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New EICR - "No earth bond to some socket boxes: C2"?

Former Community Member
Former Community Member
I have a new EICR which has the observation "No earth bond to some socket boxes: C2".


I have checked continuity between all faceplate mounting screws and the earth of the socket. They are all connected, i.e. the back box is at least earthed by the screw if not with a tail internally (I have not removed the front plates of any sockets). The earth of each socket is connected to the ring.


While it is best practice, is it a requirement of the regulations that a tail is connected internally?


many thanks



Parents
  • 0
    Well, it's not that simple is it Andy? The PSCC at the socket is not the same as on the tails, it is reduced by the cable resistance. Around the ring there are two conductors in parallel so the actual Earth is 2.0mm, and the PSCC is similarly reduced. The wire in a rewirable fuse holder has very little material around it (by design) and the fusing current is significantly lower than the CPC, even if this is 1mm2. It is very rare to find the situation you describe today, and a LOWER PSCC is actually worse for CPC failure because the fusing takes much longer so the CPC gets hotter. The I2t value is the important bit, fuses get faster and faster as the current increases, unlike magnetic circuit breakers which have a minimum time to open depending on mechanical inertia which cannot be reduced whatever the current. These cables and circuits are still considered safe, and with an RCD are even safer.
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  • 0
    Well, it's not that simple is it Andy? The PSCC at the socket is not the same as on the tails, it is reduced by the cable resistance. Around the ring there are two conductors in parallel so the actual Earth is 2.0mm, and the PSCC is similarly reduced. The wire in a rewirable fuse holder has very little material around it (by design) and the fusing current is significantly lower than the CPC, even if this is 1mm2. It is very rare to find the situation you describe today, and a LOWER PSCC is actually worse for CPC failure because the fusing takes much longer so the CPC gets hotter. The I2t value is the important bit, fuses get faster and faster as the current increases, unlike magnetic circuit breakers which have a minimum time to open depending on mechanical inertia which cannot be reduced whatever the current. These cables and circuits are still considered safe, and with an RCD are even safer.
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