I need help on probelms 10-14. I am having mixed thoughts about what the answers

Question

I need help on probelms 10-14. I am having mixed thoughts about what the answers are and could really use a helping hand.
Thank you.

The following loads will be installed: CHAPTER 8 Feeder Load Calculatio n and Installation 215 Each classroom: 12 fluorescent luminaires, 2 ft × 4 ft @ 85 VA each 20 duplex receptacles AC unit, 208-volt, 1-phase@ 5000 VA Corridor: 5 fluorescent luminaires. I ft × 8 ft @ 85 VA each 8 duplex receptacles Exterior: 4 wall-mounted luminaires @ 125 VA each 4 duplex receptacles COUNTVA/UNITNECLOAD LOAD MINIMUM LOAD CONNECTED CALCULATED BRANCH-NEUTRAL CIRCUIT LOAD Classrooms NEC 220. 12 Luminaires Subtotal Corridor NEC 220.12 Luminaires Subtotal Exterior Luminaires Subtotal Receptacles NEC 220.14(1) Subtotal Motors NEC 220.14(C) Subtotal Totals 10. The calculated load is 11. The connected load is 12. The neutral load is 13. W VA. VA. VA. hy does the NEC require the overcurrent device to be rated not less than 125% of continuous loads? 14. Explain the concept of noncoincident loads for load calculations.

Explanation / Answer

10. The Connected load is 6945 VA.

(i) In Class Room - 12 fluorescent luminaries @85 VA

12 x 85 = 1020 VA.

AC - 5000 VA

(ii) In Corridor - 5 fluorescent luminaries @85 VA

5 x 85 = 425 VA

(iii) In Exterior - 4 Wall mounted luminaries @125 VA

4 x 125 = 500 VA.

Total = 6020 + 425 + 500 = 6945 VA

11. The Calculated Load is 8681.25 VA

(i) In Class Room

6020 VA x 125% = 6020 x (125/100) = 7525 VA

(ii) In Corridor

425 VA x 125% = 425 x (125/100) = 531.25 VA

(iii) In Exterior

500 VA x 125% = 500 x (125/100) = 625 VA

Total = 7525 + 531.25 + 625 = 8681.25 VA

13. Normally, when we connect load to the circuit, It draws Current. If it draws initially 100% amp in the circuit when connecting to circuit, there comes the real problem. Because for the continuous load operation, the load current will be constant. This current flows through terminals, conductors and overcurrent devices which in turn causes more heat build up.

Inorder to compensate the heat generated in the circuit. increasing the rating for overcurrent devices, ampacity of conductor for continuous operation of load by 125 %

14. Non-Coincident Loads

It is nothing but, two or more non coincident loads (larger load & lighter load) will be in use at the same time. For calculating the Feeder Demand, only the larger load can to be used only one time for calculation purpose.

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