one for the pro's to debate...

[ColJack]

The maximum loading a double socket can take is 26A (2x13A), probably less as most are rated lower. 2.5mm2 t&e cable, clipped direct is rated at 27A.

so in your world 27 is more than 32 then?

I refer you back to 433.1.1 ( ii ) above.. cable rating must be bigger than breaker....

I don't see a problem with 433.2.2 (i)

see above..

 

[ColJack]

More likely it is allowed by 433.3.1 (ii).

I haven't gotten that far in typing the book out yet...

is it me or does 433.3.1 (i) seem a stupid thing to say..

in effect it says that you don't need to fuse down for a smaller cable on the load providing that the fuse on the supply is small enough...
I suppose that deals with the 0.75mm² drops to a pendant from the ceiling rose though...

 

[GaryMo]

433.2.2 specifically says

433.2.2 The device protecting a conductor against overload may be installed along the run of that conductor in the part of the run between the point where a change occurs ( in cross-sectional area, method of installation, type of cable or conductor, or in environmental conditions ) and the position of the protective device has neither branch circuits nor outlets for connection of current-using equipment and fulfills at least one of the following conditions:

(i) It is protected against fault current in accordance with the requirements stated in Section 434
(ii) It's length does not exceed 3 m, it is installed in such a manner as to reduce the risk of fault to a minimum, and it is installed in such a manner as to reduce to a minimum the risk of fire or danger to persons ( see also Regulation 434.2.1 )

please note the highlighted section..
would you consider a single or double socket an "outlet for connection of current-using equipment"?

your follow on argument will likely be that the plugs all contain fuses...
but it doesn't specify that and that's not entirely true either..
there are special "red" plugs that contain no fuse.. while these are not in general use they are fitted to some protable machines that have large current demands for a short duration, such as portable x-ray machines..

while the example of the hand dryers would satisfy 433.2.2 in some way if the fault current requirements were met, this is only because they have permanent connections and not outlets...

I'm seeing your point with regards to "outlet for connection of current-using equipment" so I'll change my stance a little and say that there's no problem with a 32A protective device supplying a FCU or triple socket with integrated 13A fuse via 2.5mm2 conductors providing the protective device at source satisfies the requirements of 434 for fault protection.

Going OT for a min, I've not seen these red unfused plugs you talk of. Have you got a link to one?

Also, have you got BS7671:2008 in pdf form?

 

[martinxxxxxx]

Going OT for a min, I've not seen these red unfused plugs you talk of. Have you got a link to one?

Obviously you don't have a motorbike then?

 

[GaryMo]

Nope but i'm curious

 

[ColJack]

no pics, but a link to the suggested use PDF from a hospital..

http://www.hfs.scot.nhs.uk/publications/PSAN9504.pdf

 

[martinxxxxxx]

Nope but i'm curious

There is not a motorcyclist I know that is is not familiar with the x-ray machine and has not spent hours looking round the room at everything

 

[bernardgreen]

[The maximum loading a double socket can take is 26A (2x13A), probably less as most are rated lower

One make of double 13 amp sockets was ( is ) rated at 18 amps maximum loading. That was information from the manufacturer after sockets repeatedly failed ( over heated terminals ) with a total of 5 Kwatts ( 21.75 amps ) Their advice was to replace the double socket with two singles. Solved the problem.

 

[ColJack]

I can't seem to find any other mention of them besides on protable x-ray machines..
I presume that they are either proprietary or they just buy red plugs and swap the live pin for a spare neutral pin...

 

[RF Lighting]

[The maximum loading a double socket can take is 26A (2x13A), probably less as most are rated lower

One make of double 13 amp sockets was ( is ) rated at 18 amps maximum loading. That was information from the manufacturer after sockets repeatedly failed ( over heated terminals ) with a total of 5 Kwatts ( 21.75 amps ) Their advice was to replace the double socket with two singles. Solved the problem.

I'm still building my case study on this subject, but it is a long process

 

[securespark]

For me, it's simple, unless I'm missing something here.

A run of 2.5 could be overloaded by a 32A load. Ib In Iz etc....

 

[securespark]

[The maximum loading a double socket can take is 26A (2x13A), probably less as most are rated lower

One make of double 13 amp sockets was ( is ) rated at 18 amps maximum loading. That was information from the manufacturer after sockets repeatedly failed ( over heated terminals ) with a total of 5 Kwatts ( 21.75 amps ) Their advice was to replace the double socket with two singles. Solved the problem.

I'm still building my case study on this subject, but it is a long process

You still playing with welding equipment?

 

[RF Lighting]

Nope, I'm doing it with a proper resistive load for scientific accuracy.

 

[GaryMo]

For me, it's simple, unless I'm missing something here.

A run of 2.5 could be overloaded by a 32A load. Ib In Iz etc....

Not if there's a 13A fuse downstream of the 32A device at origin protecting the 2.5mm2 conductors from overload.

 

[Spark123]

Whatever arguament is put forward for not supplying a single accessory from a 32A protective device seems to me to fall down when you start looking at it from the point of view a bog standard spur from a ring final circuit.