Connecting Romex to Armored Cable


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Old 03-29-15, 09:18 AM
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Connecting Romex to Armored Cable

Hi guys,

I'm currently renovating my home office and have a question.

The office was previously wired with BX cable (black and white wire wrapped in cloth). There were two wall sconces (with pull chain) and four outlets.

What I want to do is get rid of the BX that is in the room with the exception of the line coming in that feeds the power. Get rid of the two sconces and replace them with a ceiling light with a light switch, and three outlets.

The BX line coming in is too short (it was originally connected to one of the sconces). To get it to the light switch can I use a metal box, feed the BX into that and clamp it, then feed in Romex - ground it to a green screw, and connect the Black/Black and White/White wires together to create an extension?

Here's a picture of what I have so far:
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Also, for the sake of reference here are some diagrams I threw together to illustrate what I'm trying to do:

Old Wiring (all BX)
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New Wiring (BX power feed, everything else upgraded to Romex)
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Thoughts?
Thank you!
SB
 
  #2  
Old 03-29-15, 09:50 AM
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Your plan will work however you will have to many conductors in that box,actually you could install a 4" Sq. Box with single device plaster ring ,use a connector rated for MC on top and 2 Romex connectors on the bottom,the circuit will need to be protected by an AFCI device either a breaker or receptacle.
Geo
 
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Old 03-29-15, 10:24 AM
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Thanks @geochurchi, how do I install a 4" square box in the wall? I was going to use the single gang switch and just put a "blank" cover over it.

Take a look at the following, this is how I translated your reply.

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So the power (BX cable) goes into the junction box. In that I would take romex down to the light switch and then from the switch, run a line to the ceiling light.

Also in the box with the BX cable would be a second run of wire which runs down to the outlet.

Does that look right?
 
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Old 03-29-15, 10:31 AM
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How old is the BX? Does it have a bonding strip/wire?

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Old 03-29-15, 10:50 AM
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Like Geo mentioned you could use a 4" box and ring to do what you need.

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Old 03-29-15, 11:04 AM
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If you intend to blank off the box then that would work,just change the clamp for BX, also as Ray stated make sure it has the bond strip in the armor otherwise you can not extend that ungrounded circuit.
P/S use the deepest box you can get into the wall
Geo
 
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Old 03-29-15, 11:20 AM
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Hi @ray2047,

The house was built in 1932 so I think the BX is pretty old. There are remnants of knob and tube through the house as well, so I believe the BX came in at a later date. The cloth is pretty deteriorated at the ends so maybe 50 years old?

Here's a close up of the wire. I don't see anything that would look like a bonding strip. There is a brass/copper colored piece at the end of the cable. Not sure what that is for.

See below:
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Old 03-29-15, 12:07 PM
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I don't see anything that would look like a bonding strip.
That and the picture say it is unlikely your BX provides a reliable ground. Therefore you are going to need to run a new circuit from the breaker box.
 
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Old 03-29-15, 03:26 PM
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Another thing to consider is the load on the existing circuit that you are adding on to. I would run a new circuit even if the lack of grounding issue was not there.
 
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Old 04-02-15, 02:40 PM
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Thanks Ray. That's what I was afraid of. Appreciate everyone's help!
 
 

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