External Security Lighting help

[FredFlintstone]

Morning all,

I've got the BC officer coming out on Friday to inspect the first fix of my wiring 2 new circuits in the kitchen). Yesterday I was looking at the photocopy of the form I sent to them when I notified them, I'd stated on the form that there was to be some external wiring too but I haven't done this and figure I should get it done before Friday to avoid another first fix visit (and additional expense).

I need to install a total of 5 lights. One halogen flood at the rear, two halogen floods at the side (one towards the rear of the house and one towards the front) and two lanterns on the front of the house (one either side of the front door). All lights are PIR controlled.

Now, what's the best way to go about this? I'm good with ring mains (because they're nice and simple) but not so good with lighting circuits with the whole loop in loop out or JB things - it just confuses the hell out of me.

So, I was thinking about maybe just adding a new ring main, specifically for the lights. Instead of each point in the ring being a socket, I figure I could use a FCU with the correctly rated fuse, with a cable from the FCU going up the wall and out between ground floor ceiling and first floor floor.

Does that sound acceptable? What size MCB should I use (the new CU isn't going in at first fix - they wanna see the first fix before I install the new CU and hook it all up)? I was thinking of using 2.5mm T&E for the security light circuit. I know it's probably not necessary but I've got a load left over so may as well use it up. Therefore, as I'm using 2.5 T&E I figure a 32a MCB would be fine - I've got smaller ones though which I could use if you think that's wise.

Thanks in advance for any advice.

Fred.

 

[RobFurn]

So, I was thinking about maybe just adding a new ring main, specifically for the lights.

Fred.

A ring for the lights dont you mean Radial.

3 Halogens at 500w each and x2 60w = 7A give or take

place the radial circuit on a 10A MCB

1.5mm sq is more than adequate but use 2.5 if you must.

P.S Is there all on PIR then you dont need to worry bout switching

 

[Adam_151]

An additional visit should not incur additional expense, you've paid your notification fee and now its up to them to cover it all, the only exception is if the building notice is closed and you have to open a new one (but as the outside stuff was stated on the notice as it should be, he'd be wrong to close that before thats been done and inspected, unless you told him you changed your mind about it)

 

[FredFlintstone]

Cheers Rob,

I did mean a ring but don't know why I didn't consider a radial. The total length of the cable run from the CU to the last light will be about 20m which I believe to be OK for a radial - is that correct? Cable will be run under floorboards and will go through the wall in small lengths of round conduit.

With regards to switching, I'd like the switch for two reasons - in case I want to turn one or more off on occasion (don't know why but it's nice to have the option) and also because it's possible to override the PIR sensing and have the light on permanently by switching light off on of on thus leaving the light on permanent of necessary.

Regards

Fred.

 

[RobFurn]

20m is fine Fred, looks like you will have to get your JBs out after all if you want switching

 

[FredFlintstone]

20m is fine Fred, looks like you will have to get your JBs out after all if you want switching

Cheers.

Can't I just daisy chain the radial into supply side of the switched FCU, linking one to the next, with a single T&E cable from the load side to the light? Wouldn't that provide the switching I need?

I'm useless at technical terms. By daisy chain I mean:

CU plus 5 lights. T&E from CU to first switched FCU into supply terminals. another length of T&E from supply terminals to next switched FCU into supply terminals. Another length of T&E from 2nd FCU supply terminals onto the next and so on.

Or have I got it completely wrong?

 

[RobFurn]

Yeh you can do that Fred.

Personally I wouldn't I would use JBs, just think of a JB as a ceiling rose if your worried about the wiring. Also remember the switch wire is just 2 live wires think of them as two browns with a switch in the middle, this I belive is why people get confused.

 

[dingbat]

P.S If they're all on PIR then you dont need to worry bout switching

Chapter 46 has something different to say about this.

 

[RobFurn]

Chapter 46 has something different to say about this.

Sorry meant individual switching