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I have read a few posts with regard to Reg 421.1.201 & Similar Switchgear Assemblies, with regard to the definition of such. When 421.1.201 came into being, I was advised at the time about using certain enclosures. This advise, now seems to have changed. I've copied below my questions, and the advise I've now received from Elecsa Technical.
Elecsa Technical, 'Similar switchgear is any switchgear that conforms to the standard BS EN 61439-3 and can be assumed to be assemblies that fulfil the same fundamental application as consumer units. For example, the following would fall within the scope of Regulation 421.1.201:
• One way consumer units supplying such things as showers and the like
• TP&N distribution boards where there is a three phase supply'.
Question;
'On an occasion where a consumer unit is being replaced or relocated, it may be necessary to extend the existing final circuits. There are a few enclosures available, with internal din rail & connectors, to extend the circuits. These enclosures are not made from non-combustible materials, but of plastic. Does the definition of ‘similar switchgear assemblies’ apply to these products used in this fashion?
Reply;
'This will be the decision of the designer but it would suggest based on our guidance in this situation the enclosures and connections do not fall under ‘similar switchgear’.
Question;
'Sometimes the installation of meter tails to a new consumer have to protected by a switch fuse. Would the use of Wylex plastic switch fuse, REC 2 or similar plastic isolators, being installed in an external plastic meter box on an external wall, be defined as being installed ‘within domestic premises’?
Reply;
'The Suppliers and meter equipment would fall outside the scope of BS7671.
As a designer installing any equipment in external meter enclosures we would suggest a risk assessment is carried out to make a judgment of the likelihood that fire originating inside the enclosure or similar switchgear might lead to the outbreak of fire in the household building.
Whilst some would suggest the answers to the questions are obvious, I sort some clarification.
Elecsa Technical, 'Similar switchgear is any switchgear that conforms to the standard BS EN 61439-3 and can be assumed to be assemblies that fulfil the same fundamental application as consumer units. For example, the following would fall within the scope of Regulation 421.1.201:
• One way consumer units supplying such things as showers and the like
• TP&N distribution boards where there is a three phase supply'.
Question;
'On an occasion where a consumer unit is being replaced or relocated, it may be necessary to extend the existing final circuits. There are a few enclosures available, with internal din rail & connectors, to extend the circuits. These enclosures are not made from non-combustible materials, but of plastic. Does the definition of ‘similar switchgear assemblies’ apply to these products used in this fashion?
Reply;
'This will be the decision of the designer but it would suggest based on our guidance in this situation the enclosures and connections do not fall under ‘similar switchgear’.
Question;
'Sometimes the installation of meter tails to a new consumer have to protected by a switch fuse. Would the use of Wylex plastic switch fuse, REC 2 or similar plastic isolators, being installed in an external plastic meter box on an external wall, be defined as being installed ‘within domestic premises’?
Reply;
'The Suppliers and meter equipment would fall outside the scope of BS7671.
As a designer installing any equipment in external meter enclosures we would suggest a risk assessment is carried out to make a judgment of the likelihood that fire originating inside the enclosure or similar switchgear might lead to the outbreak of fire in the household building.
Whilst some would suggest the answers to the questions are obvious, I sort some clarification.