lighting switch from a 13amp ring main

[Richie866]

Hi Guys
I know I am probably going to get slated for this question but here goes! -I have a twin 13amp socket half way up the wall which i'm thinking of turning into a light switch/circuit - Live into the common, form the light ciruit and terminal block the neutral (if you see what I mean).
I totally appreciate this is not an official way of doing things but can anyone suggest any dangers it may impose?

 

[Taylortwocities]

can anyone suggest any dangers it may impose?

Too right I can.

Firstly
Is your socket part of the ring (ie, are there two lots of cables going into it?) or is it already a spur from a ring.

Your answer will change the way it can be done safely.

Secondly. You cannot connect a light switch & light directly into a ring final (socket) circuit. You would have to use the same size cable as used in the socket circuit all the way through. And 2.5mm² conductors do not fit into light switych terminals.

You have to use a Fused Connection Unit (aka Fused Spur) with a 3 amp fuse in it. This can act as your light switch. But you may not be able to do this simply. It depends on your answer to the first question, above.

 

[Richie866]

Yes, it is part of the ring

 

[Taylortwocities]

OK
So spur from the socket a length of 2.5mm² cable into a switched FCU. this will be your light switch.
From the load side of the FCU connect to your light using 1mm² cable.
Pop in a 3amp fuse.
Job done.

 

[Richie866]

Good point, I totally get where you are coming from, and now feel a bit of a numpty! Just a slight variation on your proposed - I want to get rid of the double socket, so if I connected the 2, 2.5mm cables straight into the load of the fsu would this still be ok. Cheers for the advice by the way

 

[xr4x4]

Good point, I totally get where you are coming from, and now feel a bit of a numpty! Just a slight variation on your proposed - I want to get rid of the double socket, so if I connected the 2, 2.5mm cables straight into the load of the fsu would this still be ok. Cheers for the advice by the way

Yes you can do it that way too.

 

[Adam_151]

The ring must be connected to the supply terminals of the switched fuse spur. The lampholder is connected to the Load.

I appreciate this is probably what you meant and it was just a typing error, but better to clarify

 

[ban-all-sheds]

Is your socket part of the ring (ie, are there two lots of cables going into it?)

There is no guarantee whatsoever that that means the socket is on a ring final.

Could be a spur with another spur running from it.

The only way to find out if it's on a ring is to test it - the presence of two cables must not be used as an indicator.


Or it could be a radial circuit which would be quite safe but won't test as a ring.


Two cables at the CU can not be used as a reliable indicator either.


There's much more to all of this than you are leading the OP to believe.

[EDIT]Formatting corrected[/EDIT]

 

[ericmark]

If you use a switched fused connection unit rather than simple light switch you could use the ring supply.

However you must maintain the ring as a ring.

Where no ceiling roses or other item which is only rated at 5/6 amp are used you may go up to a 16A supply, not a 32 amp supply. However most light fittings have something which limits the supply to 5 or 6 amp depending if fuse or MCB. Since 3A fuses are more available than 5A I would fit a 3A fuse.

There is a saying a little knowledge is dangerous and that is certainly true with electrics. It takes such a short time to test a circuit most people watching an electrician don't realise they have done it. But we do test and often we do find some thing needing correction. Often not done by us.

I am sure it's all in Wiki section.

 

[Richie866]

Cheers for all the advice guys. I've done it and it works ok. Must admit I will read up on testing circuits etc - Bet you sparkys hate us bodgers!!!

 

[sparkybird]

no we love you coz more £ for us, when we have to sort out your bodges....

NOT!

 

[ban-all-sheds]

I've done it and it works ok.

That doesn't mean that it's safe, or even that it's not more dangerous if it was already unsafe.

Did you verify that the circuit was a ring?

Did you verify that the cables at that socket were part of a ring and not a spur?

 

[rjm2k]

Cheers for all the advice guys. I've done it and it works ok. Must admit I will read up on testing circuits etc - Bet you sparkys hate us bodgers!!!

I'm no expert, just a bodger like yourself, to test if the socket was on a ring you can turn off the power and disconnect the 2 lives you fed into the switch then use a multimeter to do a continuity test between the 2, since they will be connected at the CU for a ring they will show as being connected on the meter. If they don't show as being continuous then it was probably a spur off a spur or you need to check if the circuit was radial anyway.

 

[ban-all-sheds]

Or the circuit is a radial.

 

[Richie866]

I've not yet tested it to see if it is a ring, if it was a spur off a spur what would the implications be just to supply a 60 watt outside light?