Distribution System and Substation Design

1. MIDTERM EXAM ANSWER
Presented by:
JAKE CLEO S. CORTO, REE

2. A) A 3-Floors Commercial Building with an area of 16x20 meters per floors, where 20m fronting
the street and 10% of area to be utilized as stairways/hallways. Using the dimension method
calculation, provide the following; Loads Calculations per floor, Application of Demand factor,
Feeder Conductor and Protection size per floor, & Over-all main feeder size.
Ground floor occupied as Store;
* Assume 80% of lighting as continuous load
* Small Appliances - 12kW
* Show Window - 5 meters
* Signage load
* ACU, 8 units of 2HP
2nd and 3rd floor occupied as Offices;
* General Lighting
* Small Appliances - 10kW
* ACU, 12 units of 1Hp
Administration (to serve all tenants);
* 5A Fire Alarm System
* 1 1/2 Hp Water Pump
* Stairways/ Hallways Load

3. Gen. Lighting:
Area = 16x20 = 320m²
90% x 320 = 288m²
10% x 32 = 32m²
(288m² x 33VA/m²) x 1.25 = 9,504VA
20% x (288m² x 33VA/m²) x 1.00 = 1,901VA
GL-total = 11,405VA
GROUND FLOOR (STORE):
Small Appliances: 12,000VA
5m x 200VA/0.3m = 3,333.33VA
Show Window:
Sign Load: 1,200VA
ACU’s:
8 x 12A x 230V = 22,080VA
Application of Demand Factor:
Gen. Lighting: 11,405VA
Small Appliances: 12,000VA
Total = 23,405VA
I Total = 36,755VA/230V
= 159.80A
Feeder Conductor Size:
I = 159.80A + (Largest Motor x 25%)
I = 159.80A + (12 x 25%)
I = 162.8A
*Use 2 - 60mm² THHN/THWN Copper Wire @ 50mmᴓ PVC pipe
Feeder Protection Size:
I = 159.80A - 12 + (12 x 250%)
I = 177.8A
*Use 1 - 200AT MCCB, 2P, 230V, 60Hz.
1st 3,000VA @ 100% = 3,000VA
Remainder @ 35%:
23,405VA – 3,000VA = 20,405VA
20,405VA x 35% = 7,141.75VA
Other loads:
Show Window: 3,333.33VA
Sign Load: 1,200VA
ACU’s: 22,080VA
Total Load connected= 36,755V

4. Gen. Lighting:
288m² x 39VA/m² = 11,232VA
2nd & 3rd FLOOR (OFFICE):
Small Appliances: 10,000VA
ACU’s:
12 x 8A x 230V = 22,080VA
Application of Demand Factor:
Gen. Lighting: 11,232VA
Small Appliances: 10,000VA
Total = 21,232VA
I Total = 31,461.2VA/230V
= 136.78A
Feeder Conductor Size:
I = 136.78A + (Largest Motor x 25%)
I = 136.78A + (8 x 25%)
I = 138.78A
*Use 2 - 50mm² THHN/THWN Copper Wire @ 40mmᴓ PVC pipe
Feeder Protection Size:
I = 136.78A - LM + (LM x 250%)
I = 136.78A - 8 + (8 x 250%)
I = 148.78A
*Use 1 - 150AT MCCB, 2P, 230V, 60Hz.
1st 3,000VA @ 100% = 3,000VA
Remainder @ 35%:
21,232VA – 3,000VA = 18,232VA
18,232VA x 35% = 6,381.2VA
Other loads:
ACU’s @ 100%: 22,080VA
Total Load connected= 31,461.2VA

5. Fire Alarm System:
5A x 12V = 60VA
ADMINISTRATION:
Water Pump: 1 1/2HP
10A x 230V = 2,300VA
Application of Demand Factor:
Fire Alarm System @ 100%: 60VA
Water Pump @ 100%: 2,300VA
Stairways/ Hallway @ 100%: 576VA
I Total = 2,936VA/230V
= 13A
Feeder Conductor Size:
I = 13A + (Largest Motor x 25%)
I = 13A + (10 x 25%)
I = 15.5A
*Use 2 – 8.0mm² THHN/THWN Copper Wire @ 25mmᴓ PVC pipe
Feeder Protection Size:
I = 13A - LM + (LM x 250%)
I = 13A - 10 + (10 x 250%)
I = 28A
*Use 1 - 40AT MCCB, 2P, 230V, 60Hz.
Stairways/Hallway:
32m² x 6VA/m² x 3 = 576VA
Total Load connected= 2,936VA

