Live - Single Pole MCB 6kA B Curve - VARIOUS
Live - Single Pole MCB 6kA B Curve - VARIOUS - CA106B is backordered and will ship as soon as it is back in stock.
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Live - Single Pole MCB 6kA B Curve - VARIOUS
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From £1.37 + VAT
Trade price per MCB. Volume pricing available at the Peterlee trade counter.
Single Pole MCB
One module width. Suitable for all consumer units in the Live Electrical range.
Type B MCB - 6kA
B Curve trips at 3-5x rated current. Standard for domestic and light commercial circuits.
8 Amperages
6A, 10A, 16A, 20A, 32A, 40A, 50A and 63A. All from a single product listing.
MCB - Miniature Circuit Breaker
What the Live Electrical CA Series MCB Is
The Live Electrical CA Series is a single pole B Curve MCB available in eight amperage ratings from 6A to 63A at £1.37 + VAT per device. A single pole MCB occupies one DIN rail module and provides overcurrent and short circuit protection for a single circuit. Eight part numbers cover the full range of domestic and light commercial circuit protection requirements: CA106B (6A), CA110B (10A), CA116B (16A), CA120B (20A), CA132B (32A), CA140B (40A), CA150B (50A) and CA163B (63A).
An MCB provides two types of protection. The thermal element trips on sustained overload current - when the circuit carries more than its rated current for a prolonged period. The magnetic element trips instantaneously on short circuit - when the current reaches 3 to 5 times the rated current on a B Curve MCB. After a trip, the fault is cleared and the MCB is reset by hand. No fuse replacement required.
MCBs provide overcurrent and short circuit protection only. They do not provide earth fault current protection. On circuits requiring 30mA RCD protection under BS 7671 - socket outlet circuits, bathroom circuits, outdoor circuits and circuits in high-risk locations - an RCBO or a separate RCD covering the MCB is required. Where the design specifies MCBs (for example, circuits already downstream of a whole-board RCD, or circuits in non-domestic environments not requiring per-circuit RCD protection), the Live Electrical CA Series is the cost-effective single pole MCB for the Live Electrical consumer unit range.
Which Amperage?
MCB Amperage Selection Guide - 6A to 63A
Select the MCB amperage to match the design current of the circuit after applying diversity, within the current rating of the cable. The amperage protects the cable, not the load.
6A MCB
Lighting circuits in smaller installations, secondary lighting circuits, dedicated circuits with low design current. A 6A MCB is the most conservative amperage for a standard lighting circuit and is correct where the installed load and cable rating both confirm that 6A protection is appropriate.
10A MCB
Lighting circuits in medium-sized properties, some small appliance radial circuits. A 10A MCB suits installations where the lighting load exceeds what a 6A device would carry comfortably but a 16A rating would be oversized for the cable. Always verify cable current-carrying capacity against the design current before selecting.
16A MCB
Radial socket outlet circuits, some ring main circuits in smaller installations, dedicated appliance circuits rated up to 16A, and some EV charger circuits where the maximum charge current does not exceed 16A. A 16A MCB is one of the most commonly specified amperages in domestic installations.
20A MCB
Dedicated appliance circuits where the design current falls between 16A and 32A, some electric shower circuits in smaller properties, and cooker circuits where the designed load does not warrant a 32A device. Verify the cable rating and design current before specifying a 20A MCB over 16A or 32A.
32A MCB
Standard ring final circuit protection for domestic socket outlet circuits on 2.5mm cable, 7.2kW EV charger circuits, cooker circuits and other higher-load dedicated circuits where the design current falls within the 32A rating. The 32A MCB is the most commonly used amperage for ring mains in domestic consumer units.
40A MCB
Electric shower circuits (typically 8.5kW to 9.5kW), larger cooker circuits, and higher-load dedicated circuits where the design current exceeds 32A but does not require a 50A device. A 40A MCB is also used as an outgoing device from a main distribution board to a sub-distribution board where the downstream load warrants 40A protection.
50A MCB
Large electric shower circuits (10kW and above), sub-distribution boards with moderate downstream load, and circuits with design currents between 40A and 63A. Less commonly specified in standard domestic installations than 32A or 40A, but correct where the circuit design current and cable rating both confirm 50A protection is required.
