I need to knockout a pre-punched hole in the bottom of my breaker panel. the hole size will be fairly large, but not quite as big as the outer ring.
I'm kind of wondering how to "knock out" JUST the rings I -want- knocked out, withOUT knocking out any 'undesired' outer knockouts in the same circle...
please see this image and tell me if I have it right...
toolie
Even professionals sometimes have problems getting just the ones they want out. Thank goodness for reducing donuts. You have it right as to where to start, but don't expect or even try to get the knockout removed just by hitting with a hammer and screwdriver. Usually you would start with the smaller center KO first, but in this case the next size may be easier from inside. If you look carefully at the way the knockouts are stamped you will see that they alternate between getting punched in and getting punched outwards. The center KO is stamped to be punched inward which makes it a little more difficult if you can only work from the inside. Once you get it started by hitting with the screwdriver you need to twist it. Knock it forth and back a few times to loosen it up. If you have a good pair of diagonal pliers or BX cutters you can sometimes get in there and cut one or more of those welds. Just don't try to get it real fast. Be patient and work it out. You will feel the knockouts get looser as you move them forth and back. It will be a little more difficult since the panel appears recessed in a wall. If you have a long thin screwdriver you can stick it between the edge of the wall and the edge of the panel to apply a little pressure from the outside.
The correct answer: CAREFULLY, and half the time you muck it up anyway. If the ko is protruding into the panel, like the center one, you have to punch it inward. The next ring is going outward and must be punched out in the same direction. Once the center ko is out, you may be able to pick at the others to get them out. Do be sure to have some KO washers handy just in case.
I googled "removing concentric knockouts" and really didn't find anything
What I do is pop out the center, which is pretty easy. I then take the second size and fold it completely in half, so I can grip it with lineman pliers, and gently work it back and forth until it pops.
Start by removing the center one-pice KO.
For each subsequent ring, use your pliers to carefully pry up the ring halves until they are up enough to cut each one in half with diagonal cutters leaving the two anchor points with a wing on each side. Now use the pliers to squeeze the wings together and then rock back and forth parallel to the anchor point until it breaks off. If you try to rock in the other direction it will tend to twist the next ring up.
A bit difficult to describe, but it should make sense when you're doing it.
I'm glad everyone has problem; I thought it was just me. Why don't they improve the design? It can't be that hard.
They did improve the design, they make panels without any knockouts so you can punch them as needed exactly where you want them and in the size you want. You of course need the punch set and a drill for the pilot hole.
Just hit the most inside plug where it is not connected with a tab until it pops out, then use long nose pliers to work it back and forth until the tabs snap. Just be attentive. If you take out too much you can always get the reducing rings. Another option is find another plug the right size and use that.
Occasionally I come across a pull box or something else that has very easily removed KO's. Unfortunately the concentric's sometimes break off after I've installed a connector. Then I need to use some donuts to fill the hole. With the more difficult ones you have a good chance of keeping the concentric's in place if you do it carefully.
I use a 1/8" bit to drill out the little hinge tab that you have marked as #2. Drilling out those little tabs makes it much easier to remove the rings. In commercial/industrial work where I usually have access to both sides of the box I use a knockout punch turned backwards to press the rings back in when they break loose. If you only want to remove the center KO, you can drill through the center with a small bit then use an awl to pop it out.
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