Isolated Ground

[sparky46514]

Is an isolated ground conductor required to be continuous back to the panel or can joints be made?


NEW Question-Due to the amount of stuff in a wall,12-3 w/g MC cable will have to be used to supply an Isolated ground outlet.The question is,can the conductor not in use for the outlet be reidentified so that it may bond the box to the system ground?

 

[iwire]

Re: Isolated Ground

You can treat it as any other conductor as far as splicing, but eventually it must find its way back to the main bonding jumper.

250.119(B) allows remarking a conductor in a cable green if only qualified personal will work on it, we usually use the green for equipment ground and remark the red to green with yellow bands to indicate IG.

 

[sparky46514]

Re: Isolated Ground

Thanks Bob.That is what I thought but was told something different on the remarking.

 

[hornetd]

Re: Isolated Ground

I don't believe the code permits the remarking of the number six and smaller conductors that are found in most MC cable. It would be better practice and undeniably code compliant to use type AC cable that has an insulated green conductor inside it to use as the isolated Equipment Grounding Conductor. If the application is one in which type AC cable is not permitted then you can special order type MC cable with two green insulated conductors one of which will have a yellow stripe.

Allow me to suggest to you that the best solution is to have a shield of ferrous metal that is completely bonded back to the main bonding jumper of the system that powers the circuit. That means to use a ferrous raceway or cable and if you use cable to use one that has a jacket that is listed as an Equipment Grounding Conductor (EGC). If you must use cable and the occupancy type calls for type MC then you will have to settle for less effective shielding around the circuit.
--
Tom

 

[sparky46514]

Re: Isolated Ground

Can you give me the code section that prohibits this Tom?I also think that this is moot as we used greenfield to pipe to box.Thank you for the info though. AJ

 

[hornetd]

Re: Isolated Ground

Originally posted by sparky46514:
Can you give me the code section that prohibits this Tom? I also think that this is moot as we used greenfield to pipe to box. Thank you for the info though. AJ

I believe that 250.119 of the 2002 NEC requires that Equipment Grounding Conductors (EGCs) that are #6 AWG or smaller "shall have a continuous outer finish that is either green or green with one or more yellow stripes except as permitted in this section." I cannot see how subsection B would apply in most installations short of industrial environments were an electrical maintenance staff is employed.


250.119 Identification of Equipment Grounding Conductors.
Unless required elsewhere in this Code, equipment grounding conductors shall be permitted to be bare, covered, or insulated. Individually covered or insulated equipment grounding conductors shall have a continuous outer finish that is either green or green with one or more yellow stripes except as permitted in this section.
(A) Conductors Larger Than 6 AWG. An insulated or covered conductor larger than 6 AWG copper or aluminum shall be permitted, at the time of installation, to be permanently identified as an equipment grounding conductor at each end and at every point where the conductor is accessible. Identification shall encircle the conductor and shall be accomplished by one of the following:
(1) Stripping the insulation or covering from the entire exposed length
(2) Coloring the exposed insulation or covering green
(3) Marking the exposed insulation or covering with green tape or green adhesive labels
(B) Multiconductor Cable. Where the conditions of maintenance and supervision ensure that only qualified persons service the installation, one or more insulated conductors in a multiconductor cable, at the time of installation, shall be permitted to be permanently identified as equipment grounding conductors at each end and at every point where the conductors are accessible by one of the following means:
(1) Stripping the insulation from the entire exposed length
(2) Coloring the exposed insulation green
(3) Marking the exposed insulation with green tape or green adhesive labels
(C) Flexible Cord. An uninsulated equipment grounding conductor shall be permitted, but, if individually covered, the covering shall have a continuous outer finish that is either green or green with one or more yellow stripes.
--
Tom