Proper grounding of hospital grade MC

Status
Not open for further replies.
E

e_sparks48

Member
When using MC (hospital grade) to wire the normal power circuits in a patient care area, is the ground running along the inside of the corrugated outer covering required to be bonded to the outlet box in addition to the green grounding wire?
 
The outer jacket, when listed as an EGC, will be connected to the box by the metallic connector. Is this HCFC cable which is an AC cable or the new MC cable that has an outer jacket that is listed as an EGC?
 
If your talking about the new MC just cut off the bonding strip here is some info.

Installation Instructions Provided with Every Reel and Coil
Installation instructions are required by UL to be provided with every reel and coil. When MCAP cable is installed, the installer cuts the aluminum grounding conductor flush with the armor, then secures the cable into a fitting listed for the new cable. The listed fitting provides a bonding connection between the armor and the box. An effective ground-fault current path is established because the armor is equivalent to the green insulated equipment grounding conductor in a conventional MC cable.

With self-grounding wiring devices, no equipment bonding jumper between the device and the box is needed. If the wiring device is not self-grounding, a bonding jumper from the device to the box is required. See figure 3 for the 5-step installation process.
The use of the armor as an equipment grounding conductor path distinguishes MCAP cable from conventional MC cable.
Click to expand...

I got that from the IAEI.

New Form of MC Cable Crosses Application Boundaries
 
I agree with Bob if you are using MC with an oversized AL ground wire but if you are actual using AC cable with a smaller AL ground conductor it must be bent back against the outer jacket and clamped into the connector.
 
Bea said:
but if you are actual using AC cable with a smaller AL ground conductor it must be bent back against the outer jacket and clamped into the connector.
Click to expand...


That is not required either.

I do what you suggest but it is also acceptable to cut it off flush
 
There is much confusion on the al bonding strip in AC cable. It serves only to reduce the impedance of the jacket to allow it to be used as a EGC. Cut it off, backwrap it, its function is not a EGC.
NEMA has a explanation on this.
The new MC-AP cable combines AC and MC. It will take most of the market from AC esp now that it can be used in a health care location.
 
Tom is correct. The strip serves merely to short each wrap of the sheath to its neighbor, not to conduct for the length of the cable. The sheath itself is still the EGC.
 
Another area of confusion is the redhead. Required with AC but not MC.
Has anyone actually installed the MC-AP cable? I have some samples from a IAEI convention several years ago.
 
tom baker said:
Another area of confusion is the redhead. Required with AC but not MC.
Has anyone actually installed the MC-AP cable? I have some samples from a IAEI convention several years ago.
Click to expand...
shorting bushings are not required on MC cable as it has a mylar jacket around the conductors however AC cable does not hence the required shorting bushing
 
Bea said:
shorting bushings are not required on MC cable as it has a mylar jacket around the conductors however AC cable does not hence the required shorting bushing
Click to expand...


I think that you meant anti-shorting bushing.:)
 
Status
Not open for further replies.
Top