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Topic Title: Spur from a lighting circuit??
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Created On: 13 December 2007 12:00 pm
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 13 December 2007 12:00 pm
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deleted_1_smith0101

Posts: 9
Joined: 13 December 2007

I need to put a socket in (standard socket) for christmas tree lights (transformer type plug so round pin 5A socket no good).
The only way i can see without making it a huge job, is to cut into a lighting circuit.(No power circuits reasonably close enough)
My plan is to cut the 1.0mm cable and put both ends of the cut cable into the feed side of an RCD FCU then run a cable out of the load side down to a single socket outlet. The RCD FCU will have a 3A fuse in.
Any problems with this plan? Any regs i'm contravening?
Many thanks.
 13 December 2007 12:33 pm
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iansettle

Posts: 778
Joined: 20 September 2005

Current rating of cable for a start!! what if someone else comes along and plugs in a 3kw heater for example are you a QUALIFIED electrician if so you know the answer.
 13 December 2007 12:53 pm
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rocknroll

Posts: 9677
Joined: 03 October 2005

are you a QUALIFIED electrician if so you know the answer.


Huh!

Is it any more dangerous than QUALIFIED electricians wiring a double socket off the lighting circuit in the loft for a TV amplifier, you could always stick a 3kW fire on that if it is cold when sorting out the loft

regards

-------------------------
"Take nothing but a picture,
leave nothing but footprints!"
-------------------------
"Oh! The drama of it all."
-------------------------
"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"
-------------------------
 13 December 2007 01:04 pm
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rogerbryant

Posts: 1035
Joined: 19 July 2002

Although I'm not a QUALIFIED electrician I think that if you plugged in a 3kW heater the 3A fuse would blow protecting the cable.

Best regards

Roger
 13 December 2007 01:29 pm
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AJJewsbury

Posts: 17795
Joined: 13 August 2003

Although I'm not a QUALIFIED electrician I think that if you plugged in a 3kW heater the 3A fuse would blow protecting the cable.

I agree.

Indeed even if someone replaced the 3A fuse with a 13A, the 5A/6A/10A protective device at the CU should still protect the 1.0mm2 more than adequately.

what if someone else comes along and plugs in a 3kw heater


You might want to consider what would happen if plugged in a 1kW appliance into each socket on a ring....

A label on the socket (e.g. "Lighting only - max 100W load" (or whatever you're designing it for)) along with a label against the fuse/CB at the CU would seem adequate to me.

- Andy.
 13 December 2007 01:29 pm
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Kendo1

Posts: 168
Joined: 31 January 2007

I would say that it is fine as long as you tell the client that it is only for christmas lights and nothing else. Perhaps even label it for future owners of the property (maybe even recommend that the socket gets stripped out, just leaving the FCU after christams?). Would you also write it on the MWC as a deviation from the regs??

ps I don't think there is any benefit in having a dig at people's genuine queries. No matter what level you are at, in whatever line of work, there will/should be always things that you are not 100% sure about.

Cheers
Kendo

-------------------------
Kendo
 13 December 2007 03:09 pm
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deleted_1_smith0101

Posts: 9
Joined: 13 December 2007

Thank you to the people who have replied with decent answers, I am in fact part way qualified but i work in maintenance so don't have tons of experience, which is why i find it hepful, if in doubt, to ask questions.
Firstly, let's consider the facts - The stated rating of the 1.0mm BASEC approved cable is 13A (according to the manufacturers data), not that i would ever consider using it on a circuit that would carry that amount of current continuously but the fact is, if you drew 3000w through it, the cable should handle it (3000/230=13.04A).
Secondly, i did state that the spur would be protected by a 3A fused connection unit with integrated RCD. As this is a lighting circuit the ultimate protection is via the 6A MCB so all the discussion about plugging 3kw appliances in is totally irrelevant.
All i want to know is whether this is in contravention with any regulations, i will test and issue a MWC for the job but i would like to know whether i am within the regs or not as, if there is a regulation against doing this, i won't do it.
Honestly, some of the replies... i thought i'd strayed back on to the screfix forum
 13 December 2007 03:57 pm
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gpaul2

Posts: 416
Joined: 16 February 2006

don't worry, there are people who have no peers and was born with all the knowledge, and like to belittle people that wasn't.
there are also degrees of qualifications
take a 19yr old got all the city & guilds (too many to carry ) and ask him to wire an emergency light (non maintained)then ask mr x been doing it 25yrs with no qualifications,like i said qualified don't mean competent,
ask question all you like ,it's the fool who don't

Edited: 13 December 2007 at 04:02 pm by gpaul2
 13 December 2007 03:59 pm
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davezawadi

Posts: 4259
Joined: 26 June 2002

Its not in contravention of any I can think of at the moment. It is certainly not a requirement that a socket outlet has a 13A supply capability,as stated above. Its not dangerous so no problem!

Regards
David

-------------------------
David
BSc CEng MIET
 13 December 2007 04:50 pm
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DR2366

Posts: 711
Joined: 09 April 2006

Just remember to do a minor works certificate to cover the extension to the lighting circuit.
 13 December 2007 05:10 pm
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POTTERSBARNICK

Posts: 441
Joined: 30 December 2006

Nothing wrong with it, as long as mcb is rated to protect cable and you have correct zs, but its better to connect to last rose if pos.
When sparks say you cant do it its because they have given it no thought 1 st.
 13 December 2007 05:45 pm
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briandoherty

Posts: 313
Joined: 08 May 2004

From 16th Edition (my underline emphasis):

