How many 2.5mm T&E into a 13A socket?

[Major Scott]

Not if the socket can't give it 13A.

[Major Scott]

I do not ever put a 13A fuse in a table lamp with a 3A cord, that's just stupid. Why do you think there are 3A fuses in shops?

[John Rumm]

Which (if you had any functional understanding of the issues) would make you far more concerned about having suitably short disconnection times under fault conditions than prattling on about socket current ratings.

[John Rumm]

Explain how you think it works in countries other than the UK...

[Major Scott]

I can't see a fire starting in 1 second.

[Major Scott]

And elsewhere in the thread people are saying it's ok to protect a device with a

3A flex with a 13A fuse!!!!

[Major Scott]

Their safety isn't as good as ours.

[Tim Watts]

On Wednesday 03 April 2013 15:32 Major Scott wrote in uk.d-i-y:

Correct. You're just moronic.

[Tim Watts]

On Wednesday 03 April 2013 15:42 Major Scott wrote in uk.d-i-y:

Neither do circuit breakers.

[Major Scott]

You've just proved what I just said. You have no reason for following all these rules, you just do it like a robot. I get the feeling I'm surrounded by clones, possibly controlled remotely from 10 Downing Street.

[John Rumm]

Would you call 150A for an hour a "surge"?

(because that won't blow your 100A fuse either...)

for a minimum of 4 hours...

Your 2 x 13A loads will average less than that.

[John Rumm]

Try again, that does not answer the question....

[Major Scott]

It should. Why call it a 100A fuse if you can use way more than that indefinitely?

I know a woman who melted a 4 way extension strip with two tumble driers and 2 washing machines. Some 13A fuse that was.....

[Major Scott]

You asked how it worked. Of course it will work, it just won't protect well against fire.

[Major Scott]

They blow faster.

[Major Scott]

And the earth leakage ones are a nuisance.

[Adam Funk]

Hang on, it's dogma here that British wiring is vastly superior to everything else, & that once you plug things in in foreign countries, all bets are off & you're dicing with death.

OK, seriously, is it impossible or just very unlikely for a portable appliance to develop a fault (not a dead short) that will present a fire hazard without blowing the 13 A fuse in the plug?

Why do we need 1, 3, 5, & 10 A plug fuses?

[John Rumm]

No, they are saying its ok to "protect" a 3A flex with a 13A fuse... a subtle by very significant difference. The protection that is being discussed (and the *only* one that matters with modern[1] appliances) is fault protection.

If a device needs overload protection, then it must be built into the device itself, since in most countries there will be no fuse in the plug to offer it. If a device is put on the market in one EU country, then it must be safe to sell it in all of them.

The flex needs fault protection. In the UK you can't rely on the circuit's MCB / fuse to provide that, since it will typically be a 20 or

32A circuit (a 32A MCB needs at least 160A of fault current to ensure disconnection via its "instant" magnetic response). Hence the need for the plug fuse. A 13A plug fuse is quite capable of giving adequate fault protection to a flex with a lower nominal continuous current rating. The nominal current rating is based on maintaining conductor temperatures at 70 degrees or below, during long term sustained loads, and while able to cool by natural means. This has little or no relevance to the same flex under fault conditions where it is experiencing adiabatic heating due to several hundred amps of fault current, and terminal conductor temperatures of significantly more than 70 deg C are acceptable.

Could I suggest if you want to carry on discussing this further that you try and make an effort to comprehend the different types of protection that fuses and MCBs provide?

This has nothing to do with "rules" or elf'n'safety, and everything to do with really quite basic physics.

[1] Some very old appliances (i.e. pre 70s) designed just for the UK market, may be reliant on a plug fuse for overload protection as well. With these it is important that you use the manufacturers recommended fuse.

[John Rumm]

Which only further demonstrates your deep misunderstanding of the issues.

What do you suppose would happen if you take your combustible material and spray it with a mixture of molten copper and burning PVC? Perhaps also expose it to a fireball and an explosive arc flash just for good measure...

You see, that *would* actually concern me as a proper fire risk.

[Major Scott]

Maybe if my wall was soaked with petrol.