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40A B Curve 30mA A Type 6KA 1P+N RCBO (NB3LEG-B40)

A reliable 40A residual current circuit breaker with over-current protection. Type A leakage detection, B Curve tripping, 30mA sensitivity and 6kA fault capacity make this ideal for residential and light commercial circuits.

Dual Protection in One Unit: Combines overload, short-circuit and residual current protection for comprehensive safety. Ideal for Modern Electrical Loads: Type A detection senses both AC and pulsating DC leakage from electronic devices. Reliable Trip Performance: B Curve characteristic helps reduce unnecessary trips while still protecting circuits with moderate inrush. High Fault Capacity: 6 kA short-circuit breaking capacity helps safeguard circuits against severe electrical faults. Easy Install and Monitor: DIN rail mounting and clear contact position indicator make installation and checks quick and simple.
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SKU: NB3LEG-B40
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Product Details

The Chint NB3LEG‑B40 40A B Curve 30mA A Type RCBO combines critical electrical protection and compact design in one essential safety device. Designed for use in single-phase circuits, this RCBO protects your wiring and appliances by detecting both overloads and earth leakage faults. Built to meet BS EN safety standards, it reliably safeguards electrical installations in homes, workshops, offices, and light commercial settings.

Engineered for modern electrical systems, this RCBO integrates over-current protection and residual current detection into a single module that fits neatly on a standard DIN rail. With a B Curve characteristic, it responds quickly to moderate surge currents without nuisance trips, making it suitable for general circuits such as lighting, sockets, and everyday appliances. Its Type A residual current detection senses both alternating and pulsating DC leakage, offering broader protection for circuits that include electronic loads such as LED drivers, appliances, or chargers.

The device has a rated current of 40 amps and a residual current trip threshold of 30mA, ideal for personal protection against electric shock and fire risk. The robust 6kA short-circuit breaking capacity ensures reliable disconnection during faults, helping prevent damage to equipment and wiring. Compact and lightweight, the RCBO mounts easily on a 35 mm DIN rail to make installation fast and straightforward.

Built for durability and performance, this unit includes a clear contact position indicator that shows at a glance whether the circuit is closed or open. Whether you are upgrading existing protection or specifying new installations, the NB3LEG‑B40 is a dependable choice for enhanced circuit safety and compliance.

Product Specifications

Electrical Specifications

  • Rated Current (In): 40A
  • Number of Poles: 1P+N
  • Tripping Curve: B Curve (3-5 In)
  • Residual Current Type: Type A
  • Rated Sensitivity (IΔn): 30mA (0.03A)
  • Rated Voltage (Ue): 240V AC
  • Rated Frequency: 50Hz
  • Rated Short-circuit Capacity (Icn): 6,000A (6kA)
  • Rated Residual Making and Breaking Capacity (IΔm): 3,000A
  • Insulation Voltage (Ui): 500V
  • Rated Impulse Withstand Voltage (Uimp): 4,000V
  • Break Time under IΔn: ≤ 0.1s
  • Release Type: Thermo-magnetic

Mechanical & Installation Data

  • Mounting: 35mm DIN Rail (EN 60715) via fast clip device
  • Terminal Connection Type: Cable / U-type busbar / Pin-type busbar
  • Connection Direction: From top
  • Terminal Size (Cable): Up to 10mm² (18-8 AWG)
  • Terminal Size (Busbar): Up to 16mm² (18-5 AWG)
  • Tightening Torque: 2.0 N·m
  • Electrical Life: 2,000 operations
  • Mechanical Life: 2,000 operations
  • Protection Degree: IP20
  • Contact Position Indicator: Yes (Green/Red visual indicator)
  • Pollution Degree: 2

Environmental Specifications

  • Ambient Operating Temperature: -5°C to +40°C (Daily average ≤ 35°C)
  • Storage Temperature: -25°C to +70°C
  • Reference Temperature for Tripping: 30°C

Standards & Compliance

  • Standard: BS EN 61009-1
  • Certification: CE Marked, Intertek Verified

Key Features

  • Space-Saving Design: Occupies only a single module (18mm width) in a distribution board, allowing for more circuits in a standard enclosure.
  • Type A Protection: Specifically engineered to handle the residual current profiles generated by modern electronics, such as LED lighting drivers and computer power supplies.
  • Enhanced Safety: Provides additional protection against direct contact and fire hazards resulting from insulation faults.
  • B-Curve Performance: Optimized for the protection of people and long cable lengths in TN and IT systems where low inrush currents are expected.

Shipping & Collection

Tracked Delivery (Currently 1-3 business days):

  • Free over £250.
  • £5.99 for orders under £250.
  • £5.99 for orders under £50.

Next Business Day Delivery:

  • £15 Flat Rate.

Collection:

  • Free to collect from our warehouse.

Pre-Order:

  • 5-10 Business Days delivery unless otherwise stated.

Shipping Policy

Datasheets
40A B Curve 30mA A Type 6KA 1P+N RCBO (NB3LEG-B40) - Data Sheet
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