Installing new outside PIR light, do I need a switch?

[Beeg]

Hi all,
Hoping someone will be able to give me a bit of advice.

I’m planning to install a PIR light on the outside wall of my porch to light up the driveway. There is currently a light inside my porch which I am planning to take the feed from, run the cable along the inside of the porch and then through the wall to outside.

Is it acceptable to just run 1.5mm T&E straight to the new fitting, or should I install a switch inside the porch? Can I just use a normal 1 gang single way switch and loop in the neutrals at the switch? Or would a 5A switched FCU be a better option?

Thanks
Beeg

 

[TJ Anderson]

Hi

Have you confirmed there is definitely a permanent supply at your porch light?

Also, if there is,you don't have to install a switch, but with the requirement for RCD on all domestic lighting in the 18th, putting an outside light on double pole switching is the most sensible option now.

 

[Beeg]

Hi TJ. I haven’t checked any of the existing wiring as of yet. When you say permanent live, am I right in thinking that if it is wired in the conventional method of Live in/out looped at the rose then it would have a permanent live?

Thanks

 

[TJ Anderson]

Hi TJ. I haven’t checked any of the existing wiring as of yet. When you say permanent live, am I right in thinking that if it is wired in the conventional method of Live in/out looped at the rose then it would have a permanent live?

Thanks

Yes, exactly that. You may find though that it only has one cable and is switched live and neutral only.

 

[happysteve]

A double pole switch (such as those on switched fused connection units) is advisable on circuits feeding outside lights, so that in the event of an earth fault (due to water ingress), you can isolate that part of the circuit and reset the RCD. If there isn't an RCD on that circuit at the moment, there probably will be at some point in the future.

Why 5A, out of interest? Are you installing more than 700W of lighting (which is very roughly what a 3A fuse will cope with)?

 

[Beeg]

Thanks TJ. Presumably if there is no permanent live at rose it will be in a JB above the ceiling or looped in at switch?

 

[TJ Anderson]

Thanks TJ. Presumably if there is no permanent live at rose it will be in a JB above the ceiling or looped in at switch?

Spot on!

 

[Beeg]

Thanks for your answer happysteve. I’m not sure of the exact wattage but it’s only a single ‘decorative’ lamp so wouldn’t have thought it would exceed 700W. I only said 5Amp because I know CU fuses / MCBs are rated at 5/6Amp.

Thanks again

 

[TJ Anderson]

Doe the existing circuit mcb not provide suitable protection then?

 

[happysteve]

3A or 5A will make no difference in practice. 3A is more of a standard size. Even 0.75mm flex will be fine up to 6A clipped direct, so whether it's 3A or 5A it'll be fine. If the fuse/circuit breaker is 5A/6A then there's no need for an extra fuse (unless perhaps if the manufacturer of the light specifies it) - a SFCU is often a simple/more easily available way of getting a double pole switch, that's all. I only mentioned it because the original poster specified 5A, I then pondered just how big their drive was and how brightly lit they wanted it

 

[Beeg]

TJ, both upstairs and downstairs lighting have their own 6A MCB on the CU. I understand that this would provide over current protection, I just wanted to double check there was nothing in the IEE regs that stipulated it should have a separate fuse with it being in a porch.

 

[Pete999]

TJ, both upstairs and downstairs lighting have their own 6A MCB on the CU. I understand that this would provide over current protection, I just wanted to double check there was nothing in the IEE regs that stipulated it should have a separate fuse with it being in a porch.

Best get an electrician in to do the job properly, safely and tested when complete Mate

 

[TJ Anderson]

TJ, both upstairs and downstairs lighting have their own 6A MCB on the CU. I understand that this would provide over current protection, I just wanted to double check there was nothing in the IEE regs that stipulated it should have a separate fuse with it being in a porch.

Ok. Well overload protection is not going to be an issue as it is determined. Will a BS1363 3A/5A fuse discriminate with a BS60898 6A MCB on short circuit or earth fault?

 

[Taylortwocities]

Will a BS1363 3A/5A fuse discriminate with a BS60898 6A MCB on short circuit or earth fault?

You know it won’t. The MCB will go first, every time. Even a 3A fuse will hang on longer than a 6A fuse.

 

[Beeg]

Folks, thanks for all the advice.

Just wanted to check that what I was planning to do was safe and meets regulations, which it appears it does

Thanks again
Beeg