Elevators 620 Vs. 430

[new_ee]

I did a search through the forums and never really found these questions answered.

I have a 40hp,208V,3ph hydraulic elevator with solid state starting. I want to size the disconnect (either enclosed CB or time delay fuse) in the elevator equipment room, the feeder conductors, and the CB feeding the elevator disconnect (located in main panel). I'm still on 2002 NEC.

Here we go:

1) Since the building is sprinkled I know I need shunt trip protection. Where does the shunt trip protection occur? In the disconnect in the elevator room? or in the CB feeding the elevator circuit in panel ahead of disconnect? I have read that some use a enclosed CB as the disconnect in the elevator equipment room. I have also read that you might not be allowed to have the shunt trip device located in the equipment room? Can anyone clear this up with a code reference?

2) Sizing the feeders. FLA = 114A based on table 430.150. Shop drawings say the elevator starting current is 278A and running current is 121A. However, 430 says that for feeders and SC/GF protection you use the FLA in the NEC. So using the FLA of 114A I would normally say 114 X 1.25 = 142.5A for a motor. Now, since this is an elevator I was directed by 620.22 to use table 430.22(E) which has percentages based on the nameplate current rating for intermittent use. You need to know whether the motor is rated 5 min, 15 min, 30&60 min, or continuous. The elevator shop drawings do not mention what minute rating the motor is. Of course, if I assume continuous I would need to use 121 (nameplate) X 1.4 = 169.4A for the feeder size. So which numbers do I use for elevator feeders? I'm really confused here? Is it the 142.5A or the 169.4A?

3) I think I have the fuse/or CB size down. TD fuse size is 114 X 1.75 = 199.5A so I can use 200A TD fuse as a maximum. CB size is 114 X 2.5 = 285A so I can use 300A CB as a maximum. The only question I have here is dealing with the nameplate give 278A starting current. How long does this current last for? If I use an inverse time CB thats less than 278A will it allow the elevator to start?

4) If I used enclosed CB as disconnect in elevator equipment room the CB will be sized the same as the CB in the main panel feeding the elevator circuit, correct?

 

[davidr43229]

This should help you on your way:
http://www.bussmann.com/pdf/1145.pdf
Please take the time to read it. Additionally NEC article 620.62 for Selective Coordination Elevator circuits and 620.91 (c) disconnecting means.
A simple shunt trip breaker will not be able to achieve what you want. I mean to say you can not take the shunt trip signal directly from the fire controller to the shunt trip breaker. The shunt trip within the breaker will require more current than what the controller is able to deliver to activate the shunt trip, so should you decide to go with a shunt trip breaker, you will need to install a small transformer and relay to insure proper current to the shunt trip on the breaker.
Additionally you need to monitor the fire alarm signal and the fire alarm voltage.
Your sizing of FLA of 114 amps X 1.75% is correct, for the fuse.

4) If I used enclosed CB as disconnect in elevator equipment room the CB will be sized the same as the CB in the main panel feeding the elevator circuit, correct?

620.62 for selective coordination, you must make sure that if you use a 300A CB, it must coordinate with the main.
Dave

 

[new_ee]

Thanks. I believe the elevator controller takes the input from the fire alarm control panel and the shunt trip connection on the breaker is made to the elevator controller. I will double check this information.