1. Table Of Contents
A. Determining the minimum number of lighting branch circuits: 2
Maximum power based on the Total Floor Area: ............................................................................................................... 3
BRANCH CIRCUIT CALCULATIONS ........................................................................................................................................... 5
BRANCH CIRCUIT NO. 1(General Purpose Branch Circuit) .................................................................................................. 5
BRANCH CIRCUIT NO. 2 (General Purpose Branch Circuit) ................................................................................................. 6
BRANCH CIRCUIT NO. 3 ((small) Appliance Branch Circuit) ................................................................................................ 8
BRANCH CIRCUIT NO. 4(Individual Branch Circuit) ........................................................................................................... 10
BRANCH CIRCUIT NO. 5(Individual Branch Circuit) ........................................................................................................... 11
BRANCH CIRCUIT NO. 6(Individual Branch Circuit) ........................................................................................................... 13
Load Summary: ..................................................................................................................................................................... 15
............................................................................................................................ 17
MATERIALS& NUMBER OF QUANTITIES ............................................................................................................................... 20
Single Line Diagram ............................................................................................................................................................... 22
2. A. Determining the minimum number of lighting branch circuits:
“The NEC tells us that the minimum load requirement for dwelling units is
of occupied area.”
Floor Area 18m (59.05ft)
15m (49.21ft)
Conversion Unit:
CALCULATIONS:
The estimated Floor Area:
Scale Conversion:
3. Steps to determine the minimum number of 15-ampere lighting branch circuits required for a
residence:
Calculations:
Comment:
A minimum of not less than three 15-A lighting branch circuits is required. (Below 3 branches is not
safe!)
Maximum power based on the Total Floor Area:
Wattage required per square meter for dwelling unit:
The maximum power in watts needed for lighting with an Total Floor Area
Comments:
300W + 400W = 700W is the maximum power for lighting branch circuits which is still below the
The 700W maximum lighting power is safe to use.
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5. BRANCH CIRCUIT CALCULATIONS
BRANCH CIRCUIT NO. 1(General Purpose Branch Circuit)
Lighting Load (3 lighting outlets)
Calculation no.1
The Maximum Power Load For 3 Lighting Outlets:
“The NEC provides that “100 watts shall be the maximum load for each household
lighting outlet.”
therefore:
Comment:
The 300W is the maximum power expected when all 3 lights operates at the same time.
Calculation no.2
The Maximum Total Current Load:
recall:
Comment:
The 1.36-A current is the maximum current expected when all 3 lights operates at the same time.
Calculation no.3
The Size Of The Conductor or Wire Needed For This Branch:
Refer to tables: 2-5 and 4-2
Maximum expected current load:
Use:
Wire No.:#14AWG copper wire
Wire Diameter:2.0 mm2
Wire Type:TW, THW, or THWN
No. of pieces of wire needed:2 pcs.
Wire Temperature Rating:60 C(140 F) or 75 C(167 F)
Comment:
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6. Calculation no.4
The Size Of The Conduit Pipe To Accommodate The Wires In Calculation No.3:
Refer to tables: 2-9
No. of pieces of wire needed:2 pcs.
Use:
Conduit Diameter:13 mm dia.
Maximum number of wire can accommodate:3
Size of wire: # 14
Comment:
Calculation no.5
The Size or Rating Of Over Current Fuse/Circuit Breaker Protection:
Refer to Tables: 4-1
Maximum expected current load:
Use:
Fuse/Breaker Rating:15-A
Receptacle Rating:Not over 15-A
Maximum load the fuse/breaker can carry:12 A(non-continuous), 8 A(continuous)
Comment:
BRANCH CIRCUIT NO. 2 (General Purpose Branch Circuit)
Lighting Load (4 lighting outlets)
Calculation no.1
The Maximum Power Load For 4 Lighting Outlets:
“The NEC provides that “100 watts shall be the maximum load for each household
lighting outlet.”
therefore:
Comment:
The 300W is the maximum power expected when all 3 lights operates at the same time.
