Using 1.5mm wire for external double socket

[Vedb]

Hi all,

I've got a 1.5mm wire running from the consumer unit to the outside which was previously a light. I've done away with the lights and want to repurpose the wire for a couple of plug in cameras.

Appendix 15 of BS 7671:2018 says it is acceptable to use a 1.5mm cable for a socket as long as there is a fused spur first as the cable can handle up to 15 amps and the spur will limit it to 13A anyway.

However, my question is;

As this cable goes straight from the CU, with no other lights or demand, does it still need a fused spur or can it go directly without one?

Many thanks!

 

[Murdoch]

What is the MCB or RCBO protecting this circuit?

 

[Andy™]

yes, providing the cable is protected against overload / fault currents

 

[SPECIAL LOCATION]

However, my question is;

As this cable goes straight from the CU, with no other lights or demand, does it still need a fused spur or can it go directly without one?

Many thanks!

Hello Vedb.. Welcome to the magical electrical forumbulator....
Even though some of us may appear strange.... Stick with it, bear-with-us, we all want to help you as best we can!!

But if you are walking around whilst waiting for replies..... remember the coffee machine on the fourth floor still only accepts the old larger sized 50p coins.. and some of the crisps in the vending machine in reception have not been re-stocked since the Covid lock-downs.. So DO-NOT choose "Cheese & Onion" or "Smokey Bacon" unless you like soft crisps!!!!

Meanwhile.....

All cable connections into modern consumer units will terminate into an MCB / RCBO..
(The replacement of the old fashioned fuse-wire holders).

They will all have a maximum current ratings, (e.g. 6A, 10A, 16A, 20A, 32A etc..), before they disconnecting the supply to prevent the cable being damaged in the event of a fault.

So first you need to find out what is the current rating of the MCB /RCBO in your CU that supplies this cable?

You didn't say if this 1.5mm cable is a PVC, (T&E), or SWA? As a SWA with the same sized conductors can generally carry a bit more current than T&E PVC..

As a rough rule-of-thumb depending upon installation methods 1.5mm T&E can be limited to 10A or 16A max..
Where as 1.5mm SWA is often good up to 20A!

However back to your question... If you just want to power a couple of cameras..
I'd probably just put the 1.5mm onto a 10A MCB/RCBO in the CU, and connect it to however many sockets you need..
As the 10A should be good for the cameras, and the cable will be protected no mater how it has been installed!

 

[binky]

So, at a rough guess it's on a 6A MCB, in which case the cable is suitably protected, and you can just stick a socket on the end of it.

 

[Vedb]

Many thanks for your replies all, appreciated. I will check the CU today as I've been away from site and revert with a photo

 

[mainline]

Hi all,

I've got a 1.5mm wire running from the consumer unit to the outside which was previously a light. I've done away with the lights and want to repurpose the wire for a couple of plug in cameras.

Appendix 15 of BS 7671:2018 says it is acceptable to use a 1.5mm cable for a socket as long as there is a fused spur first as the cable can handle up to 15 amps and the spur will limit it to 13A anyway.

However, my question is;

As this cable goes straight from the CU, with no other lights or demand, does it still need a fused spur or can it go directly without one?

Many thanks!

If this is a socket which is outside, then it should be RCD protected.

 

[SPECIAL LOCATION]

If this is a socket which is outside, then it should be RCD protected.

If this is a socket inside it would also need RCD protection anyway!

 

[mainline]

If this is a socket inside it would also need RCD protection anyway!

Yes, but the OP is on about putting one outside.
Your post #4 suggested that an MCB would be fine.

 

[7029 Dave]

IMO a radial circuit suppling socket should be on a 16A minimum with the 2.5mm cable.
The only 1.5mm cable I would be happy to use for this application is MICC.
Having said that all suggestions mentioned are not incorrect but IMO the circuit design is very poor.
6A protection for such a circuit COME ON.

 

[Andy™]

IMO a radial circuit suppling socket should be on a 16A minimum with the 2.5mm cable.

how you would/wouldnt do it is irrelevant. what matters is does it comply with BS7671

 

[Vedb]

The one which is labelled "outside lights" is the one in question and yes it is 6A. I've bought RCD in-built external sockets. Will this setup be sufficient?