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Old 01-31-2011, 08:50 AM   #1
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Armored Cable replace?


Hello:

I am renovating some areas of my house and have some questions about old armored wire that I have. The armored cable has only the black and white wires in it, no others. I have only one circuit in my house with the armored wire. It supplies two rooms on the second floor. Right now, I have access to replace the armored wire from the panel to the first outlet in the chain. So I have several question if I do this:

1 - Is it ok to mix the armored cables with the new 14 gauge (black, white, green) wire?

2- The armored cables in several outlet boxes are so short that the receptacle can only be pulled out about 1 inch. Can I pigtail the armored cable in the metal box and then connect to the receptacle?

3- If I can pigtail armored cable, I assume it will still be grounded to the metal box. Is there a need to attach a ground from the receptacle to the metal box?


Thanks for the help!


Last edited by zephed666; 01-31-2011 at 09:01 AM.
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Old 01-31-2011, 10:01 AM   #2
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Armored Cable replace?


The armored cable you are talking about (if is is old) is most likely BX. BX relies on the armor for the ground. Yes you can pig tail any wires that are too short in a box. Yes romex can be use as a replacement and I recommend it if you have access, It must be sized according to the size of the breaker 15a=#14 20a=#12.
Since the bx relies on the jacket and metal boxes for grounding you need to insure that connection, by installing a jumper between the bare wire of your new romex to the box

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Old 01-31-2011, 10:26 AM   #3
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Originally Posted by Saturday Cowboy View Post
The armored cable you are talking about (if is is old) is most likely BX. BX relies on the armor for the ground. Yes you can pig tail any wires that are too short in a box. Yes romex can be use as a replacement and I recommend it if you have access, It must be sized according to the size of the breaker 15a=#14 20a=#12.
Since the bx relies on the jacket and metal boxes for grounding you need to insure that connection, by installing a jumper between the bare wire of your new romex to the box
so the new romex to the box needs to be grounded in the box. Should it also be grounded to the receptacle by pigtailing it?
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Old 01-31-2011, 10:36 AM   #4
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Armored Cable replace?


I can find nothing the allows the shield of old BX cable to be used as an equipment grounding conductor. That was the problem with it and why it was redesigned to it's current style of manufacture.


The old BX (actually AC in code jargon) was created before 3 wire circuits were used. Then when an equipment grounding conductor became required and the shield was getting used as that, it was realized the shield and installation methods were not adequate.

this is from Mike Holt's forum in a thread about BX and using the shield as an egc:

Quote:
I've seen the old bx or ac without the grounding strip in a lot of old homes around here.

I've seen cases of fault current on the armor that would cause the armor to glow a dull red color in a dark attic,but the breaker would not trip.

I'd agree with Ron about it not being suitable for grounding.

Russell
simply put; if you are where you can replace the old BX, do it.

If you are using metal boxes, yes, the egc must be bonded to the box. If you are using self grounding ddevices and a metal box, you do not have to bond the egc to the device but I do it anyway. In a self grounding device, the screws and yoke are listed as an acceptable means to bond the egc to the device.
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Old 01-31-2011, 10:54 AM   #5
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Armored Cable replace?


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I can find nothing the allows the shield of old BX cable to be used as an equipment grounding conductor. That was the problem with it and why it was redesigned to it's current style of manufacture.


The old BX (actually AC in code jargon) was created before 3 wire circuits were used. Then when an equipment grounding conductor became required and the shield was getting used as that, it was realized the shield and installation methods were not adequate.

this is from Mike Holt's forum in a thread about BX and using the shield as an egc:



simply put; if you are where you can replace the old BX, do it.

