BG Circuit Protection
Devices
Surge Protection Surge protection safeguards electrical systems from transient over voltages caused by indirect light strikes. Protection is essential when over voltages could result in:
•Serious injury or loss of life •Significant financial or data loss
Mandated by the 18th Edition (BS 7671) IET Wiring Regulations from 26th September 2022, surge protection applies to all new installations, additions, and circuit alterations in the UK. Typically housed within the consumer unit, it prevents over voltages from spreading across installations and circuits, protecting connected devices. British General’s Consumer Units come with built-in Type 2 Surge Protection for optimal safety.
Arc Fault Detection Devices (AFDDs)
AFDDs protect against electrical fires by detecting arc faults within circuits. By analysing the circuit’s waveform and identifying abnormal patterns, the device disconnects power to the affected circuit, preventing fire risks.
As required by the 18th Edition of the IET Wiring Regulations (BS 7671) from 28th September 2022, AFDDs are mandatory for socket outlet circuits (up to 32A) in:
•High-risk residential buildings •Care homes •Houses in multiple occupation •Purpose-built student accommodation
Alternative to Standard circuit protection devices when additional Arc Fault Protection may be required.
Advanced electronics allow these devices to be more sensitive to arcs than conventional circuit protective devices. British General AFDDs are engineered to provide three key functions:
Overcurrent protection Residual current protection (30mA)
Continuous detection monitoring of the circuits load waveform for anomalies that would signify an arc fault within the circuit or load.
Type A Residual Current
Devices (RCDs) To prevent unwanted tripping, the 18th Edition (BS 7671) Section 531.3.2 outlines key requirements for selecting and installing RCDs:
TYPE A Type A Devices vs. Type AC Devices
Section 531.3.3 specifies that Type AC RCDs should only be used with fixed equipment where no DC components are present in the load current, such as electric heaters or filament lighting without electronic components.
For equipment containing electronic DC components, Type A RCDs or RCBOs should be used instead, as they are designed to handle both AC and DC residual currents for more comprehensive protection.
Type B Residual Current Devices
•Electric vehicle charging •Photovoltaic installations •Inverter-driven heat pumps •Equipment with electronic DC components
These devices can detect AC currents up to 1,000 Hz, rectified AC, pure DC, and pulsating DC, ensuring comprehensive protection for modern installations.
Type F RCBO’s
Type F RCBOs provide advanced residual current detection for frequency controlled appliances and equipment making them ideal for:
TYPE F
•Air conditioning controllers •Dishwashers and tumble dryers with synchronous motors •Type F is also suitable for Type AC and Type A applications
Pollution Degree 3
This is an approval rating given when testing has been performed on devices or electrical items. It ensures that both conductive pollution or dry non-conductive pollution does not become conductive when natural condensation is present.
Natural condensation can occur when an enclosure containing electrical devices/products is installed externally or in more harsh conditions than an internal application and could potentially be exposed to lower or higher ambient temperatures which could generate natural condensation which may harm the internal electrical components inside the enclosure.
Circuit Subdivision: Circuits should be subdivided and paired with individual RCDs to prevent unwanted tripping caused by normal earth leakage currents during load operation. (Refer to Section 314)
RCBOs for Individual Circuits: RCBOs are recommended for individual final circuits in residential installations. (Refer to Section 314)
Limiting Earth Leakage Accumulation: Downstream earth leakage or protective conductor currents should not exceed 30% of the RCD’s rated residual current to minimize nuisance tripping.
Effective from 28th September 2022, this regulation ensures that RCD selection limits unnecessary power disruptions.
BG Devices are tested to pollution degree 3 and also temperature tested to -25°C to + 40°C.
Changes in the standard
A clear definition of what type of circuit protection devices: Bidirectional (2-way power direction that is clearly marked accordingly). Unidirectional (1-way power direction that is clearly marked accordingly). To be considered for Installations with EV and PV battery storage, so it is important installers have devices to suit these applications.
Effective from 31st July 2024
TYPE B
(RCDs) Type B RCDs provide advanced residual current detection, making them ideal for:
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Electrical Accessories – Wiring Devices & Circuit Protection
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