MCC Line Side Conductor

[dtriplej6]

In a Motor Control Center with a 480v backplane, what table should be used to size conductors for the line side connection between the bus and the circuit-breaker.
Currently we are using two parallel 4awg XHHN-2 conductors per phase. It is a size 5 starter running a 200hp 3-phase 480v Marathon motor. The motor has a FLA rating of 225A. We recently smoked the line side conductors, and I would like to vivify the application prior to just making the repair.
Thanks
Jeremy

 

[iwire]

I am assuming copper?

The NEC does not allow parallel 4 AWGs but forgetting that the total ampacity at 75 C would only be about 170 amps.

 

[jim dungar]

In a Motor Control Center with a 480v backplane, what table should be used to size conductors for the line side connection between the bus and the circuit-breaker.
Currently we are using two parallel 4awg XHHN-2 conductors per phase. It is a size 5 starter running a 200hp 3-phase 480v Marathon motor. The motor has a FLA rating of 225A. We recently smoked the line side conductors, and I would like to vivify the application prior to just making the repair.

The factory wiring did not need to follow the NEC for wire type nor sizing.
Your field wiring will need to be done per the NEC just as if you were pulling a brand new circuit to the motor starter. 200HP says you need conductors rated for 240A minimum (don't forget to check the tap rules).

 

[weressl]

In a Motor Control Center with a 480v backplane, what table should be used to size conductors for the line side connection between the bus and the circuit-breaker.
Currently we are using two parallel 4awg XHHN-2 conductors per phase. It is a size 5 starter running a 200hp 3-phase 480v Marathon motor. The motor has a FLA rating of 225A. We recently smoked the line side conductors, and I would like to vivify the application prior to just making the repair.
Thanks
Jeremy

Is it plug or directly bolted onto the main horizontal bus?
The sizing - as mentioned by others - does not necessarily follow the NEC. It is usually factory assembly and considered part of the cubicle. The sizing is usually corresponding to the maximum size of the current rating of the MCP or MCP. Best to get it from the MCC manufacturer.

 

[dtriplej6]

Is it plug or directly bolted onto the main horizontal bus?
The sizing - as mentioned by others - does not necessarily follow the NEC. It is usually factory assembly and considered part of the cubicle. The sizing is usually corresponding to the maximum size of the current rating of the MCP or MCP. Best to get it from the MCC manufacturer.

The conductors have spring tension clips that clamp on to the bus. It is a common Siemens design.

Thanks to everyone for the input.

 

[weressl]

The conductors have spring tension clips that clamp on to the bus. It is a common Siemens design.

Thanks to everyone for the input.

Go back and buy the Siemens spare part. (Furnas?)