romex with armored

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Old 11-27-05, 11:46 AM
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romex with armored

hi,
i am running wire from an existing ceiling box to a new one. the existing wiring very old armored wiring, and it does not have a ground wire. So, I'm wondering what to do with the ground wire in the romex when i connect the it to the existing box. (i'm going to be putting in a new metal box, the existing one is just a small box that looks like a pancake box with a seperate metal piece that screws in to hold the armored cable against the box).

also, just a little background, the ceiling fixture is on 2 3 way switches up and down stairs, so I don't think pulling all the armored cable and replacing it is an option for me.

thanks in advance!
 
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Old 11-27-05, 02:38 PM
ollie
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Check with a volt meter between the hot lead and the metal box. If you have full voltage then you can use the armor as a ground. When you change the box use a BX connector and check again for voltage between the hot and new box. If ok ie full voltage. Then for the romex use a romex connector and connect the ground from the romex with a green (10x32) screw to the box. New metal boxes will have a taped hole for this screw. These green screws are available at Lowes or elect. supply. Don't use a sheet metal screw. If you don't have voltage between the hot and box you don't have a ground and can not extend the circuit.
Ollie
 
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Old 01-04-06, 05:28 PM
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hi, thank you very much for the reply.

I'd be using a digital multimeter, which i'm new to using. so, i have a dumb question. when you say to "Check with a volt meter between the hot lead and the metal box", I'm assuming you mean to take the red probe, touch the hot wire to it, then take the black probe, and touch it to the metal box. Sounds simple, but I just wanted to make sure.

thanks again for the help, sorry for the dumb question.
 
  #4  
Old 01-04-06, 05:36 PM
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Does the armored cable have a metal bonding strip (usually flat gray colored) that runs inside the armor? If not, that armor cannot be used as ground even if you could measure full voltage from hot to ground. The way that the armor acts during a short circuit will differ than a steady state measurement made with a volt meter (or an ohm meter to see continuity).
It has been proven that old style armor cable can not act as a ground, which is why the new style armored cable has a bonding strip. Only the new style is approved as a ground.
 
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Old 01-05-06, 01:25 PM
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Originally Posted by havab
i am running wire from an existing ceiling box to a new one. the existing wiring very old armored wiring, and it does not have a ground wire.
It is a violation of code to extend an ungrounded circuit without rewiring or adding supplemental ground to the existing circuit. The metal armor of BX cannot be used as a ground unless it has an integral bonding strip.
 
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