Appliance fuses

[stillp]

My understanding is that the current vs delay curves are specified only for 3A and 13A

Your understanding is not correct.

Thanks for the correction; feel free to update the Wikipedia page for BS1363, which currently says:


BS 1362 specifies sand-filled ceramic-bodied cylindrical fuses, 1" (25.4 mm) in length, with two metallic end caps of 1/4" (6.3 mm) diameter and roughly 1/5" long. The standard specifies breaking time versus current characteristics only for 3 A or 13 A fuses.

• For 3 A fuses: 0.02–80 s at 9 A, < 0.1 s at 20 A and < 0.03 s at 30 A.
• For 13 A fuses: 1–400 s at 30 A, 0.1–20 s at 50 A and 0.01–0.2 s at 100 A.

I can see why they wrote that - 3A and 13A are the only values for which the time/current characteristics are drawn as a curve (as an example), but that is not a specification, and is rather misleading.

 

[eveares]

In that case, I think you should probably fit a larger diameter flex.

Where did I say it's wired in flex??? It's wired in 1.5mm² T&E what is only a couple of meters away from it's FCU. I used the 2 Amp fuse in the FCU to give the Alarms PCB a extra layer of protection.

I also use 2 Amp BS1362 fuses in my X10 light switches as is what they come with by default and have a maximum allowed load of 400 watts. The Fuse holder slides out the bottom of them.

 

[Iggifer]

I also use 2 Amp BS1362 fuses in my X10 light switches as is what they come with by default and have a maximum allowed load of 400 watts. The Fuse holder slides out the bottom of them.

Maybe you should think about fitting a 500mA if they keep dying! Or not bother with overcomplicating things

 

[endecotp]

Here; sorry if misunderstood.

I often use 2A vs 3A fuses in sensitive equipment like alarm panels to give a extra margin of safety. Also 0.75mm² flex is rated at 6 Amps; Now say it's got a 5A load applied through it, both 3A and 13A fuses are unsustainable, thus the need for plug top fuses other than 3 and 13 amp.

 

[eveares]

Maybe you should think about fitting a 500mA if they keep dying! Or not bother with overcomplicating things

Only the Wall Dimmer Light switches have a replaceable fuse in them, they only take a line and switched line. The appliance wall switches what are suitable for CFLs/LED's do not have a replaceable fuse and also require a neutral.

Lucky I have yet to have my house burn down by a X10 device going up in flames. Mind you, was pretty scary when I removed the plug in X10 appliance module and the line pin got stuck in the trailing socket whilst being red hot.

 

[securespark]

I assumed that a fuse for the intruder alarm panel was being referred to (which wouldn't be a BS 1362 fuse).

I thought that reference was to a fuse for the supplying FCU ?

I used to install a great deal of ADE panels. Their instructions asked for a 2A 1362 in the FCU.

You can buy 1362's in 1A, 2A, 3A, 5A, 7A, 10A and 13A.

But the standard allows any size, with 3A coloured red and 13A brown. All other ratings should be black.

 

[Risteard]

I assumed that a fuse for the intruder alarm panel was being referred to (which wouldn't be a BS 1362 fuse).

I thought that reference was to a fuse for the supplying FCU ?

That's probably what he meant, but I initially took it to be the internal one in the panel.

 

[ericmark]

Although the preferred size for a plug may be 3 and 13 amp, or a fuse connection unit which takes the same size fuse it could be any in the range 1,2,3,5,7,10 and 13. Today wife came home with a new pressure cooker and I read the instructions, the lead set uses a 10A connector, the power is 732~871 watt and there are two references to fuse size in the instructions. "ASTA or BS approved type conforming to BS 1362 and of the same rating" and "Fuse Type / Value BS 1362 / 13A" it does seem wrong to stipulate a fuse larger than the rating for the lead sets plug! In the old days I would have fitted a 5 amp fuse.

In a shaver plug although some are 1A BS 646 some still use a 1A BS 1362 so always have a few in stock.

 

[ban-all-sheds]

So my choice would be to fit a 5A for a 4 amp load rather than a 13 amp from the standard stock.

Please describe what failure modes would not result in an appliance fire from a fault creating 1.8kW of heating within the appliance (nearly equivalent to a 2-bar electric fire, and 2x what the appliance is supposed to dissipate) for ever (which is what a 5A fuse could allow to happen) but which would result in a fire if the fault was larger or went on for longer.

When you do, please note that only something with a sound engineering basis will be acceptable, and that superstition, old-wives-tales, ignorance, and what you in your ignorance consider to be "common sense" will not be acceptable.

Or just go away.

 

[ban-all-sheds]

It seems to me, your gripe, if indeed a genuine one is, in fact, with the manufacturers for making products which catch fire when installed as they instruct.

As you cannot use a small fuse, would you consider it necessary to rewire the cooker with a minimum of 4mm² conductors - perhaps 6mm²?

I don't see how you could be happy when not doing so.

I can see how.

It's called lack of understanding.

 

[ban-all-sheds]

But responsible installers should .. apply fuses using a professional approach.

People keep trying to tell you that, but you won't have it.

 

[ban-all-sheds]

I used the 2 Amp fuse in the FCU to give the Alarms PCB a extra layer of protection.

THAT

IS

NOT

WHAT

THE

FUSE

IN

THE

FCU

IS

FOR.

 

[ban-all-sheds]

I often use 2A vs 3A fuses in sensitive equipment like alarm panels

What do the manufacturer's instructions for those panels say?

And particularly what do they say re installing them in France, Germany, Italy etc? I assume the equipment is CE marked?

 

[ban-all-sheds]

[/pedentry]

Actually it is 'pedantry'.

 

[ban-all-sheds]

I also use 2 Amp BS1362 fuses in my X10 light switches as is what they come with by default and have a maximum allowed load of 400 watts. The Fuse holder slides out the bottom of them.

So that's a fuse which is part of the equipment, there for providing internal protection.

Nothing to do with any fuses in plugs or FCUs, or other devices upstream, which are there to protect the cables supplying the switches.