Following Amendment 2 to the 18th Edition Wiring Regulations, the team at Electrium provide us with more detail as to the correct use of RCBOs in the workplace.
In the workplace power continuity is an important factor. Business services must not be interrupted by unwanted power outages. That’s why RCBOs (Residual Current Breaker with Over-Current) should be used when there is also a requirement for 30mA protection for the users of the installation. Additionally, personal safety is an equally important factor.
Protecting users to Amendment 2
Regulation 411.3.3 of the Wiring Regulations was revised by Amendment 2. This regulation now requires additional protection by means of a 30mA device for users of socket outlets (not rated higher than 32A) in locations where they’re liable to be used by persons of capability BA1, BA2 or BA3.
The terms BA1, BA2 or BA3 probably need some further explanation. Appendix 5 includes a list of external influences, and under the sub-heading of ‘Utilization’ BA refers to the capability of persons. BA1 is described as an ordinary person (a person who is neither a skilled person nor an instructed person) BA2 as children, and BA3 as disabled.
No exceptions permitted
So, in all locations where socket outlets (not rated higher than 32A) are liable to be used by ordinary persons, disabled persons, or children, additional protection by use of a 30mA device is mandatory. No exceptions are permitted.
Providing additional protection and maintaining power continuity is actually quite easy. Each circuit should be protected by an individual Type A 30mA RCBO. This will meet the requirements of Regulation 411.3.3 and the requirements of the business because it will eradicate unwanted tripping and guarantee that all healthy circuits remain in service.
In a modern workplace, school or university environment, for example, the connected equipment, and portable devices will have a significant impact upon the design of the installation and will no doubt bring DC influences and PE currents into consideration for both the designer and installer.
Regulation 531.3.2 requires protective conductor currents (standing earth leakage not due to a fault) to be limited to 9mA for a 30mA device in order to help to avoid unwanted tripping, but that can’t be achieved if several circuits are protected by one device.
Designers will not only have to take account of PE currents when dividing the installation into the necessary number of circuits, there are also the requirements of Chapter 31 & Regulations 314.1 to consider.
Regulation 314.1 requires the installation to be divided into the necessary number of circuits to:
– avoid danger and minimize inconvenience in the event of a single fault,
– take account of hazards that may arise from the failure of a single circuit
– reduce the possibility of unwanted tripping of RCDs,
– facilitate safe inspection, testing and maintenance.
Wherever additional protection by a 30mA device is required each circuit should be served by an individual Type A RCBO in order to meet the requirements of BS7671, including Amendment 2.
To browse the Electrium Amendment 2 support guide, click here