Calculation no.2
The Maximum Total Current Load:
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7. recall:
Comment:
The 1.81-A current is the maximum current expected when all 4 lights operates at the same time.
Calculation no.3
The Size Of The Conductor or Wire Needed For This Branch:
Refer to tables: 2-5 and 4-2
Maximum expected current load:
Use:
Wire No.:#14AWG copper wire
Wire Diameter:2.0 mm2
Wire Type:TW, THW, or THWN
No. of pieces of wire needed:2 pcs.
Wire Temperature Rating:60 C(140 F) or 75 C(167 F)
Comment:
Calculation no.4
The Size Of The Conduit Pipe To Accommodate The Wires In Calculation No.3:
Refer to tables: 2-9
No. of pieces of wire needed:2 pcs.
Use:
Conduit Diameter:13 mm dia.
Maximum number of wire can accommodate:3
Size of wire: # 14
Comment:
Calculation no.5
The Size or Rating Of Over Current Fuse/Circuit Breaker Protection:
Refer to Tables: 4-1
Maximum expected current load:
Use:
Fuse/Breaker Rating:15-A
Receptacle Rating:Not over 15-A
Maximum load the fuse/breaker can carry:12 A(non-continuous), 8 A(continuous)
Comment:
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8. BRANCH CIRCUIT NO. 3 ((small) Appliance Branch Circuit)
Convenience Receptacles Load (8 convenience receptacles outlets)
Calculation no.1
Counting the total number of plugs in all receptacle outlets:
“The NEC provides that “for each single receptacle shall be considered at no less
than 180 watts rating.”
therefore:
Comment:
The total number of plugs or gang in all receptacle outlets is 16 pieces.
Calculation no.2
The Total EstimatedPower Load:
hence,
Comment:
The power value 2,880 watts is the maximum power the 8 convenience receptacle outlets can handle.
The branch circuit no. 3 is not safe above this value.
Calculation no.3
The Maximum Expected Current Load:
recall:
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9. Comment:
Calculation no.4
The Size Of The Conductor or Wire Needed For This Branch:
Refer to tables: 2-5 and 4-2
Maximum expected current load:
Use:
Wire No.:#12AWG copper wire
Wire Diameter:3.5 mm2
Wire Type:TW, THW, or THWN
No. of pieces of wire needed:2 pcs.
Wire Temperature Rating:60 C(140 F) or 75 C(167 F)
Comment:
Derated value of 15-A is 15 x 0.80 = 12 A. 13.09A12A, thus, use #12 AWG wire conductor. The NEC Code
specifically mandated the use of 3.5 mm2 or no.12AWG copper wire as the minimum size for all types of
convenience outlet wiring.
Calculation no.5
The Size Of The Conduit Pipe To Accommodate The Wires In Calculation No.4:
Refer to tables: 2-9
No. of pieces of wire needed: 2 pcs.
Use:
Conduit Diameter:13 mm
Maximum number of wire can accommodate:2 pcs.
Size of wire:#12AWG copper wire
Comment:
Calculation no.6
The Size or Rating Of Over Current Fuse/Circuit Breaker Protection:
Refer to Tables: 4-1
Maximum expected current load:
Use:
Fuse/Breaker Rating:20-A
Receptacle Rating:15 A or 20 A
Maximum load the fuse/breaker can carry:16-A(non-continuous and Continuous)
Comment:
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10. Branch Circuit Nos. 4, 5, and 6 are for the other loads (Heavy Loads), which are
categorized as Individual Branch Circuits .
