Weird fuse deployment

[kingeri]

I was doing an EICR today on a bog standard terraced house, and as part of that was checking the fuse ratings in the boiler FCU etc. (always do this as often people can't be bothered to swap out the 13amp fuse). Anyway, found the boiler FCU was fitted with a 1amp fuse, a spur for a built-in computer desk area on the landing was fitted with a 7amp fuse, and a lighting spur in the loft was fitted with a 2amp fuse. The FCU on the landing for the towel rail in the bathroom was fitted with a 10amp fuse. Nothing actually wrong with the ratings as such, but I did find it decidedly non-standard. Anyone else seen this kind of thing?

 

[GLENNSPARK]

I had a Saturday job in a TV shop when I was at school, about 30 years ago. One of my jobs was to fit plug tops to new TVs. I was told to fit 5A fuses for colour TVs and 3A fuses for B&W TVs. Apparently, 3A fuses for colour TVs had a habit of blowing.

So in answer to your question, I use 5A fuses in 30 year old colour TVs :teeth_smile:

you would use a 5A fuse on an inductive load where a 3A fuse would be fitted if the load were not inductive....(inrush)...

 

[Kate]

introducing fused neutrals....
hmm...well i must say i expected better from you Kate...i really did..

Eh?? Was just letting them no im not on anyones side. neutral like switzerland (or sweden, some country beginning with s)

 

[Lucien Nunes]

Not domestic, but I sometimes use a smaller fuse than would be needed to protect the cable, on things that are likely to fail short such as large filament lamps or where damage is likely, to reduce the splash and to help discriminate (to a degree anyway) with upstream protection. E.g. a B20 stands a bit more of a chance of staying in vs. 7A cartridge than 13A. I have a 2A in my toolbox soldering iron etc for the same reason - if I mangle the flex I want the smallest bang possible but 1A have (or used to have) lower breaking capacity.

I only know one application that specifically asked for a 7A BS1362 fuse, which was a particular stage lighting dimmer from the 1980s that had plug-fuse-size holders. What used to puzzle people was that the circuits were rated for 2.5kW at 240V, they could never work out how the fuses survived. The idea was again to minimise the let-through when a lamp failed, to help stop the triac from blowing at the same time.

 

[SJD]

According to Wikipedia:

"When the BS1363 plug was first introduced, there were 5 fuses in the official BS1362 range which were (with their specified colour): 2 (blue), 5 (grey), 7 (black) 10 (yellow), and 13 (brown) amps. The 7 amp fuse was deleted from the official range fairly early on, though remained available for many years ..."

"The current version, BS1362:1973, allows any fuse rating up to 13A, with 3 amp (coloured red) and 13 amp (coloured brown) as the preferred (but not mandated) values when used in a plug. All other ratings are to be coloured black (this is why 5 amp fuses are now black instead of grey)."

 

[Richard Burns]

Vacuum cleaners often have five amp fuses.

 

[moospark]

Five amp plugs often have five amp fuses.

 

[44ALLAN]

Would a 1/2/3/7 or 10Amp fuse also suffice is the question if the cleaner has a 1.5mm flex?
Is the fuse there to stop the vacuum cleaner going on fire if it jams!!!

Double mars bar on offer now lol.