Fuse query

[Grummyb]

Hi funsters a question for all you electrical wizards my distribution panel has 4 32mm long 10amp fuses and I need to get some replacements and looking on an electrical wholesale website I have lots of options like 7.5 amp continuous 10amp blow or 10 amp continuous 15amp blow so which do I need

 

[xsparks]

I would replace it with the 10/15. The reason I say this is if your drawing close to the limit of a lesser rated fuse it will probably get hot and this will weaken the fuse carrier, which creates more heat and eventually the fuse becomes loose.

 

[Grummyb]

I was thinking of going for the 15 amp blow working on the assumption that if I've got 10 amp already the 7.5 might not be big enough but your theory makes good sense
Thanks

 

[xsparks]

I found that the fuse rating for my fridge on 12v whilst travelling was too near it's limit and got hot enough to stop it working. The fuse became loose and the holder became unusable and had to be replaced.

 

[Grummyb]

15 amp blow it is then

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[autorouter]

15 amp blow it is then

Agreed. Fuses are normally specified by the amps they will carry continuously without blowing. So if a 10 amp fuse is specified, it means it needs to be able to carry 10 amps without a problem.

 

[David and Sally]

You also have to take into account the surge current on start up. 10 amp continuous may well need 15 or even 20 amp surge.
Good point about the heat building up. Tight contacts must be important too.

 

[TheBig1]

remember, a fuse is there to protect the wiring, not the device. Never up the rating of a fuse without first confirming the wire it protects is safely capable of handling a higher current.

 

[donkey]

I undertook an investigation a few years back, where there was a fault on caravan lights. kept blowing car light fuse. French electrician fitted bigger fuses. Result wiring loom burnt out from front to back of car.
Geoff

 

[xsparks]

It's common practice to use fuses with a run rate and a blow rate particularly for electric motors where there is a surge current on start up. Obviously common sense is required when installing a higher rated fuse. It doesn't hurt to seek advice regarding the current capacity of the wiring in use. I would suggest that Donkeys (electrician) didn't use due diligence.

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[donkey]

It was in France, not sure they are aware of due diligence over there.
Geoff