⚡ Automatic Breaker Size Calculation
🔹 Step 1: Use the Formula
To calculate the breaker size you first need to find the current. The formula for current is:I = P / V
Where:
I =is the Current in Amps
P= is the Power in Watts
V= is the Voltage in Volts
🔹 Step 2: Add Safety Factor
Circuit breakers should not run at load all the time. So you apply a **125% safety factor**. This means:Breaker Size = I x 1.25
🔹 Step 3: Example Calculation
Lets say your **Total Load** is **3000 Watts** and your **Voltage** is **230 Volts**.Current:
3000 ÷ 230 is about **13 Amps**
Breaker size:
13 x 1.25 is about **16.25 Amps**
You select the standard size, which is **16A or 20A MCB**.
🔹 Step 4: Standard Breaker Sizes
Here are MCB ratings:* 6A
* 10A
* 16A
* 20A
* 25A
* 32A
* 40A
* 63A
Always choose the **next higher standard size**.
🔹 Step 5: Quick Reference Table
Load (Watts) | Breaker Size ||1000W | 6A–10A |
| 1000–2000W 10a–16a |
| 2000–3500W | 16A–20A |
| 3500–5000W | 20A–25A |
| 5000W+ | 32A+
🔹 Step 6: Pro Tips
* For loads like AC or heater use a **separate breaker**.* Always match **wire size with breaker**.
* Use **MCB + RCCB/ELCB**, for safety.
* For 3-phase systems the calculation is different.
= (Total Watts / Voltage) * 1.25
For example:
= (D10 / 230) * 1.25
