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Discussion Starter · #1 ·
Can I use a motor overload setting to achieve a new required ampacity? For example if I have a ton of 480 volt 1 hp motors on a conveyor and each overload is set at around 2.5 amps couldn't I use that new ampacity to help me with derating?
 

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Can I use a motor overload setting to achieve a new required ampacity? For example if I have a ton of 480 volt 1 hp motors on a conveyor and each overload is set at around 2.5 amps couldn't I use that new ampacity to help me with derating?
more specifics would help pony

~CS~
 

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I'm with CS, need more info.

With a 2.5-amp load, I don't see how derating could be a problem.

With the maximum derating requirements (35%), a #14 is still good for 5.25-amps using the 60c column.
 

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Discussion Starter · #6 ·
chicken steve said:
more specifics would help pony ~CS~
I have 70+ motors to feed for a conveyor. I'd like to run larger conduits and just derate my cccs. I'll probably run 2" rigid and stuff as many 14s as the pipe fill will allow me. Since every motor feed is thermally protected in the control tower at around 3 amps I don't even see how derating will affect me. 35% of 25 amps (14) is still about 8.
 

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I would think you would be good to go (although pulling that wire in will take some time).
 

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Discussion Starter · #8 ·
hardworkingstiff said:
I would think you would be good to go (although pulling that wire in will take some time).
Oh yes. 800' of new conveyor with 10 fully articulating turnstiles, 2 fork truck lift gates and about a gajillion proxes and light curtains
 

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I have 70+ motors to feed for a conveyor. I'd like to run larger conduits and just derate my cccs. I'll probably run 2" rigid and stuff as many 14s as the pipe fill will allow me. Since every motor feed is thermally protected in the control tower at around 3 amps I don't even see how derating will affect me. 35% of 25 amps (14) is still about 8.

hmmm, well if i've got it right, all the 14's originate from overloads in this control tower Ponydude. So what your considering is the provisions of 430.31/32 to be considered for purposes of deration in lieu if 430.52

52 addresses shorts & G-faults, 32 really doesn't...not sure if that matters here?

~CS~
 

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Conveyor wiring

I have worked on a few covveyor Systems,cement plants.Rock plants Wharehouses.What U are decribing We always ran the wires in duct 4X4 up to Realy big ones 24X8.Mount it opening side out >not up.This way U have three surfaces to come out W/ EMT,Rigid or what ever. They sell dividers to isolate different Classes. WE often ran Cat6 in these,We used dividers to isolate for 3 ph480 1 Ph 120 &16V.
 

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I'm with CS, need more info.

With a 2.5-amp load, I don't see how derating could be a problem.

With the maximum derating requirements (35%), a #14 is still good for 5.25-amps using the 60c column.
You don't base the wire size on the load, you base it off the OCPD.

I don't know the answer to ponys question I will have to think on it.
 

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I have worked on a few covveyor Systems,cement plants.Rock plants Wharehouses.What U are decribing We always ran the wires in duct 4X4 up to Realy big ones 24X8.Mount it opening side out >not up.This way U have three surfaces to come out W/ EMT,Rigid or what ever. They sell dividers to isolate different Voltages.
No code reason to isolate different voltages unless they are different classes.

But a wireway avoids derating up to 36 current carrying conductors.
 

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You don't base the wire size on the load, you base it off the OCPD.

I don't know the answer to ponys question I will have to think on it.
I've always based the wire size on the load and then the OCPD to the wire.

You are more code savvy than I, so is it wrong for us to consider the wire protected (along with the motor) from the controller to the motor at the lower ampacity (due to derating)?

Also, since #14 at the maximum derated ampacity is 8.75-amps (25*.35) and the dedicated connected load is 2.5-amps, can't I use 240.6 to protect the conductor at 15-amps if I'm using a breaker?

Does Table 430.52 require a lower (than 15-amp) OCPD to be installed? What about exception 1 to this table, does that allow the 15-amp breaker for short circuit protection?

I'm very curious as to the proper way to look at this, so I hope you think it through and give us the NEC way to view it.

Thanks
 

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is it wrong for us to consider the wire protected (along with the motor) from the controller to the motor at the lower ampacity (due to derating)?

Also, since #14 at the maximum derated ampacity is 8.75-amps (25*.35) and the dedicated connected load is 2.5-amps, can't I use 240.6 to protect the conductor at 15-amps if I'm using a breaker?

Does Table 430.52 require a lower (than 15-amp) OCPD to be installed? What about exception 1 to this table, does that allow the 15-amp breaker for short circuit protection?

I'm very curious as to the proper way to look at this, so I hope you think it through and give us the NEC way to view it.

Thanks
All great questions, I want to think on it more before sticking my foot in my mouth. :jester:

I know, why change now? :laughing:
 

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Discussion Starter · #17 ·
I'm doing it. I'm putting as many 14s in a 2" grc as I can reasonably fit. The conveyor control center has fuses and ol protection for the multiple 1hp motors. Unless someone can tell me why not, in which case I'll still do it
 

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I'm doing it. I'm putting as many 14s in a 2" grc as I can reasonably fit. The conveyor control center has fuses and ol protection for the multiple 1hp motors. Unless someone can tell me why not, in which case I'll still do it
I think you should do it! :laughing:
 

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I've always based the wire size on the load and then the OCPD to the wire.

You are more code savvy than I, so is it wrong for us to consider the wire protected (along with the motor) from the controller to the motor at the lower ampacity (due to derating)?

Also, since #14 at the maximum derated ampacity is 8.75-amps (25*.35) and the dedicated connected load is 2.5-amps, can't I use 240.6 to protect the conductor at 15-amps if I'm using a breaker?

Does Table 430.52 require a lower (than 15-amp) OCPD to be installed? What about exception 1 to this table, does that allow the 15-amp breaker for short circuit protection?

I'm very curious as to the proper way to look at this, so I hope you think it through and give us the NEC way to view it.

Thanks
I'm thinking the 14's will never see more than 2.5 amps, at least not for too long

but that figure is based on an overload, not an overcurrent protective device

maybe i've missed it, but can one derate via OL, as opposed to OCPD?

~CS~
 
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