Editing Ring circuit (section)

===Fault conditions are not apparent when in use===
Ring circuits may continue to operate without the user being aware of any problem if there are certain types of fault condition or installation errors. This gives both robustness against failure and a potential for danger.<ref name="emc">Roger Lovegrove: EMC, April 2006</ref><ref name="lovegrove">Roger Lovegrove: Ring circuits – the disadvantages. [http://www.theiet.org/resources/wiring-regulations/ringcir.cfm?type=zip Presentation papers from a public meeting to discuss the issue of ring circuits], [[The Institution of Engineering and Technology|IET]], London, October 2007 (PDF in ZIP)</ref>
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! Fault condition !! Observations
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*Part of the ring missing or disconnected can result in 2.5&nbsp;mm<sup>2</sup> cables running above rated current without this being obvious to the user.<ref>P Knowles: Ring main lining. EMC, February 2007</ref>
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* Radials with a broken connection will not function (if L or N broken), or will function with no safety earth connection (if just E broken).
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*Inadvertent cross connection between two 32&nbsp;A rings means that the fault current protection reaches 64&nbsp;A and the required fault disconnection times are violated grossly.
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* Testing at installation can prevent this, and a similar problem applies to cross-connected radial circuits although would trip residual current protection devices if fitted to either or both radials as would be to current standards in most jurisdictions.
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*Spur circuits attached to the ring can overheat if not fused at the spur-point (i.e., if a BS 5733 or similar fused spur is not used)
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* This is almost certainly a breach of the appropriate electrical standards (e.g. BS 7671 in the UK): the maximum load on any unfused spur is a single fitting.
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