New power socket from lighting circuit / redundant electric shower cable

[Stephen1111]

Morning Folks

First time poster but long time reader, the info in this forum is excellent

I’m looking to see if it’s possible to tap into a lighting circuit in the loft so as I can connect a double socket to it, this will only power a broadband modem and a wifi mesh system so both really low power draw products , my ceiling lights don’t have any loop in loop out so I’m assuming it’s at the switch or a junction box somewhere.
I do however have a pull cord light switch in the loft for loft lighting , could I tap into the feed cable before the pull cord with a junction box and connect both the feed cable to the pull cord and to my new socket from this?
My plan was to run 1.5mm from junction box then into a 3amp fused switch then feed from that into double socket or I may just connect the flex from an extension cable to the fused switch does that sound acceptable.

I do have another option where I have a redundant electric shower cable no longer in use , this is 6mm cable on a 32amp MCB in the CU , could I use this cable drop it down through the ceiling terminate it into a 3amp fused switch then either connect my double sockets the outlet side of the fused switch or connect the flex of and extension cable to the fused switch load side.

Apologies for the long post, and thanks in advance for any help, which one of these would be the better option if any are doable, I can’t get to any outlets to run a spur off.


Thanks Stephen

 

[ericmark]

314 DIVISION OF INSTALLATION
314.1 Every installation shall be divided into circuits, as necessary, to:
(i) avoid hazards and minimize inconvenience in the event of a fault
(ii) facilitate safe inspection, testing and maintenance (see also Section 537)
(iii) take account of danger that may arise from the failure of a single circuit such as a lighting circuit
(iv) reduce the possibility of unwanted tripping of RCDs due to excessive protective conductor currents produced by equipment in normal operation
(v) mitigate the effects of electromagnetic interferences (EMI)
(vi) prevent the indirect energizing of a circuit intended to be isolated.

That is what the rule book says, OK that is back from 2008, but not changed that much, so (iii) is the main point, as a fused connection unit (FCU) with 1 amp fuse should take care of that. It should have RCD protection, but a RCD FCU will do that is lights no already protected.

When one reads the rules, one does wonder how we ever got away two duel RCD consumer units?

 

[Ragnar_AT]

If you connect a double socket to the old shower circuit I see no need for an FCU. The plug fuses will take care of everything.

 

[Jurassicspark]

I do have another option where I have a redundant electric shower cable no longer in use , this is 6mm cable on a 32amp MCB in the CU , could I use this cable drop it down through the ceiling terminate it into a 3amp fused switch then either connect my double sockets the outlet side of the fused switch or connect the flex of and extension cable to the fused switch load side.,

You can. Save yourself some money by not buying a fused spur because it won't be necessary in your case. Just connect the double socket to the 6mm cable. As mentioned above, the fuses in the plug would do the job.

 

[Adam_151]

If you connect a double socket to the old shower circuit I see no need for an FCU. The plug fuses will take care of everything.

While generally I agree, I suspect that there might not be plug top fuses as these might be "wall-wart" style PSUs, I'd not be concerned if, as with the OP this is a 32A shower circuit, because thats no different to if they were plugged into a socket on the ring. However if it was say a 50A former shower cirucit then I'd be tempted to make sure I introduced a plug top fuse into it by using a four gang extension lead instead of plugging them striaght into the socket.

 

[EFLImpudence]

While generally I agree, I suspect that there might not be plug top fuses as these might be "wall-wart" style PSUs, I'd not be concerned if, as with the OP this is a 32A shower circuit, because thats no different to if they were plugged into a socket on the ring. However if it was say a 50A former shower cirucit then I'd be tempted to make sure I introduced a plug top fuse into it by using a four gang extension lead instead of plugging them striaght into the socket.

Interesting. That seems reasonable at first reading, but -

how then could wall-warts cope on a 32A circuit if they could not do the same for a 50A OPD?

 

[Ragnar_AT]

Interesting. That seems reasonable at first reading, but -

how then could wall-warts cope on a 32A circuit if they could not do the same for a 50A OPD?

A B32 might still clear a short inside the power supply while a B50 might not.

 

[EFLImpudence]

So, equally - a 50A might - or a 32A might not.

Are wall warts manufactured to cope with internal short circuits - or act as their own fuse?

 

[Harry Bloomfield]

While generally I agree, I suspect that there might not be plug top fuses as these might be "wall-wart" style PSUs, I'd not be concerned if, as with the OP this is a 32A shower circuit, because thats no different to if they were plugged into a socket on the ring. However if it was say a 50A former shower cirucit then I'd be tempted to make sure I introduced a plug top fuse into it by using a four gang extension lead instead of plugging them striaght into the socket.

Wallwarts are designed to self limit the maximum mains current they can draw - hence no need for fuses as such.