! Despite what the current product info says, they are not 3/4" knockouts. Silly thing is that it included the adapter ring for converting a 3/4" KO to 1/2".


 
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Old 08-24-20, 07:55 AM
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I just checked the PBN50 I was getting ready to install.... same thing!!! Despite what the current product info says, they are not 3/4" knockouts. Silly thing is that it included the adapter ring for converting a 3/4" KO to 1/2".
We are each other's proof that we are not crazy or idiots!
 
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