Receptacle calculations question

[Chris21]

I recently took a code quiz online and one of the ques. asked?

What is the demand on a service for 300 receptacles installed in a hospital?

I thought I had this figured out, but the answer was different than mine. I used 300X180VA= 54,000VA. Got the reduction over 10KVA(44,000) at a reduction of 50%.
Comes to 22,000+10,000= 32,000VA. This was my answer, but the quiz gave an answer of something like 20.8 Kva.
What am I missing? Is there another reduction somewhere? Any help is greatly appreciated.

 

[roger]

Look at Table 220.42, you will see Hospitals have a 40% demand for the first 50,000 and 20% for the remainder, this will give you 20.8 KVA.

Roger

 

[GMc]

Roger,

Isn't that for lighting loads?

It looks to me like Table 220.44 would be for receptacles which is like what the OP figured.

Thanks

 

[roger]

GMc, we have to look at the wording of 220.44,

220.44 Receptacle Loads — Other Than Dwelling Units
Receptacle loads calculated in accordance with 220.14(H) and (I) shall be permitted to be made subject to the demand factors given in Table 220.42 or Table 220.44.

and consider most exams are asking for the minimum allowable service or load. (not saying that is the case here, I'm just assuming and yes I know that can get me in trouble )

Roger

 

[GMc]

Roger,

Thats what I get for just looking at the Tables and not taking the time to look at the actual Article. Plus at the time I responded I was updating some prints (panel schedules) and we use Table 220.44.

Would you personally use the minumum method for design reasons? I would think you would want to go the maximum.

Thanks for the information,

 

[kingpb]

Re-read 90.1, specifically (B). I think that says it all.

Personally, I rarely ever use the minimum Code requirements, clients pay for expertise, which is usually more then minimum.

However, I don't do projects were the $ is the only driving force.

 

[roger]

GMc, in the real world I would take it on a case by case situation and probably end up some where in the middle.

Roger

 

[Chris21]

GMc, we have to look at the wording of 220.44,



and consider most exams are asking for the minimum allowable service or load. (not saying that is the case here, I'm just assuming and yes I know that can get me in trouble )

Roger

Thanks roger for clearing that one up for me. I have another one for ya:grin:
What is the ampacity of a 1/2"x4" copper busbar? Ampacity is 1000A/in2

 

[celtic]

What is the ampacity of a 1/2"x4" copper busbar? Ampacity is 1000A/in2

Show us your math..we'll either give a thumbs up or thumbs down with an explanation

 

[Chris21]

Show us your math..we'll either give a thumbs up or thumbs down with an explanation

There was just a discrepency on the test I was taking. The in.2 comes out to (2), but the correct answer on the test was 2800 amps. I thought I was losing my mind
and forgot how to do basic algebra. Right answer was 2000A.

 

[celtic]

Right answer was 2000A.

As promised:

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