Grounding Cable

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gabe044

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I'm working at an engineering consulting firm and today one of our clients told us they wanted the grounding conductor to be separate from the multiconductor cable supplying the equpiment. We are running multiconductor cables (with the ground inside the jacket) thru cable trays for around 300 ft, and they want a separate conductor for the ground rather than using the one inside the multiconductor jacket. Only one person in my department had heard of this, but no one knows why. Just wondering if anyone out there knows the reasoning behind this. Thanks a lot!
 
gabe044 said:
We are running multiconductor cables (with the ground inside the jacket)
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What are you being told to do with those grounds [equipment grounds] that are inside the jacket ?

While everything is in the cable tray, compliance is unclear, but how are you going to exit the tray and comply with 300.3(B) + 250.134(B) ? . When the cable exits, it itself is the raceway and you have a problem.

David
 
We interpreted it as; the ground inside the multiconductor cable will go unused and we will have a separate ground cable run along the tray system. We have a counduit going from the tray system to the equipment, but that would have to be resized in order to include this extra cable and still meet NEC requirements. It doesn't make a whole lot of sense to us but that could be becasue we don't know the reasoning behind doing things this way. Thanks.
 
If at no point does the jacket serve as the raceway [you use cabletray and conduit the whole way], I don't see it as a violation. . It's a strange request from the customer. . I wonder what they're trying to accomplish.

Let's see how others from this site "weigh in" on this one.

David
 
The bigger question is WHY??????????????????


What HOO DOO VOO DOO, do they expect the exterior ground to DOO DOO?
 
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Larry I am serious, this is from the field of magical mystery grounding. Do a little this, do a little that and HOPE it works. If it does, rewrite the code, rewrite electrical theory, because something worked they think. When in reality they either create an unsafe situation or maybe inadvertently solved the problem. But this hoo doo voodoo doo becomes a spec. When if they correctly followed code and checked for compliance the system would work and be safe.

And these practices come from all corners of the trade, electricians, inspectors, field techs, manufactures, suppliers and engineers.
 
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Are the gound conductors being supplied seperate from the multi-conductor cable the same size and have the same insulation type, as the grounding conductor inside the multiconductor cable?
 
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