BRANCH CIRCUIT NO. 4(Individual Branch Circuit)
Refrigerator and Water Heater Load (only 1 outlet)
Calculation no.1
The Total EstimatedPower Load (Total maximum power output of the machines):
1-unit Refrigerator @ 0.175 kW = 175 Watts
1-unit Water Heater @ 2 kW = 2,000 Watts
Total load: 2,175 Watts
Comment:
Calculation no.2
The Maximum Expected Current Load:
recall:
Comment:
Calculation no.3
The Size Of The Service Conductor or Wire Needed For This Branch:
Refer to tables: 2-5 and 4-2
Maximum expected current load:
Use:
Wire No.:#12AWG copper wire
Wire Diameter:3.5 mm2
Wire Type:TW, THW, or THWN
No. of pieces of wire needed:2 pcs.
Wire Temperature Rating:60 C(140 F) or 75 C(167 F)
Comment:
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11. Calculation no.4
The Size Of The Conduit Pipe To Accommodate The Wires In Calculation No.3:
Refer to tables: 2-9
No. of pieces of wire needed: 2 pcs.
Use:
Conduit Diameter:13 mm
Maximum number of wire can accommodate:2 pcs.
Size of wire:#12AWG copper wire
Comment:
Calculation no.6
The Size or Rating Of Over Current Fuse/Circuit Breaker Protection:
Refer to Tables: 4-1
Maximum expected current load:
Use:
Fuse/Breaker Rating:20-A
Receptacle Rating:15 A or 20 A
Maximum load the fuse/breaker can carry:16-A(non-continuous and Continuous)
Comment:
BRANCH CIRCUIT NO. 5(Individual Branch Circuit)
Electric STOVE Load (only 1 outlet)
Calculation no.1
The Total EstimatedPower Load (Total maximum power output of the machines):
1-unit Electric Stove @ 1.1 kW= 1,100 Watts
Total load: 1,100 Watts
Comment:
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12. Calculation no.2
The Maximum Expected Current Load:
recall:
Comment:
Calculation no.3
The Size Of The Service Conductor or Wire Needed For This Branch:
Refer to tables: 2-5 and 4-2
Maximum expected current load:
Use:
Wire No.:#12AWG copper wire
Wire Diameter:3.5 mm2
Wire Type:TW, THW, or THWN
No. of pieces of wire needed:2 pcs.
Wire Temperature Rating:60 C(140 F) or 75 C(167 F)
Comment:
Calculation no.4
The Size Of The Conduit Pipe To Accommodate The Wires In Calculation No.3:
Refer to tables: 2-9
No. of pieces of wire needed: 2 pcs.
Use:
Conduit Diameter:13 mm
Maximum number of wire can accommodate:2 pcs.
Size of wire:#12AWG copper wire
Comment:
Calculation no.6
The Size or Rating Of Over Current Fuse/Circuit Breaker Protection:
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13. Refer to Tables: 4-1
Maximum expected current load:
Use:
Fuse/Breaker Rating:20-A
Receptacle Rating:15 A or 20 A
Maximum load the fuse/breaker can carry:16-A(non-continuous and Continuous)
Comment:
BRANCH CIRCUIT NO. 6(Individual Branch Circuit)
Air Conditioning Equipment Load (only 1 outlet per unit)
Calculation no.1
The Total EstimatedPower Load (Total maximum power output of the machines):
Air-con rating:1horsepower or 1hp
Conversion Unit: 1 hp = 746 Watts
thus,
1-unit Air Conditioning @ 0.746 kW= 746 Watts
Total load: 746 Watts
Comment:
Calculation no.2
The Maximum Expected Current Load:
recall:
Article 6.7 of the Philuppine Electrical Code (PEC) provides that : “Branch circuit conductor supplying
a motor shall have an ampacity not less than 125% of the full load current.”
thus,
Comment:
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14. Calculation no.3
The Size Of The Service Conductor or Wire Needed For This Branch:
Refer to tables: 2-5 and 4-2
Maximum expected current load:
Use:
Wire No.:#12AWG copper wire
Wire Diameter:3.5 mm2
Wire Type:TW, THW, or THWN
No. of pieces of wire needed:2 pcs.
