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table 41.1 max. disconn. times and the extra notes

psychicwarrior
good day folks


"Where in TT systems the disconnection is achieved by an overcurrent protective device and the protective equipotential bonding is connected with all extraneous-conductive-parts within the installation in accordance with Regulation 411.3.1.2, the maximum disconnection times applicable to TN systems may be used."


Does this [also] imply that where protective equipotential bonding is not needed, then TN times can be used ?


And what reasons might there be for no similar relaxation of effectively 411.3.2.4 to 411.3.2.3  (1s to 5s  for other circuits not covered in 411.3.2.2 and in the light of the above extracted note to 411.3.2.2 Reg ) ?


Regards

Habs


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    @mapj "'m not deliberately trying to be obtuse or incomprehensible, and neither are the reg writers..."


    I would want you to know that there is no reason to presume anyone would be thinking you (or the Reg writers) would be - same goes to the many others on here prepared to generously assist on a range of questions - I didn't and wouldn't presume that and its a shame my words gave that impression.


    Thank you for the additional comments. What you state makes sense...and dare I say now, obviously ! ;-)


    I was stuck on the thought that where a low impedance existed to allow an OPD to be used, then it would likely clear other circuit faults just as rapidly and did not give thought to the 411.3.2.4 retained for protecting against risky longer TN clearances being designed in.



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  • 0
    @mapj "'m not deliberately trying to be obtuse or incomprehensible, and neither are the reg writers..."


    I would want you to know that there is no reason to presume anyone would be thinking you (or the Reg writers) would be - same goes to the many others on here prepared to generously assist on a range of questions - I didn't and wouldn't presume that and its a shame my words gave that impression.


    Thank you for the additional comments. What you state makes sense...and dare I say now, obviously ! ;-)


    I was stuck on the thought that where a low impedance existed to allow an OPD to be used, then it would likely clear other circuit faults just as rapidly and did not give thought to the 411.3.2.4 retained for protecting against risky longer TN clearances being designed in.



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