Radial off a ring circuit

[Gringoking88]

Hi all,

I have been asked to add a couple of sockets and add power to an existing strip light (currently disconnected) in a garage. There is presently an SWA 2.5 mm cable that is apparently live but taped up, hanging loose in the garage which is fed from a 32a ring circuit located in a utility room. Before you say it yes I know that is madness to leave a live wire like that but it was nothing to do with me (it really wasn't)!

I called the NICEIC just to clarify the RCD situation and was advised to add a garage unit with RCD protection and use two 6amp breakers. My question is why do the breakers have to be limited to 6amps, e.g. I get in effect it would be like having a spur but dont understand why I cant have larger breaker?

Please go easy as I'm just trying to educate myself.

Thanks in advance.

 

[Pete999]

Pete,

Thanks for taking the time helping me out!

There is not RCD protection at the CU and I was going to add RCD protection but was thinking where the SWA terminates within the garage. I still dont understand this 6amp breaker thing though lol

Without having the benefit of seeing the actual job, it sounds like you have an SWA feeding some sockets of low loading in a garage. Feed into a a socket and take the supply to the lighting through a suitably sized fuse via a FCU from the socket. Providing you have the RCD at the start of the swa.

 

[Gringoking88]

I have what?

Without having the benefit of seeing the actual job, it sounds like you have

 

[Pete999]

I have what?

Not sure what happened there Mate see my later posts. Post 16

 

[Gringoking88]

Pete,

At present the SWA is being fed from a ring main, located in the main houses utility room and at present just taped up "to make safe" in the garage. What I need to do is add a garage CU in the garage incorporating RCD protection from this taped up SWA cable then I need to add 2x double sockets within the garage, 1 external double socket outside the garage and 1 garage light all from this existing 2.5 mm SWA cable. The need for RCD I get, its just why NICEIC said to use a 6amp breaker for the lights and a 6amp for the sockets thats the bit I dont get???? Cheers again also you mentioned about a mentor and I noticed on your profile "PROUD TO BE A MENTOR IN THE TRAINEE SECTION." what exactly is this and how does it work?

Not sure what happened there Mate see my later posts. Post 16

 

[Deleted member 9648]

Andy,

I am registered as a domestic electrician with the NICEIC but am learning everything by reading and researching myself. I have completed my 17th edition, domestic installers course and building regs but am fully aware I don't have the experience or qualifications of more experienced sparks, hence why I might appear to ask silly questions. Yes I am "qualified / registered" but would still consider myself a trainee.

......I cant help but wonder how many clients using an NICEIC domestic installer assume they are getting the real deal. No offence to the OP but personally I would feel conned if I found out my NICEIC approved DI was unsure about such a simple electrical job.

 

[Deleted member 9648]

Pete,

At present the SWA is being fed from a ring main, located in the main houses utility room and at present just taped up "to make safe" in the garage. What I need to do is add a garage CU in the garage incorporating RCD protection from this taped up SWA cable then I need to add 2x double sockets within the garage, 1 external double socket outside the garage and 1 garage light all from this existing 2.5 mm SWA cable. The need for RCD I get, its just why NICEIC said to use a 6amp breaker for the lights and a 6amp for the sockets thats the bit I dont get???? Cheers again also you mentioned about a mentor and I noticed on your profile "PROUD TO BE A MENTOR IN THE TRAINEE SECTION." what exactly is this and how does it work?

Probably because an unfused spur must serve a maximum of one double outlet. If it is to serve more it must be fused at 13a via an FCU in order to prevent overload of the spur cable. Another way of achieving this is to limit the OCPD's on the spur to 2x6a mcb's....which obviously equates to 12a max load.
There you go....despite my derogatory post I've been helpful!

 

[Gringoking88]

Wirepuller,

Your right, your initial post was derogatory and unhelpful lol, but guess you have redeemed yourself lol

But seriously thank you. I would not do something I hadnt clarification over and am doing my best to learn as much as I can in a self taught way. I'm 36 and trying to change career direction but can't afford just to stop working to be an apprentice or equivalent hence why I read and question.

Thanks again.

