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As we move towards a new regulatory future and the publication on July 1st of the IET’s 18th Edition of the Wiring Regulations, one of the main drivers for making changes to the existing rules has been to further enhance safety standards.
In this regard, work is already underway to help electrical contractors and further protect consumers. The increasing specification and installation of residual current circuit breakers with overcurrent protection (RCBOs) is evidence of a tangible focus on safety for all. The RCBO combines RCD and overcurrent protection.
Residual current devices (RCD’s) monitor circuits on a permanent basis, to detect earth leakage current. This is achieved by continuously measuring the amount of current on the line and neutral within a circuit, looking for an imbalance. The reason for this is that in the normal functioning of an electrical circuit the value of current is the same throughout the circuit, however underneath fault conditions some of this current can flow to earth. This could be through a person touching an exposed part of the circuit and the current flowing through them to earth, with potentially severe consequences. BS 7671 states that where additional protection is required the RCD providing this protection should be rated at 30mA or less.
The second element of this device is the incorporation of a miniature circuit breaker, which will disconnect the circuit if the current demand is too high. This excessive current could be an overload or a short circuit. This will cause the MCB element of the RCBO to react, and without such protection, the circuit could become overloaded causing a risk of fire. In essence, the combined functionality of the RCBO offers protection to people, equipment and buildings.
Efficient installation and testing
While the merits of RCBOs are well understood from a safety perspective, installation and testing requirements can be both time consuming and costly.
As an example, local councils overseeing a change of tenancy in rented properties or social housing under their jurisdiction have to carry out an Installation Condition Report. Checks need to be made to ascertain that the electrical installation is still fit for purpose and has not been tampered with in any way by previous occupants in order that the property can be safely handed to new tenants. This requires a testing regime to be undertaken.
In addition, busy electrical contractors are looking to complete consumer unit installations as efficiently and quickly as possible. Any improvement to the time taken for either installation or testing can result in a speedier turnaround and better productivity.
After consulting with a number of contractors and listening to the practical hurdles they face with RCBO installation and testing, Hager embarked upon a new product development to see how it could improve the installation and testing process of RCBOs for the installer. The result has been the creation of a new range of 6kA Reduced Height RCBOs, ranging from 6-32A.
Easier and quicker
With a reduced height of 92mm, the new Hager RCBO creates more working space in consumer units where multiple RCBOs are to be used, thereby helping installers to undertake the connection of the outgoing circuits and the flying neutral lead far more easily.
The absence of the functional earth reduces the number of connections in the consumer unit, as well as eliminating the requirement to remove the functional earth while carrying out insulation resistance testing. Importantly, the removal of the functional earth also eliminates the challenge of connecting dissimilar conductors in the same terminal in a secure manner.
The RCD part of the Reduced height RCBO is also Type A, meaning that the device provides tripping on alternating sinusoidal residual current and pulsating direct current. This ensures the RCD is suitable for circuits likely to supply loads with electronic components. Initial market feedback to this latest solution has been extremely positive, as contractors have been able to complete tasks in less time. Listening to and acting upon installer feedback is an important issue for product manufacturers if the right solutions for today’s marketplace are to be developed.
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