MCap cable

[Pizza]

Can I use the 10awg aluminum bonding wire in MCap cable as an equipment grounding conductor?
I can't find anything that says I can't.
I've done it in the past where I ran the cable into something that has a plastic housing but also had a ground terminal or lug.


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[fmtjfw]

NO

 

[jumper]

Southwire says this about their MCAP:

Equipment Grounding Conductor = Combined Interlocked Armor
and Full-Sized Bare Aluminum Grounding/Bonding Conductor

Which I interpret as saying both are needed for an acceptable EGC.

 

[infinity]

I agree, no.

 

[tom baker]

Why would you want to. The cable armor is considered the EGC, which is the great advantage of MC AP over MC

 

[Pizza]

Why would you want to. The cable armor is considered the EGC, which is the great advantage of MC AP over MC

Like I said I have come across a few pieces of equipment that have had a plastic housing or plastic knockout entry but have had metallic parts that needed to be grounded by means of a grounding terminal or pig tail inside the equipment.
For example I've seen small circulating pumps come this way, also some commercial hand dryers.
AP is all I had in the truck at the time, you know that goes....


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[Cow]

Is there an MCap connector with threads that you could install a bond bushing on and then a bonding jumper from that to the ground screw/lug in the equipment?

 

[kwired]

Southwire says this about their MCAP:

Equipment Grounding Conductor = Combined Interlocked Armor
and Full-Sized Bare Aluminum Grounding/Bonding Conductor

Which I interpret as saying both are needed for an acceptable EGC.

Anyone know why the smaller aluminum bond wire was good enough for AC cable but isn't for MC-AP?

Is there an MCap connector with threads that you could install a bond bushing on and then a bonding jumper from that to the ground screw/lug in the equipment?

Typical "2 screw" MC/AC connectors should be acceptable.

 

[infinity]

Anyone know why the smaller aluminum bond wire was good enough for AC cable but isn't for MC-AP?

Typical "2 screw" MC/AC connectors should be acceptable.

I would guess that it's because the cable armor on that type of AC is much thicker.

 

[ActionDave]

They make aluminum AC? I'm used to seeing steel AC with a steel bonding strip.

 

[peter d]

Throw a 1/2" bonding bushing on there and call it done.

 

[winnie]

Since the EGC in MC-AP is full size, I don't see any reason that it wouldn't be acceptable as an EGC on its own. I guess I disagree with jumper on this point; I figure that combination of armor and wire is required when connecting to the armor, but that the wire itself is sufficient when connecting to the wire.

But since the whole point of MC-AP is that you don't need to deal with managing the ground wires in the box, for the most part there is no reason to use it in this fashion. Going into a plastic box might be a good reason. The bonding bushing approach is probably better so that you don't need to deal with wire connectors suitable for aluminium wire....

-Jon

 

[iwire]

Since the EGC in MC-AP is full size, I don't see any reason that it wouldn't be acceptable as an EGC on its own. I guess I disagree with jumper on this point; I figure that combination of armor and wire is required when connecting to the armor, but that the wire itself is sufficient when connecting to the wire.

But that is outside the listing, so that would be a no go.

 

[peter d]

Since the EGC in MC-AP is full size, I don't see any reason that it wouldn't be acceptable as an EGC on its own.

Going off the top of my head, #10 AL is not a listed EGC in 250.122.

 

[kwired]

Going off the top of my head, #10 AL is not a listed EGC in 250.122.

Sure it is, good for 20 amp OCPD and 12 AWG AL good for 15A.

 

[winnie]

Take a look at section 2.3 of http://www.southwire.com/commercial/mcap-engineer-specifications.htm

The grounding/bonding conductor in MC-AP is specifically sized to be compliant with 250.122, and must be an 8000 series conductor material.

The interlocked armor must be in contact with the ground wire, and the interlocked armor must be listed as suitable for grounding.

One might argue that 2.3 (C) doesn't say that the grounding/bonding conductor needs to be a listed conductor...but 2.3 (A) doesn't mention listing for the circuit conductors either.

