Elevator feeder and disconnect sizing

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storeytime

storeytime

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Texas
Good day! I have some questions on an elevator I was asked to feed power to. Here are the specs I was given:
25 HP Elevator Motor
Motor nameplate rated current at rated horsepower - 69 amps
Motor locked rotor current for solid state starting - 207 amps
Single phase control load on main supply is 1.3 amps
Motor Code Letter B
They recommend a 100 amp fused disconnect.

My questions:
This facility has 1PH, 240V power. I am installing a phase convertor to get 3 PH power.
1 - From what I have been looking at, I need to protect for 89 amps (69 x 1.25 = 86.25 ---- Motor Code Letter B = 3.54% ----- 86.25 x 3.54% = 89.3 amps)
So, I would protect with a fused disconnect with 100A fuses. (Code recommends a little higher to eliminate nuisance tripping which might trap people in the elevator)
2 -I have to first protect the phase convertor - 100A ?
3 - After the phase convertor, motor controller protection - 100?
4 - They asked for a pit sump pump, GFCI, and lights which have not been roughed in. I can get the GFCI and lights from a circuit in the elevator equipment room. Might need more juice for the sump pump. To get that is there anything that
says I couldn't use a load center with main breaker for the first disconnecting means and feed the phase convertor and sump pump out of that?
 
bump
(I'm unable to answer your question but bumped it up to hopefully get some input)
 
Last edited:
Unusual to not have some input. Hopefully someone with expertise in this area will see the thread.
(I am going to move it to NEC thread to see if we get a better audience)
 
storeytime said:
Good day! I have some questions on an elevator I was asked to feed power to. Here are the specs I was given:
25 HP Elevator Motor
Motor nameplate rated current at rated horsepower - 69 amps
Motor locked rotor current for solid state starting - 207 amps
Single phase control load on main supply is 1.3 amps
Motor Code Letter B
They recommend a 100 amp fused disconnect.

My questions:
This facility has 1PH, 240V power. I am installing a phase convertor to get 3 PH power.
1 - From what I have been looking at, I need to protect for 89 amps (69 x 1.25 = 86.25 ---- Motor Code Letter B = 3.54% ----- 86.25 x 3.54% = 89.3 amps)
So, I would protect with a fused disconnect with 100A fuses. (Code recommends a little higher to eliminate nuisance tripping which might trap people in the elevator)
2 -I have to first protect the phase convertor - 100A ?
3 - After the phase convertor, motor controller protection - 100?
4 - They asked for a pit sump pump, GFCI, and lights which have not been roughed in. I can get the GFCI and lights from a circuit in the elevator equipment room. Might need more juice for the sump pump. To get that is there anything that
says I couldn't use a load center with main breaker for the first disconnecting means and feed the phase convertor and sump pump out of that?
Click to expand...
I know next to nothing about elevators because we are not allowed to touch them but I'll take a half swing at it.
The size of the roto-phase would be roughly twice that of the motor, the manufacturer you choose will have a lot to say about this. 100A protection for it sounds small.

25hp sounds like a big motor for an elevator to me. Maybe it is not, but a roto-phase big enough to drive it is going to be running 24/7, no? How many trips a day are going to be made in this elevator? Would a VFD that will convert single to three phase work for your application?
 
This a hydraulic lift type elevator. I guess that's the reason for the smaller motor?

The phase convertor was picked by the elevator company according their specs and it is bought and onsite already.
The specs say 80 starts per hour.

The specs I mentioned are form the elevator company's power data sheet they sent out, so I have to assume the power convertor that was specified matched their power specs.

As you can probably tell, I know nothing about elevators. In fact I'm shocked that the elevator project manager can't just answer these questions. I've asked him and he refers me to the formulas I used to come up with my numbers.
 
I'm not out there right now to look at name plate. Will get that later.

The main thing that will help me is if someone can tell me this. Do I need to do a motor name plate rating (69A) times 1.25? The motor is not continuous duty but is intermittent. Their specs say "This equipment is used for an intermittent elevator duty cycle."
 
AS stated earlier, I don't feel I have the expertise to offer much help, but in direct answer to your question, you might look at Table 430.22(E) which may either assist or hinder.
 
storeytime said:
I'm not out there right now to look at name plate. Will get that later.

The main thing that will help me is if someone can tell me this. Do I need to do a motor name plate rating (69A) times 1.25? The motor is not continuous duty but is intermittent. Their specs say "This equipment is used for an intermittent elevator duty cycle."
Click to expand...

augie47 said:
AS stated earlier, I don't feel I have the expertise to offer much help, but in direct answer to your question, you might look at Table 430.22(E) which may either assist or hinder.
Click to expand...
Need more info. Namely the "Time rating" of the motor 430.7(A)(6).

Assuming a continuous duty rated motor, Table 430.22(E) says your conductors need to be sized at 140% of nameplate current rating. Note this has nothing to do with SC/GF or overload ratings.

Also, do not mistake Design Letter for Code Letter regarding locked-rotor amperes. See 430.7(A)(8) & (9).

FWIW, elevators are not my area either.
 
From an installer POV

From an installer POV

This was in NC, you rules and requirements might be well different.
Last Elevator I did where based on EE and Elevator Spec drawings.

* Thiswas a Lift Elevator all drive services where in penthouse.
We needed to have additional two set of conductors into penthouse light and GCFI.
We split the circuits at the main MDP!

Need to get a hold of elevator installer ASAP, the installer will tell you where
they want their equipment and clue you into, well just about every thing that is needed to their two spaces. They might even state the your piping be at the back of the space! In no case could we use any part of their electrical elevator raceway. Nor where we allowed to go vertical in the shaft-way, IE floor to floor.

Be sure to ask about smoke detectors and location of smoke detector(s),W/ hydraulic you usually only need F/A in pit, but ask about top.
If sprinkled the F/A head need to be two feet from each other.

It will be tight, I wired one light switch once that was getting turned on and off as it lifted or dropped! :) Get with the elevator pep's.

We are not allowed to put the pit light switch behind the pit ladder.

We needed five circuits to elevator. Nothing shared. I guess you could use your power circuits as you described.

Circuitfor the pit GFCI. \ usually combine in a pipe
Circuitfor pit lights. /
Circuitfor sump. \

Circuit for Cab Lights this needs a disconnect (fused)in Elevator Room,then back to Elevator shaft.*

Circuit for motor this needs a disconnect(fused)in Elevator Room,then back to Elevator pit shaft.*

Need multiple boxes for F/A (Up to three) in Elevator Room and pipe to Motor disconnect in elevator room, this is just another drop point from the usual run F/A piping on the floor.

You need a cross over pipe from F/A panel to Main Panel for shunt breaker.

I don't know anything about the phase converter.

All as I recall.

Hope this helps.
 
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Thanks for all the help. I used 90% of motor rating because it is a 30, 60 minute rating and then added 3.54% for the locked rotor.
 
storeytime said:
Thanks for all the help. I used 90% of motor rating because it is a 30, 60 minute rating and then added 3.54% for the locked rotor.
Click to expand...
Used this for what? 90% of motor rating is just for minimum conductor ampacity. Motor SC&GFP will likely be higher. OLP is not based on either of the preceeding.

I have no idea where you are getting the add 3.54% for locked-rotor current, but assume you are taking the 3.54 value from Table 430.7(B) Code Letter B. As I mentioned earlier, do not mistake a Code Letter for a Design Letter. They are not the same thing. A nameplate which has locked-rotor current listed will typically not have a Code Letter?which is for the purpose of letting you know how much lock-rotor current is. The values in Table 430.7(B) are as-is multipliers... not percentage multipliers.
 
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