grounding

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eager2learn

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Mennifee,Ca
I'm working in a very old house that has only 2 prong outlets. there's no ground wire in any of the outlets. the homeowner wants new outlets installed. my question is how can i ground the outlets properly? I've heard that you can attach the ground to neutral together because in residential wiring there both terminated on the same bar. Can this be applied or is this restricted by the N.E.C.
 
Re: grounding

Section 250.130(C) describes the methods for providing equipment grounding (bonding) when receptacles are replaced or branch circuits are extended. Another option is to follow the allowances of section 406.3(D)(3). This section will permit replacement of the devices without providing an equipment grounding means.

And no, bonding the grounded (neutral) conductor to the grounding screw is a violation and may create a hazard. See section 250.24(A)(5).
 
Re: grounding

What is the wiring method of the house? Many old houses around here have two prong receptacles but are wired with type AC cable (BX), so a ground may already exist in the metallic wall box. This should be checked first since you may only need to use a self grounding receptacle as a replacement for a two prong receptacle.
 
Re: grounding

By infinity: Many old houses around here have two prong receptacles but are wired with type AC cable (BX), so a ground may already exist in the metallic wall box. This should be checked first since you may only need to use a self grounding receptacle as a replacement for a two prong receptacle.
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You can not use the BX sheatheing as a grounding conductor. It is not listed for this purpose. The sheathing will not provide a low impedance path and can heat up and cause a fire, This is why newer type AC cable hase a grounding conductor in it and BX does not have what 320.100 requires.

320.100 Construction.
Type AC cable shall have an armor of flexible metal tape and shall have an internal bonding strip of copper or aluminum in intimate contact with the armor for its entire length .
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Re: grounding

You can not use the BX sheatheing as a grounding conductor. It is not listed for this purpose. The sheathing will not provide a low impedance path and can heat up and cause a fire, This is why newer type AC cable hase a grounding conductor in it and BX does not have what 320.100 requires.
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This is not correct. The outer jacket of type AC cable is a listed grounding conductor. Maybe you're confusing this with MC cable where the outer jacket in not a listed grounding conductor. In fact, type HCFC or health care facility cable (also a type AC cable) is used for redundant grounding where as the outer jacket is one grounding conductor and the insulated green conductor is the other. The NEC does not consider BX to be a poor grounding conductor or it wouldn't be permitted or listed as such.

[ June 10, 2005, 08:02 PM: Message edited by: infinity ]
 
Re: grounding

Infinity, read Waynes post again and notice the distinction between AC and BX that Wayne has correctly pointed out.

Roger
 
Re: grounding

I'm lost, what distinction? BX and type AC cable are the same thing.

[ June 10, 2005, 08:19 PM: Message edited by: infinity ]
 
Re: grounding

Where do you find the definition of BX?

Roger
 
Re: grounding

You probably don't. It's a slang name for type AC-armored cable. They are synonymous. Rumor has it that the first BX cables were made in the Bronx,NY and had the letters BX labelled on it, hence the name slang name BX.
 
Re: grounding

Infinity, does the BX you're refering to have a grounding tracer (aluminum runner along it's length) in contact with the covering which is necessary to insure the grounding potential of the cable?

Roger
 
Re: grounding

infinity BX is slang and many around here still refer to Type AC as BX.

The difference is this.

If it the old stuff, without the bonding strip it is not suitable for grounding. Using it for a ground may cause more problems than not.

If it the newer stuff with the bonding strip it is a grounding means.
 
Re: grounding

Ooops, hit the "Reply With Quote" by accident
:eek:
Roger

[ June 10, 2005, 08:37 PM: Message edited by: roger ]
 
Re: grounding

Yes, it's a type AC cable. Type AC must have the strip or tape to be listed as a type AC cable. That's why I had mentioned in my original post that it's not uncommon around here to find an old house with armored cable and two prong receptacles. The listed grounding conductor does exist at the receptacle in the form of the metallic jacket of the AC cable. This means that a three prong self grounding receptacle can replace the two prong receptacle and no further action would be required.
 
Re: grounding

If it the newer stuff with the bonding strip it is a grounding means
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Newer is a relative term. I don't know when the bonding strip was required within the AC cable but I've seen cable that's at least 40-50 years old with the bonding strip in it.

I just found this on Google:
QUOTE] AC(BX) Armor clad cable
BX is the common trade name for AC. BX was the trademark of cable made by G.E.'s Sprague Electric division.

189?- Gus Johnson and Harry Greenfield patent AC

1910- AC receiving acceptance.

1920s or the early 1930s widespread adoption.

1932 NEC- Armored cable was officially called Type AC

1952- Aluminum clad AC introduced.

1959 NEC- Aluminum bonding wire required under metal sheathing.
[/QUOTE]

[ June 10, 2005, 08:47 PM: Message edited by: infinity ]
 
Re: grounding

Originally posted by infinity:
If it the newer stuff with the bonding strip it is a grounding means
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Newer is a relative term. I don't know when the bonding strip was required within the AC cable but I've seen cable that's at least 40-50 years old with the bonding strip in it.
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Are you sure it was that old?

Roger
 
Re: grounding

In my area it is usually either old non grounding BX, NM without ground, NM with reduced ground or 'modern' NM.

Grounding type AC is very rare around here in single family dwellings.
 
Re: grounding

well now that i have some attention - if i replace all the rececptacles with g.f.i.'s this will be suitable for the installation of proper grounging methods = correct
 
Re: grounding

Are you sure it was that old?

Roger
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Grounding type AC is very rare around here in single family dwellings.
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The aluminum grounding strip has been required within type AC cable or BX since 1959 so any house wired with it sometime after 1959 would have an outer jacket that is a listed grounding conductor.

Regarding GFCI protection a non grounding receptacle can be replaced with a GFCI receptacle where no ground exists as long as the it is labeled that there is no ground present.

[ June 11, 2005, 07:50 AM: Message edited by: infinity ]
 
Re: grounding

Originally posted by infinity:
The aluminum grounding strip has been required within type AC cable or BX since 1959 so any house wired with it sometime after 1959 would have an outer jacket that is a listed grounding conductor.
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Interesting to know that, thanks. :)

By the time 1959 came around NM had replaced the use of BX in this area. The only 60s era BX I will see will be in commercial buildings and yes it has a bonding strip.

If I see BX in a house around here it is a safe bet it does not have the bonding strip. :(

It seems this old BX was the hot thing to use around here when fishing in existing houses.

There are a ton of houses around here with this old BX that I think dates back to the 20s and 30s.
 
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