MC & Art 517

[augie47]

After having a CMP member correct me years ago I began requiring all areas covered by Art 517.13 (Patient Care) that were subject to personal contact be wired with a method incorporating an equipment ground in a metallic raceway which is an approved ground return path also. This eliminated "standard" (interlocking) MC as acceptable.
I am aware the those areas above 7-1/2 ft and switches outside the patient care vicinity did not require the "redundant" grounding of both an insulated conductor and a "approved" s metal raceway.
I was under the belief that "standard" (interlocking) MC was acceptable in those areas as it is an approved grounding means per Art 250.118, but, in more in-depth reading it appears that is not the case. In that the sheath "itself" (key word from 517) is not a grounding means, MC can not be used
in these "exceptional" areas either, even though a 6 ft flexible conduit "whip" without insulated ground would be acceptable.
Am I correct on this ?

 

[Dennis Alwon]

Gus, It appears that southwire makes a HCF MC AP cable for that purpose.

 

[SEO]

Per section 517.13 (A) you are correct. On a side note in Michigan all flexible conduit requires a grounding conductor regardless of the amperage of the circuit.

 

[iwire]

Gus IMO you where correct until the MCap came out recently that Dennis linked to.

Before MCap became available Hospital Grade AC would have to be used.

 

[SEO]

I think that Gus was referring that the "standard" mc could not be used in that application because the outer sheath was not listed for grounding. The new hc mc which has been approved would be ok.

 

[Dennis Alwon]

I think that Gus was referring that the "standard" mc could not be used in that application because the outer sheath was not listed for grounding. The new hc mc which has been approved would be ok.

I believe we are all saying the same thing. :smile:

 

[iwire]

I believe we are all saying the same thing. :smile:

Naw ............. that never happens.

 

[chris kennedy]

I believe we are all saying the same thing. :smile:

And I agree with you all. I have yet to use the new MC as the AC is readily available here.

 

[Flex]

We are currently doing a job with HCF MC AP. I was trying to figure out why the hell there would be a full size (#12) Aluminum wire in the casing. I remember the real thin wire that I used to wrap around the anti-short but the #12 is to big for that. The instructions say just to cut it off at the end of the mc jacket. Is it really that important or kind of overkill?

 

[SEO]

Naw ............. that never happens.

This might be a first. Maybe somebody will chime in and break the chain.

 

[Dennis Alwon]

The instructions say just to cut it off at the end of the mc jacket. Is it really that important or kind of overkill?

Who knows? I am sure there are testing procedures that are necessary to pass before it can be used in HCF. Apparently the #12 wire does just that.

 

[chris kennedy]

We are currently doing a job with HCF MC AP. I was trying to figure out why the hell there would be a full size (#12) Aluminum wire in the casing. I remember the real thin wire that I used to wrap around the anti-short but the #12 is to big for that. The instructions say just to cut it off at the end of the mc jacket. Is it really that important or kind of overkill?

The jacket complies with this...

The metal raceway system, or metallic cable armor, or sheath assembly shall itself qualify as an equipment grounding conductor in accordance with 250.118.

and the #12 complies with this...

The grounding terminals of all receptacles and all non?current-carrying conductive surfaces of fixed electrical equipment likely to become energized that are subject to personal contact, operating at over 100 volts, shall be connected to an insulated copper equipment grounding conductor. The equipment grounding conductor shall be sized in accordance with Table 250.122 and installed in metal raceways or as a part of listed cables having a metallic armor or sheath assembly with the branch-circuit conductors supplying these receptacles or fixed equipment.

 

[Flex]

and the #12 complies with this...

Im referring to the aluminum #12

 

[Twoskinsoneman]

Im referring to the aluminum #12

The stuff I've used hade a #10 al boding wire bonding the interlock.

I'm talking the 12/2 and 12/3 stuff

 

[peter d]

Im referring to the aluminum #12

If it's MC Ap, then you cut off the aluminum bonding wire upon termination.

 

[Flex]

If it's MC Ap, then you cut off the aluminum bonding wire upon termination.

Yea I just snip it with my dykes. It might be a #10 Aluminum.

 

[TOOL_5150]

Whats the difference between the blue hospital grade MC and regular MC? Other than the color and cost.


~Matt

 

[peter d]

Whats the difference between the blue hospital grade MC and regular MC? Other than the color and cost.


~Matt

I've never heard of "blue hospital grade MC" as there is no such thing that I'm aware of. The product you might be referring to is the AFC MC Tuff product which has a blue armor on it. The difference between it and regular MC is MC Tuff is lightweight steel armor whereas regular MC is aluminum.

As for "Hospital Grade MC" it's actually HCF and it's Type AC cable. However, the Southwire MC Ap product is now made to replace the HCF cable.

 

[TOOL_5150]

hmm allright. next time I see the blue armored stuff, ill take a closer look at it.

Thanks Peter.


~Matt

 

[Pierre C Belarge]

AC cable would be permitted in the location that Augie is discussing.

MCAP -
14AWG ungrounded conductors - 12AWG Al bonding conductor
12AWG ungrounded conductors - 10AWG Al bonding conductor
10AWG ungrounded conductors - 8AWG Al bonding conductor

HCF MCAP
*the same as above