WI Master's Exam Questions

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Scotty B.

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I recently took the WI master's exam. Here is a couple questions that threw me:

1) In a 4 unit condo complex, there is an 8 stall parking garage (2 stalls per unit). There is a also a landlord house and 120/240 house panel. What is the maximum number of branch cicuits allowed to feed the parking garage?
A) 1
B) 2
C) 4
D) 8

2)For a 2500 sq. ft retail store, what is the minimum number of 20A branch circuits required for general illumination?

Would appreciate any input.
Thanks
 
Scotty B. said:
1) That's where it is...Thanks

2) How did you arrive at 4 circuits?...............
2500VA x 3VA per sq.ft.(per T220.12)=7500VA
7500/120 =62.5A
62.5/20 =3.125 (4 circuits) ???????
Click to expand...
Yes, that calculation shows that 4 circuits are required. 3 circuits will not provide the required VA.
 
While the code in 225 only permits a single branch circuit or feeder to supply a second building, that could be an issue in this case if each unit owner needs to pay for the power used at his parking space. I think 225.30 needs some type of exception that would do the same thing that Exception #1 to 230.40 does for service entrance cables for multiple occupancy buildings.
 
Scotty B. said:
2) How did you arrive at 4 circuits?...............
2500VA x 3VA per sq.ft.(per T220.12)=7500VA
7500/120 =62.5A
62.5/20 =3.125 (4 circuits) ???????
Click to expand...

My approach is more along the lines of...lighting load is continuous, therefore a 20A lighting branch circuit could be loaded up to 1920VA. (making the assumption that the circuits are 120V. The question is rather vague.) 7500VA/1920VA=3.9, so 4 circuits minimum required.

I suppose you can say that the minimum required lighting branch circuits would be 1, if the lighting was supplied at 480V.
 
Scotty B. said:
I recently took the WI master's exam. Here is a couple questions that threw me:

1) In a 4 unit condo complex, there is an 8 stall parking garage (2 stalls per unit). There is a also a landlord house and 120/240 house panel. What is the maximum number of branch cicuits allowed to feed the parking garage?
A) 1
B) 2
C) 4
D) 8

2)For a 2500 sq. ft retail store, what is the minimum number of 20A branch circuits required for general illumination?

Would appreciate any input.
Thanks
Click to expand...

Does not say separate building
 
david luchini said:
My approach is more along the lines of...lighting load is continuous, therefore a 20A lighting branch circuit could be loaded up to 1920VA. (making the assumption that the circuits are 120V. The question is rather vague.) 7500VA/1920VA=3.9, so 4 circuits minimum required.

I suppose you can say that the minimum required lighting branch circuits would be 1, if the lighting was supplied at 480V.
Click to expand...

States must comply the Fed Energy regulations....I don't have a copy of the Fed rules but our state does not allow anything close to those figures for lighting wattage per sq. ft. - so that usage would not come into play.
 
dana1028 said:
States must comply the Fed Energy regulations....I don't have a copy of the Fed rules but our state does not allow anything close to those figures for lighting wattage per sq. ft. - so that usage would not come into play.
Click to expand...

Our state does not enforce the 'energy code' via the electrical inspection division. Just the NEC. This will be an area of big change as EV chargers multiply.

Table 220.12 - the VA used for calcs - no adjustment or correction for that, just use the table VA. This seems like a load calc question, I could be wrong - maybe it's a branch circuit question.

Funny this thread hasn't been moved to the exam forum.
 
Can't get back to my last post to add:

Seems to be some uncertainty whether demand is a continuous calculation or not. To me anyhow:confused: I derated a church lighting question as continuous on my Masters Exam and was right. But couldn't find where it was required - not sure a 1 hour service = 3 hours lighting use. IIRC my question was regarding quantity of branch circuits.

Anyone have a code reference for demand vs. branch ckt count?
 
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