What Circuits Need a 32A RCBO? UK Installer Guide
A 32A RCBO is commonly used where a circuit needs 32A overcurrent protection together with residual-current protection in one device. Typical examples can include ring final socket circuits, suitably designed radial circuits, cooking appliances, EV charge points and supplies to garages or outbuildings.
The connected equipment alone does not determine the rating. The protective device must suit the circuit design, cable current-carrying capacity, installation conditions, fault protection requirements and the equipment manufacturer’s instructions.
👉 Browse 32A RCBOs
Jump To:
What Circuits Commonly Use a 32A RCBO?
A 32A RCBO can be specified for several domestic and light-commercial circuit types. The examples below are common applications, not automatic design rules.
| Circuit or Load | Is 32A Common? | Main Selection Point |
|---|---|---|
| Ring final socket circuit | Yes | The ring arrangement, conductors and installation must support the design. |
| Radial socket circuit | Sometimes | A radial may use a different rating depending on conductor size and installation conditions. |
| Cooker or hob circuit | Often | Use the appliance data, circuit design and permitted diversity. |
| Single-phase EV charge point | Often | Follow the charger manufacturer’s overcurrent, RCD and DC protection requirements. |
| Lower-output electric shower | Sometimes | Calculate the design current. A 7.5kW shower draws more than 32A at 230V. |
| Garage, outbuilding or sub-main supply | Sometimes | Assess maximum demand, cable route, voltage drop and downstream protection. |
| Lighting circuit | Normally no | Lighting circuits are generally protected at a lower current rating. |
What Size RCBO Is Used for a Socket Circuit?
A 32A RCBO is commonly used for a domestic ring final socket circuit. The 32A rating applies to the complete circuit arrangement; it does not mean that an individual socket or connected appliance is expected to draw 32A.
Radial socket circuits require separate consideration. Depending on the conductor size, installation method, circuit length and design conditions, a radial circuit may be protected at 20A, 32A or another appropriate rating.
Where socket circuits supply workshop equipment or loads with higher starting currents, the trip curve also needs to be considered. A C Curve device should only be selected where the load characteristics justify it and the required fault-disconnection conditions can still be achieved.
How Many Kilowatts Can a 32A Circuit Supply?
On a nominal 230V single-phase supply, 32A equates to approximately 7.36kW using the basic calculation:
Power = Voltage × Current
230V × 32A = 7,360W, or 7.36kW
| Nominal Load | Approximate Current at 230V | 32A RCBO? |
|---|---|---|
| 6.0kW | 26.1A | Potentially, subject to the complete design |
| 7.0kW | 30.4A | Potentially, subject to the complete design |
| 7.2kW | 31.3A | Common for suitable 32A equipment |
| 7.5kW | 32.6A | Not a simple 32A match |
This conversion is only a starting point. The equipment’s stated current, duty, power factor where relevant, manufacturer instructions and the circuit’s installation conditions still determine the final protective-device rating.
Is a 32A RCBO Suitable for Cookers, Showers and EV Chargers?
Cookers and Hobs
A 32A circuit is common for many domestic cookers and hobs, but there is no universal cooker RCBO size. The connected load, manufacturer information, circuit arrangement and any applicable diversity need to be assessed.
Induction technology does not automatically mean that a C Curve RCBO is required. The equipment’s starting characteristics and manufacturer’s protective-device specification should decide the curve.
Electric Showers
A 32A RCBO may suit some lower-output showers where the design current and cable arrangement permit it. At 230V, a nominal 7.5kW load is approximately 32.6A, so it should not be described as an automatic match for a 32A device.
Higher-output showers commonly require a higher protective-device rating and a cable selected for the actual load and installation conditions.
EV Charge Points
Many single-phase EV charge points operate at approximately 7.2kW or 7.4kW and are associated with a nominal 32A charging current. The charger manufacturer’s instructions must still determine the required overcurrent characteristic and residual-current arrangement.
The RCD type is a separate decision from the 32A current rating. Depending on the protection built into the charging equipment, the installation may require Type A, Type F or Type B residual-current protection and suitable DC fault-current protection.
For the full EV-specific selection requirements, see what type of RCBO you need for an EV charger.
Garages, Outbuildings and Sub-Mains
A 32A RCBO can sometimes protect a supply to a garage, workshop, outbuilding or smaller downstream distribution board. Maximum demand, circuit length, cable type, installation method, voltage drop, earthing arrangement and downstream protection all need to be considered.
How Do You Know If 32A Is the Correct RCBO Rating?
