3/5/13 Amp Fuses For Plugs And Fused Spurs...

[OnlQQker]

As most people really don't have an understanding of electricity whatsoever, and the amount of times I have come across the wrong size fuse in a plug or FCU.

I don't know but surely this should be addressed somehow.

Moulded plugs are all good as well on the new table lamp somebody has just purchased, but one day the fuse blows and a 13amp one is most of the time shoved back in.

Seems rather a deadly issue to me!

Just thinking out loud again.

 

[Lister1987]

And why just London Fire Brigade

Harking back to the AMD3. change to metal cu, believe it was LFBs persistence that made it go through.

came across this; https://electrical.------.org/wirin...tection-against-fire-the-fire-officer-s-view/

 

[static zap]

Is it true , most appliance cables now 0.75mm ?
Reason for 15A .. Fuse busting capability.
..Thanks to fuse less European plugs ...
(Dumbed down like somewhere else )

 

[telectrix]

a bit unrelated, but.... my lady's Ford (2012 vintage) has a BS1361 socket in back of centre console, so ther must be an inverter somewhere. it wasn't working. investigation found that the inverter was fed , along with the cig'lighter from a 10A fuse, which had blown. 10A@12V eaquates to 0.5A @ 240V. bloody pointless when the female of the species plugs in hair dryer/straighteners etc. it would even struggle to charge a mobile phone. what's the point?

 

[static zap]

some numpty takes out a 3A fuse and replaces with a 13A. BOOM ...... Darwinism strikes again.

Probably of an old laptop , they had the power mobile phones have now ! ( Fancy accesories -were Silly money )
... or other low current purposes ..The mind would boggle... ouch ...

 

[Darkwood]

I think there is somewhat of a confusing idea of plug top fuse rating here, for the majority of plug tops the fuse is simply there for short circuit protection and not overload as the majority of appliances would sit in the category of fixed load device/item.

If you actually look at old vacuum cleaners (bigger motors) or fridges etc you will note that the fuse (13amp) is larger than the rated current carrying capacity of the flex so for all purposes it cannot be there for overload protection as the flex would readily melt and short before the fuse popped, inrush on both these items limit the choice of fuse fitted to 10amp and 13amp but as we no longer recognise 10amps our PAT testing values then we see 13A been the fitted fuse of choice.

Noted here that this does not apply to extension with multiple outlets as this by its nature does need to overload protect the cable as it does not fit in the fixed load category even if items plugged in do, noted it is easy to plug in various heavy loads and exceed the flex rating so fusing needs to be correct.

Smaller fuse ratings are commonly put on electronic goods with low inrush and low current demands, it can be argued that it helps protect the electronics in the event of a S/C by reacting quicker but in truth a dead short will not be all too fussy at blowing a 13amp or a 3amp instantaneously and if a device has sensitive electronics then by good design it should have a quick acting fuse integral to the electronics.

The only risk of fire I see is if the load is not fixed which is rare in normal domestic items although those that carry say motors etc will have integral thermal protection anyway by design, a stalled motor should be protected in other ways than a plug top fuse.

 

[Lucien Nunes]

Returning to the original point, these days almost all appliances are fine with a 13A fuse. They are designed to withstand being protected at 16A for EU-wide compatibility, which as mentioned has driven the general use of 0.75mm² flex. The only plugs that definitely require a smaller fuse are extension leads rated <13A (which are a menace anyway) and old appliances and lights with 0.5mm² flex or where the manufacturer stipulated that fuse size. FCUs might require a fuse <13A for some dopey extractor fan or to achieve disconnection times where deriving a long radial circuit with high Zs, but this is a limited application and typically again a 13A fuse would probably offer sufficient protection.

We have to look at the plug fuse in context today. Applilances are built with more internal protection against overload and faults, so a plug fuse <13A is no longer a key component in appliance safety. Its other purpose, to allow appliances to be used on highly rated circuits (32A) is still a boon, but that doesn't require any fuse other than 13A. I say it is a boon because it allows us to do more with less, because the additional diversity of one 32A circuit over two 16A circuits often allows it to do the work of three or four 16A circuits without nuisance tripping. But it would be impractical to fit flexes suitable for fault protection by a B32, so the fuse pays its way.

E2A crossed with DW, very similar ideas there.

 

[Darkwood]

Think we posted same time there @Lucien Nunes and more or less coming to the same conclusion hovering around the same reasons.. I don't post as often so I am happy to claim mine was first ?

 

[Lucien Nunes]

It's almost like the moulded plugs should have a mini mcb built into it but perhaps that technology isn't here yet

I proposed a different solution in the mid 1980s, around the time IEC 60906-1 16A plugs were on the table as a possible global standard. My approach was to build the MCB into the socket, so that 16A sockets with unfused plugs could still be used on 32A circuits. The idea was that the plugs would be smaller, neater, cheaper and less prone to overheating (a disadvantage of a fused plug). The MCB would simply replace the switch in the socket. It could be mechanically interlocked with the plug so that it would only operate with the plug pushed fully home, and would trip if the plug was pulled out.

To retain the benefit of being able to fuse down below 16A, I also saw the possibility of two different profiles of plug that either engaged or missed a lever in the socket that would alter the MCB calibration. E.g. moulded plugs to be protected at 5A would miss the lever, 16A versions would depress it, and rewireable plugs would have a tab that could be folded to one side or the other according to application. That could then be interlocked with the flex clamp so that fitting an oval or small diameter flex would cause the clamp to press on the edge of the tab and prevent it being flipped over to the 16A side.

But IEC 60906 and my ideas were all ahead of the times. Brazil and SA have since adopted the plug, and the MCB-socket is available from Bticino in Italy.

 

[ipf]

I remember having a couple of multi plugs in the 70's. They were adaptable to 13 amp, 5amp round pin and 15amp round pin, fitted to leads so you could pick up what supply was available. Thinking about it, I can't remember if they were fused or not......anyone remember them?
I'm sure I'll still have one, stuck away somewhere....determined to find that now.

 

[Lucien Nunes]

That was the Fitall. It had to be fused at 13A because of the 13A pins (there has never been an unfused 13A variant.)
JW has a page:

Fitall Plug by R.W. Rumble (G.B.) Ltd

An unusual plug which can fit into five different socket outlets, including 13A, 15A and 5A.

www.flameport.com

 

[ipf]

'nuff said.

That was the Fitall. It had to be fused at 13A because of the 13A pins (there has never been an unfused 13A variant.)
JW has a page:

Fitall Plug by R.W. Rumble (G.B.) Ltd

An unusual plug which can fit into five different socket outlets, including 13A, 15A and 5A.

www.flameport.com

That looks like the one, with the slider at the bottom. Really handy. That long since, I couldn't remember the fuse.

Get this class for a body shop welder.....'nuff said.

 

[Lucien Nunes]

Looks OK to me, I think it's one of these: