New ROMEX into old boxes

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  #1  
Old 11-30-14, 05:41 PM
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New ROMEX into old boxes

OK so I fished all new Romex for my light circuits replacing the old cloth romex. The existing boxes are metal with (actual diameter 5/8") knockouts and a double clamp. How do you secure new wire in these boxes? I am concerned the wire will be clamped onto the sharp knock out lip. also some clamps don't hold the wire tight. Do they make something so that these old boxes can be used or must they be replaced? Below is a picture any suggestions or experience welcome. Thank You.

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  #2  
Old 11-30-14, 06:01 PM
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Welcome to the forums!

I would just replace the boxes with plastic remodel boxes. It will be easier to fish too.
 
  #3  
Old 11-30-14, 06:28 PM
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I already fished all the wires not anticipating having this problem. So fighting wires is done. If I have to replace boxes I will, but want to try and avoid it so I don't mess up the plaster walls.
 
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Old 11-30-14, 06:48 PM
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Push in Romex connectors may work.

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  #5  
Old 11-30-14, 07:00 PM
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I tried the push in connectors but the knock out is not a standard size measures 5/8 where the 1/2 Knock outs measure 7/8. I could not find smaller than the standard 1/2 push in connectors.
 
  #6  
Old 11-30-14, 07:23 PM
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The boxes you have use the built in clamp. I doubt they even have a 1/2" KO.
 
  #7  
Old 11-30-14, 07:36 PM
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Thanks for all the replys. Pcboss do you know if they sell the clamps to replace or add to that style box? Also when clamped some do not actually clamp the wire they diameter is too big. While others do clamp it but seems to clamp on the knock out lip which I think could puncture the Romex. Is this ok? Am I over thinking it?
 
  #8  
Old 11-30-14, 08:01 PM
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I have never seen the style that is in your box.
 
  #9  
Old 11-30-14, 08:11 PM
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Thanks. I've got 7 boxes and 3 different style clamps in them but they are all the same boxes. Maybe worth just trying the replacement route.
 
  #10  
Old 12-01-14, 12:11 AM
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I like Ray's suggestion...1/2" push in connectors measure what? 7/8"? Are you sure...are you measuring the narrowest part?
The ones we use are thinner than Ray's pic. Also, you need a ground screw.
How are those boxes mounted? I don't see a screw inside the pic. I would replace them, as plastic boxes are cheap, and come with plastic clamps. I've gotten lucky and replaced boxes without the need for mudding...Hand sawzall with narrow metal blade can chop screws attaching box.
 
  #11  
Old 12-01-14, 03:59 AM
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Yes I bought the smallest push ins and tried no luck hole is too small. The ground is easily added. I believe they are mounted with tab that are nailed to the studs. Starting to look like I'll be taking the multimaster to them and trying to swap for plastic ones. Thanks
 
  #12  
Old 12-01-14, 06:34 AM
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Yes I bought the smallest push ins and tried no luck hole is too small.
Twistouts for cables are generally not round and are much smaller than a typical 1/2" knockout. Those are very old boxes, I'd just use the original cable clamps. Just curious, do you see a name on them? The oldest boxes I have ever seen were clearly marked with the Appleton name.
 
  #13  
Old 12-01-14, 06:46 AM
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If you replace the boxes look for the Smartbox style that screws to the stud from the inside of the box. Much more secure.
 
  #14  
Old 12-01-14, 07:16 AM
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The boxes are marked GE sp7074. The house was built in 1948 had original version of cloth romex. With using them I'm concerned with the clamp pushing the romex on the knock out edge, is this not an issue or the same way modern ones clamp also?
 
  #15  
Old 12-01-14, 07:23 AM
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The house was built in 1948 had original version of cloth romex. With using them I'm concerned with the clamp pushing the romex on the knock out edge, is this not an issue or the same way modern ones clamp also?
New metal boxes have a different style clamp. If the existing clamps worked well since 1948, I'd use them again, but not overtighten them. PC boss has a good suggestion too if you want to replace the boxes.

pcboss

If you replace the boxes look for the Smartbox style that screws to the stud from the inside of the box. Much more secure.
 
  #16  
Old 12-01-14, 07:43 AM
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The boxes are marked GE sp7074. The house was built in 1948 had original version of cloth romex. With using them I'm concerned with the clamp pushing the romex on the knock out edge, is this not an issue or the same way modern ones clamp also?
 
  #17  
Old 12-01-14, 07:49 AM
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The old box looks like it's Bakelite. I doubt if the edges of knockouts are sharp enough to cut into sheathing. I would use the existing clamps and just gently tighten them against cable. It doesn't take much pressure to provide the required strain relief.
 
  #18  
Old 12-01-14, 10:55 AM
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Brian, that is a black steel box. It predates Bakelite by quite a few years. One of the giveaways is the chamfer on the back of the box.
 
  #19  
Old 12-01-14, 11:07 AM
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Yup it is black steel box. If its that old I'll give cutting them out a shot and try to find someone local who sells the smartboxes.
 
  #20  
Old 12-01-14, 04:48 PM
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Thanks Boss,
I can see the difference now, and I can see why that original clamp is not desirable.
 
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