Equipotential Bonding of HV Motor

[Jereb]

Hey guys,
I've just come across a situation i'm a little confused about. Currently we have a HV motor which is earthed through it's supply cable which carries it back to the MEN of the entire machine it is working in. However we have been asked to put another earth from the chassis of the motor to the framework immediately next to it. I've been told this is to reduce touch potential and that is fine but i am having trouble with the sizing of this additional earth cable?

 

[waross]

As a minimum, the same size as the grounding conductor in the supply cable. Some petroleum processing facilities ground all motors to the adjacent steelworks and use a minimum of #6 AWG. On larger motors the size is increased to the code minimum for equipment grounding conductors.

Bill
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"Why not the best?"
Jimmy Carter