🔒 Circuit Breaker Size Calculator
Estimate the right MCB rating for a circuit. Enter load power and voltage.
How to Size a Circuit Breaker
A circuit breaker (MCB) protects a circuit's cable from overload and short circuit. The rule of thumb is to take the load current, apply a 1.25 safety factor for continuous loads, then choose the next standard breaker rating above that figure — common UAE sizes are 6, 10, 16, 20, 25, 32, 40, 50 and 63 A. Crucially, the breaker must never be larger than the cable can safely carry; an oversized breaker leaves the cable unprotected. This tool gives a starting estimate, but final selection depends on cable size, installation method and DEWA regulations, so it should always be confirmed by a licensed electrician.
Frequently Asked Questions
What's the difference between an MCB and an RCCB?
An MCB protects against overload and short circuit; an RCCB protects people against earth-leakage shock. Most circuits need both.
Can I just fit a bigger breaker if mine keeps tripping?
No — that's dangerous. A tripping breaker usually signals an overload or fault. Fitting a larger one removes the protection. Get it inspected.
Does the cable size matter?
Yes. The breaker and cable must be matched so the breaker trips before the cable overheats.
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