Circuitprotection: don’t mix and match
Watch out if you mix and match consumer units and circuit protection devices from different manufacturers, because you could be liable if something goes wrong. Andrew Brister reports
R
ecent incidents have highlighted the potential dangers of mixing circuit protection devices of one manufacturer with the system infrastructure of another manufacturer.
The most common example of this practice is when an
installer tries to fit miniature circuit breakers (MCBs) from manufacturer ‘A’ into the consumer unit of manufacturer ‘B’. Assemblies such as consumer units, distribution boards and panel boards are tested with specific devices installed, invariably those of the same manufacturer.
The testing and certification for the assembly (the
consumer unit and protection devices) is undertaken to BS EN 60439-3, formerly BS 5486, whereby the complete assembly is subjected to tests at specified load conditions. ‘Although devices may appear similar, their dimensions, technical performance and termination features are not necessarily compatible,’ explains Keith Smith, BEAMA’s deputy director. BEAMA is concerned about the issue and has released a Technical Bulletin – Safe selection of devices for installation in assemblies. But how widespread is the problem? ‘Every so often,
on an online forum I come across an argument about whether electricians can use different manufacturers’ circuit breakers in a board,’ says Paul Sayer, technical standards manager for Hager. ‘I have even seen a wholesaler advertising MCBs for use in another manufacturer’s board. It is surprising how many people believe that this is acceptable and do not realise the safety implications of what they are doing.’ Schneider Electric’s Tom France agrees: ‘We have seen
people trying to force devices into distribution and panel boards which the board isn’t designed to accept. We’ve even seen breakers fitted the wrong way round.’
Certification If the installer does decide to mix components and assemblies, they should be aware that this will invalidate any testing/certification and warranty originally supplied by the manufacturer. ‘It is the responsibility of the installer who intends to mix different manufacturers’ devices in an assembly, to undertake testing and ensure conformity with BS EN 60439,’ says Keith Smith. If this is not done, there is a probability that, in the event of death, injury, fire or other damage as a direct result of a failure of this assembly, then the installer would be held accountable under health and safety legislation. ‘Just to be clear, this is not just a manufacturer protecting their sales, there are
56 ECA Today March 2012
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