How to change a fuse on a plug socket

[winston1]

However, I was talking about the possibility of a 'sold alone' cable+plug being plugged into something which drew >2.5A.

If you are still referring to fig 8 cable and connector I don't think there are any appliances that they fit that draw>2.5A.

 

[JohnW2]

If you are still referring to fig 8 cable and connector I don't think there are any appliances that they fit that draw>2.5A.

That may well be true (and one would hope that it would be), but is something over which the manufacturer of cables/connectors has no control.

Kind Regards, John

 

[SUNRAY]

With lighting I would say more down to ceiling rose which is used as a junction box and only rated 5 amp.

As to connectors and cable the C13 to C16A have been a problem for those doing inspection and testing of in service electrical equipment (PAT testing for short) as the same plugs can be used from a computer to a kettle and although all are rated 10 amp, the cable is often too thin to supply 10 amp and it needs very careful inspection to see what cable is used.

I have not had a 10A fuse blow even when used with a 3 kW kettle, however some items do draw the 3 kW for longer than the time taken to boil a kettle. I was told there are two preferred sizes, 3 amp and 13 amp, I would buy packs of 3 amp, but always seemed to have an excess of 13 amp. But should one really fit a 13A fuse to a lead set only rated 10A even if the kettle it supplies is rated 3 kW? Is this

so you can boil two kettles together?

Well for a start those sockets should not fit into a kettle if it has been made to regs. Or is this another reg that has slipped away unnoticed?

 

[SUNRAY]

As we have observed before, it seems that one needs a current of at least 21A-22A to ever blow a 13A BS1362 fuse (even if that current persists 'for ever').

Kind Regards, John

Having been using 13A plugs for high power applications for years I can confirm that 13A fused do in fact fail quite regularly when run at full current.
I was one of those lucky people to get the license to buy and use unfused 13A plugs and they were reliable.

 

[JohnW2]

Having been using 13A plugs for high power applications for years I can confirm that 13A fused do in fact fail quite regularly when run at full current.

I can't argue with (and don't doubt) your experiences, but if they ever blow with under 20A, I presume they must be out-of-spec ...

Kind Regards, John

 

[SUNRAY]

I can't argue with (and don't doubt) your experiences, but if they ever blow with under 20A, I presume they must be out-of-spec ...

View attachment 140034

Kind Regards, John

Oh yes I am very aware of the specs and graphs, and we tried a whole range of different makes and truly didn't find a significant difference.
The application was event lighting and running at 13A continuously for hours on end the fuses do get ****king hot, my theory was the regular heating and cooling created fatigue within the fuse. We got to the stage of constantly changing fuses before they failed.
But then we discovered that license and our problems went away.

 

[ban-all-sheds]

I was merely pointing out that ban-all-sheds had apparently posted in the wrong thread

I picked up on an error in an advert clearly these large firms are not proof reading their own pages. Even when they passed my comments, they did not actually alter there own replay which is clearly wrong.

Looks ok to me, the headline was probably written by someone else. What issues did people find?

The "headline" is surely just the description of those G4 LED lamps, and the problem Eric is reporting is what Screwfix say about supplying a lamp marked 50/60Hz from an 'LED driver' or 'electronic transformer'.

 

[ban-all-sheds]

The fuse is still to protect the cable.

Against what?

In this post, Eric again fails to recognise that in almost all cases the fuse needs to protect the cable against faults, not overloads:

If you look at the range of fuses that will fit a plug you have 1, 2, 3, 5, 7, 10 and 13 amp, if you look at flex you did have 0.5, 0.75, 1, 1.25, and 1.5 mm² this gives you 3, 6, 10, 13, 16 amp, so you would only need the 3, 6, 10 and 13 amp fuse, however a 6 amp fuse is not made, but even a 13A fuse will remain intact and the 32A MCB will open instead, with a short circuit, and in real terms cable damage is always short circuit. So why make the whole range? Well I would say it is a historic thing, before we joined the EU we did use the fuse in the plug to protect the appliance, however to harmonise it was realised that if UK stuff was taken into Europe it could be a problem when the plug is changed. So the rules changed, not sure what date, but my son is 40 now, so it was at least 25 years ago when they went to school. At that time what was written on the plate was used to work out fuse sizes.

Today there are two things which control the fuse size, one the cable, and two the connector, it does not matter what size cable is used with a fig of 8 lead set, that socket is rated 2.5 amp so the fuse will be no bigger than 3 amp. We have a range of connectors rated 0.2 (shaver) 2.5, 6, 10 and 16 amp, ups there we go again with 6 amp and we only have 5 or 7 amp fuses.