-Jon

 

[iwire]

Take a look at section 2.3 of http://www.southwire.com/commercial/mcap-engineer-specifications.htm

The grounding/bonding conductor in MC-AP is specifically sized to be compliant with 250.122, and must be an 8000 series conductor material.

The interlocked armor must be in contact with the ground wire, and the interlocked armor must be listed as suitable for grounding.

One might argue that 2.3 (C) doesn't say that the grounding/bonding conductor needs to be a listed conductor...but 2.3 (A) doesn't mention listing for the circuit conductors either.

-Jon

Take a look at 250.118 of the NEC.

It does not allow using the bare conductor in MC without the armor as an. EGC.

So both the listing and the code prohibit it.

 

[winnie]

Take a look at 250.118 of the NEC.

It does not allow using the bare conductor in MC without the armor as an. EGC.

So both the listing and the code prohibit it.

Which version of 250.118?

In the 2011 version, 250.118 (10) gives three options for an MC cable egc. 250.118 (10) (b) is for the _listed_ combination of interlocked armor and grounding conductor, 250.118 (10) (c) is for the _listed_ smooth or corrugated sheath armor possibly combined with a grounding conductor. So for options (b) and (c) any grounding wire would only be acceptable in combination with the armor in a listed assembly.

250.118 (10) (a) however refers back to 250.118 (1), the description of a full size wire used as egc. 250.118 (10) (a) does _not_ require the armor (or armor and wire combination) to be listed as a grounding conductor.

Has 250.118(10)(a) changed in the 2014 edition? Or does 250.118(1) no longer permit bare aluminium EGCs?

Thanks
Jon

 

[kwired]

Which version of 250.118?

In the 2011 version, 250.118 (10) gives three options for an MC cable egc. 250.118 (10) (b) is for the _listed_ combination of interlocked armor and grounding conductor, 250.118 (10) (c) is for the _listed_ smooth or corrugated sheath armor possibly combined with a grounding conductor. So for options (b) and (c) any grounding wire would only be acceptable in combination with the armor in a listed assembly.

250.118 (10) (a) however refers back to 250.118 (1), the description of a full size wire used as egc. 250.118 (10) (a) does _not_ require the armor (or armor and wire combination) to be listed as a grounding conductor.

Has 250.118(10)(a) changed in the 2014 edition? Or does 250.118(1) no longer permit bare aluminium EGCs?

Thanks
Jon

copied from 2014:

250.118 Types of Equipment Grounding Conductors.


The equipment grounding conductor run with or enclosing the circuit conductors shall be one or more or a combination of the following:

(1) A copper, aluminum, or copper-clad aluminum conductor. This conductor shall be solid or stranded; insulated, covered, or bare; and in the form of a wire or a busbar of any shape.
....

(10)Type MC cable that provides an effective ground-fault current path in accordance with one or more of the following:
(a) It contains an insulated or uninsulated equipment grounding conductor in compliance with 250.118(1)
(b) The combined metallic sheath and uninsulated equipment grounding/bonding conductor of interlocked metal tape–type MC cable that is listed and identified as an equipment grounding conductor
(c) The metallic sheath or the combined metallic sheath and equipment grounding conductors of the smooth or corrugated tube-type MC cable that is listed and identified as an equipment grounding conductor

It doesn't indicate that there were any changes from 2011.

 

[iwire]

Which version of 250.118?

In the 2011 version, 250.118 (10) gives three options for an MC cable egc. 250.118 (10) (b) is for the _listed_ combination of interlocked armor and grounding conductor, 250.118 (10) (c) is for the _listed_ smooth or corrugated sheath armor possibly combined with a grounding conductor. So for options (b) and (c) any grounding wire would only be acceptable in combination with the armor in a listed assembly.

250.118 (10) (a) however refers back to 250.118 (1), the description of a full size wire used as egc. 250.118 (10) (a) does _not_ require the armor (or armor and wire combination) to be listed as a grounding conductor.

Has 250.118(10)(a) changed in the 2014 edition? Or does 250.118(1) no longer permit bare aluminium EGCs?

Thanks
Jon

Jon, with Mcap you do not have a bare EGC. You have a listed cable assembly that you must use as listed.

That puts 250.118(1) out of the picture.

Forget about what will work and think about what is allowed.