Compliant?

Is there still something that we've all missed?  Please let me know, it's driving me mad!  I've been retired for three years but your question has prompted me to order a copy of the 18th ed.  Should I wait for it to arrive and spend some times searching through it, or do you consider that it is compliant?

I think we've agreed that the B40 can't be relied upon to provide fault protection (either L-N or L-PE) to the 1.0mm² cable. (The 30mA RCD probably won't help much either, even for L-PE faults - above 575A the energy let-though (I²t) of the RCD for 40ms will exceed the withstand (k²S²) of the cable (13,225A²s for 1mm² with k=115).)


So we're looking at whether the three conditions of 434.2.1 to allow fault protection to be positioned downstream of the reduction of c.s.a. are satisfied. If it helps at all that particular regulation seems not to have changed for a very long time - it's practically identical to 473-6 in the 15th Ed.


(i) 3m rule - at 2.5m long that's an easy pass.

(ii) and (iii) are the stumbling blocks - whether it's installed in such a manner to reduce the risk of faults, fire and danger to persons, to a minimum.  I'm still not comfortable that it is - the whole setup feels to me a order of magnitude away from the situations where this regulation is normally applied, but perhaps Z (who as see it of course) is more comfortable with it?


  - Andy.

Is there still something that we've all missed?  Please let me know, it's driving me mad!  I've been retired for three years but your question has prompted me to order a copy of the 18th ed.  Should I wait for it to arrive and spend some times searching through it, or do you consider that it is compliant?

I think we've agreed that the B40 can't be relied upon to provide fault protection (either L-N or L-PE) to the 1.0mm² cable. (The 30mA RCD probably won't help much either, even for L-PE faults - above 575A the energy let-though (I²t) of the RCD for 40ms will exceed the withstand (k²S²) of the cable (13,225A²s for 1mm² with k=115).)


So we're looking at whether the three conditions of 434.2.1 to allow fault protection to be positioned downstream of the reduction of c.s.a. are satisfied. If it helps at all that particular regulation seems not to have changed for a very long time - it's practically identical to 473-6 in the 15th Ed.


(i) 3m rule - at 2.5m long that's an easy pass.

(ii) and (iii) are the stumbling blocks - whether it's installed in such a manner to reduce the risk of faults, fire and danger to persons, to a minimum.  I'm still not comfortable that it is - the whole setup feels to me a order of magnitude away from the situations where this regulation is normally applied, but perhaps Z (who as see it of course) is more comfortable with it?


  - Andy.