spacerspacerspacerspacerAdvertise Here
DIY Doctor
      Home   Contact   
neweysonline.co.uk - The newest tool of the trade

WELCOME TO OUR REPLACING A LIGHT FITTING PROJECT

This project is presented by neweysonline.co.uk - The newest tool of the trade

Summary: Replacing a Light Fitting. Understanding a lighting circuit.

Share and bookmark DIY Doctor

Link to DIY Doctor - Click Here RSS news feed DIY Doctor RSS Feed  Email Bookmark and Share


Please also see our project on the New Wiring and Cable Colours .

The first rule here is, if you are in any doubt whatsoever, get an electrician. Electricity kills.

Please remember when attempting any electrical installations at home that you are obliged to get the completed job tested by a fully qualified electrician and obtain a minor works certificate. Failure to do this may render your house insurance invalid and you may have difficulty selling your home. Wickes have asked us to point out that a full range of electrical safety instructions are available from their website in the Good Ideas Leaflets, electrical section. You can also buy the tools and products you need for many electrical projects from the tools store below this project

PLEASE SEE OUR PROJECT PART P BUILDING REGULATIONS

See also, lights and switches wiring in wall lights, electrical safety

                

Click on books to buy.

The most common mistake made by people wishing to change their light fittings, eg bulbs for spotlights etc, is that they take down the existing light and ceiling rose without marking or taking note of where all the cables went.

Then comes the mistake, they join all the reds together, then all the blacks, earths are connected, switch turned on and "PING" the fuse blows or the trip-switch flicks off. Why ? Well, 99% of the time one of the black wires belongs to the switch cable that controls that light. Both wires, red and black, are live wires in a switch as you will see a little later. The black wire for the switch should have a little bit of red tape around it, or a little red sleeve on it. This makes the job of identifying the switch cable easy. If there is no such labeling, an indicator is necessary.

Make sure you mark any wires and cables yourself when necessary.

Not as big deal to sort out, but first it is important to understand how the lights work in your house. The diagram below shows the circuits involved. ( Please note some older houses may be wired differently in junction boxes which will be located under the floor/loft, the principle is the same).

Power comes into the house to your fuse board or consumer unit. The lights are fed from this via (generally) two circuits. One for upstairs lights and one for downstairs. Both of these circuits should be on 5 amp fuses or MCB's (Miniature Circuit Breakers). This fuse, in theory, allows up to 12 100W bulbs to be used on that circuit, in practice no more than 8 are normally fitted. The cable runs from the consumer unit, to the first light fitting in the ceiling of that floor, it enters the ceiling rose where it is looped in and out to feed the next light, etc etc. At the same time a cable is connected into the ceiling rose to the switch that controls that light. With ordinary "one way" lighting, ie one switch controls only one light, the diagrams and explanations below apply. For two and three way lighting diagrams, which can be identified by additional yellow and blue wires within the lighting switch cables, follow the link.

When you have removed your existing light fitting and are faced with a mass of cables hanging out of the ceiling, life is a little daunting...But it is not as complicated as it looks.

You can see from the above that the loop wires (all wires in this kind of lighting circuit belong to the lighting "loop") are connected to terminal blocks. The live terminal is fed from the consumer unit and in turn gives live power to the other cables in the circuit, in this case 1 supplies the live power from the source, where it is taken by cables 2 & 3. The neutrals of cables 1 & 2 are joined together in the neutral terminal block, this is where the neutral side of any light fitting will go.  Cable 3 is the switch cable. As you can see more clearly from our diagram in lights and switches  this cable interrupts the live flow with a switch. The switch simply cuts off the live current. The red and black wire either side of the ceiling rose are coloured like this for clarity to show live and neutral. With your light fitting flex, they will be brown (LIVE) and blue (NEUTRAL).

Electrical Goods from Neweys On Line

 

When you have removed your existing fitting, you will need to know which wires go to the switch. Hopefully, as explained above, they will be labeled with either a piece of red tape on the black wire, or a small red sleeve. If you have no indication whatever of which three (red, black and earth) wires form the switch cable then you will need a circuit tester. To use this device  is not difficult but you must turn all the lighting power off first and take out the fuses so they cannot be turned on by accident. This meter can be bought from the the tool store below this page.

 

POCKET MULTIMETER ANALOGUE
When the power is OFF and fuses out, turn off the light switch, ie make sure the switch is in the off position. Now it is a case of trial and error. Hold the red and black terminals of your circuit tester to a red and a black wire that appear in the same cable. (Using the diagram above, this would mean either cable 1, 2 or 3. Then turn on the light switch (With all power off to the lighting circuits, there is no power to the switch). If you have connected to the switch cable, the circuit tester will indicate that you have completed a circuit. If not , it will not move and you try the next set of black and red wires that are in a cable together. When you have identified the switch cable, mark the black with some insulating tape and even put a piece of tape around the cable sheath so there can be no mistake.

 Ideally, your new light fitting will fit over your ceiling rose and there will be no need to take it apart. The live and neutral of the new fitting simply connect to the live and neutral the old fitting was removed from. If this is not the case, then we will, need to adapt the rose connections to suit the fitting you have. The easiest way to do that is by making all existing connections into cable connectors (minimum 5 amp) or a junction box, as shown left . The live cables will be joined as they were in the ceiling rose, as will the neutrals, and finally, but very importantly, the earths. With these connections made, the live, neutral and earth from your new light fitting can be connected. The base of most modern light fittings is big enough to conceal these new connections but occasionally one has to make a larger hole in the ceiling to push the junction box into. The light fitting is then screwed up as normal. 

