External Security lights - Domestic - RCD or Not

[claret73]

Am replacing 2x PIR Lights outside Front & Back at my Dad's place for 150W PIRs. I am going to utilise a Socket Spur in the loft for the feed and was replacing the socket for a FCU to provide the 2x Loads. Just wondering as the back light will be fitted next to the kitchen window, accessible to anybody via ladders should I consider RCD Protection? This would have to be an RCD FCU in the loft as the board is a 3036 rewireable.

All the cable runs will be clipped direct to joists in the loft. What do people think about using RCD Spurs? I know it only provides protection for the new section of cable but I'd be opening a 'Massive' Can of worms if I have to start considering RCD near the board.

 

[Richard Burns]

If you are replacing existing lights can you not use the supplies that are already there rather than running a new supply?
30mA RCD protection for the lights would only be required if there are cables <50mm in the wall.
From your description you are coming off a socket circuit which would require 30mA RCD protection, irrespective of the cable depth.
There would be little point in providing an RCD FCU just for the lighting part of the circuit; your best bet would be to open the can of worms and install a stand alone 30mA RCD beside the CU and divert that whole circuit through the new RCD.
You would need to check the socket circuit to ensure there are no problems on it before fitting the RCD but this would be the best solution, I believe.

 

[telectrix]

exactly as richard says.

 

[malcolmsanford]

Sorry gentleman have to disagree providing the spurred light circuit off the socket installation meets disconnection times for the protection device, then there is no need to provide additional protection by an RCD.

It would seem the additional cable is going to be clipped surface and therefore not liable to regulation 522.6.6.

Richard why would the existing socket circuit need RCD protection ?
IMO in the introduction it states that

The regulations apply to the design, erection and verification of electrical installations, also additions and alterations to existing installations. Existing installations that have been installed in accordance with earlier editions of the regulations may not comply with this edition in every aspect. This does not mean that they are unsafe for continued use or requiring upgrading.

For me that what denote if the existing installtion never required RCd protection when it was designed then it does not need them now,if you assess it is not required.And of course if your addition did require that RCD protection then you must provide it.

I have no problem with making the installation perhaps safer with RCD protection but it is not a requirement IMO in this case.

 

[Deleted member 26818]

30mA RCD protection for socket-outlets is required where they are intended for general use by ordinary persons, or to supply mobile equipment outdoors.
The requirement applies to the socket-outlets, not the circuits.
The requirements for 30mA RCD protection of circuits, only applies to circuits of special locations, such as locations containing baths or showers, construction sites, etc.
As such the socket spur in the loft, is fine as it is, it does not require 30mA RCD protection, or changing to an FCU.

 

[telectrix]

hmm. i had an argument with a fellow spark, who has also been a lecturer. i had wired a RCD FCU feeding 2 sockets to an existing non-RCD socket. he said that as i had modified the RFC, then i should have fitted RCD protection the the RFC as the 6" of cable from the existing socket to the RCD FCU was not RCD protected. btw, this 6" ofcable was buried >50mm deep in a stud wall.

 

[malcolmsanford]

I would agree Tel if the spur was for sockets, and if you are needing to provide additional protection to those sockets as per reg 411.3.3 so IMO it I would provide it for the entire circuit as it is leaving the installation safer. But there is nothing in the regs that say you have to provide the entire circuit with RCD protection, ask the lecturer to provide us one.

Unlike in special locations ie a room containing a bath or shower, where reg 701.411.3.3 tells us all circuits of the location must have additional protection by RCD and so many argue even if you just installing a fan, it is not just the loop leading into the room that needs RCD protecting but the whole circuit, and I would provide an RCD at the CU for that circuit. Some argue that it does not mean that Tel, that is for them to decide and to sign off the work, I will not argue with them.

 

[Deleted member 26818]

hmm. i had an argument with a fellow spark, who has also been a lecturer. i had wired a RCD FCU feeding 2 sockets to an existing non-RCD socket. he said that as i had modified the RFC, then i should have fitted RCD protection the the RFC as the 6" of cable from the existing socket to the RCD FCU was not RCD protected. btw, this 6" ofcable was buried >50mm deep in a stud wall.

You should have provided the 6" of the cable to the RCD FCU with additional protection.
This could have been achieved by protecting the whole circuit with RCD protection (thus negating the necessity for an RCD FCU), burying the cable at a depth greater than 50mm, installing the cable on the surface of the wall, installing the cable in earthed conduit or trunking or by providing the cable with mechanical protection sufficient to prevent penetration by screws or nails.

