Ac or mc??

[Mike01]

AC or MC? according to 330.108 indicates type MC cable used to provide an equipment grounding conductor, it shall comply with 251.118(10)
(250.118(10): type mc cable where listed and identified for grounding in accordance with the following: a.the combined metallic sheath and grounding conductor of interlocked metal tape-type MC cable.
b. the metallic sheath or the combine metallic sheath and grounding conductor of the smooth or corrugated tube type MC cable.
& 250.122 (sized based on the OCPD).
Where AC cable 320.108is required to provide an adequate path for fault current as required by 250.4(A)(5) or (B)(4) to act as and equipment grounding conductor.

my question is what's the difference either should be rated for the fault currents correct? so why two different construction methods.

 

[erickench]

I'm not sure what your question is.

 

[TOOL_5150]

my question is what's the difference either should be rated for the fault currents correct? so why two different construction methods.

They are both rated for the fault current, AC uses the sheath as the EGC, MC has its own EGC inside the jacket. MC has plastic barrier in the jacket, AC has paper. AC is pretty much not used anymore, and MC is.

~Matt

 

[Rockyd]

MC has AC beat almost all the way around. Just supporting alone AC (4.5') vs MC (6') makes a big difference. MC does not require an qnti-short. MC can be ran almost anywhere, providing it is listed. In industrial Jacketed MC is the rule, not the exception for saving money. Check out MC ap, you'll never buy AC again.

 

[Mike01]

whats the difference??

whats the difference??

HFC cable is acceptable in a hospital application but MC is not? when you look at the NEC under MC and AC it refers to different sections in 250 for grounding AC cables refers to 250.4(A)(5) or (B)(4) where as MC refers to 250.118(10) and 250.122.

250.4(A)(5) refers to effective ground fault current path where 250.118 talks about the "combined metallic sheath and grounding conductor" and 250.122 indicates the minimum size ground Do this mean to get the ground fault path for 250.122 for mc you need to use the conductor and the sheath where as in AC you can just use the sheath. .Just curious if they both intend to do the same thing then why two different section 250 references?

 

[erickench]

In a hospital there are isolated ground receptacles. The EGC wire would be used for the IGR and the metallic sheath of an MC cable (all purpose) contains an aluminum grounding/bonding conductor used for grounding the other equipment. You would need two different EGCs in a hospital.

 

[tom baker]

They are both rated for the fault current, AC uses the sheath as the EGC, MC has its own EGC inside the jacket. MC has plastic barrier in the jacket, AC has paper. AC is pretty much not used anymore, and MC is.

~Matt

There are some new products out:
MC AP has an al bonding strip, same as AC. It saves 30% on installation time.
The new AC is similar to MC in that is uses a mylar covering.

 

[benaround]

In a hospital there are isolated ground receptacles. The EGC wire would be used for the IGR and the metallic sheath of an MC cable (all purpose) contains an aluminum grounding/bonding conductor used for grounding the other equipment. You would need two different EGCs in a hospital.

This is just not true.

 

[TOOL_5150]

There are some new products out:
MC AP has an al bonding strip, same as AC. It saves 30% on installation time.
The new AC is similar to MC in that is uses a mylar covering.

True, but it does me no good being a residential electrician. I dont see why it can be used in commercial, but not residential.

~Matt

 

[don_resqcapt19]

True, but it does me no good being a residential electrician. I dont see why it can be used in commercial, but not residential.

Why can't you use it in residential? There in nothing in the NEC that says you can't.