Are recessed power sockets available in the UK

[EFLImpudence]

I was making the point that if you go the continental way then you no longer have any protection related to the size of the flex.

I assume you mean their appliances use flex rated below 16A.
Is that correct?

Note that BS1363 does not require the fuse rating to be lower than the rating of the flex. For 0.5mm flex it says a 3A fuse should be used unless this poses a problem with inrush currents in which case a 5A fuse should be used.

I suppose that must be considered satisfactory for a short inrush.

For all other flex sizes it lists it says a 13A fuse is fine.
But not a 13A fuse with 0.5mm cable ?

Why do we fuse lighting circuits at 6A?
I thought that was because internal wiring and flex drops were rated 6A.

In the rest of europe they seem perfectly happy to put 0.5mm flex on unfused plugs.
What happens when there's a fault ?

You can do that here for fixed loads where the cable will not be overloaded providing the fault current conditions are met.


One explanation could be that in Britain the CCC of cables is vastly underrated.
I know it's not a straight comparison but 5A fuse wire has a CSA of just 0.03mm².

 

[RF Lighting]

One explanation could be that in Britain the CCC of cables is vastly underrated.
I know it's not a straight comparison but 5A fuse wire has a CSA of just 0.03mm².

That doesn't really work. A 5A fuse is designed to get so hot it melts at a little over 5A. You don't really want fully loaded installation cables running at over 1000°C.

 

[EFLImpudence]

No, but my point is that 3A 0.5mm² flex is 16.7 times the CSA of 5A fuse wire

 

[RF Lighting]

Yep, that's so it doesn't get hot.

 

[stillp]

Can't find the statistics at the moment, but some mainland European countries have many more fires of electrical origin than the UK. From memory I believe the French figures are about 5 times ours. Perhaps we're doing something right?

 

[Monkeh]

No, but my point is that 3A 0.5mm² flex is 16.7 times the CSA of 5A fuse wire

And under 3A of load it barely even becomes warm, and the 5A fuse wire could be as high as several hundred degrees at 5A (don't believe me? Look at a fuse with a thermal camera some time. Plastic bodied automotive fuses have been known to melt).

 

[SimonH2]

Can't find the statistics at the moment, but some mainland European countries have many more fires of electrical origin than the UK. From memory I believe the French figures are about 5 times ours. Perhaps we're doing something right?

I was wondering about that - but was afraid to ask

 

[EFLImpudence]

According to the graph 5A fuse wire doesn't melt until 9A.

Therefore the 16.7 times the CSA of the flex may actually be able to handle more than 3A.

Not really sure what we're discussing.
I was trying to answer Simon as to why it was acceptable to fuse 0.5mm² flex at 5A when inrush was involved.

 

[Monkeh]

According to the graph 5A fuse wire doesn't melt until 9A.

Therefore the 16.7 times the CSA of the flex may actually be able to handle more than 3A.

Fuse wire is not copper.

0.5mm² can certainly handle more than 3A. But not with a maximum operating temperature of 70C (which you never want to hit, because then it's actively hot to the touch, sticky, and smells bad), and not at any length due to volt drop.

 

[RF Lighting]

Fuse wire is not copper

Yes it is.

 

[EFLImpudence]

Fuse wire is not copper.

The figures I quoted are for tinned copper fuse wire as in BGB.

0.5mm² can certainly handle more than 3A. But not with a maximum operating temperature of 70C (which you never want to hit, because then it's actively hot to the touch, sticky, and smells bad), and not at any length due to volt drop.

Are you saying there is absolutely NO tolerance in the 3A rating of 0.5mm² flex?

Following that - Are you saying there is absolutely NO tolerance in the 64A rating of 10.0mm² T+E?

 

[Monkeh]

Fuse wire is not copper

Yes it is.

Okay, not all fuse wire is copper. Better?

 

[Monkeh]

Are you saying there is absolutely NO tolerance in the 3A rating of 0.5mm² flex?

Following that - Are you saying there is absolutely NO tolerance in the 64A rating of 10.0mm² T+E?

Tolerance is there for a reason. Just like I'm stepping out of this pointless argument for a reason.

 

[RF Lighting]

Are you saying there is absolutely NO tolerance in the 3A rating of 0.5mm² flex?

Not if you want it to remain cool in normal use. Try running some 0.5mm² at say 4A and 6A and 10A and see what happens.

Following that - Are you saying there is absolutely NO tolerance in the 64A rating of 10.0mm² T+E?

See above.

 

[JBR]

Any idea of vintage? I'd say almost certainly pre-war and, at a guess, suggest they may have been designed for DC because of the safety feature to prevent pulling the plug when turned on.

I've never seen one of them in all my career! Looking at the design and materials I think its likely to be from between 1920 and 1940 ish, but it is very unusual as BS 546 would have been the standard plug / socket by this time.

I was tempted to reply 17 times but, no!

Yes, it's interesting isn't it? These sockets were in a Victorian end-terrace house with off-licence shop in Bradford (not that the sockets would have been Victorian!). The two old ladies from whom we bought it were not the sort to update things at all, and it wouldn't surprise me if the electrics had been untouched since the 1920s. Still, to have such safety features at that time must have been very forward-thinking.

I would be interested to learn the vintage of this particular plug/socket, so I live in hope that someone here may have that information.