Neutral at Motor Control Center

[cdcengineer]

I have a motor control center serving more than a dozen 480V, 3-phase motors. There is not a single load which would require a neutral or grounded conductor.

Is there any reason why we should have a neutral / grounded conductor run to this equipment (other than future)? I assume there would be a neutral bar, but to be honest I haven't seen the insides to an MCC in years.

Thx

 

[petersonra]

I have a motor control center serving more than a dozen 480V, 3-phase motors. There is not a single load which would require a neutral or grounded conductor.

Is there any reason why we should have a neutral / grounded conductor run to this equipment (other than future)? I assume there would be a neutral bar, but to be honest I haven't seen the insides to an MCC in years.

Thx

the only time i have seen an MCC with a neutral is when it is being used as service eqipment.

 

[kwired]

I have a motor control center serving more than a dozen 480V, 3-phase motors. There is not a single load which would require a neutral or grounded conductor.

Is there any reason why we should have a neutral / grounded conductor run to this equipment (other than future)? I assume there would be a neutral bar, but to be honest I haven't seen the insides to an MCC in years.

Thx

As long as it is not the service equipment you do not need to supply it with a neutral if none of the supplied loads utilize the neutral.

 

[cdcengineer]

Just got off the phone with Sq D and you're right. The neutral bar would be special order. The standard (unless service entrance) is w/o neutral.

Thx

 

[iwire]

We work at a couple of facilities that use MCCs as distribution equipment so they have neutrals.

 

[petersonra]

We work at a couple of facilities that use MCCs as distribution equipment so they have neutrals.

we have had a few that way. municipal wells usually.

 

[Jraef]

Even if the MCC is the service entrance, most mfrs offer a "Neutral Landing Lug / Plate" that is just a place to terminate (or bond if necessary) the Neutral conductor from the service drop. It doesn't need an entire N bus running through the MCC. Saves $$.

 

[petersonra]

Even if the MCC is the service entrance, most mfrs offer a "Neutral Landing Lug / Plate" that is just a place to terminate (or bond if necessary) the Neutral conductor from the service drop. It doesn't need an entire N bus running through the MCC. Saves $$.

I have never seen one with a bus. Just one with a neutral terminal for bringing in the neutral and bonding it.

 

[Jraef]

I have never seen one with a bus. Just one with a neutral terminal for bringing in the neutral and bonding it.

I just had to do one on a 62 section MCC. They had Lighting Panelboards at the same voltage as the MCC (480/277) strewn throughout the lineup. I tried to convince the end user that it would cost a LOT less to bunch them all at the incoming service end so that he didn't need to pay for the N bus all the way along the lineup. But I only mentioned it once and then took his money from him. He was insistent on the locations because "it made sense with relation to the arrangement of other equipment starters for those areas". In other words because a cluster of starters and drives was feeding a particular area of the production floor, he wanted the LP for that area to be located in among those starters in the MCC lineup. So that meant the fist LP was 10 sections from the incomer, the 2nd was at around 22 sections in, the 3rd at about 40 sections and the 4th at the very end. 62 sections of 2000A full rated Neutral bus bar at probably $800 per section (at the end user price) just so the LPs could be grouped with the starters.

As if anyone is going to give a rat's you-know-what where the LPs are in 6 months... If they are just in the same room, most people are happy enough.