Small problem about a plug fuse

Section62

Bendy_House said:

Anyhoo, as you know, if the OP follows all of my advice, they will have a good night's sleep, and get the correct info from either the manufacturer, or with our assistance on here. Unless you have driven them away.

I'd hope they took the advice in the fourth post in the thread, and had a very relaxing night.

Risteard

Section62 said:

Mutton_Geoff said:

Section62 said:

I would check the manual/instructions (if you can find them) for the correct rating, but otherwise replace the 13A fuse for a 5A one as soon as you can.

The freezer won't 'blow up', but you have a lower level of protection than you had before.  Aged fuses can blow for no reason, so the fact this one has blown means you can't be sure that either the freezer is faulty, nor that a 5A fuse is the wrong rating.  It could just be a random failure of a fuse.

I'm sorry, that's nonsense. Fuses protect the cable, not devices. The freezer will be fine on a 13A fuse although many fridges/freezers are not designed to be operated in ambient temperatures below 5 or 10C.

Disagree. What you are suggesting is unsafe.

Fuses and other protective devices protect the circuit downstream of the protective device.  You can't separate the cable and the appliance - the cable needs to be protected, but so does the appliance, both form part of the circuit.  There will be wiring and/or circuit boards within the appliance which, unless given additional protection, will rely (to a greater or lesser extent) on the protection given by the fuse in the plug or FSU.

You can't know that the freezer "will be fine" on a 13A fuse without knowing the rating of the internal wiring and components and/or the presence of additional internal protective devices.  In any event, if the cable from the plug to the freezer requires protection by a 5A fuse then a 5A fuse is what needs to be fitted.

No idea what the ambient temperature has to do with the fuse rating.  Low ambient temperatures make most freezers work harder, but that won't determine whether a 5A or 13A fuse should be fitted.

Replacing a 5A fuse with a 13A fuse gives a lower level of protection. That should be an undisputed fact.

Technically he is correct. The fuse is there to protect the cable. If the appliance needs protection for the appliance then it should be internally fused. That said, if the appliance manufacturer has specified a certain rating of fuse then at least to prevent arguments if something goes wrong it would be prudent to observe that.

GDB2222

I loaned an extension reel to a builder, who attached a wallpaper steamer to it, but didn’t bother to pull all the cable out of the reel. By the time the fuse 'blew', the insulation on the cable inside the reel had melted completely. If it had cooked a bit more inside there before the conductors touched, it might have caught fire. 

Curiously, it was the 30A MCB that switched itself off, rather than the 13A fuse in the plug. Or, maybe they both went at the same time, as I don’t remember checking the plug fuse afterwards. 

daveyjp

If the appliance has had a 5A fuse since new it needs a 5A fuse when it is replaced.

Would anyone saying a 13A will be fine also suggest a paperclip, which will do the job?

GDB2222

The OP hasn’t been online since posting. Hope she’s okay?

Bendy_House

Catching up on lost sleep.

Bendy_House

GDB2222 said:

I loaned an extension reel to a builder, who attached a wallpaper steamer to it, but didn’t bother to pull all the cable out of the reel. By the time the fuse 'blew', the insulation on the cable inside the reel had melted completely. If it had cooked a bit more inside there before the conductors touched, it might have caught fire. 

Curiously, it was the 30A MCB that switched itself off, rather than the 13A fuse in the plug. Or, maybe they both went at the same time, as I don’t remember checking the plug fuse afterwards. 

That is weird.

I wonder if perhaps the RCD went? Or the MCB was actually an RCBO?

Or, most likely, both the fuse and MCB did go simultaneously.

When cables heat up, their resistance increases. There is also, I understand, an inductive resistance (impedance?) when a cable is coiled, and both of these would surely have had the effect of reducing the overall current flow drawn by the steamer. So, most likely, the wires did end up touching.

 

Ectophile

daveyjp said:

If the appliance has had a 5A fuse since new it needs a 5A fuse when it is replaced.

Would anyone saying a 13A will be fine also suggest a paperclip, which will do the job?

No, because a paperclip will not comply with BS5362 BS1362. (Fixed per next comment by Risteard)

Risteard

Ectophile said:

daveyjp said:

If the appliance has had a 5A fuse since new it needs a 5A fuse when it is replaced.

Would anyone saying a 13A will be fine also suggest a paperclip, which will do the job?

No, because a paperclip will not comply with BS5362.

To clarify, it's BS 1362

Bendy_House

I think I've just worked out what 'BS' stand for.