"553-04 Lighting points
553-04-01 At each fixed lighting point one of the following accessories shall be used:
(i) a ceiling rose to BS 67
(ii) a luminaire supporting coupler to BS 6972 or BS 7001
(iii) a batten lampholder to BS 7895, BS EN 60238 or BS EN 61184
(iv) a luminaire designed to be connected directly to the circuit wiring
(v) a suitable socket-outlet
(vi) a connection unit to BS 5733 or BS 1363-4
.
A lighting installation shall be appropriately controlled, e.g. by a switch or combination of switches to BS 3676 and/or BS 5518, or by a suitable automatic control system, which where necessary shall be suitable for discharge lighting circuits.
553-04-02 A ceiling rose shall not be installed in any circuit operating at a voltage normally exceeding 250 volts.
553-04-03 A ceiling rose shall not be used for the attachment of more than one outgoing flexible cord unless it is specially designed for multiple pendants.
553-04-04 Luminaire supporting couplers are designed specifically for the mechanical support and electrical connection of luminaires and shall not be used for the connection of any other equipment.
"

So who's to say that you don't adopt 553-04-01(v), and install "a suitable socket-outlet" to the lighting circuit, as a lighting point, for supplying lights (or whatever). Reasonable labelling (and / or reasonable location, e.g. at high level) should help overcome the temptation to plug heavy current using equipment into it (thereby avoiding nuisance trips); it would be hard to argue that such a labelled / located socket outlet, even if it is to BS1363, is not a "a suitable socket-outlet". Also,553-04-01(vi) refers to "a connection unit to...BS 1363-4", which is a standard Fused Connection Unit.

Brian

-------------------------
Regards,

Brian
 13 December 2007 06:12 pm
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butlermiles

Posts: 264
Joined: 18 November 2004

Is there such a thing as an unqualified electrician


Nick

Edited: 13 December 2007 at 09:54 pm by butlermiles
 13 December 2007 06:32 pm
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johnsam3203

Posts: 152
Joined: 19 October 2006

Why dont we go back to the plug in adapter that granny used to run the iron of. No cpc conection No rcd protection
But it worked. No labels either. I seriously cant recomend a return to these adaptors ( there are some still around) .
At least Smith0101 has asked the question , There are others out there who would just do it regardless of the possible consequences..
 13 December 2007 07:56 pm
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BigEddie

Posts: 22
Joined: 20 April 2007

Easiest way and one which should keep qualified and unqualified electricians happy.
Install the 5a socket outlet.
Fix a 5A plug top to a short extension lead after cutting off the 13A plug top.Plug light transformer into the extension.
No fixed wiring contraventions/arguments.
As mentioned earlier by others ,even if it's a four way extension and some muppet plugs a kettle in to it the 5/6A protection will operate and keep both property and persons safe.
One happy customer will there be.Yo-Ho-Ho
 13 December 2007 08:17 pm
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aligarjon

Posts: 4053
Joined: 09 September 2005

sorry if its a stupid question,i take it its an indoor tree with in door socket and lights,and not external.Gary

-------------------------
Specialised Subject. The Bleedin Obvious. John Cleese
 13 December 2007 09:12 pm
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mark2spark

Posts: 1444
Joined: 15 November 2006

On (new build) bungalows, we wire mixed ceiling light & 5A wall socket points, so can't see any problem.

-------------------------
I am prone to talking complete bol***ks at times, please accept my apologies in advance.
 13 December 2007 09:47 pm
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beaver74

Posts: 378
Joined: 07 February 2007

Originally posted by: aligarjon

sorry if its a stupid question,i take it its an indoor tree with in door socket and lights,and not external.Gary


should'nt matter as it is going through a r.c.d spur
 14 December 2007 12:02 am
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DOUGIE1000

Posts: 4243
Joined: 13 August 2005

Originally posted by: smith0101

Thank you to the people who have replied with decent answers, I am in fact part way qualified but i work in maintenance so don't have tons of experience, which is why i find it hepful, if in doubt, to ask questions.

Firstly, let's consider the facts - The stated rating of the 1.0mm BASEC approved cable is 13A (according to the manufacturers data), not that i would ever consider using it on a circuit that would carry that amount of current continuously but the fact is, if you drew 3000w through it, the cable should handle it (3000/230=13.04A).

Secondly, i did state that the spur would be protected by a 3A fused connection unit with integrated RCD. As this is a lighting circuit the ultimate protection is via the 6A MCB so all the discussion about plugging 3kw appliances in is totally irrelevant.

All i want to know is whether this is in contravention with any regulations, i will test and issue a MWC for the job but i would like to know whether i am within the regs or not as, if there is a regulation against doing this, i won't do it.

Honestly, some of the replies... i thought i'd strayed back on to the screfix forum



Often cooker extractor fans and tv ammplifiers are from the lighting circut.

I would definetly label it as lighing use, the DIYer might deside to change all the sockets to new ones no relising that its off another circut.

I would pay the extra £2 and get the socket engraved though

-------------------------
Dougie
Power Plus Electrical.co.uk

My mission is to live as long as possible......so far so good!
 14 December 2007 09:30 am
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boxy

Posts: 3
Joined: 13 December 2007

A slight aside but still related to this topic:

A guy recently installed central heating in my house and was about to finally connect the boiler to the ring main.

Up he went with a torch into the loft after pulling the single 30A BS3036 fuse (there were also two 5A fuses for the lights).

It was a cold day and a fan heater had been running in the kitchen to take the chill off. I happened to wonder through and heard the purring of the fan motor, thought, then shouted 'John. Before you touch anything...'. The heater was still going.

It turns out a single socket near the sink had been connected to the downstairs lights - probably to connect an iron, sometime in the past.

I suggested he work with the main switch off, just in case, which he did. It was a bit of a worry at the time and shows how important labelling is when things are done 'differently'.

The whole house is now being wired from scratch with a new CU, especially once the crumbling rubber stuff was found all over the place.
IET » Wiring and the regulations » Spur from a lighting circuit??

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