Minimum branch circuit sizing - InspectionNews

Wendell Swedberg · #1 (**permalink**) 05-02-2008, 04:45 PM

Okay, what did I not add in for the computation:

ICC question: An 8kVA range has a branch circuit calculated ampere load. The minimum sizing for the branch circuit is:

a) 26.7
b) 33.3
c) 34.8
d) 36.36

The answer is A.

I get 8000/240 = 33.3 (B).....

Thanks!

W

Jerry Peck · #2 (**permalink**) 05-02-2008, 05:25 PM

Quote:

Originally Posted by Wendell Swedberg

Okay, what did I not add in for the computation:

Wendell,

It's not what you didn't add in, it's what you didn't (apparently) read and apply.

From the 2006 IRC.

- E3602.9 Branch-circuit load for ranges and cooking appliances. It shall be permissible to calculate the branch-circuit load for one range in accordance with Table E3604.2(2). The branch-circuit load for one wall-mounted oven or one counter-mounted cooking unit shall be the nameplate rating of the appliance. The branch-circuit load for a counter-mounted cooking unit and not more than two wall-mounted ovens all supplied from a single branch circuit and located in the same room shall be calculated by adding the nameplate ratings of the individual appliances and treating the total as equivalent to one range.

- - E3602.9.1 Minimum branch circuit for ranges. Ranges with a rating of 8.75 kVA or more shall be supplied by a branch circuit having a minimum rating of 40 amperes.

Did you go to Table E3604.2(2)?

And read the footnotes applicable at the top?

Especially footnote 'a', which takes you to footnote 'd', which gives you the correction factor to apply (Demand Factor), which then gives you the answer (which also happens to be answer A ).

Richard Moore · #3 (**permalink**) 05-02-2008, 05:47 PM

Or the NEC version, which is effectively the same...(33.33 x .80 = 26.7)

"ICC question: An 8kVA range has a branch circuit calculated ampere load. The minimum sizing for the branch circuit is:" (my bold)

That's the tricky bit as there are special calculations for some types of circuits. ranges being one of those.

Richard Moore · #4 (**permalink**) 05-02-2008, 06:07 PM

I have a question...

When you take the ICC exam, is it open book? I mean no one expects you to memorize all the tables do they?

Jerry Peck · #5 (**permalink**) 05-02-2008, 07:28 PM

Quote:

Originally Posted by Richard Moore

When you take the ICC exam, is it open book?

Yes, but timed.

If you don't "know" enough of it, and "know" where to quickly find a good portion of the rest of it, you will run out of time and not complete the test.

It's the same with all the ICC tests: you have to "know" the easy stuff, "know" where to quickly find most of the rest of the stuff, from then on it is reading the question correctly (easy to 'over read' it) and know to look at the exceptions and footnotes - most times they will use the footnotes, if you are lazy or in a hurry you will skip the footnotes, and then you will fail.