433.1.204

Ring final circuit, 2.5mm T+E, 32 amp over current protection.

433.1.204 says 2.5mm minimum cable size.

Is that for the ring, and unfused spurs?

For example, a small load device needs to be fed by a single socket outlet, fed in 1.5mm T+E, from an unfused spur off the ring (in fact a single socket outlet next to a double socket outlet on the RFC).  Fault current complies, it has RCD protection, and the plug top fuse gives the overload protection, but 433.1.204 says it must be 2.5mm cable to the single socket.

Is that correct?

Parents
  • A truly single socket will be OK, a single spur to a double socket may not be. I'd be less worried about a fused spur as there is less risk of unfused 2 way adaptors and a change to a double socket later.

    But the whole point of the one reel of 2.5mm and no thought it is indeed the lack of thought, One could make an optimum ring thicker near the CU and thinner at the far point, but we don't.

    Mike.

Reply
  • A truly single socket will be OK, a single spur to a double socket may not be. I'd be less worried about a fused spur as there is less risk of unfused 2 way adaptors and a change to a double socket later.

    But the whole point of the one reel of 2.5mm and no thought it is indeed the lack of thought, One could make an optimum ring thicker near the CU and thinner at the far point, but we don't.

    Mike.

Children
  • I agree. While it may not conform to the stipulations of Appendix 15, I don’t perceive any safety concerns. Additionally, according to table 4D5, a clipped direct 1.5mm cable is capable of handling 20 Amps.

  • A truly single socket will be OK,

    Provided the length of the spur < 3 m ? (If you are referring to downstream device providing protection against overcurrent), AND adiabatic met for both L-N and L-PE faults.

    HOWEVER

    THe problem with socket-outlets, some would argue, is that there is no protection against the use of multiway extension leads permitting long-term moderate overload currents that might damage equipment, but not operate the OCPD ... if you subscribe to that chain of thought ... NO, it's a straight non-conformity with BS 7671