Emergency Standby Generator

[KMeni]

Are metered record loads an acceptable way of determining Generator Sizing? Is load shedding required by NEC Code if there are no designed emergency panelboard(s) on the power riser system?

 

[topgone]

Are metered record loads an acceptable way of determining Generator Sizing? Is load shedding required by NEC Code if there are no designed emergency panelboard(s) on the power riser system?

When you said "metered record loads", does your metering have a demand meter? Energy meters record the average load for a metering period. The demand meter records how big your load was in any 15 minute span. Even with demand meter telling me XXX kW, it could have missed a power draw spike which occurred just before the demand meter acted to record the scheduled recording event (load spike in between the 15-minute span).

We size generators according to the maximum load it is thrown with, else your protections will trip your generator,IMO.

 

[KMeni]

The Client is using a Modhopper Wireless Data Acquistion System, so i assume it is capable recording peak loads..

 

[don_resqcapt19]

If the generator is an optional stand-by system and it has an automatic transfer switch, you have to size the generator for the total load per the Article 220 load calculations or use automatic load management system. 702.5.5(B)(2) As far as the load, 702.5(B) says per the Article 220 calculations or other "approved" methods. Talk to you AHJ about the "approved" methods. He may accept the demand readings.

 

[kingpb]

You have to use maximum peak loading, while also paying attention to motor starting sequences as the inrush can have a major impact depending on how large or how many.

Also, if there is a transformer that will be energized, you could have quite a bit of inrush to tend with.