contesting the Wa Administration Exam

[CaseyM]

I correctly answered 4 out of the 7 questions on the Washington State Administration Major Calculations exam this Saturday. I've taken this final section four times now. I'm using (to the best of my knowledge) the Mike Holt technique for standard multi family dwellings
Using Mike Holt's o2 electrical calculation book's multifamily dwelling unit standard load calcultaion I am unable to correctly answer the following question. For the integrity of the test I will maintain nearly the exact form of the question but use different numbers.

What is the feeder demand load on a 120/240 volt service for a 43 unit multifamily dwelling where each 750 square foot unit contains: There are no house or laundry loads to consider.
1 7.7 kw Range
1 14500 watt baseboard heater
1 .6 kva garbage disposal
1 1200 watt water heater
1 1400 watt dishwasher

43 units times 750 square feet times 3 va per square foot equals 96750va
two small appliance branch circuits in each of the 43 dwellings equals 129000va
There are no laundry loads to cinsidder so this is it for the general lighting and receptacles, small-appliance and laundry circuits
the total is 225750va
Using the 220.11 lighting demand factors in the 02 nec, dwelling unit lighting and receptacle loads are permitted to be 100% for the first 3000va 35% for the next 117000va and 25% for the remainder. This brings the lighting and receptacle load to 70387.5va
the total heat load is 623500va
The appliance load using the 220.17 appliance load demand factor is 103200va
There is no clothes dryer to consider.
The cooking equipment load using 220.19 collumn b is 66220va.
the total comes to 3597 amps
This hypothetical answer does not match the hypothetical test answers. If I'm doing something wrong I'd like to know. If there is a problem with the question I'd like the points.

 

[CaseyM]

Re: contesting the Wa Administration Exam

Yes, I know the heater load is out of left field but it's the pocess that counts.

 

[charlie b]

Re: contesting the Wa Administration Exam

I'll try to look it over sometime this morning. But just to clarify one point: You said the question asked for "feeder demand load" for a multi-family dwelling unit. Are you interpreting that as meaning "service" to the whole building?

Also, were one or more of the available answers at least close to your answer?

 

[charlie b]

Re: contesting the Wa Administration Exam

Using your numbers, would one of the "test answers" be 3559 amps? In other words, in the actual test, was your answer about 40 amps higher than one of the possible choices?

I think your cooking load is high. Table 220.19 says that you must use Column C, unless otherwise permitted by Note 3. When you read Note 3, it says that "it shall be permissible" to use Columns A and B in a certain way. But that doesn't mean that you have to. With your numbers, it works out to your advantage to use Column C (i.e., you get a smaller answer).

I agree with the rest of your calculation.

 

[CaseyM]

Re: contesting the Wa Administration Exam

Thanks for taking a look. For now I'm going to stick with my range calculation because I've always been taught that way, but I do see your point, and that may in fact be what Washington is doing. Unfortunately my answer fell nearly in the middle of two answers so I eeny meeni miny moed it. For a hundred and some dollars I get to meet with the chief electrical inspector and discuss it further.

 

[charlie b]

Re: contesting the Wa Administration Exam

Originally posted by CaseyM: For now I'm going to stick with my range calculation because I've always been taught that way (emphasis added)

I beg you to rethink that strategy. Let's put aside this specific question, and what the right and wrong answers to this question might be, and talk about general things. If you choose to continue to do something that you have recently discovered is wrong, for the simple reason that the wrong way is the way you were taught, then you are going to run into difficult times during your career.

A better strategy is to distrust what you were taught, and distrust what you think you have recently discovered, and so go back to the basics, discover the right path, and then proceed along the right path. If you are willing to spend a hundred bucks to help you discover the right path, then I would say you are spending your money wisely, and I wish you good fortune.