Securing MC/AC cable to existing outlet box

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  #1  
Old 03-30-12, 08:45 PM
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Securing MC/AC cable to existing outlet box

Standard 4" Steel Box in Wall.
I suppose a good wack of a flathead screw will be able to get a knockout out.

I plan to run a new line to this box if doable...

Do they make special fittings that I can use to secure a BX cable in a 1/2 knockout or 3/4 ........that I can secure to the box IF I only have access to the *inside* of the box ?
 
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Old 03-30-12, 08:56 PM
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Not that I know of. Others may. If not, and if the box does not have built-in internal MC connectors, you can either replace it with one that does or remove it, open a KO, and use an exterior connector. That helps keep the interior roomy for devices, besides.

BTW, good luck opening a KO from the inside of a box.
 
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Old 03-30-12, 08:57 PM
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If I could replace it.....that would easier said than done. It's facing a exterior wall, no access to remove. Moreso, it's on a tiled wall....
 
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Old 03-30-12, 10:04 PM
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Originally Posted by pingable View Post
It's facing a exterior wall, no access to remove. Moreso, it's on a tiled wall....
Is it on or in a wall? How is it secured (mounted) to the wall? A picture might help.
 
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Old 03-31-12, 04:48 AM
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It's not that difficult to remove a knockout from the inside of a box, electricians do it every day. To secure your new cable, srip the sheathing from about 8" from the end of the cable and install the MC connector on the cable, but without the locknut. Tape the exposed conductors together and now, fish the MC down into the wall and through the knockout. Then, install the locknut. That's the short version, but it really isn't as difficult as you may think.
 
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Old 03-31-12, 06:13 AM
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Thanks Joe. Found the same advice on another place....
It never dawned on me to put the connector on the cable and then fish. Brilliant ;-)

All I've ever done was with open walls, so it's always been *new work* - secure to box, and give it that extra 1/4" turn with a channellock to snug up that connector real good to the box.

I know AI has some sort of quasi connector that has tabs to lock to the box. It's plastic if I recall....

Call me old school. Been swinging metal boxes and bx cable forever. The only time I use romex is running for a transformer to LV undercab lighting
 
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Old 03-31-12, 07:07 AM
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Joe's method is the one we use. If possible, take out a KO that is pushed into the box. Take a flat screw driver and push very tightly to the KO and give it a twist. The KO should move a little to give you an opening to get the rest of the screw driver in to pry the KO into the box.

I know AI has some sort of quasi connector that has tabs to lock to the box.
I have used the fittings you mentioned for fishing, and it can be done, but it is VERY hard to get them to snap in. Ones with locknuts are much easier.
 
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Old 03-31-12, 06:17 PM
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Any secret sauce advice on knocking out the knockout from the inside of the box.

It's a tile backsplash so I want to keep vibration to a minimum...
 
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Old 03-31-12, 06:22 PM
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A method is described in post #7 to remove the knockouts
 
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Old 03-31-12, 06:26 PM
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I just triple read #7.

So in essence

Remove Locknut...
Hold Wire and drop it enough to get some clearance.
Do the screwdriver push and then I'm in the clear from there as far as what to do ..
 
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Old 03-31-12, 08:38 PM
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Not quite. I'll try again.

Move the wires so they are out of your way.

Look for a KO that is not flush with the box but is stamped in. Many steel boxes have them.
Take a sharp, flat screwdriver and place the blade tight to the edge of the KO.
While holding it tight, give the screwdriver a twist and try to get the KO to move a little.
Once you get a small opening, insert the screwdriver into the hole and pry the KO into the box, not out.
Grab the KO with a pliers and twist it out.

If this does not work, or you do not have a KO that is punched into the box, you will have to push the KO out. To do that place your screwdriver blade on the edge of the KO and wack it with a wacking tool (hammer, lineman's pliers, etc) You will have to bend it back and forth to break it off so this method can be harder to do.

If this is still not clear I will think of another way to explain.
 
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Old 03-31-12, 10:07 PM
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If you don't find a knockout that's raised enough to move by twisting a sharp screwdriver at its edge, and you have to tap/whack one to get started, placing your screwdriver blade on the KO near an edge, and 90 degrees away from the knockout's attachment point may help you get it to pivot and show you an edge you can work with.

You can also drill a hole through a knockout, just large enough to fit your smallest strong screwdriver into, and use that as a lever to start twisting the KO.
 
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Old 04-01-12, 07:29 AM
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Old 04-01-12, 08:25 AM
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Jeez......I could prob make one of those for a lot less than $20. A screwdriver, a torch and a piece of flat stock.
 
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Old 04-01-12, 01:39 PM
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I was just thinking the same. Drill it out...make a access hole for a screw to get in there to leverage it.

It's going to take some force knocking it from the inside, (I'm sure doable).....and the tiles on this backsplash is a custom one off tile. so I'm looking to be as less intrusive as possible when it comes to vibration, etc on this area.
 
  #16  
Old 04-01-12, 02:55 PM
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Adorable! I can imagine that I would use that less often than the drill-mountable cable puller I lusted after for awhile. Of course, it costs a lot less too. But I think I'd rather pony up for a Klein 98002BT. And I can get that for less than $10. Not really useful if you don't have drywall around the panel or box, is it?
 
  #17  
Old 04-02-12, 07:07 PM
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I have one of those, but forgot where I put it.
 
  #18  
Old 04-02-12, 08:21 PM
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I hate it when that happens! Does sometimes, though, especially right after I've put it to some really good use.
 
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