If you are using metal boxes, yes, the egc must be bonded to the box. If you are using self grounding ddevices and a metal box, you do not have to bond the egc to the device but I do it anyway. In a self grounding device, the screws and yoke are listed as an acceptable means to bond the egc to the device.
I am going to try to replace as much as the old BX cable as possible, but I do not want to start ripping out walls. Attached are two images on what I plan on doing. One is the new romex with a graound wire, the other is the exisiting BX wires that need to be pigtailed in order to pull the receptacle out. Are these diagrams the correct way?
Attached Thumbnails
Armored Cable replace?-romex.jpg   Armored Cable replace?-bx.jpg  
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Old 01-31-2011, 11:28 AM   #6
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Armored Cable replace?


no. You cannot do that. The metal shield is not listed to be used as an EGC so that means you cannot extend the circuit, at all. You can only extend a currently legal circuit which means one with an egc already.

and legally, you cannot add onto the wires to make them long enough. Most inspectors I know will turn a blind eye to it in an existing installation such as what you are doing but that doesn't make it legal.

and with the bottom pic; not legal. either a two wire recep or a GFCI would be the only legal device there.

and same thing for the top recep.

Last edited by nap; 01-31-2011 at 11:30 AM.
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Old 01-31-2011, 11:31 AM   #7
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Armored Cable replace?


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no. You cannot do that. The metal shield is not listed to be used as an EGC so that means you cannot extend the circuit, at all. You can only extend a currently legal circuit which means one with an egc already.

and legally, you cannot add onto the wires to make them long enough. Most inspectors I know will turn a blind eye to it in an existing installation such as what you are doing but that doesn't make it legal.

So both of those are unacceptable? How am I suppose to connect the new romex to exisitng BX cable then? I thought that was the correct way. And I can;t pigtail the BX cables inside the metal box? Am I suppose to use all 4 screws on the receptacle? And one of my receptacles has 3 BX cables running into it, shouldn;t that be pigtailed regardless?

thanks again!
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Old 01-31-2011, 11:37 AM   #8
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Armored Cable replace?


Quote:
zephed666;581754]So both of those are unacceptable? How am I suppose to connect the new romex to exisitng BX cable then?
you can't.

.
Quote:
And I can;t pigtail the BX cables inside the metal box?
there is a requirement the free wire entering the box must be 6" long. If it is not 6" long there is no way to splice onto it to make it legal. As I said, a lot of inspectors will overlook adding onto a too short wire in an existing installation though. They aren't all heartless.

Quote:
Am I suppose to use all 4 screws on the receptacle?
you can pigtail for the purposes of adding in for the recep and such. The only issue I was speaking to was the adding onto a too short wire to make it long enough.

Quote:
And one of my receptacles has 3 BX cables running into it, shouldn;t that be pigtailed regardless?
again, pigtailing is fine (and actually how I prefer to do things). it's the free length of the incoming and outgoing wire that is the only problem I was addressing with the pigtail issue.
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Old 01-31-2011, 11:49 AM   #9
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Armored Cable replace?


Is the romex in the top diagram the circuit supply from the panel?
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Old 01-31-2011, 11:51 AM   #10
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Armored Cable replace?


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Originally Posted by nap View Post
you can't.

. there is a requirement the free wire entering the box must be 6" long. If it is not 6" long there is no way to splice onto it to make it legal. As I said, a lot of inspectors will overlook adding onto a too short wire in an existing installation though. They aren't all heartless.

you can pigtail for the purposes of adding in for the recep and such. The only issue I was speaking to was the adding onto a too short wire to make it long enough.

again, pigtailing is fine (and actually how I prefer to do things). it's the free length of the incoming and outgoing wire that is the only problem I was addressing with the pigtail issue.
Please bare with me.

I wanted to replace the BX from the panel to the 2nd floor since i have access at this time. But I cannot replace all the other BX wire since I do not have access. So from what I understand, I cannot mix romex wire with BX cable. So if I wanted to replace the BX cable, it's either all or nothing? (I did read that you can connect romex to BX as long as the ground from the romex is connected to the BX clamp screw.)

As for the pigtailing, if i have 2 BX cables running into a box, can I pigtail them to the recpetacle? Right now they are just screwed directly to the receptacle.

