Elevator circuit sizing

tkrussell · Feb 7, 2008, 09:55 AM

I am assuming you are an electrician, so I will speak in our lingo.

You should refer to Article 620 of the NEC just to be sure your not missing anything.

Art 620 will refer you to Art 430.

To begin with need to refer to Table 430.250 of the NEC.

A 30 HP 3 Ph 208 volt motor will draw 88 amps.

Feeder wire size is to be rated at least 125% of this value, or 110 amps, and this can be #2 copper, rated at 115 amps in the 75 Deg C column of Table 310.16.

If you can determine the duty cycle of this motor, you may use smaller wire. I don't think the savings would be that great to make it worth researching this, so forget this.

The short circuit device also uses the value from Table 430.250. A Time delay fuse can be 175% of 88 amps, thus the 150 amp fuses. An inverse time circuit breaker can be the max of 250% of 88 Amps =220 amps, a standard size 200 amp breaker can be used, and should be sufficient to start the motor.

noely · Jan 6, 2012, 05:13 AM

what is kind of contactor that use elevator control

tkrussell · Jan 6, 2012, 08:26 AM

Quote:

Originally Posted by noely

what is kind of contactor that use elevator control

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Elevator circuit sizing

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