This Old House - Jan/Feb p.53

[tonyi]

Pic shown in mag is of cloth/rubber BX

"ARMORED CABLE (BX)

...The sheath provides a ground, so grounded recepticals are easy to retrofit..."

This statement strikes me as flat out dangerous telling people its OK to put 3-prongers on an old BX system. If OTHER measures are taken, like GFCI protecting it, then it would be OK, but lacking AC's bond wire this stuff can fail to trip a breaker and sometimes heats up like a filament if something faults to it and the OCPD doesn't trip due to its resistance.

[ December 28, 2003, 10:58 PM: Message edited by: tonyi ]

 

[jimwalker]

Re: This Old House - Jan/Feb p.53

With most everything being 2 prong ungrounded i don't understand people trying to replace them with grounded recepticles.When we run insurance inspections that is the number one problem i find.Some simply think they have solved a problem because it screws to a metal box.The ungrounded ones actually cost more but big orange sells them.Have seen some use the adapters to get a ground and then plug in a power strip to protect there electronics

 

[goldstar]

Re: This Old House - Jan/Feb p.53

Just curious, but isn't the armor and the shunt wire part of the grounding system of the AC cable ? It was always my understanding that if you replace a 2-prong receptacle with a 3-prong you should use self-grounding receptacles. If you have a situation where there is knob & tube you're supposed to GFI that circuit because it has no EGC reference. Have I been misinformed or does anyone else know something that I don't ?

 

[iwire]

Re: This Old House - Jan/Feb p.53

If it is newer AC cable with the shunt wire yes you are all set.

If it is the old BX without the shunt wire it is not OK for grounding.

 

[tonyi]

Re: This Old House - Jan/Feb p.53

A recent code change now requires a gnd wire to the box in most cases. The self grounding clip doesn't work well when there's another layer(s) of rock, some paneling, a box extender, etc and 2" screws that are a little loose

Old cloth/rubber BX won't have the internal bond wire modern AC has. This wire isn't a gnd even though its not uncommon to find it was brought into a panel onto a gnd/neutral bar. The armor and bond together act as a system to create the gnd. Continuity of the bond wire isn't particularly important either - it could be broken in several places and the "system" would still function OK. The short bit of armor in the area of a broken bond wire is more than sufficient to conduct the fault current on its own across the break. It would take a huge number of breaks in the bond to really compromise the integrity of the whole system.

 

[iwire]

Re: This Old House - Jan/Feb p.53

Originally posted by tonyi:
A recent code change now requires a gnd wire to the box in most cases. The self grounding clip doesn't work well when there's another layer(s) of rock, some paneling, a box extender, etc and 2" screws that are a little loose

Can you point me to that code change?

 

[jxofaltrds]

Re: This Old House - Jan/Feb p.53

"This statement strikes me as flat out dangerous"

Aren't most home improvement programs riddled with errors?

Mike P.

 

[racraft]

Re: This Old House - Jan/Feb p.53

In some states you cannot legally buy two prong outlets. If you need to replace an outlet in these states that has no ground then you either obtain an ungrounded outlet in another state and illegally install it, or you retrofit the outlet with a ground, rewire it or use a GFCI and mark accordingly.

 

[jxofaltrds]

Re: This Old House - Jan/Feb p.53

"In some states you cannot legally buy two prong outlets"

This is scary. Why? Because people will buy the reg. outlets and not the GFCIs.

When you buy a switch with a ground do they make you pull a egc for it?

Maybe "we" should send some of our comments to these "professional" politicians.

Mike P.

 

[jxofaltrds]

Re: This Old House - Jan/Feb p.53

PS

If these states have codified the NEC how can they "outlaw" 2 prong outlets?

Mike P.

 

[jimwalker]

Re: This Old House - Jan/Feb p.53

Stopping someone from buying a 2 prong is just flat out stupid.They now don't replace that worn out loose recepticle.GFCI most likely won't fit some old steel box's.They might even replace the 2 prong with a 3 prong.

 

[big john]

Re: This Old House - Jan/Feb p.53

Who prohibits the purchase of non-grounding receptacles? If reinstalling those on an un-grounded circuit is a perfectly acceptable practice by NEC standards, who thinks they know enough to contradict this?

I've done a lot of work in Newark, NJ where many of the houses are old enough to have been around before electrical service was even available. Every single house I've worked in I've seen at least one grounding-type receptacle installed on an ungrounded circuit. None of them have had GFCI protection on the branch circuit.

It is my opinion that without GFCI protection putting a grounding type receptacle on an ungrounded circuit is far more dangerous than simply putting in a new non-grounding receptacle:

If there is a ground fault in an appliance plugged into an illegally installed grounding receptacle, not only will that ungrounded circuit not clear the fault and the shock hazard will remain, but if the wiring method is BX the fault currents can heat the armor to the point of creating a fire hazard. Were the receptacle properly replaced with a non-grounding type, the only danger present would be that of a shock hazard.

-John

 

[jimwalker]

Re: This Old House - Jan/Feb p.53

Exactly.We tell the home owner to either replace them with 2 prong or rewire the circuit.$2 cure is usually the one they pick.Insurance companies are getting smart , when new buyer needs insurance they must get electrician to sign it as meeting certain conditions.It's far from saying everything is perfect but does get rid of grounded receptacles where a ground isn't available and open wiring gets fixed.

 

[mjf]

Re: This Old House - Jan/Feb p.53

I was taught to run a green grounding pitail to a metal box,and install a 3 prong recepticle. What is this shunt wire that is being reffered to? The last thing I want to do is something dangerous. Haven't replaced any 2 prong outlets in about ten years(when I was working under licenced electrician), but I've got a job this week that involves them. Any help to be safe and code compliant would be greatly appreciated.

 

[dave81]

Re: This Old House - Jan/Feb p.53

Just because you have a metal box doesn't mean you have a grounded box. Check to see if the bx is suitible for a ground path if it is great make sure its bonded to a gounded system somewhere. If not replace with a new 2 prong device, or put a GFI in and mark it without ground,or pull a new EGC to the box or pull a whole new romex to the box.

 

[mjf]

Re: This Old House - Jan/Feb p.53

Originally posted by iwire:
If it is newer AC cable with the shunt wire yes you are all set.

If it is the old BX without the shunt wire it is not OK for grounding.

please explain what this shunt wire is, is it that thin silver color wire ?

 

[stamcon]

Re: This Old House - Jan/Feb p.53

Mike, the "shunt wire" is the bond strip. Yes, it's that "thin silver colored wire".

 

[mjf]

Re: This Old House - Jan/Feb p.53

Thank you stamcon

 

[caosesvida]

Re: This Old House - Jan/Feb p.53

I agree especially the one about tv show
"electricians". I had to stop watching them, it was rediculous, the shows are an electrical hazzard "how to"!

 

[jes25]

Re: This Old House - Jan/Feb p.53

I agree about the shows but what is worse is home depot. That slogan you can do it we can help is just sick. Who can help a flunky apprentice working at the HD ( no offense to any HD workers I know there is a few guys that know what there talking about). I think the slogan should be "We can help you burn down your house like the 40,000+ every year from electrical related fires"