Right or wrong

[ebee]

Is a 2.5 T & E cable protected by either a 30Amp rewireable fuse or a type B 32A or 30A MCB serving one twin socket only
1/ Safe ?
2/ to Regs ?

 

[Lectrician]

Safe, yes.

To regs - Not a standard circuit...

Ideal, no.

Would I? If I didn't have another breaker on me, and needed to finish a job.

 

[partpdoctor]

hi eebe
are you the same eebe who lurks on the IEE forum?

 

[JohnD]

hang on...

you don't mean a ring with a single socket on it, you mean a radial with just one (double)socket on it?

Then 2.5mm should be on a 20A MCB or lower. Not 32A.

Incidentally,a double socket is not safe for 2 loads at 13A each, it will overheat. Is rated at 13A for the two sockets together (Should be OK at 20A MCB though a 16A would be better. But not a 32A).

 

[ricicle]

Incidentally,a double socket is not safe for 2 loads at 13A each, it will overheat. Is rated at 13A for the two sockets together

I'm still not convinced on this one, was there any manufacturers proof .None of the instructions I've ever seen quote this.

 

[Adam_151]

All MK socket-outlets are manufactured to comply with BS1363 part 2: 1995 and are rated at 13A per unit. Double socket-outlets have been manufactured and tested to exceed this rating by margin that allows electrical safety and reduces the risk of heat and mechanical damage to components due to overloading. It should be noted that BS1363 part 2: 1995 does not allow double sockets to operate at twice the permissable maximum loading and it should be remembered that double socket-outlets are not manufactured to be able to withstand a 26A load for sustained periods of time.

Research by ourselves and third party organisations has shown that all MK double sockets can safely withstand a continuous load of 19.5A for an indefinite period. Increasing the load slightly will begin to cause heat and mechanical stresses on the components in a relatively short period. Testing showed that a load of 22.3A was sufficient to cause heat stress that would cause a browning of the faceplates and sufficient heat to cause insulation damage to cable cores. A load of 24A for 43 hours was sufficient to cause significant heat damage to the material in which the socket-oulet was situated and within 75 hours sufficient to cause significant damage that would lead to the very real potential of fire.

MK recommend that users of their sockets consult professional design Engineers when designing installations to avoid the possibility of heat and mechanical stress to components and installations caused by overloading of MK socket-outlets

 

[ricicle]

Cheers Adam, I do remember seeing that now on a previous post

What about other manufacturers, do they declare the same?

 

[equitum]

Interesting..in terms of safety the 2.5 cable has the same protection afforded to that of the length serving a spur so I cant see why it cannot be deemed safe.....although for a 2.5mm cable installed in an insulated wall, for example, the capacity of the cable is 21A which although is less than the overcurrent device...is no different than a spur.

Practically would you plug over 4.8KW of load into the same double socket !?

EDIT: Not forgetting correction factors, in particular that of 0.725 for BS3036

 

[Adam_151]

I don't know, the important bit is where they point out what BS1363 requires, of course a device can exceed the requirements of the standards its made to, but I'd assume MK (and probably crabtree) are the ones who would do this to the greastest extent, the cheapo ones from a shed/wholesalers are likely to not aim so high and I dare say if pushed all you would get out of them is "this device meets BS1363" or similar

If you go really cheap from a market stall you'll be lucky if it meets BS1363 at all!

 

[ebee]

hi eebe
are you the same eebe who lurks on the IEE forum?

Yes I lurk there too and asked the same question so I thought it only fair to ask here.

 

[RF Lighting]

Incidentally,a double socket is not safe for 2 loads at 13A each, it will overheat. Is rated at 13A for the two sockets together

I'm still not convinced on this one, was there any manufacturers proof .None of the instructions I've ever seen quote this.

The good old washing machine / tumble dryer combo

 

[securespark]

 

[JohnD]

Akthough, to be fair, both of those seem to have overheated from the RHS pin on the plug, so it might have been a burning loose contact.

The MK lab report led me to expect a more generalised heat damage.

 

[ricicle]

Yes, that looks to be localised pin heating not general overheating which would, I suspect, take place inside in the connection between the cable terminals and conducting bars.

 

[DESL]

That's why it used to be good practise to connect washing M/C to flex outlets before the advent of moulded plugs.

I was told, by an old stager, that fixed (high load) appliances should never be on a plug as contacts weaken over time and cause arcing resulting in overheating.