Wiring a motor - can't fit everything in 2.5" conduit. Is there any other way?

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Twophase

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Trying to wire a motor. Due to tight space, I have to use 2.5" conduit at the max. 275A FLA motor.

I initially thought of using parallel conduits. They issue with doing so is that my controller has only two terminations for ground. If I use parallel conduits, I won't have any ground terminals for my input power.

Based on the amperage, I need to use 500MCM

Is there any way to do this and fit it in 2.5 with a ground? The only thing I could think of is using aluminum conductors, and I've been told that is frowned upon (is it?)

I saw different tables in the NEC for "fixture wire" and "compact building wire". What's the difference?
 
I would guess that the EGC would be no larger than #3. Can you run two of them in separate conduits and connect them to each other (wire nut, clamp, or other device) inside the controller, then run only one to the terminal?
 
I've been instructed that "the controller cannot be used as a junction box"

Any issues with aluminum conductors if properly installed?
 
Twophase said:
Trying to wire a motor. Due to tight space, I have to use 2.5" conduit at the max. 275A FLA motor.

I initially thought of using parallel conduits. They issue with doing so is that my controller has only two terminations for ground. If I use parallel conduits, I won't have any ground terminals for my input power.

Based on the amperage, I need to use 500MCM

Is there any way to do this and fit it in 2.5 with a ground? The only thing I could think of is using aluminum conductors, and I've been told that is frowned upon (is it?)

I saw different tables in the NEC for "fixture wire" and "compact building wire". What's the difference?
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You could try two sets of 3/0 copper. Even with the derating you should be good.

AL conductors are typically Compact
 
Sounds like the only issue is the lack of openings at the EGC termination point.

Why not just change the ground lugs out to something that will accommodate what you need?


Jap>
 
Twophase said:
I've been instructed that "the controller cannot be used as a junction box"
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I will ask the membership for opinions on this, but I believe that bringing in two EGCs from separate conduits and connecting them together before connecting to the ground terminal would not be considered using the controller as a junction box.
 
Looks like I can fit 3x500 with a #4 ground. I'm coming directly from a transformer (transformer to controller to motor). Would this be considered an "equipment ground" or is this a "grounding electrode" scenario?
 
Not sure if it matters, but this is fire pump territory, so there is no thermal protection. Controller has magnetic only breakers.
 
Twophase said:
I've been instructed that "the controller cannot be used as a junction box"

Any issues with aluminum conductors if properly installed?
Click to expand...
Aluminum conductors not going to help you. They take up more space per rated amp size when compared to copper.
 
Twophase said:
I'm coming directly from a transformer (transformer to controller to motor). Would this be considered an "equipment ground" or is this a "grounding electrode" scenario?
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Quite possibly neither. For starters, where is the first overcurrent protection device that is downstream of the transformer's secondary terminals?
 
charlie b said:
Quite possibly neither. For starters, where is the first overcurrent protection device that is downstream of the transformer's secondary terminals?
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I'll have to look that up. Based on that, I can size the wire based on the NEC equipment ground table
 
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