0

What size circuit breakers does a home need? Cable sizes, RCDs and the consumer unit

The Journal · Oct 7, 2026

What size circuit breakers does a home need? Cable sizes, RCDs and the consumer unit

Written by Engin Demirel · Electrical technician, master instructor · 12 years of experience

Short answer: In homes, lighting circuits typically use a 10 A breaker with 1.5 mm² cable and socket circuits a 16 A breaker with 2.5 mm² cable. Large loads such as ovens, hobs, air conditioners, water heaters and EV chargers each get their own circuit. The breaker protects the cable, so its rating must not exceed what the cable can carry. A 30 mA residual current device (RCD) is also needed to protect people. Values below are typical IEC practice; local wiring rules always take precedence.

Breaker and cable by circuit (typical values)

  • Lighting: 10 A – 1.5 mm²
  • Sockets: 16 A – 2.5 mm²
  • Washing machine / dishwasher, air conditioner, water heater: own circuit, 16 A – 2.5 mm²
  • Built-in oven: own circuit, 16–20 A – 2.5–4 mm² (per the rating plate)
  • Electric hob: per the manufacturer's wiring diagram; often 32 A – 6 mm² single-phase or 3 × 16 A three-phase
  • EV charging (7.4 kW single-phase): own circuit, 32 A – 6 mm²; 11 kW three-phase: 3 × 16 A – 5 × 2.5–4 mm²

These values are for short to medium runs. Longer runs increase voltage drop and need a larger cable; installation method (in conduit, grouped, hot surroundings) also reduces current-carrying capacity. The final choice is made by calculation.

B and C curve breakers

The letter shows how much inrush current the breaker tolerates. A B curve trips instantly at 3–5 times its rating, a C curve at 5–10 times. Because LED drivers and motors have high inrush currents, C curve breakers are common in homes; B curve suits long runs and low fault currents.

Residual current device (RCD)

An RCD disconnects the circuit when current leaks to earth, for example through a person touching a live part. Homes use 30 mA RCDs, required by wiring regulations in most countries, including Turkey. Choose type A over the basic AC type, as it also detects pulsating DC leakage from electronics. EV charging needs a type B RCD, or a charger with 6 mA DC leakage detection plus a type A RCD.

Why does a breaker trip?

  • Overload: several powerful appliances on one circuit (heater + kettle + oven). Fix: move the load or add a circuit.
  • Short circuit: damaged cable, wet socket, faulty appliance. The breaker trips immediately; if it will not reset, have the wiring checked.
  • If the RCD trips: a damp junction box or socket, or a faulty appliance with a heating element (washing machine, water heater) are the usual causes. Unplug appliances one by one to find the fault.
  • Fitting a larger breaker is not a fix: the cable overheats and becomes a fire risk.

What a good consumer unit looks like

  • Every circuit is labelled ("Living room sockets", "Kitchen oven" etc.).
  • Splitting circuits across several RCDs (or RCBOs per circuit) stops one fault from blacking out the whole home.
  • A surge protection device (SPD) protects electronics from lightning and grid surges.
  • Leave spare ways for a future EV charger, air conditioner or solar system.

Your supply capacity is set by the distribution company; large loads like EV charging may need a capacity increase or a three-phase supply. Wiring and consumer unit work must be done by a qualified electrician.

In Bursa, ENGN provides electrical installation, consumer unit upgrades and EV charger installation.

Frequently asked questions

What breaker size for a socket circuit?

Socket circuits typically use a 16 A breaker with 2.5 mm² cable; lighting circuits 10 A with 1.5 mm². Local rules apply.

How many amps can 2.5 mm² cable carry?

In home wiring, 2.5 mm² cable is usually protected by a 16 A breaker. Run length, installation method and ambient temperature change its capacity.

Should I use a B or C curve breaker?

C curve is common in homes as it tolerates the inrush current of LED drivers and motors. B curve is preferred on long runs.

Is an RCD mandatory?

30 mA RCD protection is required for homes in most countries, including Turkey. Type A is recommended.

What should I do if a breaker keeps tripping?

Reduce the load on that circuit; if it continues there may be a short circuit or a faulty appliance. Never fit a larger breaker; have an electrician check it.

What breaker does an EV charger need?

A 7.4 kW single-phase charger needs its own circuit with a 32 A breaker and 6 mm² cable; 11 kW three-phase needs 3 × 16 A, plus type B or 6 mA DC leakage protection.