Circuit Load (Amps) = Appliance Wattage / Circuit Voltage But hold on—you can't max out the breaker! Electrical codes (like NEC) require breathing room. We follow the 80% rule : Safe Continuous Load = Circuit Breaker Rating × 0. 8 Example: Need a circuit for your 1,800W. Before we dive into calculations, let's get familiar with a few essentials: 1. Your Project's Total Power Demand This isn't just adding up wattages randomly. Think of your home as a busy kitchen—not every appliance runs at once. Do you really need the hair dryer, microwave, and vacuum running. Calculation of total connected load: The total connected load and hence the total current is calculated for deciding the cable size, rating of main switch board and distribution board. Covers general-purpose lighting circuits, small appliance circuits, laundry. 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. Branch Circuit-1: 4 No of 1Phase. Why do you need GFCI or AFCI breakers? Choosing the right size and setup for your distribution box keeps your electrical system safe and working well. You leave space for safety devices like. This project involves combining an enclosure, protective devices, and various receptacles into a single, portable, or semi-permanent unit. The result is a dedicated power.