Apt. Demand AC/ESH Code question

[twh]

My book falls open to the page with rule 8-106(4).

8-106(3) states "Where two or more loads are installed that only one can be used at any one time, the one providing the greatest demand shall be used in determining the calculated demand." If this rule were applied, solution 'B' would be correct.

If the writers of the code had wanted to use paragraph 3, they could have done so. They included 8-106(4) because they wanted heating and air conditioning treated differently. I don't think that we can change the wording of the rules if we don't like the results.

8-106(4) states "Where it is known that electric space heating and air-conditioning loads are installed and will not be used simultaneously, whichever is the greater LOAD

[twh]

oops ...

shall be used in calculating the demand."

Using the exact wording of the rule, I think solution 'A' is correct.

In any event, I wonder if it can be said that they cannot be used simultaneously when it is possible for air conditioning to be running in one apartment and heating in another.

[Gerry B.]

Here is the problem, what is the answer?

A 9 unit Apt complex, each unit has ESH of 3.5 kW, and AC of 3.0 kW.
*They can not be used at the same time.
How many kW does this load(s)contribute to the MAIN SERVICE calculations?

Do you do this:
(A)
9 * 3000 = 27000 W AC
9 * 3500 = 31500 W ESH
Then compare the totals above to see that the ESH is the larger of the two? And THEN apply Section 62 to get an answer of 26.125 kW ???

OR

Do you do this:
(B)
9 * 3000 = 27000 W AC
9 * 3500 = 31500 W ESH
THEN apply Section 62
10,000 + (.75 * 21,500) = 26.125 kW

Do you now compare the 26.125 kW for the ESH
and the AC at 27.0 kW and arrive at an answer of 27.0 KW as the demand towards the MAIN SERVICE?

This is the subject for much debate in the office these days, depending on how you read the rules.
Is there anyone with a difinitive answer to this?

[Gerry B.]

Ahhh, one vote for A and one for B. This is where we are at here with this question as well. I looked in the Handbook and if I am looking at it correctly it appears that A is the correct method. However I have been told as well that the Handbook is riddled with errors too.
The rules that have been referred to above are where I am as well.
This is an answer that I need to get to the bottom to, to have someone who is the overall authority tell me, A or B.
At this time I am trying to find out who/where this authority would be and pick his brain.
Keep the input coming guys, and if I do acheive my quest I will be sure to get back to you all here.

[twh]

Perhaps the authority you seek is set out in Appendix C10.

[Gerry B.]

That is a great start, and I got a call into CSA to get me the appropriate form to send in with my inquiry.
C.11 states that they need a question in the form so that they can give a 'yes' or 'no' answer to, makes it clear cut that way.....

[electric-ed]

During my years as an Apprenticeship Instructor, I have always used your "method B", as per the handbook.
I hope I was teaching it correctly. [img]eek.gif[/img]

Please let us know what you find out from CSA. My bet is that they will not contradict their handbook.

Ed

[twh]

How do you suppose they will deal with Appendix C, where it states "Interpretations shall be based on the literal text and not on the intent"?

[bigrockk]

Well after digging through my old learning material it seems we used method "A" based on the fact that rule 8-106(4)does not state anything about applying demand factors before deciding which is the greater load.

That said, folling is a quote from the Handbook:
In Subrule (4), we intend that where electric space heating and air-conditioning loads are installed, interlocks not be required, since common sense generally dictates that one does not heat and cool at the same time. We intend that the larger of the electric space heating or air-conditioning loads be used after any demand factors allowed by other Sections of the CE Code, Part I, have been applied.

So, it seems that the intent is to use method "B"
but I have been told to never trust the handbook as it has alot of mistakes.
It would be good to get some more input on this as the more I type the more I am confusing myself..LOL

[Gerry B.]

Well I got the answer from CSA. I posed the same question to them as I did here and they got back to me and stated positively that Method B is what they consider to be the correct answer.
However, I was told that in Alberta we will use Method A.