So we need 2.5, 6, 10 and 13 amp fuses to protect cable and connector, but that's not what we can buy.

 

[JohnW2]

I'm confused. Admittedly it would have been even clearer had he included a quote, but the reference to "the headline" by JohnD (to which BAS responded) was surely a reference to the "headline" of the article cited in this OP of this thread, and nothing to do with eric's other thread (in which context there really was no "headline" as such, just the 'title' of the Screwfix listing), wasn't it?

 

[John D v2.0]

I'm confused. Admittedly it would have been even clearer had he included a quote, but the reference to "the headline" by JohnD (to which BAS responded) was surely a reference to the "headline" of the article cited in this OP of this thread, and nothing to do with eric's other thread (in which context there really was no "headline" as such, just the 'title' of the Screwfix listing), wasn't it?

Clearly your interpretation is correct, although presumably it's easier than average to find some ambiguity in my post.

 

[JohnW2]

Clearly your interpretation is correct, although presumably it's easier than average to find some ambiguity in my post.

Thanks for confirming. I have to say that it didn't even occur to be that there was any potential ambiguity - and any 'ambiguity' presumably existed only for those who tried to link your comment to the last couple of lines of eric's preceding post.

As I wrote, brief quotes avoid these potential issues of uncertainty about teh context of a post!

Kind Regards, John

 

[ban-all-sheds]

I have to say that it didn't even occur to be that there was any potential ambiguity

Nor I.

and any 'ambiguity' presumably existed only for those who tried to link your comment to the last couple of lines of eric's preceding post.

Not at all.

It immediately followed Eric's post, and there was absolutely nothing to indicate that it was not a reply to it. No ambiguity.

Imagine it as a spoken conversation, and you had heard Eric say what he had written, and then heard John say what he wrote.

As I wrote, brief quotes avoid these potential issues of uncertainty about teh context of a post!

Indeed.

 

[John D v2.0]

As I wrote, brief quotes avoid these potential issues of uncertainty about teh context of a post!

Yes, I try to when I can, and I will make more effort in future, but I'm usually using the site when rushing on or off a bus, or waiting for my tea to brew! So I don't always want to fight with the non mobile friendly features of the site (otherwise people wouldn't get the "benefit" of my wisdom!)

 

[ericmark]

So if I caused a problem.

As to overload v fault not easy to show how they are that much different, OK where a fault is a short circuit, but where some windings in a motor go short circuit that fault will produce an overload, so the grinder for example blows a fuse before it goes on fire, and this is due to both a fault and overload.

Cable is no different, 150 meters of yellow flex has a scaffold pole dropped on it which causes a overload and fault, if we assume line to earth then we want the fault to draw enough current to operate an overload device be it a fuse or a MCB or even one of those little red buttons working on thermal only. So 1.5 mm² at 55 volt keeping it simple at 0.029Ω per meter 55/16 = 3.4375Ω/0.029Ω = 118.5345 meters, so as to if the protective device will open or not depends on how close to end of cable.

OK a welding set may produce an overload which is not due to a fault, however 90% of overloads are the result of a fault even if the fault is mechanical like a sized bearing.

 

[JohnW2]

As to overload v fault not easy to show how they are that much different, OK where a fault is a short circuit, but where some windings in a motor go short circuit that fault will produce an overload, so the grinder for example blows a fuse before it goes on fire, and this is due to both a fault and overload.

Yes, but you seem to be using "fault" in the everyday sense, whereas in terms of circuit/cable protection, it has a very specific meaning, relating to to a 'fault' of negligible impedance (i.e. a 'short circuit'), such that the resulting 'fault current' would be the PFC of the circuit.

The OPD of any circuit (e.g. a 32A MCB or 30A fuse protecting a ring final circuit) is required to provide adequate 'fault protection' for the entire circuit. Adequate 'fault protection' therefore usually already exists, regardless of the rating of a fuse in a plug (or, indeed, even if that fuse is replaced with a nail!).

If the nature of the load is such that a 'fault' (everyday sense) of non-negligible impedance (i.e. an 'overload') is 'likely' to arise, then the cable supplying that load has to be adequately protected against that overload current - and, if the CCC of the cable downstream of the plug is less than the CCC of the fixed wiring (which should be afforded adequate overload protection by the circuit's OPD), then there may be a need for a fuse in the plug to provide 'overload' protection for that downstream cable.

Kind Regards, John