Fuses (not a serious question)

[Scott]

I left a plug fuse in my jacket pocket, which I then washed at 40 degrees (mix programme). Could I still use it (after drying out obviously) or will its electrical properties be compromised?

[Brian Gaff (Sofa 2)]

I'd try it and see. Is it one of those filled with what looks like talc? Brian

[Scott]

I don't know what's inside it and to find out would destroy the fuse.

Also, what if it appears to work? Could it not then let through far more than the rated current?

As I say, it is not a serious question as I will be using a new fuse out of the packet.

[spuorgelgoog]

AIUI plug fuses are sand filled (unless they're counterfeit, when they're not)

I suppose it would work okay in normal use as the fusewire would have lower resistance than the damp sand, but if a fault ruptured the fusewire all the current would pass through the damp sand, which might then explode.

You could try it in the garden with a very long extension lead ...

Owain

[Scott]

What if the damp sand cooled the fusewire? Could it not then allow an excess current to pass?

Since you raise the issue, is there a way to identify counterfeit fuses? Can it be done by weight or perhaps by sound?

[spuorgelgoog]

"A genuine BS1362 fuse weight is 2 grams on average, anything higher or lower than this weight could mean it has not been filled with the required quartz sand."

"The combined weight of the 8 fuses is 18g. The weight of 8 genuine fuses on the same scales is 23g. " with video of fake fuse going bang

Owain

[Scott]

Thanks very much. Is the weight the same regardless of amperage?

The links are helpful too.

[spuorgelgoog]

I would expect so, within the resolution of domestically-available scales for the variation in thickness of the fuse wire.

If you've got access to a lab that can weigh an anorexic gnat's todger - or are weighting batches of thousands of identical fuses - you might be able to discern a difference.

Owain

[FMurtz]

I would think it would dry out in short order.

[Bill Wright]

Less the variation in weight of the displaced sand.

Bill

[Brian Gaff (Sofa 2)]

Well your question is unanswerable but assuming its not got wet inside and is simply glass and wire, I think it will be fine. Fuses are pretty crude devices, and long before it got to its rated blowing current, I'd imagine the heat would evaporate the water. Brian

[John Rumm]

For the price of a fuse I would not risk it, since its impossible to say how it would perform under fault conditions. Any moisture inside would convert to steam on a high current fault, and make the enclosure more likely to rupture.

[Scott]

You're on the the ball this morning, Mr.

[Scott]

Thanks. Seriously, that was my plan but I just wondered out of curiosity.

[tabbypurr]

It would need to be dried out, eg in an oven at a bit above 100C. Trouble is you'd be hard pressed to tell when it was dry. If water remained it would explode under heavy fault current. Mains plug fuses are metal wire connected to metal end caps with a ceramic tube filled with sand, so the materials themselves would not be affected significantly by short water exposure.

[whisky-dave]

But would that sand weigh more than the extra thickness of the fuse wire ?

Occasionaly I've picked up a resistor (when a student has asked me what reistance it is) and held it in my hand and said that weighs about 1 kilo ohm.

They look at me in amazement, then I say I know it's 1k because of the colour code that's why you should know the resistor colour code and how to use it !.

[Chris Green]

Hardly, the resistance of the wire inside it will be a fraction of an ohm, the resistance of the 'damp sand' (or whatever) will be tens if not hundreds of ohms. Water isn't a very good conductor, distilled water is almost an insulator, it's mostly down to dissolved impurities that water conducts at all.

[Scott]

Would detergent make a difference when it has been in the washing machine - or heat?

(Again, not a serious question as I shall use a new fuse out of the packet when the time comes. )

[Scott]

Would detergent make a difference when it has been in the washing machine - or indeed heat?

(Again, not a serious question as I shall use a new fuse from the packet when the time comes.)

[Chris Green]

It would make it somewhat conductive as opposed to not conductive at all but I still think the resistance of the 'damp sand' would be up in the hundreds of ohms.