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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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    true - 13A fuses and 16A breakers do not really discriminate,  (13A fused spurs might actually have closer protection if they were wired up with a 16A MCB instead)  but that is what we mean by a 13A circuit - one that can take 13A all day, but cuts off after some rather indeterminate time at 20A, and the cable rating reflects that (hopefully), in that a cable rated for X amps continuous, can carry a few times X for a short time.


    (fuses have the nice feature of not jamming or welding, and not having a problem with not getting faster with larger fault currents, so are better for dead shorts, - a disconnection is pretty much guaranteed, only the number of bits of busted ceramic to be swept up afterwards rises with the PSSC.)
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    true - 13A fuses and 16A breakers do not really discriminate,  (13A fused spurs might actually have closer protection if they were wired up with a 16A MCB instead)  but that is what we mean by a 13A circuit - one that can take 13A all day, but cuts off after some rather indeterminate time at 20A, and the cable rating reflects that (hopefully), in that a cable rated for X amps continuous, can carry a few times X for a short time.


    (fuses have the nice feature of not jamming or welding, and not having a problem with not getting faster with larger fault currents, so are better for dead shorts, - a disconnection is pretty much guaranteed, only the number of bits of busted ceramic to be swept up afterwards rises with the PSSC.)
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