Fuse replacement 2A with 3A

[scooterscot]

The one thing no one has mentioned. Fire.

Is this a table lamp or similar load? Perhaps the appliance and it's cable were only ever rated to withstand a couple of amps.

Make you sure your smoke alarms are working.

[bogeyman]

The one thing no one has mentioned. Fire.

Is this a table lamp or similar load? Perhaps the appliance and it's cable were only ever rated to withstand a couple of amps.

Make you sure your smoke alarms are working.

Good point actually.

Although probably the cheapest, flimsiest, flat twin-core has a tolerance of more than a few amps above rated.

Heating and fire issues are probably more to do with bad connections, oxidisation, breakage of wires in stranded cables etc. that cause the current to flow though a higher than normal resistance causing a local heating effect.

The local heating effect exacerbates the cause of the problem and eventually the connection will fail - if it hasn't heated up enough to set fire to the insulation or something first.

A correctly rated fuse would do nothing to mitigate this.

[suityou01]

Exactly. As I said originally, I wasn't condoning the practice of overrating fuses, just trying to point out that, given the manufacturing tolerances, there wasn't much difference in this specific case.

Sorry BM gotta jump in here.

BS1362 starts at 3A. This is your bog standard 1363 plug cartridge fuse.

The 2A fuse is likely to be the glass kind that came from inside a device. The OP has prolly got his PC power supply in bits and has found a blown fuse and wants a cheap quick fix, rather than jolly on over to Maplin and buy a pack of 10 for £2.69

According the the great british wiring regs, a fuse is a protective device. It is there to protect the equipment not the operator I should hasten to add.

The 3A fuse has a greater circumference than the 2A glass fuses and would bend the clamp so that is a problem, although when the relevant 2A fuse was sought the clamp could be bent back to tightly clasp the 2A fuse. Repeated abuse of the clamp would result in metal fatigue though.

Also, given the tolerances argument, lets say for arguments sake they are both +-10%

This means the peak current for the 2A fuse is 2.2A and 3.3A for the 3A chap.

So an extra 1.1A could be provided to the unit.

IIRC P(ower) = V*I

so at 230V P = 230 * 2 = 460W @ 2A

and the power @ 3A would now be
P=230 * 3 = 690W

An extra 230W of power.

Now given our tolerance of +-10% the peak current is 3.3A

P=VI = 230 * 3.3 = 759W

So our little 460W device is now 3 quarters of an electric bar fire.

These devices are rated by the designers for a reason, and 2A was chosen to protect the device. Worst case a small fire, best case a knackered set as the thing that blew the fuse in the first place has not been cured, and has just has an extra 1.1A pulled through it.

HTH

[DimPrawn]

Kick it and then try plugging it into another plug hole - easy.

I bet you say that to all the men.

[bogeyman]

You need the ZeitGhost(tm) Fusetester.

It tests every fuse to destruction.

Patented.

You are the acknowledged expert here, I think.

What's your view?

[Moscow Mule]

I bet you say that to all the men.

Coffee keyboard moment....

[cailin maith]

I bet you say that to all the men.

[DaveB]

Kick it and then try plugging it into another plug hole - easy.

As the Actress said to the Bishop.

[Andy2]

I wonder if OP is still alive ?

[bogeyman]

Sorry BM gotta jump in here.

BS1362 starts at 3A. This is your bog standard 1363 plug cartridge fuse.

The 2A fuse is likely to be the glass kind that came from inside a device.

Yep but there are still many 2A plug cartridge fuses around. I have a couple in my box of fuses, but as you say 3A is now the minimum.

I guess the reason that BS1362 starts at 3A, is that there was no point rating a plug cartridge fuse at anything less.

Nowadays, any device that draws less than 3A from the mains should have internal protection (internal glass fuses etc.) against overloads, shouldn't it?