ground question

Reply

  #1  
Old 05-23-05, 03:55 PM
Member
Thread Starter
Join Date: Dec 2004
Posts: 237
ground question

i was reading on a post below about 2 wire bx...my house is older and still to date nyc uses 2 wire bx,from what i understand the bx casing carries the ground ...i had a major renovation 2 years back and the liscenced electrician used the 2 wire bx and nothing hooked up to the ground on the outlets,and with 2 different outlet testers(plug in type) it shows all is fine with my outlets in my house.....im hoping i understand this right,and that the outlet tester is not showing a false ground....any comments is appreciated thanks
 
Sponsored Links
  #2  
Old 05-23-05, 04:07 PM
ElectricalMan's Avatar
Member
Join Date: Feb 2005
Location: Harrisonburg
Posts: 744
lovmy4x4,

Well you are kinda half right....the wire may be 2 wire but they dont call it BX any longer..it is AC cable and actually has a band or strip wrapped with the outer case to maintain the ground and is fine....but the older style BX may look the same but it is not the same...

The problem with the older BX is that since it does not carry the ground well it has a issue when a hot line comes in contact with it...I have seen BX glow a bright red from coming in contact with the hot and the metal jacket so it is not a good source of a ground...

However, if you are looking for safety versus the REAL need for a ground like to a computer and so on...the safety quick fix is to install GFCI recepts on the first recept in each circuit.....being it is an old house I would imagine not nearly the circuits as some we do today...

Now some may argue the BX can be grounded and in some areas of the US the debate still goes on...take my own area in Virginia...the inspectors say the code allows for it...and he can't turn it down but he as well as others know the possible issues of it being used as a ground.

In the end the GFCI is the fastest and quickest method to making it safer...not better...just safer but remember you need to leave the 2 hole plugs in the house......the GFCI works off the hot and neutral balance so you are fine...they dont need a ground to function correctly...

Hope this helps...
 
  #3  
Old 05-23-05, 04:10 PM
ElectricalMan's Avatar
Member
Join Date: Feb 2005
Location: Harrisonburg
Posts: 744
P.S....

I am sure the electrician used AC cable and made sure the connectors were on correctly and made sure the strip or bonding wire in the cable did not enter the box but was wrapped back along the connector...the ground was using the case in that installation....it looks the same as BX but it is not the same........

Granted...you WILL get some ground from the old BX.....it's what you DONT get that bothers many people.....again in the 1999 CODE they are still technically allowing it...many inspectors I talk to dont agree with it but say they cant refuse it.........
 
  #4  
Old 05-23-05, 04:16 PM
Member
Thread Starter
Join Date: Dec 2004
Posts: 237
thanks electrical man,yes it is ac cable with the thin wire wrapped back along the spirl cable...i do have a few older bx lines but basically all my computer room,bathroom ,kitchen and living room and bed room outlets ,including air conditioner outlets are upgraded with ac wire....thanks again....
 
  #5  
Old 05-23-05, 04:20 PM
ElectricalMan's Avatar
Member
Join Date: Feb 2005
Location: Harrisonburg
Posts: 744
Great.....you are lucky...I run into so many older homes with BX and a grounding issue....I have actually seen the cable get as red and glow.....now i know some homes that use the BX as ground and they are still here...I just dont like it so when ever I see BX i like to errr on the caution side and suggest the GFCI unless they wish to get into fixing the issue...

You should be fine....the older BX did not have the wire in the cable.
 
  #6  
Old 05-23-05, 06:03 PM
JHPIV
Visiting Guest
Posts: n/a
GFCI for 2 wire system

It has been mentioned in this thread that you can install a GFCI with two wires. I live in an older house (1927) and am trying to put in a GFCI into a bathroom I'm doing. I have Knob and Tube wiring coming to the vanity light which I am planning to use for both the GFCI and a new switch for the light (there is no switch now). Can I install a GFCI using this tw wire circut? How do I wire the outlet?
 
  #7  
Old 05-23-05, 06:40 PM
Member
Join Date: Sep 2000
Location: United States
Posts: 18,497
Can I install a GFCI using this tw wire circut?
Yes.

How do I wire the outlet?
According to the directions that come with the GFCI. It's pretty simple. I recommend you spend $15 on a voltage "tick" tester so that you can tell which wire is the hot and which wire is the neutral. Be very careful when handling that old wire so that you don't damage it.
 
  #8  
Old 05-24-05, 05:19 AM
Member
Join Date: Nov 2004
Location: USA
Posts: 973
Originally Posted by JHPIV
It has been mentioned in this thread that you can install a GFCI with two wires. I live in an older house (1927) and am trying to put in a GFCI into a bathroom I'm doing. I have Knob and Tube wiring coming to the vanity light which I am planning to use for both the GFCI and a new switch for the light (there is no switch now). Can I install a GFCI using this tw wire circut? How do I wire the outlet?
Is this GFCI you propose in the bathroom replacing an *existing* receptical, or are you wanting to ADD a receptical where there currently is none?

If it is a replacement, then do as John said...

However, if you are wanting receptical where there currently is none, it probably cannot be on this circuit (correct me if I'm wrong John). Todays code does not allow a bathroom receptical to be on a circuit that is shared by other parts of the house (with the exception that it can serve recepticals in additional bathrooms), nor does it allow a bathroom receptical on anything other than a 20AMP circuit (thus requiring #12 wire). IF only one bathroom is served by a 20AMP circuit, it is allowed to have recepticals and lights on the same circuit.

If it is at all possible, I would recommend that you run a new, 20A, grounded circuit to this bathroom to serve this new receptical. If you run it only to this one bathroom, you could use it for all the 110V wiring in that bath. Alternately, you could run the same circuit to other bathrooms recepticals, in which case ONLY bathroom recepticals could be served by it.
 
  #9  
Old 05-25-05, 04:17 PM
JHPIV
Visiting Guest
Posts: n/a
GFCI for 2 wire system

Well, given how much trouble it would be to run a new circut to this bathroom for the outlet, and the fact that there has not been one there before, I think I will just pull a loop for a switch for the vanity light, and plug my electric toothbrush in somewhere else. Thanks for the info, and the advice.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
'