Does the running the equipment grounding conductor that is part of the phase conductors that are routed from the motor control center ground bus to the motor frame ground lug satisfy NEC Article 250.112 (C) and (L). I have heard some inspectors require a separate ground be run from the motor frame to the ground grid. Is this a vailid requirement?
Grounding of Motors
- Thread starter jnh
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Re: Grounding of Motors
The EGC is usually sufficient. I have seen engineering spec that require a grounding grid. The AHJ may have been enforcing the grid ground because it was on the construction documents, and an engineer's change order would be required to remove this requirement.
The EGC is usually sufficient. I have seen engineering spec that require a grounding grid. The AHJ may have been enforcing the grid ground because it was on the construction documents, and an engineer's change order would be required to remove this requirement.
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- Bremerton, Washington
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- Master Electrician
Re: Grounding of Motors
The EGC needs to be run with the circuit conductors, to minimize the impedance (see section 250.130(B). You could also bond the motor frame to some grounding grid, but not in liu of 250.130(B). I suspect the reason the separate ground is used as this is done in power plants and generating stations.
The EGC needs to be run with the circuit conductors, to minimize the impedance (see section 250.130(B). You could also bond the motor frame to some grounding grid, but not in liu of 250.130(B). I suspect the reason the separate ground is used as this is done in power plants and generating stations.
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