ELEVATOR EQUIPMENT

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mhayes

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HOW DO I GO ABOUT SIZING A CIRCUIT BREAKER, CONDUCTORS AND FUSES FOR AN ELEVATOR MOTOR. INFO: 208V, 3PHASE, 72 FLA, 327 LRA, 109 SA. THANKS TO ALL IN ADVANCE.
 
G

Guest

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Re: ELEVATOR EQUIPMENT

Not quite enough info here. The nameplate should tell you what the duty cycle of this motor is. look at 430.22(E) and the table on the next page. As you can see elevator motors may fall into one of thes categories. The ones Ive seen are rated continuous so I have used 140 to size my conductors. This results in your case with a conductor of 100.8 amps.By the letter of the code you need #3 but # 2 is probably ok. Your call. With most elevator Installers they will have a spec for you to adhere to that spells out what they require for wire size etc. Most elevator controller also require a shunt trip breaker to feed the motor control also. you must also look on the nameplate for the design letter to determine what fuse and breaker to use. Lets say its design B so use a maximum time delay fuse of 175% of 72 or 126 amps and a breaker of 250 % of 72 or 175. Hope this gives you some direction and as I say most elevtor installations have a spec sheet that spells out what is required.
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
Re: ELEVATOR EQUIPMENT

Are you just doing this for an exercise? Your questions are best left to engineers, and in all the states I have worked in, an engineers stamp would be mandatory along with the manufacturers info.


Roger
 

charlie tuna

Senior Member
Location
Florida
Re: ELEVATOR EQUIPMENT

i would add - make sure to go to a "heavy duty" disconnect switch and lean towards up-sizing the feeder conductors.
 

james_mcquade

Senior Member
Re: ELEVATOR EQUIPMENT

roger is correct,
this may be ok for an excercise, but if this is a real application, you need a pe to stamp the plans #1 and #2 you will be taking on a large responsibility for your work. again, if this is a real application, are you licensed, bonded, and insured to work on elevators?
james
 

nvcape

Senior Member
Re: ELEVATOR EQUIPMENT

Most of the time, when putting the plans together, we don't even get the exact horsepower size until later, let alone the actual submittal.
As a general rule, if given 25 HP, we size the wire and breaker to 30 HP and have a fused disconnect in the elevator room. When the submittal finally comes in, we follow it and need to size the fuses. Last week, the motor was a standard 25 HP, about 3 jobs back, it had a 30% service factor.
 
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