grouping factor of a cable with irratic use

[blue eyes]

Hi Guys

I am trying to work out a system to be run in a small church like premises with irratic use.the system is to be in trunking so grouping is going to be effected by using the loadings of each circuit(which is not for long periods)is there any way of over coming these restriants I know I could say with confidence that grouping can be done away with due to the usage of the circuit but these would then fall foul of the regs.
the regs do say all factors are designed for circuit at full load with constant use.. but I find no allowance made to factor a irratic load.

any help would be great as the cable are so large

cheers Blue eyes

 

[Sav]

Hi,
What sort of erratic loads are we talking about?

Best regards,
Sav

 

[blue eyes]

nothing realy ketle is realy the highest load there will be lighting circuits will not be high due to it being spread around

 

[FatBob]

Appendix 4 Table 4C1 Note 9: if a cable is expected to carry not more than 30% of its grouped rating, it may be ignored for the purpose of obtaining the rating factor for the rest of the group, but it depends on what you mean by erratic?

 

[blue eyes]

Appendix 4 Table 4C1 Note 9: if a cable is expected to carry not more than 30% of its grouped rating, it may be ignored for the purpose of obtaining the rating factor for the rest of the group, but it depends on what you mean by erratic?

yes my problem is such as a 2kw ketle which can run on and off but when it is running it uses more than 30% of 20A circuit thus should be factored for grouping,it is just stupid but i cant find a way to use common sense