⚡ Electrical Load Calculation for Homes – Step-by-Step Guide (2025)
(Complete Residential Load Calculation with Formula, Examples & Table)
Accurate electrical load calculation is essential before installing wiring, MCBs, inverter, UPS, or applying for a new electricity connection. Wrong load estimation leads to frequent tripping, voltage drop, overheating, and high electricity bills.
In this article, we explain how to calculate home electrical load using simple steps and real examples.
✅ What Is Electrical Load?
Electrical load means the total power consumed by all electrical appliances in a home.
It is measured in Watts (W), Kilowatts (kW) or kVA.
🧮 Step-by-Step Load Calculation for a Home
Step 1 – List All Electrical Appliances
Prepare a list of equipment room-wise.
Example:
- LED bulbs
- Fans
- TV
- Mixer grinder
- Refrigerator
- Washing machine
- AC
- Water heater (geyser)
- Water pump
Step 2 – Note the Wattage of Each Device
You can find wattage from:
- Nameplate on the appliance
- Manufacturer website
- Energy star label
Typical home appliance wattage:
| Appliance | Watt |
|---|---|
| LED Bulb | 9W – 12W |
| Ceiling Fan | 60W – 80W |
| TV | 100W – 150W |
| Refrigerator | 150W – 250W |
| Mixer | 500W – 750W |
| Washing Machine | 500W – 1000W |
| Geyser | 2000W – 3000W |
| AC (1 Ton) | 1200W – 1500W |
| Water Pump (0.5 HP) | 370W |
Step 3 – Multiply Quantity × Wattage
For example:
5 fans × 70 W = 350 W
10 LED bulbs × 10 W = 100 W
1 AC × 1500 W = 1500 W
Do this for all appliances.
Step 4 – Apply Demand Factor (Diversity Factor)
Not all appliances run at the same time.
Residential demand factor = 0.6 to 0.7 (60–70%)
So,
Total Connected Load × 0.7
= Maximum Demand Load
This gives a realistic load requirement.
Step 5 – Convert to kW and kVA
Formula:
- kW = Watts / 1000
- kVA = kW / Power Factor
Power Factor for houses ≈ 0.90
Example:
If total load after diversity = 6000W →
kW = 6 kW
kVA = 6 / 0.9 = 6.66 kVA
This helps when applying for EB load approval.
📘 Sample Home Load Calculation (2BHK Example)
Living Room
| Appliance | Qty | Watt | Total |
|---|---|---|---|
| LED Bulbs | 4 | 10 | 40 |
| Ceiling Fan | 2 | 70 | 140 |
| TV | 1 | 140 | 140 |
| Set-top Box | 1 | 20 | 20 |
| Subtotal = 340 W |
Bedroom 1
| Appliance | Qty | Watt | Total |
|---|---|---|---|
| LED Bulbs | 3 | 10 | 30 |
| Ceiling Fan | 1 | 70 | 70 |
| AC (1 ton) | 1 | 1500 | 1500 |
| Subtotal = 1600 W |
Bedroom 2
| Appliance | Qty | Watt | Total |
|---|---|---|---|
| LED Bulbs | 3 | 10 | 30 |
| Ceiling Fan | 1 | 70 | 70 |
| Subtotal = 100 W |
Kitchen
| Appliance | Qty | Watt | Total |
|---|---|---|---|
| LED Bulb | 2 | 10 | 20 |
| Mixer | 1 | 500 | 500 |
| Refrigerator | 1 | 200 | 200 |
| Subtotal = 720 W |
Bathroom
| Appliance | Qty | Watt | Total |
|---|---|---|---|
| Geyser | 1 | 2500 | 2500 |
| Subtotal = 2500 W |
Other Loads
| Appliance | Watt |
|---|---|
| Water pump (0.5 HP) | 370 |
| Washing Machine | 600 |
| Subtotal = 970 W |
🔢 Total Connected Load
340 + 1600 + 100 + 720 + 2500 + 970 = 6230 W
🔥 Apply Demand Factor
Max Demand = 6230 × 0.7 = 4361 W (≈ 4.36 kW)
Approx = 4.5 kW required.
🔌 EB Load Requirement
Because utility requires kVA:
kVA = kW / PF = 4.36 / 0.9 = 4.85 kVA
So the home requires 5 kVA sanctioned load.
🔧 MCB / Main Breaker Selection
Choose breaker based on kW:
Formula:
Current (A) = kW × 1000 / (Voltage × PF)
= 4.36 × 1000 / (230 × 0.9)
= ≈ 21A
Recommended Main MCB:
- 32A DP MCB
- For flats: 6 sqmm wire
- For villas: 10 sqmm wire
⚙️ Inverter/UPS Sizing
Take only essential loads:
Lights + Fans + TV
Example essential load = 1200 W
Inverter size = 1200 ÷ 0.8 = 1500 VA
Battery needed for 3 hours backup:
Battery AH = (Load × Backup Hrs) / (Battery Voltage × Efficiency)
= (1200 × 3) / (12 × 0.8) ≈ 375 AH
Use 150Ah × 3 batteries.
💡 Benefits of Correct Load Calculation
✔ No frequent tripping
✔ Avoids cable overheating
✔ Correct MCB rating
✔ Accurate EB sanctioned load
✔ Safe and stable home wiring