Probably because an unfused spur must serve a maximum of one double outlet. If it is to serve more it must be fused at 13a via an FCU in order to prevent overload of the spur cable. Another way of achieving this is to limit the OCPD's on the spur to 2x6a mcb's....which obviously equates to 12a max load.
There you go....despite my derogatory post I've been helpful!

 

[Octopus]

Probably because an unfused spur must serve a maximum of one double outlet. If it is to serve more it must be fused at 13a via an FCU in order to prevent overload of the spur cable. Another way of achieving this is to limit the OCPD's on the spur to 2x6a mcb's....which obviously equates to 12a max load.
There you go....despite my derogatory post I've been helpful!

Not sure I agree with this. The spur needs to be limited to 13A at the "ring", not by 2 x 6A MCB's (which could be changed by any Tom, Dick or Abdul later) in the garage CU.

You need to fit 1 x 16A and 1 x 6A IMHO and explain to the client why you can do this. The 13A fuse is unlikely to blow with 16A plus a light going though it!

 

[joehat]

Why put a cu in?

Why not just use a 13a RCD sfcu and feed sockets of this and where practical add a sfcu for lighting anywhere after the 13a rcd point??


Sent from my iPhone using Tapatalk

 

[sparksburnout]

(which could be changed by any Tom, Dick or Abdul later) in the garage CU. Is this a PC related regulation now then? What happened to Harry (or Harriet), have they been dropped from the famous 3?

 

[Deleted member 9648]

Not sure I agree with this. The spur needs to be limited to 13A at the "ring", not by 2 x 6A MCB's (which could be changed by any Tom, Dick or Abdul later) in the garage CU.

You need to fit 1 x 16A and 1 x 6A IMHO and explain to the client why you can do this. The 13A fuse is unlikely to blow with 16A plus a light going though it!

Was just trying to explain the NICEIC advise to put two 6a mcb's in...which equates to 12a so is really the same thing as limiting the load to 13a. I wouldn't do it that way either. However if you are going to go down the line of thought that an unskilled person might change the mcb's.....that same person might disconnect the 13a FCU and link out the cables....or might stick a 50a mcb on a 6.0mm cooker supply for the new super-range....If that person changes the mcb's in the garage without verifying the load capability of the supply,thats their lookout,not the original installers.

 

[Adam W]

Why put a cu in?

Why not just use a 13a RCD sfcu and feed sockets of this and where practical add a sfcu for lighting anywhere after the 13a rcd point??


Sent from my iPhone using Tapatalk

Without being able to do anything else, that's what I'd probably go for. I usually use an example of a vacuum cleaner because it's a high current consumption appliance which gets plugged in wherever it can be, but in a garage it could be a lawnmower, portable heater, power tool of some description, or whatever - as soon as that gets used the breaker will trip as if there were a fault, and you get a callback to "fix" it, or someone comes along and changes it for a 32A "because that's what it should be for sockets".

 

[Pete999]

Pete,

At present the SWA is being fed from a ring main, located in the main houses utility room and at present just taped up "to make safe" in the garage. What I need to do is add a garage CU in the garage incorporating RCD protection from this taped up SWA cable then I need to add 2x double sockets within the garage, 1 external double socket outside the garage and 1 garage light all from this existing 2.5 mm SWA cable. The need for RCD I get, its just why NICEIC said to use a 6amp breaker for the lights and a 6amp for the sockets thats the bit I dont get???? Cheers again also you mentioned about a mentor and I noticed on your profile "PROUD TO BE A MENTOR IN THE TRAINEE SECTION." what exactly is this and how does it work?

Someone like me is able to help there are many of us.

I don't understand why they said use 6amp breakers, how is the SWA connected to the Ring Final Circuit (not a ring main anymore)? lets try and take your problem step by step, so answer that question first and see how we get on, OK

 

[Octopus]

(which could be changed by any Tom, Dick or Abdul later) in the garage CU. Is this a PC related regulation now then? What happened to Harry (or Harriet), have they been dropped from the famous 3?

I've "copied" that line from Jon Gaunt @ Talk 2 me radio!

 

[telectrix]

what's a personal computer got to do with the thread? :38: