Reading the markings
- 1
- B
The trip characteristic. The letter identifies the current range for rapid magnetic operation.
- 2
- 16 A
Rated current In = 16 A under the manufacturer’s specified conditions. It is not an exact trip threshold: 16.1 A does not require an immediate trip.
- 3
- 6000
When boxed as Icn under IEC/EN 60898-1, 6000 means a short-circuit breaking capacity of 6000 A (6 kA), not an allowable load.
- 4
- 230/400 V~
Rated voltage; ~ means alternating current. Markings and their positions vary by model.
Contents
10, 16, 20, 25 A: how many appliances?
The number is rated current in amperes. A higher value corresponds to more power at the same voltage, only if the cable and entire circuit are suitable. Add the power of appliances operating at the same time, not their count.
| Rated current | Power at 230 V |
|---|---|
| 6 A | ≈ 1.38 kW |
| 10 A | ≈ 2.3 kW |
| 13 A | ≈ 2.99 kW |
| 16 A | ≈ 3.68 kW |
| 20 A | ≈ 4.6 kW |
| 25 A | ≈ 5.75 kW |
| 32 A | ≈ 7.36 kW |
| 40 A | ≈ 9.2 kW |
P ≈ 230 × In · cos φ ≈ 1
Total power
2 kW
Approximate current
≈ 8.7 A
Below the rating · 16 A
Educational single-phase calculation at 230 V: I ≈ P / 230, assuming power factor 1. Appliance powers are examples; check input power on the nameplate. The washer is heating water; the fridge compressor is running without its starting surge. This is neither a three-phase calculation nor a trip-time prediction.
Simultaneous load examples
- Kettle + LED lamp2.01 kW · ≈ 8.7 A
- Kettle + Heater4 kW · ≈ 17.4 A
- Kettle + Washing machine4.2 kW · ≈ 18.3 A
- Kettle + Oven5 kW · ≈ 21.7 A
- Kettle + Heater + Washing machine6.2 kW · ≈ 27 A
Why it trips
- Consumer unit
- Circuit cable
- Appliances
Normal operation
A 2 kW kettle draws about 8.7 A at 230 V, below the 16 A rating in this example. Current passes through the breaker, cable and appliance.
Two mechanisms work inside: a heated strip responds to sustained overload, an electromagnet to high current. The drawing shows the fault before disconnection. Actual trip time depends on current, temperature and the device.
How long until the breaker trips? Try it
Choose a scenario and run it. The breaker, the cable temperature and the time-current chart move together; time runs faster than in real life.
Educational model. The band is drawn through the IEC/EN 60898-1 test points at 30 °C; the line between them is an interpolation. The “sample breaker” is one notional device: its thermal time constant is estimated from test reports, not taken from the standard. Look up the trip time of your own breaker on the manufacturer’s curve. In a warm enclosure a breaker trips sooner: by about 5 % in current for every 10 °C above 30 °C. Cable heating is shown as an order of magnitude: one time constant estimated from tests on cables in thermal insulation, installation method A1, 30 °C. It is not a fire prediction. The short-circuit current is calculated for a 20 m line with a notional supply impedance of 0.35 Ω. The real current depends on your supply; an electrician determines it by measuring Zs.
B, C and D compared
B16, C16 and D16 all have a 16 A rating. Their rapid magnetic trip ranges differ. Change the rating to compare the ranges in amperes.
3–5, 5–10 and 10–20 are multiples of the breaker rating. For B16: 3 × 16 = 48 A and 5 × 16 = 80 A. The bars use a fixed 0–800 A scale: drag the slider to move and resize the ranges. Colour identifies B, C and D, not a level of danger.
Magnetic trip range · A
B16
3–5 × 16 A = 48–80 A
Often used for circuits with low starting currents. LED drivers can still have significant inrush.
C16
5–10 × 16 A = 80–160 A
For higher starting currents, including some motors. Fault current at the end of the circuit must be checked.
D16
10–20 × 16 A = 160–320 A
For large inrush, such as certain transformers and motors. A calculated choice, not an upgrade from C.
B/C/D characteristics under IEC/EN 60898-1. Bars show ranges, not exact thresholds or complete time-current curves. In is rated current. Below a bar, thermal tripping can still occur. Use the manufacturer’s curve for operating times.
How a breaker is selected
Check the load and cable first, then the characteristic and disconnection conditions. A higher rating or changing B to C does not fix the cause of tripping.
- 01
Load → cable → rating
Design current Ib ≤ rated current In ≤ cable current capacity Iz. Iz depends on material, cross-section, installation method, temperature and grouping. “1.5 mm² with 16 A” alone proves neither safety nor overload.
- 02
Starting current → characteristic
An electrician compares inrush with the trip curve and verifies that the minimum fault current causes disconnection within the required time.
- 03
Short-circuit current → breaking capacity
Breaking capacity must suit the prospective short-circuit current at the installation point. Voltage, poles, protection coordination and local requirements also matter. A panel plan helps prepare the information; it does not replace these checks.
Common questions
Can C16 supply more load than B16?
No. Both are rated at 16 A. C tolerates a higher brief current surge before magnetic tripping; it does not increase the circuit’s load capacity.
Can I replace B16 with C16 to stop tripping?
Only after the cause and circuit have been assessed. C needs more current for guaranteed rapid operation; a long circuit may not provide enough fault current.
Does 16 A mean exactly 3.68 kW?
At 230 V and a power factor near 1, P ≈ U × I = 3.68 kW. Other loads need a different calculation. This estimate does not establish the capacity of any particular socket.
Does an MCB protect against electric shock?
It does not replace an RCD: dangerous body currents can be far below its threshold. An RCBO combines overcurrent and residual-current protection.
Which breaker for an induction hob, oven or washing machine?
Each usually gets its own circuit. The rating follows the cable and the installation manual: an oven or washing machine is often on 16 A, an induction hob on 32 A or a three-phase connection. An electrician confirms the cable size and the final choice.