Hotel load calculation demand factors

[shortcircuit1]

Lets say you have 4 stories of hotel building. If panel L feeds lighting on each floor,panel R feeds receptacle load.If the connected lighting load on each floor is 20kW,receptacle load is 10kW and equipment load is 50kW. If you have a switchboard with a distribution section having individual breakers for lighting,receptacle panels. My idea is to have feed through panels on each floor. Do you apply the demand factor from table 220.42 for lighting,220.44 for receptacle to the total connected load on all the floors to size the breaker in the switchboard:
1.Lighting:10+30x0.4=22kW.
2.Receptacle:10+30x0.5=25kW

Breaker in switchboard for lighting=70a for 208/120v service.
Breaker in switchboard for receptacle:70a for 208/120v service.

(OR)

Do you take demand factor on each floor individual panels connected kW and then add all them up to size your breaker in the switchboard?
Each floor connected kW for lighting =20kW
Demand load=10kW
Each floor connected kW for receptacle=10kW
Demand Load=10kW

For 4 floors it will be 40kW for lighting and 40kW for receptacle which will need 125 breaker for each in the switchboard.

Which one is right?

 

[david]

.If the connected lighting load on each floor is 20kW,receptacle load is 10kW and equipment load is 50kW.

What happened to the 50 KW equipment load on each floor

You size a feeder based on the load on that feeder

If you are the electrical engineer why would you design a single feeder that takes out all the lighting in a 4 story hotel if you trip a single feeder overcurrent device.

 

[shortcircuit1]

What happened to the 50 KW equipment load on each floor

You size a feeder based on the load on that feeder

If you are the electrical engineer why would you design a single feeder that takes out all the lighting in a 4 story hotel if you trip a single feeder overcurrent device.

Well instead of running 4 different feeders to 4 floors which first of all adds up cost to your feeder length,extra breakers in switchboard.In feed through scenario you are just running one feed fro the SWBD to the panel and then just the short run from panel on first floor to second floor. I understand that it doesnt give much flexibility but the owner doesnt care about that he wants a cheaper system. YOu are increasing the number of breakers you need in the switchboard which sometimes may prompt you to add a distribution section which is not cheap

Size a feeder based on load on the feeder????? :?I mean my question was whether you size the feeder based on the connected load on each floor and then you apply the demand factor to total connected load or you just take demand factor at each floor for corresponding floors and then add them up....

 

[m sleem]

Do you take demand factor on each floor individual panels connected kW and then add all them up to size your breaker in the switchboard?

No, first is correct but second is easier , because of that most of engineers doing second approach.

 

[david]

Size the feeder originating at the main switch board the same way you would size a service except the calculations are based only on the total load of the feeder being sized.