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5. Calculate Size of Main ELCB/ Branch MCB of Distribution Box

CALCULATE SIZE OF MAIN ELCB & BRACH MCB OF DISTRIBUTION BOX

Design Distribution Box of one House and Calculation of Size of Main ELCB and branch Circuit MCB as following Load Detail. Power Supply is 430V (P-P), 230 (P-N), 50Hz. Consider Demand Factor 0.6 for Non Continuous Load & 1 for Continuous Load for Each Equipment.

  • Branch Circuit-1: 4 No of 1Phase, 40W, Lamp of Non Continues Load + 2 No’s of 1Ph, 60W, Fan of Non Continues Load. * Branch Circuit-2: 2 No of 1Ph, 200W, Computer of Non Continues Load. * Branch Circuit-3: 1 No of 1Ph, 200W, Freeze of Continues Load. * Branch Circuit-4: 8 No of 1Ph, 40W, Lamp of Non Continues Load + 2 No’s of 1Ph 60W, Fan of Non Continues Load. * Branch Circuit-5: 4 No of 1Ph , 40W, Lamp of Non Continues Load + 1 No’s of 1Ph 60W, Fan of Non Continues Load.+ 1 No’s of 1Ph 150W, TV of Continues Load * Branch Circuit-6: 1 No of 1P , 1.7KW, Geyser of Non Continues Load. * Branch Circuit-7: 1 No of 1Ph, 3KW, A.C of Non Continues Load. * Branch Circuit-8: 1 No of 3Ph, 1HP, Motor-Pump of Non Continues Load.

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Fault Current Voltage Fault Current 230V 6KA 430V 10KA 11KV 25KA

Class of MCB/ELCB/RCCB Type of Load Class Sensitivity Lighting B Class I∆n:30ma Heater B Class I∆n:30ma Drive C Class I∆n:100ma A.C C Class I∆n:30ma Motor C Class I∆n:100ma Ballast C Class I∆n:30ma Induction Load C Class I∆n:100ma Transformer D Class I∆n:100ma

Size of MCB/ELCB Current (Amp) Lighting Load MCB/ELCB (Amp) Heating/Cooling/Motor-Pump Load MCB/ELCB (Amp) 1.0 to 4.0 6 16 6.0 10 16 10.0 16 16 16.0 20 20 20.0 25 25 25.0 32 32 32.0 40 40 40.0 45 45 45.0 50 50 50.0 63 63 63.0 80 80 80.0 100 100 100.0 125 125 125.0 225 225 225.0 600 600 600.0 800 800 800.0 1600 1600 1600.0 2000 2000 2000.0 3000 3000 3000.0 3200 3200 3200.0 4000 4000 4000.0 5000 5000 5000.0 6000 6000 6000.0 6000 6000

CALCULATION:

SIZE OF MCB FOR BRANCH CIRCUIT-1:

  • Load Current of Lamp= (No X Watt X Demand Factor)/Volt =(4X40X0.6)/230=0.40Amp * Load Current of Fan= (No X Watt X Demand Factor)/Volt =(2X60X0.6)/230=0.31Amp * Branch Circuit-1 Current as per NEC = Non Continues Load+125% Continues Load * Branch Circuit-1 Current as per NEC =(0.4+0.31)+125%(0) =0.73Amp * Type of Load=Lighting Type * Class of MCB=B Class * Size of MCB=6 Amp * No of Pole of MCB=Single Pole

SIZE OF MCB FOR BRANCH CIRCUIT-2:

  • Load Current of Computer = (No X Watt X Demand Factor)/Volt =(2X200X0.6)/230=1.04Amp * Branch Circuit-2 Current as per NEC = Non Continues Load+125% Continues Load * Branch Circuit-2 Current as per NEC =(1.04)+125%(0) =1.04Amp * Type of Load=Lighting Type * Class of MCB=B Class * Size of MCB=6 Amp * Breaking Capacity: 6KA * No of Pole of MCB=Single Pole

SIZE OF MCB FOR BRANCH CIRCUIT-3:

  • Load Current of Freeze= (No X Watt X Demand Factor)/Volt =(1X200X0.6)/230=0.87Amp * Branch Circuit-3 Current as per NEC = Non Continues Load+125% Continues Load * Branch Circuit-3 Current as per NEC =(0.87)+125%(0) =0.87Amp * Type of Load=Lighting Type * Class of MCB=B Class * Size of MCB=6 Amp * Breaking Capacity: 6KA * No of Pole of MCB=Single Pole

SIZE OF MCB FOR BRANCH CIRCUIT-4:

  • Load Current of Lamp= (No X Watt X Demand Factor)/Volt =(8X40X0.6)/230=0.83Amp * Load Current of Fan= (No X Watt X Demand Factor)/Volt =(2X60X0.6)/230=0.31Amp * Branch Circuit-4 Current as per NEC = Non Continues Load+125% Continues Load * Branch Circuit-4 Current as per NEC =(0.83+0.31)+125%(0) =1.15Amp * Type of Load=Lighting Type * Class of MCB=B Class * Size of MCB=6 Amp * Breaking Capacity: 6KA * No of Pole of MCB=Single Pole

SIZE OF MCB FOR BRANCH CIRCUIT-5:

  • Load Current of Lamp= (No X Watt X Demand Factor)/Volt =(4X40X0.6)/230=0.42Amp * Load Current of Fan= (No X Watt X Demand Factor)/Volt =(1X60X0.6)/230=0.16Amp * Load Current of TV = (No X Watt X Demand Factor)/Volt =(1X150X1)/230=0.65Amp * Branch Circuit-5 Current as per NEC = Non Continues Load+125% Continues Load * Branch Circuit-5 Current as per NEC =(0.42+0.16)+125%(0.65) =0.57+0.82=1.39Amp * Type of Load=Lighting Type * Class of MCB=B Class * Size of MCB=6 Amp * Breaking Capacity: 6KA * No of Pole of MCB=Single Pole

SIZE OF MCB FOR BRANCH CIRCUIT-6:

  • Load Current of Geyser= (No X Watt X Demand Factor)/Volt =(1X1700X0.6)/230=4.43Amp * Branch Circuit-6 Current as per NEC = Non Continues Load+125% Continues Load * Branch Circuit-6 Current as per NEC =(4.43)+125%(0) =4.43Amp * Type of Load=Heating & Cooling Type * Class of MCB=C Class * Size of MCB=16 Amp * Breaking Capacity: 6KA * No of Pole of MCB=Single Pole

SIZE OF MCB FOR BRANCH CIRCUIT-7:

  • Load Current of A.C= (No X Watt X Demand Factor)/Volt =(1X3000X0.6)/230=7.83Amp * Branch Circuit-7 Current as per NEC = Non Continues Load+125% Continues Load * Branch Circuit-7 Current as per NEC =(7.83)+125%(0) =7.83Amp * Type of Load=Heating & Cooling Type…