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B S EN 60439 Part 1 describes a system for classifying the various forms of separation to be provided principally for:
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Protection against contact with live parts belonging to the adjacent functional units
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Limitation of the probability of initiating arc faults
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Protection against the passage of solid foreign bodies from one unit of an assembly to an adjacent unit
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Manufacturers of switchboard assemblies employ many variations of design to meet this protection and any other additional market requirements.
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This means utilised to achieve these conditions may be partitions or barriers of metallic or non-metallic materials. The partitions or barriers may provide individual separate compartments or alternatively, barriered sub-sections. In general, the cost of an Assembly increases with enhanced levels of separation, but choosing the most expensive arrangement will not necessarily lead to the most appropriate solution.
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Achieving Separation
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The fundamental requirements in the standard are performance criteria and not constructional details on how separation should be achieved. There is a requirement that assemblies are divided by means of partitions or barriers (metallic or non-metallic) into separate compartments or barriered sub-sections, but not for example:
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• Each functional unit to be in its own compartment;
• partitions & barriers to be manufactured from earthed metal, etc
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Separation can be achieved in several ways. Depending on a particular application & the requirement for maintenance, this may include:
a) PVC sleeving, wrapping or plastic coating of conductors
b) Insulated terminals shields or PVC ‘boots’
c) Rigid insulated barriers or partitions
d) Compartments formed from earthed metal
e) A device’s integral housing
Where a Specifier or user has a particular preference, this should be clearly stated at the enquiry stage.
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