External Grounds for cord fed equipment

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bearhunter

New member
The Company I work for requires external grounds for 480v Cord fed equipment eg. Welders, portable fans, etc. This external ground is required in addition to the 4th conductor(green) in the molded cord assembly. Their standard requires a bare ground wire to be attached to the frame of the equipment and to the plug shell at the point of connection. My question is this, what does the code say about parallel grounding paths for cord and plug connected equipment, and should this ground wire be allowed to serve in addition to the grounding conductor in the cord. What are the dangers/advantages to this?
 

tom baker

First Chief Moderator
Staff member
Re: External Grounds for cord fed equipment

This is allowed as a supplementary ground see section 250.54. I explain this type of ground rod as being installed when you don't have anything better to do.

I would like to know what the purpose of the ground rod. It will not assist in clearing a line to case fault. Ground rods are to stablize the voltage to ground and to prevent overvoltage from lighting. If in your case, the ground rod is to clear a line to case fault, has anyone ever tested the ground rod resistance?

I see no advantage, and the disadvantage is a false sense of security....unless you have stock in a ground rod company, or its a time and materials job.
 

gwz2

Senior Member
Location
Indiana
Re: External Grounds for cord fed equipment

As long as the EGC with the circuit conductors ( 250.134(B) is the proper size (250.122), I do not know of any code text prohibiting any amount of other grounding paths.

I would think that almost all FEEDERS have more paths than the one required, i.e. concrete, earth, building steel, intercom lines, coax cable runs, conduit supports, water lines, metal ducts, etc.
 

bennie

Esteemed Member
Re: External Grounds for cord fed equipment

I think the ground conductor is for visual confirmation of continuity, and possibly for static charge dissipation or diversion.
 
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