The device rating should sit within the design relationship between the load and the cable. In practical terms, installers assess:
- Design current: the expected current required by the circuit or connected equipment
- Manufacturer instructions: any specified protective-device rating, curve or RCD type
- Cable capacity: conductor size after applicable installation and correction factors
- Circuit arrangement: ring final, radial, dedicated appliance circuit or sub-main
- Voltage drop: particularly for longer garage, outbuilding and EV charger circuits
- Fault protection: prospective fault current, earth fault loop impedance and required disconnection time
- Breaking capacity: the device must be suitable for the prospective fault level
- Residual-current type: Type A, F, B or another suitable arrangement according to the connected load
- Load characteristics: including starting current, electronic equipment and the likelihood of unwanted tripping
Compare 32A RCBO options
32A B Curve vs C Curve vs High Immunity RCBOs
The 32A rating describes the device’s rated current. The B or C curve describes its instantaneous overcurrent operating characteristic, while high-immunity features relate to resistance against certain causes of unwanted residual-current tripping.
| 32A RCBO Type | Typical Characteristic | When to Consider It |
|---|---|---|
| B Curve | Instantaneous operation within the B characteristic range, commonly described as 3–5 times rated current | Circuits with relatively predictable starting characteristics where the complete design supports a B Curve device |
| C Curve | Instantaneous operation within the C characteristic range, commonly described as 5–10 times rated current | Suitable higher-inrush equipment where manufacturer requirements and fault-disconnection conditions permit it |
| High Immunity | Additional resistance to selected transient or leakage conditions that can cause unwanted tripping | Electronic or disturbance-prone circuits where high-immunity protection is appropriate |
High immunity is not a substitute for choosing the correct current rating, overcurrent curve or residual-current type.
Compare 32A RCBO Options
Power & Data UK supplies 32A RCBOs across B Curve, C Curve, high-immunity, switched-neutral and multi-pole configurations.
Current options include:
- High Immunity Type A Mini RCBO – 32A B Curve (WRB132B-030)
- High Immunity RCBO – 32A B Curve, Type A, 30mA (WER32B-030)
- High Immunity RCBO – 32A C Curve, Type A, 30mA (WER32C-030)
- Single Module 2 Pole RCBO – 32A B Curve (WRN32B-030)
Check the individual product specification before ordering, particularly the curve, residual-current type, pole arrangement, breaking capacity and consumer-unit compatibility.
32A RCBO FAQs
What size RCBO is normally used for a socket circuit?
A 32A RCBO is commonly used for a domestic ring final socket circuit. Radial socket circuits may use 20A, 32A or another suitable rating depending on the conductor size, installation method and complete circuit design.
Does a ring final circuit need a 32A RCBO?
32A protection is common for a correctly designed ring final circuit, but the existing circuit arrangement and test results must be verified before selecting or replacing the device.
How many kilowatts is 32A at 230V?
32A at 230V is approximately 7.36kW using the basic single-phase calculation. This figure alone does not confirm the correct protective-device or cable rating.
Can a cooker use a 32A RCBO?
Yes, many cooker and hob circuits use 32A protection. The appliance data, diversity, cable capacity and manufacturer instructions determine whether it is suitable for the particular installation.
Can a 32A RCBO supply an EV charger?
Many single-phase charge points have a nominal 32A charging current. Confirm the manufacturer’s required overcurrent curve, RCD type, DC protection, pole arrangement and any upstream requirements.
Is a 32A RCBO suitable for a 7.5kW shower?
Not as a simple assumption. A nominal 7.5kW load draws approximately 32.6A at 230V, so the equipment data and complete circuit design need to be checked.
Does a 32A circuit always need 6mm² cable?
No. There is no universal cable size for every 32A circuit. Ring or radial arrangement, conductor type, installation method, grouping, insulation, ambient temperature, voltage drop and fault protection all affect cable selection.
Should a 32A RCBO be B Curve or C Curve?
Use the curve required by the load characteristics and manufacturer’s instructions while confirming the necessary fault-disconnection conditions. A C Curve device is not automatically required for every EV charger, motor or induction hob.
Is a Type A RCBO always required?
The residual-current type should be selected for the currents and frequencies the connected equipment can produce. Type AC is restricted to suitable fixed equipment where it is known that the load current contains no DC components; electronic and inverter-driven loads commonly require another RCD type.
Compare 32A B Curve, C Curve, high-immunity, switched-neutral and multi-pole RCBOs for domestic, commercial, EV and renewable-energy circuits. Check the individual device specification against the circuit design and connected equipment before ordering.
👉 Browse the full 32A RCBO range
Electrical circuits and protective devices should be designed, selected, installed and tested by a suitably qualified person in accordance with the applicable edition of BS 7671, the equipment manufacturer’s instructions and the conditions of the installation.