Electrical Load Calculator (Appliance List)
Calculate total connected load, recommended sanctioned load, and MCB rating from a list of household appliances with wattage and quantity.
Appliance schedule
Per-appliance breakdown
| name | wattage | quantity | subtotalW |
|---|---|---|---|
| LED bulb | 9 | 10 | 90 |
| Ceiling fan | 75 | 4 | 300 |
| Refrigerator | 200 | 1 | 200 |
How this works
We sum wattage × quantity across the appliance schedule, then add the standard 25% buffer for diversity and future expansion. The MCB rating is the smallest IS 3961 standard rating that covers the single-phase load current at 230 V.
connectedW = Σ (wattage × quantity)
connectedKw = connectedW / 1000
sanctionedKw = connectedKw × 1.25
loadA = connectedW / 230 (single-phase)
mcbAmps = first IS 3961 rating ≥ loadAStandard residential MCB ratings (IS 3961): 6, 10, 16, 20, 25, 32, 40, 50, 63 A.
Worked example
10 LED bulbs (9 W), 4 ceiling fans (75 W), 1 refrigerator (200 W):
- LEDs =
10 × 9 = 90 W - Fans =
4 × 75 = 300 W - Fridge =
1 × 200 = 200 W - Connected = 590 W = 0.59 kW
- Sanctioned ≈ 0.74 kW (with 25% buffer)
- Load amps =
590 / 230 ≈ 2.57 A - MCB ≈ 6 A
Sources
- IS 3961 (Recommended current ratings for cables) and IS 8828 (Miniature circuit-breakers — standard ratings)
FAQ
What is the difference between connected and sanctioned load?
Connected load is the simple sum of every appliance's wattage — it is the worst case where everything switches on at the same instant. Sanctioned load is what you ask the utility to provision; it includes a buffer for diversity (not everything runs simultaneously in practice) and for future appliances you might add. The 25 percent buffer used here is the standard residential allowance — bump it to 50 percent if you expect to add air conditioning or an electric heater later.
How is the MCB rating chosen?
We compute the load current as connected watts divided by 230 V (the assumed single-phase supply voltage), then pick the smallest standard IS 3961 / IS 8828 MCB rating that covers it. Standard residential ratings ladder is 6, 10, 16, 20, 25, 32, 40, 50, 63 A. Selecting an MCB strictly smaller than the load amps causes nuisance trips; selecting one too large means a fault won't trip protection in time, so the smallest covering rating is the right choice.
Does this size the wire as well?
No — the MCB is sized here, but the wire that feeds it is sized by the Wire Size Calculator using both the load current and the voltage drop across the run length. A 16 A MCB on a 50 m feeder will normally need a 4 mm² conductor to keep voltage drop under 3 percent, even though a 2.5 mm² conductor is rated for 19 A continuous. Always size the wire with both checks.
What voltage does this assume?
230 V single-phase, the South Asian residential standard. Three-phase loads (most commercial buildings, large pumps, large air conditioners) divide the load roughly equally across three phases, so the per-phase current is the connected watts divided by (1.732 × 415 V). For single-phase residential calculations the 230 V figure is correct as-is.
How accurate are the wattage figures I should enter?
Use the rated watts on the appliance nameplate or the manufacturer's data sheet. LED bulbs are typically 5–15 W, ceiling fans 60–80 W, refrigerators 150–250 W (running, much higher at startup), 1.5-ton split air conditioners 1500–2200 W, geysers 2000–3000 W, microwave ovens 1000–1400 W. The connected-load total is dominated by the heaviest appliances — get those right and the headline figure is accurate to within 5 percent.
Why are the breakdown rows exportable to CSV?
The CSV export gives you a procurement-ready bill of appliance loads to attach to your sanctioned-load application or share with the electrical contractor. It includes name, unit wattage, quantity, and subtotal watts for each row in the same order as the on-screen table. Print the page (with the on-screen breakdown) for a one-page summary, or download the CSV for spreadsheet use.