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Grounding new outlets when house has old two wire no ground

Asked Jan 30, 2011, 03:07 PM — 6 Answers

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ma0641's Avatar
ma0641 Posts: 6,212, Reputation: 2489
Plumbing Expert
  
#2

Jan 30, 2011, 03:12 PM
What type of wiring is in the house? How old? Some older BX wiring used the conduit as ground. Old Knob abd Tube may or may not have a ground wireCheck for a ground by testing for voltage between the black wire and the box. If you get 120V you have a ground and could use a ground clip on the box.. If you are sure there is no ground, you need to run a separate ground wire, perhaps to a grounded water pipe running in the house.
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hkstroud's Avatar
hkstroud Posts: 8,469, Reputation: 3424
Home Improvement & Construction Expert
  
#3

Jan 30, 2011, 03:56 PM
Outlets cannot be grounded if you have no ground wire.

You can replace ungrounded outlets with grounded type outlets by replacing the first outlet in the circuit with GFI outlet, feed the remaining outlets through the GFI, replace the remaining outlets with regular grounded type outlets and mark them "ungrounded".
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stanfortyman's Avatar
stanfortyman Posts: 4,881, Reputation: 1326
Electrical & Lighting Expert
  
#4

Jan 30, 2011, 04:00 PM


Quote:
Originally Posted by ma0641 View Post
Old Knob abd Tube may or may not have a ground wire
I've never known K&T to have a ground.


Quote:
Originally Posted by ma0641 View Post
Check for a ground by testing for voltage between the black wire and the box. If you get 120V you have a ground and could use a ground clip on the box..
Only partially accurate. Even if a ground reading is found it may mot be a safe ground to use.
If armored cable was used it must have a bonding strip inside the sheathing. Old BX/AC cable without this strip is not legal or safe to use as an equipment ground.


Quote:
Originally Posted by ma0641 View Post
If you are sure there is no ground, you need to run a separate ground wire, perhaps to a grounded water pipe running in the house.
Using a water pipe is a last resort, and only allowable if certain specific are met. Safe to say this is not a good idea.

Running a new cable is always the best bet.
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Barndoor's Avatar
Barndoor Posts: 3, Reputation: 10
Junior Member
  
#5

Jan 30, 2011, 06:36 PM
Hey Guys, The house was built in 1950 it has wiring that looks like a dark black woven material.
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hkstroud's Avatar
hkstroud Posts: 8,469, Reputation: 3424
Home Improvement & Construction Expert
  
#6

Jan 30, 2011, 07:02 PM
Old style non metallic cable. Probably doesn't have ground wire but look closely. I've seen it with a ground wire and used with ungrounded outlets. The electrician just connected ground to the box or just folded it back up into the cable clamp.
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Barndoor's Avatar
Barndoor Posts: 3, Reputation: 10
Junior Member
  
#7

Jan 31, 2011, 05:18 AM
Thanks a lot you all have been very helpful. Barndoor
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