63A MCB
Incomer or outgoing protection in sub-distribution boards, large single-phase circuits with high connected loads, electric heating circuits, and circuits feeding sub-panels for outbuildings or commercial units. The 63A MCB is the highest amperage in the CA Series range and is typically used as a main device or on circuits where a full 63A single-phase supply is being distributed.
Always size the MCB to protect the cable, not the load. The MCB rating must not exceed the current-carrying capacity of the protected conductor. Refer to BS 7671 Tables for cable current ratings and correction factors. Where in doubt, consult a qualified electrical designer.
Trip Characteristic
Type B MCB and B Curve Explained
The trip curve determines how quickly the MCB's magnetic element responds to short circuit conditions. Choose B Curve for most domestic and light commercial circuits.
B Curve (Type B MCB) This product
Instantaneous magnetic trip at 3 to 5 times rated current. The correct specification for circuits with resistive and lightly inductive loads: lighting, socket outlets, general domestic appliances and consumer electronics. Standard for domestic new-build and refurbishment consumer units.
C Curve (Type C MCB)
Instantaneous magnetic trip at 5 to 10 times rated current. Used where higher inrush currents occur on starting: single-phase motors, transformers, some commercial lighting (fluorescent with electromagnetic ballasts) and compressors. Not required for standard domestic circuits.
A Type B MCB (B Curve MCB) trips instantaneously at 3x to 5x the rated current. This means a 32A B Curve MCB will trip instantaneously between 96A and 160A on a short circuit. This is fast enough to protect the cable on any standard domestic resistive or lightly inductive circuit without nuisance tripping during normal switched loads. For circuits where motor starting or transformer energisation produces inrush currents that could cause a B Curve MCB to nuisance-trip, a C Curve MCB is specified instead. For all standard domestic circuits, the B Curve MCB is the correct device.
MCB vs RCBO
When to Use an MCB and When to Use an RCBO
MCBs and RCBOs both protect against overcurrent. The difference is whether per-circuit earth fault protection is also required.
| Factor | Single Pole MCB (this product) | Type A RCBO |
|---|---|---|
| Price + VAT | £1.37 | £8.19 |
| Overcurrent protection | Yes | Yes |
| Earth fault (30mA RCD) protection | No - requires separate RCD | Yes - 30mA built in |
| DIN rail modules | 1 | 1 |
| Fault isolation | Trips one circuit only if not sharing an RCD | Trips one circuit only - per-circuit protection |
| Pulsating DC fault detection | N/A - no RCD function | Yes - Type A detects sinusoidal AC and pulsating DC |
| Use on socket circuits | Only if already downstream of a whole-board RCD | Yes - provides the required 30mA protection |
| Best for | Circuits not requiring RCD protection; installations with whole-board RCD; commercial circuits with non-domestic design | New domestic consumer units; circuits requiring per-circuit 30mA protection; EV charger circuits; full BS 7671 Amendment 2 compliance |
MCB or RCBO? The one-question test
Does the circuit require 30mA RCD protection under BS 7671? If yes, specify an RCBO - or an MCB downstream of a whole-board RCD. If no, an MCB is the simpler and less expensive choice. For new domestic consumer units on new-build work, the current standard is RCBOs throughout. Live Electrical Type A RCBOs are £7.95 + VAT from Harbro.
Technical Specifications
Live Electrical CA Series MCB Full Specification
| Range | Live Electrical CA Series |
| Type | Single pole MCB (Miniature Circuit Breaker) |
| Trip characteristic | B Curve (Type B MCB) - instantaneous magnetic trip at 3-5x In |
| Amperages available | 6A, 10A, 16A, 20A, 32A, 40A, 50A, 63A |
| Part numbers | CA106B / CA110B / CA116B / CA120B / CA132B / CA140B / CA150B / CA163B |
| Breaking capacity (Icn) | 6kA (6,000A) |
| Voltage rating (Ue) | 230-400V AC |
| Poles | Single pole (1P) |
| DIN rail width | Single module |
| Electrical endurance | 20,000 cycles |
| Compatible enclosures | All consumer units and enclosures in the Live Electrical range |
| Trade price at Harbro | £1.37 + VAT (£1.64 inc.) per MCB |
Frequently Asked
MCB Questions: 6A to 63A, Type B and Single Pole
What is an MCB?
