Full Load Current Of Industrial Control Panel

[crispy_copper]

How is the full load current determined for the purposes of marking per NEC 409.110(2)?

I understand when sizing the conductors for a panel that controls several motors 430.24 requires a 125% factor for the largest motor FLC and other continuous non-motor loads. For the purposes of the panel full load current though, is this calculated by only using 100% of the FLC for all of the motors and other load currents, or are there multipliers that must also be applied?

 

[Jraef]

I go by 430.7(D), which references 430.24, but adds that you only need consider all loads that could be operating at the same time.

 

[dm9289]

Also on an MCC if you have a 2000 amp MCC you have to feed with cable of that ampacity. As you know people always add to the extra buckets.

 

[petersonra]

Also on an MCC if you have a 2000 amp MCC you have to feed with cable of that ampacity. As you know people always add to the extra buckets.

Not true. There is no requirement in the code to include any provision for any future changes.

 

[petersonra]

I go by 430.7(D), which references 430.24, but adds that you only need consider all loads that could be operating at the same time.

I would use the procedure in ul508a for determining flc of the icp.

 

[dm9289]

Not true. There is no requirement in the code to include any provision for any future changes.

What I’m assuming is your over 800amp no next size up and if the factory assembly has a 2000 amp breaker your feeder must be able to handle a 2000amp load.
Perhaps I read too much into the question

 

[petersonra]

What I’m assuming is your over 800amp no next size up and if the factory assembly has a 2000 amp breaker your feeder must be able to handle a 2000amp load.
Perhaps I read too much into the question

The feeder conductors have to be protected at their ampacity which is unrelated to main breaker rating. Just like you could feed a 200 Amp main cb panel with 100 amp conductors from a 100 amp cb

 

[oliviamaya]

Appreciated

 

[dm9289]

The feeder conductors have to be protected at their ampacity which is unrelated to main breaker rating. Just like you could feed a 200 Amp main cb panel with 100 amp conductors from a 100 amp cb

I see what your saying I guess selective coordination is more of a preference concept not a code concept.

 

[petersonra]

I see what your saying I guess selective coordination is more of a preference concept not a code concept.

Nothing prevents effective selective coordination by running a smaller feeder than the rating of the mcc main cb. Probably makes it easier.

 

[Jraef]

The feeder conductors have to be protected at their ampacity which is unrelated to main breaker rating. Just like you could feed a 200 Amp main cb panel with 100 amp conductors from a 100 amp cb

Yep, true. Happens all the time. I’m quoting one right now with 600A bus and a 600A main CB being fed from a 400A feeder in the switchgear. The 600A main in the MCC is basically just a switch now as it will never trip.