building ground grid

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snjeza

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Does equipment grounding conductor has to be run in each raceway together with phase conductors? Can each peace of equipment forming the circuit be separatelly grounded to the building grounding grid and not having equipment grounding conductor in the raceway?
 
snjeza said:
Does equipment grounding conductor has to be run in each raceway together with phase conductors? Can each peace of equipment forming the circuit be separately grounded to the building grounding grid and not having equipment grounding conductor in the raceway?
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1. Generally, there is no prohibition on running a supplementary EGC around your plant and bonding things to it, if that is what you are calling your "grounding grid". It serves no real purpose in most cases, but it is not prohibited.

2. You have to run an EGC with every set of conductors in a raceway. In many cases, it is permissable to use the raceway itself as an EGC.

Condition 1 above cannot be used in place of condition 2 above.
 
snjeza

snjeza

Bob,

it's a power plant and they usualy use grounding grid to ground equipment. I almost never see equipment grounding wire in the raceway. They have rigid conduits and cable trays if that can be considered as equipment grounding.
 
Rigid metal conduit and cable tray can both be used as equipment grounding conductors. There is nothing worng with the additional grounds to grids, etc.

Good circuit design would require you to include a ground with the individual electrical circuits running to equipment, even though your code, the NESC, may not.

Jim T
 
don_resqcapt19 said:
A connection to a grounding grid does not take the place of an equipment grounding conductor.
Don
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Don, if this is an ungrounded system, is an EGC still required to be run with feeders and branch circuits?
 
don_resqcapt19 said:
A connection to a grounding grid does not take the place of an equipment grounding conductor.
Don
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Huh?

I have seen, and grounded many a xfmr, switchgear, and the like by means of connection to the ground grid. That's part of it's function, as well as to keep everything on an equipotential plane, thereby reducing step and touch potentials to safe levels.
 
King,
I have seen, and grounded many a xfmr, switchgear, and the like by means of connection to the ground grid.
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I stand by my statement. The conductor you are talking about is not an EGC. The code does not permit a connection to a grounding grid to replace an EGC.
Don
 
David,
Don, if this is an ungrounded system, is an EGC still required to be run with feeders and branch circuits?
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Yes, the NEC requirements for equipment grounding are the same for grounded and ungrounded systems.
Don
 
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