We are up grading a plant belt drive motor.It is about600ft from the breaker in the mcc room.The motor is 100 hp 460vac delta feed.we plan on a 3/0cu thwn feeder with 2"rigid conduit, and a short piece of raintight flex at the motor because of movement.Will we need to run an external ground from the motor to rigid conduit or will we be in compliance with our internal ground wire?
wire size in rgid conduit
- Thread starter shiprec
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- Bremerton, Washington
Re: wire size in rgid conduit
The conduit itself can serve as the equipment grounding conductor, however an insulated equipment grounding conductor is highly recommended, esp with a delta supply as the voltage to ground is 480 not 277.
The equipment grounding condutor (what you call a ground) must be run with the ciruit conductors to minimize the circuits ground fault return path impedance. An external equipment grounding conductor is limited to 6 ft. For circuits over 250 V to ground, any concentric or eccentric knockouts have to be bonded around, see 259.97.
[ June 08, 2003, 05:39 PM: Message edited by: tom baker ]
The conduit itself can serve as the equipment grounding conductor, however an insulated equipment grounding conductor is highly recommended, esp with a delta supply as the voltage to ground is 480 not 277.
The equipment grounding condutor (what you call a ground) must be run with the ciruit conductors to minimize the circuits ground fault return path impedance. An external equipment grounding conductor is limited to 6 ft. For circuits over 250 V to ground, any concentric or eccentric knockouts have to be bonded around, see 259.97.
[ June 08, 2003, 05:39 PM: Message edited by: tom baker ]
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