Circuit Load Calculator
Enter the number of sockets, lighting power, and equipment power to estimate circuit total load current, for selecting MCB and distribution design.
Input Data
Results
At a glance:Total circuit power = sockets × per-socket power + lighting power + equipment power; design current = total power × diversity ÷ voltage. Round the design current up to a standard MCB (6/10/16/20/32/40 A) with margin. The diversity factor reflects not all sockets at full load at once. This calculator is a rough distribution estimate; final design and verification must follow BSD/BS7671 and the power company's requirements.
Formula
Total power = sockets × per-socket + lighting + equipment
Design current = total power × diversity / voltage
$$P = n\, p_s + P_l + P_e$$$$I = \frac{P\, d}{V}$$How to Use
- Enter the number of sockets and per-socket power.
- Enter the lighting and other equipment power.
- Set the diversity factor and voltage.
- The system outputs the design current and suggested MCB.
Case Studies
Room socket circuit
6 sockets×300W, lighting 200W, no equipment, 0.8, 230V.
Total 2000W; design current ≈7A, choose 10A MCB.
Kitchen circuit
8 sockets×300W, lighting 100W, equipment 1500W, 0.9, 230V.
Total 3900W; design current ≈15.3A, choose 16A MCB.
FAQ
What does the diversity factor do?
Residential sockets rarely all run at full load; multiplying by 0.7–0.9 avoids an oversized MCB that loses its protective meaning.
Why does the kitchen need a dedicated circuit?
The kitchen has many high-power appliances, so it usually has a dedicated circuit with a larger MCB, avoiding sharing a breaker with other sockets.
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References
Content review: Calculatorism Editorial Team. Results are for reference only; please refer to the relevant authorities for the official figures.