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Grid switch ratings enquiry

Farmboy
Had an interesting chat with a tech dept this afternoon after coming across some grid switches in a domestic kitchen.


Four grid switches (sharing a common backbox) are each fed via their own 16A cb's, and each feeds 1G sockets (for a cooker hood, fridge freezer, etc). Ignoring the cable sizes (the focus being on the grid switches), given the 13A plug fuses limits the loads in each cct, would you have the current rating of the grid switches equal to or higher than the 16A cb's (e.g. 20A), or lower (but equal to or higher than the socket rating e.g. 13A/14A)?


F
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    What about fault currents? 559.5.1.204 allows a lighting circuit to be protected by an over current protective device up to 16 Amps, but we generally use 6 Amp rated light switches. There is normally no problem with that.



    But you can't just ignore all the other regulations because you've compiled with one of them.  Have a read of 536.4.2.3 that I mentioned earlier.

     

    Neither the light switch nor the grid switch has to survive after closing onto a fault, and probably won't



    Maybe not, but it might be nice if it survived if it was already closed when the fault occurred - and in any event it needs not to blow up to the extent of taking someone's arm off or eye out - how can you show that's the case if you don't have any consideration of the energy let-though by the protective device?


       - Andy.
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  • 0

    What about fault currents? 559.5.1.204 allows a lighting circuit to be protected by an over current protective device up to 16 Amps, but we generally use 6 Amp rated light switches. There is normally no problem with that.



    But you can't just ignore all the other regulations because you've compiled with one of them.  Have a read of 536.4.2.3 that I mentioned earlier.

     

    Neither the light switch nor the grid switch has to survive after closing onto a fault, and probably won't



    Maybe not, but it might be nice if it survived if it was already closed when the fault occurred - and in any event it needs not to blow up to the extent of taking someone's arm off or eye out - how can you show that's the case if you don't have any consideration of the energy let-though by the protective device?


       - Andy.
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