Nec 2017 section 700.4

[hhsting]

From NEC 2017:

“700.4 capacity

(A) capacity and rating. An emergency generator shall have adequate capacity and rating for all loads to be operated simultaneously….”


Does the part operated simultaneously mean when doing load calculation for sizing generator have cap city greater than demand load or connected load which one?

 

[gene6]

I'd say in terms of the NEC its always the Article 220 calculated load

 

[hhsting]

I'd say in terms of the NEC its always the Article 220 calculated load

Article 220 load is demand load that has factor which mean sometimes on would not connected load be load thats on all the time?

 

[don_resqcapt19]

They revised this in the 2020 to make it clear that you use the load calculation from Article 220 or another approved method.

700.4(B) Capacity.
An emergency system shall have adequate capacity in accordance with Article 220 or by another approved method.

There is almost never a case where the actual load exceeds the load calculated in accordance with Article 220.

 

[LarryFine]

demand load or connected load which one?

Connected load refers to everything, including loads like A/C and heat that can't/won't run simultaneously.

Demand load refers to loads that can be left on or can self-start if an outage occurs when nobody is home.

The reason for load-shedding is to reduce the generator capacity required to meet the demand of the load.

In my opinion, a clothes dryer need not be counted because it must be manually restarted after an outage.

 

[hhsting]

Connected load refers to everything, including loads like A/C and heat that can't/won't run simultaneously.

Demand load refers to loads that can be left on or can self-start if an outage occurs when nobody is home.

The reason for load-shedding is to reduce the generator capacity required to meet the demand of the load.

In my opinion, a clothes dryer need not be counted because it must be manually restarted after an outage.

Speaking if load shedding is this like a special device on generator or generator manufacturer has to provide separately?

 

[LarryFine]

Speaking if load shedding is this like a special device on generator or generator manufacturer has to provide separately?

They're normally built into the ATS itself. Some come with a separate module.

 

[Fred B]

Speaking if load shedding is this like a special device on generator or generator manufacturer has to provide separately?

They're normally built into the ATS itself. Some come with a separate module.

There are newer types that are independent of ATS requiring no wired connection to the ATS or generator to shed the loads. Generac has one originally up to 50A but now been told they have one that'll handle up to 100A of shedding. They still have the original ones that wire to the ATS that initially primary used for Air Conditioning cut out.
Comes in handy when a customer doesn't want to spend for a larger genset adequate for every load.
You can use ones by the specific gen mfg. or one I've used was mfg by PSP Products https://www.pspproducts.com/load-management/ they have worked quit well and you can even get customizable one's, just need to provide your requirements. I've used both this and Generac load sheds. Both have been equally responsive.

 

[don_resqcapt19]

Speaking if load shedding is this like a special device on generator or generator manufacturer has to provide separately?

You cannot shed loads that are served by an Article 700 system. Where the standby source supplies other than Article 700 loads, the standby by source needs to have the ability shed loads so that it can supply the emergency loads. The transfer switch for Article 700 load is not permitted to supply any other loads.