 

 

Using the same numbers for the cables as above in the ceiling rose diagrams, this is how the junction box would be wired to replicate the circuit. The red tape on the switch live side of the circuit is shown. Good luck with your project and remember to stay safe.

For regulations governing heights of sockets etc, please click here.


neweysonline.co.uk - The newest tool of the trade



Much more construction information is available in our bookstore. All the tools and fittings you need in the toolstore.


Forums

[ Goto pageGoto page: 1, 2 ]




Are you a tradesman ? Get your very own webpage with ProblemSolved all for FREE - Click here



Share and bookmark DIY Doctor

Link to DIY Doctor - Click Here RSS news feed DIY Doctor RSS Feed  Email Bookmark and Share


Electrics
Post new topic
 Topics   Replies   Author   Views   Last Post 
No new posts Distribution board
11 calabash 474  
sparx View latest post
No new posts Power Supply to Garage
14 AjayK46 983  
kbrownie View latest post
No new posts shower wiring
4 dave6953 236  
dave6953 View latest post
No new posts installing new downlighters into excisting ceiling lights?
1 beano 140  
kbrownie View latest post
No new posts Chasing Electrics
6 Russpeace 281  
kbrownie View latest post
No new posts Electrical Supply to the Consumer Unit
3 Nik1969 228  
Nik1969 View latest post
No new posts Microwave / Combi connection
4 Gavona 122  
kbrownie View latest post
No new posts Tumble dryer heater
1 alanandly 82  
stoneyboy View latest post
No new posts Dimmer Switch on mains fluorescent downlighters?
2 conks 374  
Gavona View latest post
No new posts now sorted
1 shezbabe1 107  
kbrownie View latest post
No new posts swimming pool heater
2 pickovet 109  
moggy1968 View latest post
No new posts Bathroom lighting
3 melvin 230  
kbrownie View latest post
No new posts 4 way switch for hall lights and separte switch for landing
1 precious 225  
kbrownie View latest post
No new posts fuse box neutral switch
3 gary29 161  
kbrownie View latest post
No new posts what lights to use in bathroom/shower room
4 rose 280  
moggy1968 View latest post
No new posts maximum demand
1 maveric 153  
kbrownie View latest post
No new posts putting up a bedroom light no ceiling rose
2 lea 228  
moggy1968 View latest post
No new posts Wiring kitchen fixed appliances
5 spinkox 689  
spinkox View latest post
No new posts Bedroom Lights Flickers off
3 lightoff 265  
kbrownie View latest post
No new posts Help needed before i pull my hair out!!!!
1 pc6844 205  
rosebery View latest post
No new posts living room lights
3 pc6844 571  
kbrownie View latest post
No new posts Storage heater blowing fuse
13 citywest 1422  
DONFRAMAC View latest post
No new posts Single pole use of DP FCU
6 van 399  
sparx View latest post
No new posts Outside light switch and lights
3 ronecc 426  
ronecc View latest post
No new posts checking to see if a circuit has power going to iy
1 faber 192  
rosebery View latest post
No new posts Removing Pattress Box
4 nrg1977 402  
nrg1977 View latest post
No new posts 17th Edition question
7 livewire 613  
livewire View latest post
No new posts Coaxial or Cat5e
0 JamesMich 186  
JamesMich View latest post
No new posts Fused Spur in Bathroom
4 mtk2105 422  
mtk2105 View latest post
No new posts Low Voltage Halogen System
1 Lavondys 299  
kbrownie View latest post
No new posts Replacement bathroom light zone 1
4 Stavros 473  
Stavros View latest post
No new posts Ceiling light fitting
[ Goto pageGoto page: 1, 2 ]
19 Doreen 2482  
bd3cc View latest post
No new posts 2way light switch
3 GRAY28 1303  
moggy1968 View latest post
No new posts Radials or rings for electric ovens?
4 Tezza100 536  
moggy1968 View latest post
No new posts electric shock
7 alastair 696  
moggy1968 View latest post
No new posts Vertical Cooker Switch and Socket
14 dpeilow 1813  
moggy1968 View latest post
No new posts merlin gerin contactor problem
7 danny001 366  
sparx View latest post
No new posts Extending a shed lighting circuit
4 mobythevi 570  
mobythevi View latest post
No new posts 3 phase,please help
1 BOXMAN32 503  
sparx View latest post
No new posts Ceiling pull switch wiring
3 delphi200 448  
delphi200 View latest post
No new posts Double Switch for Ceiling Lights - Help Please
2 DodgyBisc 454  
DodgyBisc View latest post
No new posts Kitchen fun
1 markhar 320  
kbrownie View latest post
No new posts Wiring a Rangemaster 110 Cooker - correct cable?
1 conks 310  
kbrownie View latest post
No new posts DP FCU used as SP ok?
1 van 203  
sparx View latest post
No new posts rewiring a garage & new supply
3 bertelli_ 803  
kbrownie View latest post
No new posts Adding new extra set of downlights to kitchen
2 MR.OJ 247 539  
MR.OJ 247 View latest post
No new posts wiring a europian light in us home
2 rtdriver 271  
sparx View latest post
No new posts tools of the trade
4 livewire 318  
livewire View latest post
Display topics from previous:  
Post new topic     -> Electrics
Jump to:  
     
     
  
Search Diy Doctor

Related projects
#


© Copyright Diydoctor Ltd 2009  Developed by Boson Media  Hosted by Rackspace