An MCB (Miniature Circuit Breaker) is a resettable protective device that automatically disconnects a circuit when the current exceeds the rated value (overload protection, thermal trip) or when a short circuit occurs (instantaneous magnetic trip). After a trip, the MCB is reset manually once the fault is cleared. MCBs provide overcurrent and short circuit protection only - they do not provide earth fault current protection. The Live Electrical CA Series single pole B Curve MCB is available in 6A, 10A, 16A, 20A, 32A, 40A, 50A and 63A at £1.37 + VAT.
What is a Type B MCB?
A Type B MCB (also called a B Curve MCB) trips instantaneously on short circuit when the fault current reaches 3 to 5 times the rated current. A 16A B Curve MCB trips instantaneously between 48A and 80A. A 32A B Curve MCB trips between 96A and 160A. This is the standard trip characteristic for domestic and light commercial circuits with resistive and lightly inductive loads - lighting circuits, socket outlets and general appliances. Type C MCBs trip at 5 to 10 times rated current and are used where motor or transformer inrush currents could cause a B Curve device to nuisance-trip.
What is a single pole MCB?
A single pole MCB switches and protects the line conductor only, occupying one DIN rail module width. In a consumer unit with a double pole main isolating switch, single pole MCBs are fitted on the individual circuit ways - the main switch isolates both line and neutral when the installation needs to be fully de-energised. Single pole MCBs are the standard for individual circuit protection in domestic consumer units. The Live Electrical CA Series is a single pole MCB suitable for all consumer units in the Live Electrical range, including the LSMC10M-SP, LSMC14M-SP and LSMC18M-SP.
What is a 16A MCB used for?
A 16A MCB (CA116B in the Live Electrical CA Series) is used for radial socket outlet circuits, ring main circuits in smaller installations, dedicated appliance circuits where the design current does not exceed 16A, and some EV charger circuits rated up to 3.6kW. A 16A MCB is one of the most commonly specified amperages in domestic consumer units alongside 6A (lighting) and 32A (ring main). At £1.37 + VAT it is available from Harbro's Peterlee trade counter for same-day collection.
What is a 32A MCB used for?
A 32A MCB (CA132B in the Live Electrical CA Series) is the standard protection device for a domestic ring final circuit on 2.5mm two-core cable, providing overcurrent protection for the socket outlets throughout a property. It is also used for 7.2kW EV charger circuits, cooker circuits and higher-load dedicated radial circuits. The 32A B Curve MCB trips instantaneously between 96A and 160A on a short circuit. On new domestic installations, a 32A RCBO is now the preferred specification for ring main circuits over an MCB behind a shared RCD, to provide per-circuit earth fault protection.
What is a 63A MCB used for?
A 63A MCB (CA163B in the Live Electrical CA Series) is used as an incomer or main device in sub-distribution boards, large single-phase circuits with high connected loads, circuits supplying outbuilding or workshop sub-panels, and electric heating circuits where the design current approaches 63A. It is the highest amperage in the CA Series range. The 63A B Curve MCB trips instantaneously between 189A and 315A on a short circuit.
What is the difference between an MCB and an RCBO?
An MCB provides overcurrent and short circuit protection only. An RCBO provides overcurrent protection and 30mA earth fault protection in a single module. Circuits requiring RCD protection under BS 7671 - socket outlets, bathrooms, outdoor circuits - need an RCBO or an MCB downstream of a whole-board RCD. Where the design does not require per-circuit RCD protection, an MCB at £1.37 + VAT is the simpler and more cost-effective option. Live Electrical Type A 30mA RCBOs are available at £8.19 + VAT from Harbro for circuits requiring earth fault protection.
Where can I buy MCBs in the North East?
Live Electrical CA Series single pole B Curve MCBs in 6A, 10A, 16A, 20A, 32A, 40A, 50A and 63A are stocked at Harbro Electrical, 5 & 6 Whitworth Road, Peterlee, Co Durham, SR8 2LY. Mon to Thu 7:30am to 5:00pm, Fri 7:30am to 4:00pm, Sat 8:30am to 12:30pm. Call 0191 518 1998 to check current stock. We supply electrical contractors across Peterlee, Hartlepool, Sunderland, Durham and Seaham. Free UK Mainland delivery on orders over £70.
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