125% Continuous Rule - Panelboards

[AWinston]

So I am sizing the service for a growing facility (a lot of lights and AC units). I know NEC 210.19 states that the minimum ampacity of a conductor for continuous loads shall be 125%. When sizing the panelboard, am I supposed to size the panel according to that as well? The total connected load is 1512A, but the Total estimated demand after applying the 125% demand rule to certain loads is 2223A. Is my panelboard/switchboard supposed to be sized for 2223A? I'm second guessing myself because one of the "engineers" at the power company is saying otherwise.

 

[Smart $]

So I am sizing the service for a growing facility (a lot of lights and AC units). I know NEC 210.19 states that the minimum ampacity of a conductor for continuous loads shall be 125%. When sizing the panelboard, am I supposed to size the panel according to that as well? The total connected load is 1512A, but the Total estimated demand after applying the 125% demand rule to certain loads is 2223A. Is my panelboard/switchboard supposed to be sized for 2223A? I'm second guessing myself because one of the "engineers" at the power company is saying otherwise.

Let's apply some logic...

408.30 General. All panelboards shall have a rating not
less than the minimum feeder capacity required for the load
calculated in accordance with Part III, IV, or V of Article
220, as applicable.

215.2(A), assuming not more than 600 volts, requires the feeder capacity to be "not less than the noncontinuous load plus 125 percent of the continuous load" ... "as calculated in Parts III, IV, and V of Article 220."

 

[Smart $]

... The total connected load is 1512A, but the Total estimated demand after applying the 125% demand rule to certain loads is 2223A. ...

Please explain...

1512A × 125% = 1,890A

...which is substantially less than 2223A. Something afoul here.

 

[Dennis Alwon]

Please explain...

1512A × 125% = 1,890A

...which is substantially less than 2223A. Something afoul here.

I think the op is guesstimating future loads.

 

[Carultch]

So I am sizing the service for a growing facility (a lot of lights and AC units). I know NEC 210.19 states that the minimum ampacity of a conductor for continuous loads shall be 125%. When sizing the panelboard, am I supposed to size the panel according to that as well? The total connected load is 1512A, but the Total estimated demand after applying the 125% demand rule to certain loads is 2223A. Is my panelboard/switchboard supposed to be sized for 2223A? I'm second guessing myself because one of the "engineers" at the power company is saying otherwise.

Unless you have equipment that is continuous duty rated, the sizing algorithm is 125% of the continuous loads + 100% of the noncontinuous loads.

The power company (utility) is not governed by the NEC, and has a different set of rules to follow, and may not be familiar with the rules that govern your scope of work.

In your example 1512A * 125% = 1890A, which means that if this were the only load (assuming it is all continuous), I would use a 2000A switchboard.
If you are anticipating future loads, as another poster guessed, such that your 125% cont + 100% noncont = 2223A, then I would use a 2500A switchboard.

 

[AWinston]

Thanks everyone for the insight. And yes, I was doing the calcs on an excel spreadsheet that was picking up a bad cell. Either way, the power company didn't take into account the 125% rule. I was starting to lose my mind!:?