Wire Temperature Rating:60 C(140 F) or 75 C(167 F)
Comment:
A current load of 4.25-A can be served by a 2pcs., N0.14 TW copper wire, but the PEC Code
limits the size of the convenience outlet to No.12AWG copper wire. Specify No. 12 THW copper wire
for branch circuit no.6.
Calculation no.4
The Size Of The Conduit Pipe To Accommodate The Wires In Calculation No.3:
Refer to tables: 2-9
No. of pieces of wire needed: 2 pcs.
Use:
Conduit Diameter:13 mm
Maximum number of wire can accommodate:2 pcs.
Size of wire:#12AWG copper wire
Comment:
Calculation no.6
The Size or Rating Of Over Current Fuse/Circuit Breaker Protection:
PEC Code on branch circuit protection for a single motor provides that: “It shall be increased by 250%
of the full load current of the motor.”
thus,
Refer to Tables: 4-1
Maximum expected current load:
Use:
Fuse/Breaker Rating:30-A
Receptacle Rating:30 A
Maximum load the fuse/breaker can carry:24-A(non-continuous ) and 12-A (Continuous)
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16. Calculation for the Size and
Ampacity of the Service
Entrance& Main Disconnecting
Means
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17. CALCULATING THE SIZE AND AMPACITY OF THE SERVICE ENTRANCE CONDUCTOR AND THE MAIN
DISCONNECTING MEANS
Size of supply conductor and equipment for delivering energy from the electricity supply to the
wiring system of the residential:
Calculation no.1
The Total EstimatedPower Load from Branch Circuit 1 to Branch Circuit 6 (TOTAL CONNECTED
LOAD:
thus,
Comment:
Calculation no.2
The Total Load of the Branch Circuit 1 to Branch Circuit 6:
recall:
therefore,
Comment:
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18. Calculation no.3
The Computation for the Demand Factor:
Apply 80% demand factor as permitted by the National Electrical Code(NEC)
Calculation no.4
The Size Of The Service Conductor based on the calculation in No.3:
Refer to tables: 2-5 and 4-2
Maximum expected current load:
Use:
Wire No.:#8 AWG copper wire
Wire Diameter:8.0 mm2
Wire Type:T or TW
No. of pieces of wire needed:2 pcs.
Wire Temperature Rating:60 C(140 F)
Comment:
Calculation no.5
The Size Of The Conduit Pipe To Accommodate The Wires In Calculation No.4:
Refer to tables: 2-9
No. of pieces of wire needed: 2 pcs.
Use:
Conduit Diameter:20 mm dia.
Maximum number of wire can accommodate:2 pcs. max.
Size of wire:#8 AWG copper wire
Comment:
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20. MATERIALS& NUMBER OF QUANTITIES
MATERIALS QUANTITY
Safety Switch, 30-A, 2 DPST, 250 volts 1 pcs.
Fuse cutout, two branches 1 unit
30-A fuse 2 pcs.
20-A fuse 2 pcs.
15-A fuse 2 pcs.
8.0 mm2 TW copper wire 50 mts.
3.5 mm2 TW copper wire 1 roll
2.0 mm2 TW copper wire ½ roll
13 mm diameter PVC conduit pipe 18 pcs.
20 mm diameter PVC conduit pipe 5 pcs.
One gang switch with plate 4 pcs.
two gang switch with plate 2 pcs.
two gang convenience outlet (small appliance) 6 pcs.
Cooking unit outlet 2 pcs.
Junction box with screw 7 pcs.
Receptacle with screw 8 pcs.
Utility box 14 pcs.
Incandescent lamp 4 pcs.
Fluorescent lamp 4 pcs.
Meter base 1 pcs.
Electrical tape (large) 2 pcs.
comment:
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22. Single Line Diagram
M
Lighting Outlets (3) Lighting Outlets (4)
Lighting Outlets (3)
Lighting Outlets (3)
Convenience Receptacle Outlets (8) Refrigerator & Heater Outlet (1)
)
Electric Stove Outlet (1) Air conditioning Equipment Outlet (1)
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