Armored Cable as Equipment ground

[TiredDude]

My 1960 house has armored cable for most of the wiring.

The armored cable has a positive and neutral wire but also a smaller, unsheathed, probably aluminum wire that is not connected to anything. I get a good ground reading from the receptacles.

I understand that 2 wire BX without the third wire is not considered code compliant as an equipment ground, but maybe my armored cable is.

Hoping for some good news on this one from the knowlegeable guys here at GJ.

Thanks

 

[Norcal]

If all of that AC cable is like what is pictured then your in luck, it has the bond wire so it can be used for grounding.

 

[TiredDude]

If all of that AC cable is like what is pictured then your in luck, it has the bond wire so it can be used for grounding.

Super! Thanks Norcal. I had researched and was thinking that was right, but wanted a knowledgeable person to confirm this.

I have read a lot of your comments and learned a lot from reading in this forum and having you confirm this puts my mind at ease.

 

[TiredDude]

So, if I install 3 prong grounded receptacles, do I need to run a ground to the box? Or will the receptacle contact to the metal box suffice?

I don't think the boxes have holes for a ground screw.....

 

[rockwithjason]

most receptacles have a grounding yoke that connects the mounting screw to the yoke of the receptacle. if you don't have a ground screw provision in the box then connect the ground to the ground lug on the receptacle and the yoke will bond thru the mounting screw into the box.

 

[TiredDude]

most receptacles have a grounding yoke that connects the mounting screw to the yoke of the receptacle. if you don't have a ground screw provision in the box then connect the ground to the ground lug on the receptacle and the yoke will bond thru the mounting screw into the box.

No yoke in box. The AC comes in with a connector, like an EMT connector. Set screw outside the box and a nut on the inside like an EMT connector. That is all that is in the boxes.

I guess I could use grounding clips on the boxes - just want to make sure it is required. Seems redundant because if the box is grounded then the receptacle should be grounded. Adding a second ground connection seems unnecessary.

But whatever code requires, I will do it.

 

[Norcal]

Use "self-grounding" receptacles, not all are & the normal variety residential ones are not, please note that tamper resistant receptacles are required.

 

[TiredDude]

Use "self-grounding" receptacles, not all are & the normal variety residential ones are not, please note that tamper resistant receptacles are required.

God, I haven't seen any tamper resistant that wouldn't be better labeled "use resistant"!

So, self grounding is sufficient without the grounding clip?

Thanks again.

 

[wyliesdiesels]

God, I haven't seen any tamper resistant that wouldn't be better labeled "use resistant"!

So, self grounding is sufficient without the grounding clip?

Thanks again.

"use resistant"- I hate TR receptacles!

yes, a self grounding receptacle is sufficient!

 

[Charles (in GA)]

Self grounding receptacles are the ones with a spring wire, or a flat metal clip riveted to the yoke of the receptacle, that makes turning that screw difficult, it ensures a positive electrical contact between the yoke of the receptacle, and the screw, and when screwed into a metal box that is grounded, provides a positive ground for the receptacle.

See the silver piece of metal beneath the head of the top screw on this receptacle? That is the spring clip that rubs tightly on the screw, this makes it self grounding.

In this pic, look closely at the receptacle on the right, far right screw. You will see two wire ends poking thru small holes, just above and below the screw head. If you were to look at the back side, you would see the wire crossing over, it rubs tightly on the screw, again, the self grounding feature.

Here is the back side, the receptacle, on the bottom, the right screw, the only one without the orange retainer disc, has the wire crossing past the screw, this is the self grounding.

Charles

 

[TiredDude]

Self grounding receptacles are the ones with a spring wire, or a flat metal clip riveted to the yoke of the receptacle, that makes turning that screw difficult, it ensures a positive electrical contact between the yoke of the receptacle, and the screw, and when screwed into a metal box that is grounded, provides a positive ground for the receptacle.

See the silver piece of metal beneath the head of the top screw on this receptacle? That is the spring clip that rubs tightly on the screw, this makes it self grounding.

In this pic, look closely at the receptacle on the right, far right screw. You will see two wire ends poking thru small holes, just above and below the screw head. If you were to look at the back side, you would see the wire crossing over, it rubs tightly on the screw, again, the self grounding feature.

Here is the back side, the receptacle, on the bottom, the right screw, the only one without the orange retainer disc, has the wire crossing past the screw, this is the self grounding.

Charles

Nice post and thanks for the explanation.

Further question: I have an outlet that apparently is not a "self grounding", but I installed it and my tester shows a proper ground, which thinking about it makes sense as the flange is metal and does contact the box.

Is this an effective ground? Is the real difference one of the outlet being "listed" as self grounding?

It sort of seems implausible that the small copper wire across the screw slot would provide any enhancement to the grounding capacity of the outlet. Is it more of a visual indicator that the outlet is indeed listed as opposed to an inherent improvement in grounding from the wire?

Thanks

 

[Norcal]

A "self-grounding" receptacle has been tested & listed by a NRTL, Nationally Recognized Testing Lab., such as UL, I do not like to rely on them but have from time to time.

 

[TiredDude]

A "self-grounding" receptacle has been tested & listed by a NRTL, Nationally Recognized Testing Lab., such as UL, I do not like to rely on them but have from time to time.

Thinking about getting one of these bits and just drilling and tapping the boxes for wires instead of using the self grounding stuff.

Greenlee DTAP10-32 Combination Drill and Tap Bit, 10-32NF
http://www.amazon.com/Greenlee-DTAP10-32-Combination-Drill-10-32NF/product-reviews/B000FCGRXM/ref=dp_top_cm_cr_acr_txt?ie=UTF8&showViewpoints=1

 

[Norcal]

Might consider the whole kit.


http://www.amazon.com/dp/B0041FIR1E/?tag=atomicindus08-20

 

[TiredDude]

Might consider the whole kit.


http://www.amazon.com/dp/B0041FIR1E/?tag=atomicindus08-20