Elevator Circuit

[Ben Trueblood]

I have a 200 Amp breaker feeding a 200 Amp fused disconnect for an elevator.
the elevator is a 25 HP 208 V 3 Phase. According to the motor table the FLA for sizing conductors and overcurrent protection is approx. 75 Amps before adding the 125%.
According to my understanding if I use time delay fuses at a starting % of 175% of the FLA I would need way less than 200 A more like 150A fuses.
Originally the elevator was going to be sized larger and that is why the 200Amp breaker was originally considered.
My question is what size conductors am I required to run from my panelboard to the disconnect if i leave the 200Amp breaker in? Do I have to run 200Amp rated wire even though I am only feeding a motor?

Thanks

 

[davidr43229]

Ben,
You are correct in 175% of FLA, which equates to a 150amp Fuse. However what state are you in?
I ask this because most states on the NEC 2005 require a shunt trip overcurrent protection device for people movers on the elevator circuit, additionally you can not directly take the shunt trip signal directly to the shunt trip device. It will burn it out in many cases.
Just my $.02

 

[sparky59]

does the motor require a shunt trip if there is no sprinkler system?

 

[davidr43229]

Depends on the state, certainly selective coordination. And Sparkie, you are correct. I believe that Shunt trip is only required if there is a sprinkler head.
Michigan disallows shunt trip. Fire rated doors.

 

[BossMan20]

in washington d.c. we use heat detectors in the elevator machine room, elevator pit and sometimes the top of the shaft mounted within 18" of the sprinkler head and the heat detector activates the shunt trip. the theory is the heat detector will go off around 120 degrees F (give or take 10 degrees) anyway it will go off before the sprinkler head pops because of the lower temp setting (the sprinker head pops around 125-135). the shunt trip kills the power to the machine so there isn't an electrical hazard.

 

[BossMan20]

but to answer your ? 240.6 gives standard ampere ratings of ocpd's. the way i see it the wiring would have to be good for at least 180 amps. let's say for instance you pulled wire rated for 175 amps, then you must use a 175 amp breaker beacuse that is a standard ocpd rating. if you pull wire rated at 180 amps you can use the next higher standard ocpd which is 200 - so long as the load isn't greater than 180 amps, which it isn't. hope this helps.
sincerly,
Mark R.
Master Electrician

 

[e57]

My question is what size conductors am I required to run from my panelboard to the disconnect if i leave the 200Amp breaker in? Do I have to run 200Amp rated wire even though I am only feeding a motor?

Thanks

You wouldn't protect a #14 at 20A would you? The same applies here, you still need to protect the wire at it's 310.15 rating no matter what the load on it. See 240.4

Boss20 has a point about rounding up, but I would not suggest it with a large motor.

However having had a problem with high in-rush (LRA) with a long elevator feeder before I would leave the feeder and it's OCP as large as possible, and fuse for the equipment at it's size at the equipment. The one I had to deal with sounded like the four hoursemen everytime the thing went up, it would rattle the conduit. Which resulted in a year long finger pointing party between the original electrian, and the elevator co. And eventually replacement of the feeder. I say CYA, and have it spec'ed BSE. (By Someone Else)

 

[BossMan20]

so it seems you would have to run 3/0 copper or 4/0 aluminum based on ambient temp of 86 degrees per table 310.16

 

[BossMan20]

240.4 AND 240.4 (B) make it clear that this would be acceptable as long as the breaker he's using doesn't have trip adjustments on them that allow it to be set higher than 200 amps. anyway the 3/0 cu is good for 200 amps only the 4/0 al is 180 amps. and as for small conductors 240.4 (D) deals with them.

 

[BossMan20]

cya- i like that

 

[brian john]

David:

Most shunt trips I am familiar with have internal clearing contacts that open the power too the shunt coil as the CB opens. Though as posted in another thread there are different styles. Under voltage release are energized all the time and open the CB on loss of power.

 

[davidr43229]

Brian,
Most certainly you are correct. I talk to Elecrtical Engineering firms all the time, and what they sometimes do... is take the shunt trip signal from the fire alarm diectly to the shunt trip breaker. I did a study on the amount of current required to trip or actuate shunt trip breaker and the CB manufacturers are all over the board.
1 breaker manufacturer only requires 25ma to actuate, while 2-3 others required 40-50ma. I also did a study of Fire Alarm manufacturers and the capable power coming from their module, which ranged from 25ma to 40ma.
Clearly, you have to know both of these, if you are to connect the shunt trip signal from the fire alarm controller to the shunt trip on the breaker. Most Engineering firms around here have not done that.
I gave a presentation to Ohio, where upon a break during that presentation, he informed me that they found a site that has already blown 3 modules, and asked for my advise.
Conclusion: taking the shunt trip signal directly from the fire alarm directly to the shunt trip breaker will not work. The amperage of the fire alarm controller is not enough to actuate the shunt trip breaker, and will cause the fire alarm module to burn out.
Just my $.02