ECN Forum Forums General Topics of the Trade General Discussion Area Metal clad , Armored clad ?

Whats the difference and can you use it in a hospital enviroment in southern california

The difference that counts is the armor jacket of AC cable is a grounding conductor.

The armor of MC cable is generally not a grounding conductor.

If your working in an area that requires redundant grounding you will need to use hospital grade AC cable.

iwire,What is hospital grade AC.I'm a canuck so we may not have it here or if we do it's not required.We use just regular ac90.We do use ISO ac90 which has both an insulated ground and bare ground in our LIM panels.

517.13 (a) All branch circuits serving patient areas shall be provided with a ground path for fault current by installation in a metal raceway system, or a cable having metallic armor or sheath assembly.
Am i reading this wrong

drgnz23,

As Bob said, you must use Type HCF cable. This is a form of AC cable, colored green to indicate that it's HCF.

HCF is constructed to include an insulated grounding conductor to meet this requirement. As with all AC cable, the armor is suitable for grounding.

drgnz23, you are reading 517.13(A) correctly. The metallic raceway or cable sheath shall itself be a ground path for fault current and there shall also be a wire conductor ground path for fault current.

HCF or HCFC meets this requirement.

Check out this link.
http://www.afcweb.com/table2_.html

Now, depending on what code cycle you are dealing with, you may or may not be allowed to use this wiring method for the "Emergency System" wiring.

Roger

[This message has been edited by Roger (edited 08-26-2005).]

I'm curious about how exactly this works--what do you do with the two grounds? I'm guessing that the armor ground is used to ground the box, and the insulated ground is for an isolated ground on the receptacle itself?

I don't understand what the rational is for the two grounds. If someone could explain what advantages they are supposed to bring, I would love to understand this.

Thanks!

No the 'extra' is not for isolated grounding.

It is simply for redundancy.

Call it a 'back up ground'.