Holt's 2020 Electrical Exam Prep Question

[paullmullen]

In section 11.9 there is a question about Office Building Calculations:

Look at where I have circled 125% in red below. Why do we apply 125% here. There is no statement in the problem that these are continuous loads. Am I missing something important here?

 

[gene6]

220.40 sends you to part II (220.10)
220.10 points to 220.14.
220.14(D) Covers the lighting at the maximum VA of the equipment and lamps.
210.20a is mentioned in the table 220.42 but nothing in 220.14(D) implies adding 125%.

As i understand is 125% adder only applies if its a feeder or branch circuit.
It appears service conductors or panelboard can be 100%.
So he must be using a feeder in the question.
Others will probably chime in and correct me as its late and I am not a calcs expert.

 

[Little Bill]

Non dwelling lighting is considered a continuous load.

 

[gene6]

Non dwelling lighting is considered a continuous load.

Bill are you talking about a service or feeder ?

 

[Little Bill]

Bill are you talking about a service or feeder ?

I was answering as to why the pictured text said 125%. That is the actual lighting load and it is figured by 125%.

 

[gene6]

Bill do have a code section reference?
The reason I ask is I see the requirement in a feeder calc under 215.2, and 210.19(A) for branch circuits, but I see no such reference in 230.31(A) or 408.30.

 

[paullmullen]

Non dwelling lighting is considered a continuous load.

That's what I eventually decided as I was explaining this to my wife. Office lights would be on longer than the 3-hour threshold for being continuous.

 

[gene6]

While its good practice to add the 125%, and everyone does that in practice, I think the question is technically incorrect because it references part III of article 220 which has no such requirement for a continuous load. If the article 220 was going to reference another article requiring the continuous factor it would be in the beginning under the section title “Other Articles”.
In addition 230.31(A) Covers service conductor ampacity and also has no such requirement.
There are examples of other appliances that are treated as continuous loads for 'branch circuit' sizing but not for 'service conductor' sizing.
And using part III implies service conductor sizing.
Every step in the question has a code reference, except the continuous part.

 

[gene6]

Disregard my posts as the nice fella pointed out in the other thread its under 230.42.
Thanks and god bless.

 

[paullmullen]

Non dwelling lighting is considered a continuous load.

So as I looked at other example solutions, I see that when you use 220.12 you do not add 25% but if you do the actual connected load calc then you add 25%. It is as though T220.12 implicitly includes the additional 25% in it (if required), but I cannot find the code reference for this.

Here's how I am interpreting the wording:

1. 220.12 says, that T220.12 is the minimum lighting load.
2. The actual lighting load, may be larger.
3. A non-dwelling occupancy assumes a continuous load (code reference? or just practice?), so multiply actual by 1.25
4. Now compare the result of step 3 with the result of step 1. Choose the larger because T220.12 only specifies the minimum. Also, 230.42 implies the same.

In short: If using T220.12, just take the value there and be happy. If calculating actual load, add 25%. Doing both sets of math and comparing the result is the right move.

One last question: Are there any non-dwelling occupancies in which adding 25% would not make sense?

(Note that this topic is also addressed here: https://forums.mikeholt.com/threads/table-220-12.69895/.

 

[GoldDigger]

Why does 30,000 x 1.30 equal 39,600?

 

[ggunn]

Why does 30,000 x 1.30 equal 39,600?

My calculator says 39,000.