6. Ground Flr (L.O & C.O):
23,405VA
SERVICE ENTRANCE OVER-ALL:
Application of Demand Factor:
Main Feeder Conductor Size:
I = 429.18A + (Largest Motor x 25%)
I = 429.18A + (12 x 25%)
I = 432.18A
*from PEC table 3.10.1.16 (216.09A/225A)
Use 2 sets of 2- 100mm² THHN/THWN Copper Wire @ 50mmᴓ
PVC pipe each set
2nd & 3rd Flr (L.O & C.O):
21,232VA x 2 = 42,464VA
Sub-Total = 65,869VA
1st 3,000VA @ 100% = 3,000VA
Remainder @ 35%:
65,869VA – 3,000VA = 62,869VA
62,869VA x 35% = 22,004VA
Total (L.O & C.O) = 25,004VA
Loads connected= 2,936VA
Administration loads:
Over-all Other loads:
Ground Floor: Loads connected= 26,613.33VA
2nd & 3rd Floor:
Loads connected= 22,080VA x 2 = 44,160VA
Over-all Total Connected load = 98,713.33VA
I Total Connected = 98,713.33VA/230V
= 429.18 Amperes

7. B) Given the electrical lighting and power layout plan, legends and specifications of a two-storey
residential house with centralized air conditioning units and other special loads. Using the actual
calculation, provide the following; Loads Calculations, Load Schedules, Riser Diagram, & Main
Feeder Conductor and Protection size.
* ACU1- 1Hp, ACU2- 2Hp, ACU3- 1Hp, ACU4- 2Hp, ACU5- 1Hp
* Water Heater- 2kW
* Jacusi - 3kW
* Range - 2.5kW

8. Load Calculation (Per Circuit):
Circuit 1: (1Hp ACU)
1 x 746W = 746 x 1.25 = 932.5 or 950W
950W/230V = 4.13A
Circuit 2: (2Hp ACU)
2 x 746W = 1492 x 1.25 = 1,865 or 1,900W
1,900W/230V = 8.26A
Circuit 3: (Water Heater)
2000W/ 230 = 8.70A
Circuit 4: (1Hp ACU)
1 x 746W = 746 x 1.25 = 932.5 or 950W
950W/230V = 4.13A
Circuit 5: (2Hp ACU)
2 x 746W = 1492 x 1.25 = 1,865 or 1,900W
1,900W/230V = 8.26A
Circuit 6: (Convenience Outlet)
8 x (180W x 2) = 2,880W
2,880W/230V = 12.52A
Circuit 7: (Jacusi)
3000W/ 230 = 13.04A
Circuit 8: SPARE
Circuit 9: (Water Heater)
2000W/ 230 = 8.70A
Circuit 10: (Convenience Outlet)
8 x (180W x 2) = 2,880W
2,880W/230V = 12.52A
Circuit 11: (1Hp ACU)
1 x 746W = 746 x 1.25 = 932.5 or 950W
950W/230V = 4.13A
Circuit 14: (Lighting Outlet)
36 x (40W) = 1,440W
1,440W/230V = 6.26A
Circuit 13: (Convenience Outlet)
7 x (180W x 2) = 2,520W
2,880W/230V = 10.96A
Circuit 15: (Water Heater)
2000W/ 230 = 8.70A
Circuit 16: (Lighting Outlet)
30 x (40W) = 3,000W
3,000W/230V = 13.04A
Circuit 17: (Lighting Outlet)
15 x (100W) = 1,500W
1,500W/230V = 6.52A
Circuit 12: (Convenience Outlet)
7 x (180W x 2) = 2,520W
2,880W/230V = 10.96A
Circuit 18: (Lighting Outlet)
40 x (40W) = 1,600W
3,000W/230V = 6.96A
Circuit 19: (Range)
2500W/ 230 = 10.87A

9. Circuit 20: (Lighting Outlet)
15 x (100W) = 1,500W
1,500W/230V = 6.52A
Circuit 21: SPARE
Circuit 22: (Water Heater)
2000W/ 230 = 8.70A

10. Schedule of Loads & Main Feeder Size and Protection:

11. Riser Diagram:

12. END