In the OP's case, it appears that he is just replacing existing fittings, and additionally intends replacing the existing socket-outlet with an FCU.
He hasn't indicated why he intends replacing the socket-outlet with an FCU?

 

[Richard Burns]

Malcolm
I was advising according to the requirement you mention of also additions and alterations to existing installations the alteration is being made to the socket circuit, i.e. the existing installation is being modified. Once this has happened then the possibility exists (but is not made clear in the regs) that the smallest section you can adequately test is the entire circuit and you would not then be able to say the tested circuit met BS7671. When completing the certificate you could state that the section installed is the fused spur lighting section of a socket circuit.
In this case I would likely leave out the RCD protection if the customer wasn't happy, but if it was for my Dad and at my cost I would put the RCD in. I have always protected bathroom circuits on BS3036 CUs with an RCD when modifying.

 

[claret73]

In the OP's case, it appears that he is just replacing existing fittings, and additionally intends replacing the existing socket-outlet with an FCU.
He hasn't indicated why he intends replacing the socket-outlet with an FCU?

When the roof was replaced, the handy roofers damaged the socket pattress and left it lying on the loft floor with the back exposed! As he doesn't require a socket in the loft, I decided to utilise the feed (which is spurred off the RFC) and put a switched FCU in its place. I just felt this provided minimal isolation if he needed to replace a lamp.
Anyhow...the said can of worms got opened as I began to test the circuit. I/R reading on the ring L&N-CPC 0.34ohms! So began taking a look as he'd mentioned some old VIR Cable to a few points downstairs. So now going to look into changing these legs, which in turn may necessitate RCD Upgrade, but then I'm changing a cable like for like...

 

[telectrix]

as usual regs can be ambiguous, different guys have different interpretations. i agree with yous, malc and spin. btw, i did say that on the job i did, the link from socket to RCDFCU was greater than 50mm deep ( just). my original intent was to divert the RFC through a RCD, but the 3036 wylex is under the kitchen sink. at my age , don't think i could have done it, crawling in the bottom of the sink unit.

 

[Octopus]

I love these cans of worms.

If the "donor" socket is in the loft and the cabling for the outside lights is surface mount for fixed lighting why is an RCD required.

IMHO maybe you should change the socket for a FCU as the cables are not buried or accessible.

Tin hat on!

 

[telectrix]

or even put a plug on a flex to the outside lights/PIR. then regulations would not apply.

 

[Deleted member 26818]

This is definately becoming a can of worms.
BS7671 and Part P do not actually use the term 'like for like' as far as I'm aware.
Whilst Part P allows for the replacement of cabling (as long as the rating is not affected) without requiring notification, BS7671 does not excempt such a replacement from having to comply with the current Regulations.
Sorry Tel, I've never been to sure which sign < or > means 'less than'.
I get it worked out, then next time I forget it.

 

[telectrix]

eassily remembered spin, from my maths teacher at school. the arrow points to the lower of the 2 values. e.g.10>9.

 

[Deleted member 26818]

eassily remembered spin, from my maths teacher at school. the arrow points to the lower of the 2 values. e.g.10>9.

I understand it when there are figures in use Tel, 50>40 or 40<50.
Where I have trouble is when words are used as in concealed >50mm or <50mm from the surface of a wall, that's when my brain stops working.
I sort it out, then the next time, i's all gone gone.
This is why I always yse the words less than rather than a symbol.

 

[telectrix]

ah, i see. i have the same problem sometimes have to look up Ia,Ib,In etc. when in a rush, can't remember which is which sometimes. couple of beers usually sorts the fuzz out thhough.

 

[claret73]

or even put a plug on a flex to the outside lights/PIR. then regulations would not apply.

This is how it currently stands. T&E on a Plug Top. Each light fitting having its own Cable feed & Plug. Just felt that given I'm replacing the fittings, it would be a better looking job to do it like this, albeit unnecessary...still, doesn't get around the fact that having tested the circuit (and even if I was whacking in flex on a plug, surely it should be tested) I have unsatisfactory reading on I/R.

It's just one of those. My folks aren't looking to stay in the house much beyond a few more years, so the expense of causing damage to the decor (another typical example of Domestic) doesn't run well with my Dad. Just trying to do a nice job around current Regs & Part P but as I know too many interpretations or ways of doing it to satisfy without causing too much aggro...

 

[Deleted member 9648]

There's a lot to be said for locating a security light close to a socket in the house...As Tel said....plug,flex ,light....no testing...no paperwork...cheap and effective. Excessive regulation tends to result in finding ways to get around it and make life simpler,If you hard wire a can of worms may indeed be opened,time money...reams of form filling....end result is the same,a working light.