And I understand that there needs to be 6" of wire, but this wiring is from the 50's and there is not 6" of wire in any of my receptacles. But what is the difference from what you mentioned - adding into a receptacle? Isn't that pretty much the same thing? I mean, adding a pigtail to the bx wires that are only 3" long. So instead of them connected directly to the receptacle, I'll connect them with the pigtail...

thnaks again for the help!

Last edited by zephed666; 01-31-2011 at 11:55 AM.
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Old 01-31-2011, 12:01 PM   #11
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Armored Cable replace?


Quote:
zephed666;581765]Please bare with me.
no problem


Quote:
I wanted to replace the BX from the panel to the 2nd floor since i have access at this time.


Quote:
But I cannot replace all the other BX wire since I do not have access. So from what I understand, I cannot mix romex wire with BX cable. So if I wanted to replace the BX cable, it's either all or nothing?
you cannot extend a circuit that is fed with BX. In other words, where you are running the NM to, you can attach a new 3 wire circuit there. If there is BX running out of that box, you cannot extend the other end of the BX run.

basically; consider the BX as a 2 wire circuit and the NM as a 3 wire circuit.

You can extend a 3 wire circuit. You cannot extend a 2 wire circuit. Once your 3 wire circuit drops down to a 2 wire circuit, you cannot extend that part of the circuit.

Quote:
As for the pigtailing, if i have 2 BX cables running into a box, can I pigtail them to the recpetacle? Right now they are just screwed directly to the receptacle.
yes

Quote:
And I understand that there needs to be 6" of wire, but this wiring is from the 50's and there is not 6" of wire in any of my receptacles. But what is the difference from what you mentioned - adding into a receptacle? Isn't that pretty much the same thing? I mean, adding a pigtail to the bx wires that are only 3" long. So instead of them connected directly to the receptacle, I'll connect them with the pigtail...
there is no difference and as a result, the over all installation is still illegal because there is not 6" of free wire on the incoming and outgoing cable.

As I said though; a lot of inspectors tend to overlook existing installs with too short free wire. It still doesn't make it legal though.
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Old 01-31-2011, 12:29 PM   #12
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Armored Cable replace?


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no problem




you cannot extend a circuit that is fed with BX. In other words, where you are running the NM to, you can attach a new 3 wire circuit there. If there is BX running out of that box, you cannot extend the other end of the BX run.

basically; consider the BX as a 2 wire circuit and the NM as a 3 wire circuit.

You can extend a 3 wire circuit. You cannot extend a 2 wire circuit. Once your 3 wire circuit drops down to a 2 wire circuit, you cannot extend that part of the circuit.

yes



there is no difference and as a result, the over all installation is still illegal because there is not 6" of free wire on the incoming and outgoing cable.

As I said though; a lot of inspectors tend to overlook existing installs with too short free wire. It still doesn't make it legal though.
So i should leave everything as is. From what you are saying, I cannot run a new romex NM cable from the panel to the 2nd floor to replace the current BX wire. Are there any options to replace that wire or no need?
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Old 01-31-2011, 12:43 PM   #13
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Armored Cable replace?


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So i should leave everything as is. From what you are saying, I cannot run a new romex NM cable from the panel to the 2nd floor to replace the current BX wire. Are there any options to replace that wire or no need?
I see no possible reason code or otherwise why this would not be acceptable.
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Old 01-31-2011, 12:47 PM   #14
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I see no possible reason code or otherwise why this would not be acceptable.

So I can use romex cable and BX armored cable (2 wire) together? I am getting 2 differing opinions now...
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Old 01-31-2011, 12:49 PM   #15
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Armored Cable replace?


The first recep as in the first diagram would be code compliantly grounded. The downstream receps with the BX would of course not be compliantly grounded through BX sheating and should NOT be three prong receps unless fed from the load side of a GFCI at the first recep and then appropriately labeled "no equipment ground".


Last edited by brric; 01-31-2011 at 12:53 PM.
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