Plastic switch in external meter box

Presumably something with a lot of high current terminal connections is, purely on probabilistic grounds, more like to to go whoosh than a FCU or fuse switch.

From the pictures I've seen overheating tends to happen on high current terminals - either tails to incomer, incomer to bus-bar, bus-bar to high rated OPD, or outgoing terminal of the same, or on the N bar connections for the other side of the same circuits. Lower demand circuits - e.g. lighting circuits and most of the time ordinary socket circuits, individul MCBs for CH controls or alarm panels don't seem to draw enough current for enough time to pose as much of an overheating risk. So while your 16-way split load CU might look like a complete mess and full of potentially loose terminals, I suspect only a relatively small proportion are actually at a high risk of seriously overheating if loose - maybe those associated with the incomer and perhaps shower or cooker circuits. So a switchfuse carrying perhaps the entire load for an installation might well be somewhat lower risk by virtue of having fewer terminals - but perhaps only by maybe a factor of two or so rather than any order of magnitude.


I could see the argument could be different for a large number of  long duration loads though - say an off-peak CU feeding storage heaters.


DNO/supplier equipment overheating isn't entirely unknown either - so a reduced number of vulnerable terminals is no guarantee.


   - Andy.

Presumably something with a lot of high current terminal connections is, purely on probabilistic grounds, more like to to go whoosh than a FCU or fuse switch.

From the pictures I've seen overheating tends to happen on high current terminals - either tails to incomer, incomer to bus-bar, bus-bar to high rated OPD, or outgoing terminal of the same, or on the N bar connections for the other side of the same circuits. Lower demand circuits - e.g. lighting circuits and most of the time ordinary socket circuits, individul MCBs for CH controls or alarm panels don't seem to draw enough current for enough time to pose as much of an overheating risk. So while your 16-way split load CU might look like a complete mess and full of potentially loose terminals, I suspect only a relatively small proportion are actually at a high risk of seriously overheating if loose - maybe those associated with the incomer and perhaps shower or cooker circuits. So a switchfuse carrying perhaps the entire load for an installation might well be somewhat lower risk by virtue of having fewer terminals - but perhaps only by maybe a factor of two or so rather than any order of magnitude.


I could see the argument could be different for a large number of  long duration loads though - say an off-peak CU feeding storage heaters.


DNO/supplier equipment overheating isn't entirely unknown either - so a reduced number of vulnerable terminals is no guarantee.


   - Andy.