Exterior light spur off ring main socket??

[ben lee]

Hello knowledgable peeps,

Looking at the legality and mostly safety of wiring a up/down exterior light via a switch spurred from a socket protected by rcd.
Newish home (5 years) so modern electrics.
I was going to use 1.5mm twin and earth but thinking i might have to use 2mm as from the socket?......... Looks some what like this.

External Light
I
I (I represent 1.5mm2 cable)
I
Interior Switch
I
I
I
Internal Socket

Can you please advise if this would be do-able....

Ta!

Ben

 

[DIYWell]

Not quite sure what you're trying to do, but if it's run a light permanently connected to the ring main, I'd spur off from a convenient socket to a FCU fitted a 3A fuse to derate, then run lighting cable to the switch and to the light. Light should have the appropriate IP rating. Don't think there's any need for an RCD.

It's a similar set up to running table lamps from 5A round pin sockets controlled by wall switches.

But what do I know, I'm not a sparky )

 

[bernardgreen]

Use a double pole FCU ( or switch ) to allow the external lamp to be fully isolated ( Live and Neutral disconnected, Earth remains connected ). When the lamp is damaged or saturated with (rain) water it can be isolated and thus prevent the faulty lamp from tripping the RCD and turning off power to the sockets.

 

[ben lee]

Thanks guys, yep - i figured it would be a FCU in the circuit before the switch but was trying to avoid for the asthetics and limited space near the socket.

 

[ban-all-sheds]

Use a switched FCU.

 

[winston1]

After the FCU use 1.0 mm cable not 1.5mm.

 

[bernardgreen]

deleted

 

[Anteaus]

Not sure about latest regs but it used to be OK to have a short length cable of smaller gauge than the breaker rating before the FCU, provided it was very unlikely to ever get shorted. The peace-of-mind solution is to use 2.5mm to the FCU, which would be very unlikely to fail before a 32A breaker tripped anyway.

 

[ban-all-sheds]

After the FCU use 1.0 mm cable not 1.5mm.

Why?