Elevator

[sparky76]

Hey guys. Don't have my book in front of me. I'm looking at a 20HP/208V/3phase (duh) motor. What size breaker am I going to need? Thanks in advance.

 

[Dennis Alwon]

Hey guys. Don't have my book in front of me. I'm looking at a 20HP/208V/3phase (duh) motor. What size breaker am I going to need? Thanks in advance.

From Table 430.250 20 hp 3phase 208 volts we get 59.4 amps but I would use nameplate.

 

[haskindm]

430.6(A)(1) tells you to use the table values INSTEAD of the namplate rating to determine the size of the short-cicuit and ground-fault protection (circuit breaker). The nameplate rating would ONLY be used to size the overload protection (heater).

 

[Dennis Alwon]

430.6(A)(1) tells you to use the table values INSTEAD of the namplate rating to determine the size of the short-cicuit and ground-fault protection (circuit breaker). The nameplate rating would ONLY be used to size the overload protection (heater).

Wouldn't an elevator motor be considered high torque? I don't know just asking.

 

[iwire]

The elevator companies have always told us the feeder size, usually much larger then really needed then they fuse it down at the disconnect we provide.

 

[peter d]

The elevator companies have always told us the feeder size, usually much larger then really needed then they fuse it down at the disconnect we provide.

Any idea why they do this? I'm guessing it's so they're covered in case they decide to put a bigger motor in?

 

[iwire]

Any idea why they do this?

'Cause they are elevator prima donnas. :grin:

I'm guessing it's so they're covered in case they decide to put a bigger motor in?

I don't really know, just CYA, maybe due to the long lengths of these feeders they had voltage drop issues and just found it easer to say give me a 150 amp feeder when the machine is tagged 75 etc.

I do know they get stuck in their ways, I did an elevator retrofit and the elevator guy explained to me his equipment had to have a copper EGC or it would not operate, if I tried to use the conduit as ground he would know. He also explained how it is a code violation to use the conduit as ground. :roll:

 

[peter d]

I do know they get stuck in their ways, I did an elevator retrofit and the elevator guy explained to me his equipment had to have a copper EGC or it would not operate, if I tried to use the conduit as ground he would know. He also explained how it is a code violation to use the conduit as ground. :roll:

I'm sure you thanked him afterward for enlightening an ignorant electrician like yourself.

That wasn't the Foxboro elevator, was it?

 

[iwire]

I'm sure you thanked him afterward for enlightening an ignorant electrician like yourself.

He got his ground and I did not bother getting into it with him.

That wasn't the Foxboro elevator, was it?

Could be.

I believe they asked for a 480V 3PH 100 amp feeder and then installed 65 amp fuses at the disconnect.

 

[peter d]

I believe they asked for a 480V 3PH 100 amp feeder and then installed 65 amp fuses at the disconnect.

I distinctly remember running that 100 amp feeder into that ancient panel.

 

[chris kennedy]

He got his ground and I did not bother getting into it with him.

Tuesday Jan. 29th 2008. 5:29PM

Bob admits he run a Cu. EGC in EMT.

I'll go ahead and save this one.:grin:

 

[iwire]

Tuesday Jan. 29th 2008. 5:29PM

Bob admits he run a Cu. EGC in EMT.

I'll go ahead and save this one.:grin:

:grin:

We where hired by the elevator company, I have to give them what they pay for. I would have brought him an IG as well if he paid for it. :grin:

 

[peter d]

Tuesday Jan. 29th 2008. 5:29PM

Bob admits he run a Cu. EGC in EMT.

I'll go ahead and save this one.:grin:

Oh but it gets better. We had to run some other circuits for the cab lights, the elevator machine room lights and receptacles, etc. And Bob actually had us run a separate neutral for each circuit!!!!!!













Which, actually was a good thing because later we had to go back and change some stuff around.......the shared neutral would have been a problem.