13amp spur wired with only 1mm T&E - change to a fused s

[TechD]

Hi,
I have been looking at a socket in my loft, which a boiler is plugged into (with a 3 amp fuse fitted to the 3 pin plug).

However, the wire supplying the power to the single socket appears to only be 1mm T&E - which I am unsure if this is a high enough rating.

To avoid having replace the underated(?) cable which is run via joists under carpetted floor boards, is it permitted to simply remove the plug socket, and replace with a "13 Amp Switched Spur with Flex Outlet and Neon - but fit this with a 3AMP fuse, meaning when the boiler is serviced the double pole switch is turned off and seen to be done by the neon light to isolate it?

Many thanks.

 

[plugwash]

really that 1mm cable should be protected by a suitablly rated fuse

i presume its currently connected to the back of a socket. Disconnect it from there run a peice of 2.5mm from the socket to a switched fused connection unit (with 3A fuse) near the socket and connect the 1mm cable to that switched fused connection unit

then in the loft just use a junction box to join the cable from the boiler to the 1mm cable

 

[TechD]

That was fast...
I am not entirely sure I follow you, but, can i simply "insert" the 3 Amp Fuse Switched Spur into the circuit by cutting the 1mm T&E cable and slotting the fused spur inbetween, which the means whatever is plugged into the plug socket is limited to 3 amp max current draw?

 

[plugwash]

you should really use 2.5mm for the part of the run between the socket and the fused spur

using a socket to connect the boiler to the end of this wouldn't be a huge deal but a junction box may be better as it would stop idiots plugging anything else in

so in summary

socket on ring
short run of 2.5mm T&E
FCU with 3 amp fuse
long run of 1mm T&E
junction box or similar
final connection in flex or whatever.

 

[Damocles]

Are you sure this 1mm cable is connected to the sockets supply somewhere and not to the lighting circuit? Anyone playing games like this might have just connected the boiler to the lights. (which would then be fused correctly)

 

[Big_Spark]

Are you sure this 1mm cable is connected to the sockets supply somewhere and not to the lighting circuit? Anyone playing games like this might have just connected the boiler to the lights. (which would then be fused correctly)

That is a valid comment, however I would say that no socket should ever be connected to a lighting circuit, si the installation of the spur would be equally incorrect as someone could upgrade the fuse to 13A at some point in the future.

IF, and it's a big IF, the 1mm cable does come from the lighting, the boiler should, in an ideal world, have a new suply brought to it and the existing one disconnected, however if there are practical reasons why this cannot happen, replace the 13A with a 5A round pin lighting socket and put the equivilent plug on the boiler. This means that no-one can plug a 13A device into this circuit in future.

However, before you do anything, it is imperetive that you determine the origin of the 1mm circuit feeding the socket at the moment. Only then can you make an accurate and informed decision on how to best solve yout problem.

 

[TechD]

The supply originates from a sockets ring on the bedroom floor - so it is currently fed by a 30amp fused supply from the fuseboard. It is def not from lighting circuit.

 

[TechD]

Whilst looking at the options of running a new cable to the boiler socket - I have looked in the loft, and there is an obsolete 6mm electric shower cable running to a pull cord switch in the bathroom. (fused by a 30amp fusexat CU) As there is no longer an electric shower, could I simply remove the 6mm cable from the pull cord switch, put it into a 45amp junction box, and the join to a 2.5mm cable and run that across the loft joist (3 mtrs) to the boiler socket - which would then be able to run at 13 amps via fused plug if ever needed. The existing 1mm cable would then be removed from its connections. This is preferred as it avoids taking up any carpets, floorboard etc.
Thanks for any help.

 

[mapj1]

sounds fine - just label the fuseboard down stairs 'loft sockets' or something, so there is no confusion with any shower that may be later added. If you drop to 2.5mm size cable, you can only put one double socket on it, unless you make a proper ring or 4mm radial circuit, for a 30A supply. Otherwise drop the fuse to 15A or 16A breaker and make it a 2.5mm radial with any numbre of sockets
Or instead of the 45A junction box, use a switch-fuse unit with a 13A fuse, and a deep back box (6mm is not the easiest to get into the back of a switch fuse..)

 

[TechD]

Thanks - I appreciate the guidance. I'll go with the 45amp j-box as I have one lying around.

TD.