Gus Ferguson asks a question about a ring circuit arrangement and concerns about its suitability. It has been answered by SELECT (Theme – Installation Tips):
Question: We have been asked to approve the wiring arrangements indicated on the attached pdf. In the first diagram, the first spur (from the RCBO) is to serve a water heater and the second spur (from the RCBO) is to serve a feature fire which will be plugged into the socket protected by the switched fused connection unit. Spurred cables will be sized to accommodate the fixed loads.
In the second diagram, this is an existing wiring arrangement and we have been asked to replace existing fans served by the 2nr spurs.
Whilst we appreciate these arrangements may not be best practice, we are struggling to come up with a reason why this cannot be done. Can you advise?
Click below to download the attachment (PDF - kB file size).
Answer: Reference should be made to Regulation 433.1.103 and Appendix 15.
The first diagram would appear to meet the requirements, other than that Appendix 15 advises that immersion heaters should not be connected to a ring. As the diagram suggests that the water heater spur is supplied from the ring final circuit at the consumer unit, it would be better if this was supplied from a separate protective device.
The second diagram would not appear to meet the requirement that only one item of fixed equipment should be supplied from an un-fused spur.
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