Oven & hob on 13amp fused spur

gkenyon:

. . .

But, how is that any different to portable appliance testing that fails equipment just because the person employed to do the inspection and testing isn't aware of the design of a particular appliance - I've seen that lots too. Or the company who decided to change all the fuses in the BS 1363 plugs on monitors in the office I was working in from 13 A to 3 A based on power on the rating plate - within a week, most of the 3 A fuses had blown due to inrush !

. . .

 

Forgive me if this seems like a slight deviation but there lies a tale or two. It seems to be a question of official standards, widely available "helpful information" and the practical situation - there is lack of meeting of minds among these.


"Helpful information" often accompanies things likes assorted packs of BS 1362 cartridge fuses. Information like "3 A fuse suitable for appliances up to 720 W", based on a simple calculation assuming mains supply at 240 V. No account taken of initial inrush of current or power factor - and of course mains is at 230 V nowadays. In the case cited above, it sounds as though someone made the decision based on this rather tenuous advice rather than on experience.


In the dimming and distancing days of tungsten filament lamps, I used to fit 5 A fuses to portable lamps run off 13 A sockets. 3 A fuses would often blow when the lamp failed; 5 A fuses usually did not. Where the manufacturer of an appliance recommends a fuse size, I follow that recommendation and do not pretend to "improve" things by fitting a lower rating.


I have often wondered why 3 A, rather than 5 A, seems to be the official standard for the lower fuse rating. It is not compatible with fuse ratings on a consumer unit, where you will not find a rating less than 5 A. So an appliance running off an unfused plug would be protected at not less than 5 A. Despite being "non standard", 5 A fuses are readily available in most popular retail outlets, and sometimes even recommended by appliance manufacturers. (Does anyone have any ideas on this?)


As for computer monitors, they usually receive their mains supply from kettle-type connectors. I have found that the fuses factory-fitted in the 13 A plugs of these are often rated at 10 A, another non-standard size and not so easily available. I presume the reason for this  is to "officially protect" the IEC C14 plug, which is rated at 10 A. However I would not be overly worried if a 13 A fuse were fitted. The fuse is to protect the lead and the connector at the other end, but not the monitor, which should have is own internal fusing.

gkenyon:

. . .

But, how is that any different to portable appliance testing that fails equipment just because the person employed to do the inspection and testing isn't aware of the design of a particular appliance - I've seen that lots too. Or the company who decided to change all the fuses in the BS 1363 plugs on monitors in the office I was working in from 13 A to 3 A based on power on the rating plate - within a week, most of the 3 A fuses had blown due to inrush !

. . .

 

Forgive me if this seems like a slight deviation but there lies a tale or two. It seems to be a question of official standards, widely available "helpful information" and the practical situation - there is lack of meeting of minds among these.


"Helpful information" often accompanies things likes assorted packs of BS 1362 cartridge fuses. Information like "3 A fuse suitable for appliances up to 720 W", based on a simple calculation assuming mains supply at 240 V. No account taken of initial inrush of current or power factor - and of course mains is at 230 V nowadays. In the case cited above, it sounds as though someone made the decision based on this rather tenuous advice rather than on experience.


In the dimming and distancing days of tungsten filament lamps, I used to fit 5 A fuses to portable lamps run off 13 A sockets. 3 A fuses would often blow when the lamp failed; 5 A fuses usually did not. Where the manufacturer of an appliance recommends a fuse size, I follow that recommendation and do not pretend to "improve" things by fitting a lower rating.


I have often wondered why 3 A, rather than 5 A, seems to be the official standard for the lower fuse rating. It is not compatible with fuse ratings on a consumer unit, where you will not find a rating less than 5 A. So an appliance running off an unfused plug would be protected at not less than 5 A. Despite being "non standard", 5 A fuses are readily available in most popular retail outlets, and sometimes even recommended by appliance manufacturers. (Does anyone have any ideas on this?)


As for computer monitors, they usually receive their mains supply from kettle-type connectors. I have found that the fuses factory-fitted in the 13 A plugs of these are often rated at 10 A, another non-standard size and not so easily available. I presume the reason for this  is to "officially protect" the IEC C14 plug, which is rated at 10 A. However I would not be overly worried if a 13 A fuse were fitted. The fuse is to protect the lead and the connector at the other end, but not the monitor, which should have is own internal fusing.