How long do (plug) fuses last

Wyndham

Had a bedside lamp blow the bulb, and then found that it had also blown the fuse. Found our 'box of spare fuses' and have fixed it, and all seems well.

However, the replacement fuse has been in the box for some time - I'm talking years and maybe about 20. Do they have a 'shelf life'? Would I be better off buying a new one?

RobM99

I wouldn't think they'd decay much -they're metal, after all. As for new ones, £2.10 for 10 at Screwfix. Use the correct ampage,  1A for a light. Fuses protect equipment, not people!

Wyndham

RobM99 said:

I wouldn't think they'd decay much -they're metal, after all. As for new ones, £2.10 for 10 at Screwfix. Use the correct ampage,  1A for a light. Fuses protect equipment, not people!

The old fuse was 3A, so that's what I've replaced it with. Do you think that's wrong? Not sure I was aware that there was a 1A fuse if I'm honest...

Leon_W

We've had an E.K Cole (Ekco) Bakelite radio in the family since about 1947, which, i'm reliably informed, still has it's original Bakelite MK 3 pin plug, fuse and braided cable.  All still in excellent condition and working to this day. I do not think fuses have a shelf life   

Edited to add.  We've had those bedside lamps from the likes of B&M and The Range with the small, clear, incandescent globe type bulbs. They're rubbish, and 9 times out of ten take the fuse with them when the bulb blows. I've since fitted equivalent LED bulbs which are much better.

Section62

RobM99 said:

I wouldn't think they'd decay much -they're metal, after all. As for new ones, £2.10 for 10 at Screwfix. Use the correct ampage,  1A for a light. Fuses protect equipment, not people!

Fuses protect cables, equipment AND people.

You won't get a 1A BS1362 fuse from Screwfix.

3A is commonly the correct rating for portable lamps/lights. If there is no label on the lamp saying what the correct rating is, and the fitted fuse is anything other than 3A, then further investigation is required.

RobM99

My mistake, 3 amp.   However I doubt a 13A fuse in bellwire would protect the cable!

Section62

Wyndham said:

However, the replacement fuse has been in the box for some time - I'm talking years and maybe about 20. Do they have a 'shelf life'? Would I be better off buying a new one?

They don't decay to any appreciable extent.  You are probably better off with a 20-year old one than trying to buy a new one which isn't a 'fake' (and therefore possibly not correctly manufactured).  If you buy replacements only get them from the most reputable retailers (e.g. supermarkets, DIY chains etc)

Bendy_House

Anyone got a definitive explanation why blowing filament bulbs often trip MCBs (or even fuses, as per the OP)?!

Read a few, but they don't seem quite convincing.

Section62

RobM99 said:

However I doubt a 13A fuse in bellwire would protect the cable!

Which is why no electrically competent person would use a 13A fuse to protect bellwire.

victor2

Bendy_House said:

Anyone got a definitive explanation why blowing filament bulbs often trip MCBs (or even fuses, as per the OP)?!

Read a few, but they don't seem quite convincing.

Nothing definitive, but I've always assumed a shorter part of the dying filament manages to connect the two pins together in its final hurrah and take enough of a surge to blow the fuse.

Scrounger

Bendy_House said:

Anyone got a definitive explanation why blowing filament bulbs often trip MCBs (or even fuses, as per the OP)?!

Read a few, but they don't seem quite convincing.

Broken filament falls down inside the bulb and shorts the supply?

Sounds plausible.


Scrounger