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I want to wire up additional lights but I'm not sure about the best way to get a supply to the switches. Can you advise?
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If you look at the lighting ring main in your loft, you will see that you have a power feed that loops onwards to each light fitting from the fuse box. The last fitting is where you should pick up your power and feed on to the first of your new fittings.
You then feed a pair of wires down to the switch, red being the switch feed and black the switch return. The fitting should then be connected across the 2 black wires, as the switch return (usually identified with red electrical tape) is live when the switch is on. (The 2 reds will be joined.)
The feed on to the next fitting should then be connected to red (live) and black (the neutral) from the last fitting and so on.
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I want to supply my garden shed with electricity. What are the rules about putting a cable underground?
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To supply power to a shed or detached garage you will need the following:
1. RCD protected supply at the fuse box, or as a fused and protected spur
2. Sufficient armoured cable to reach the destination
3. 2 way fuse box or consumer unit to mount in the shed/garage
4. Suitable fuses or MCBs for the circuits to be installed
5. Suitable sockets and wiring (2.5mmT&E)
6. Suitable lighting and wiring (1.5mm T&E)
7. Cable clips for the armoured cable, or bury the cable at least 600mm down in the ground
The size of the armoured cable (2.5mm 3-core or bigger) will depend on the cable length and the load to be placed on it.
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Where can I pick up power for an outside light?
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You can pick the power up from either of the following two places, just use the one that is easiest for you:
1. From the lighting ring main.Firstly, you will need to pick up the feed from the nearest lighting point, then run the feed to the new lighting point. Connect the Black wire (Neutral) to the Blue wire on the light fitting. Run a pair of wires to the switch point. The Black wire of the switch pair is the switched Live. This should return to the light fitting and connect to the Brown. The 2x Reds are joined.
2. From the power ring main (sockets).If you use a socket for the feed, the next stop will be a Fused Switched Spur.This will fuse the supply down to 3 Amps and act as a light switch. You should then run the cable to the light fitting.
Remember: Earth to Earth and Earth points on all cable and metal fittings.
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For the garden, what is the difference between mains and low-voltage lighting?
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Low voltage lights tend to give a softer more contained light when used in the garden. Their use is ideal for pathways, ponds and small shrubs. Low voltage lighting is easy to install and safe as it operates on 12volts, which is beneficial if children or animals are using the garden. The transformer is sited indoors by simply plugging into a socket. Costs can be kept down by using a kit that supplies lights, wiring and a transformer. Alternatively, parts are available separately to build a custom designed lighting solution.
An alternative to low-voltage lighting is solar power. No cabling is required for solar powered lights as the unit self-charges during daylight hours then lights up when dark. However, this is a more expensive option.
Mains powered lights have the benefit of being much brighter and are therefore more suited to larger areas, such as a tree or the front of a property. Mains voltage lighting needs a degree of electrical understanding to install, and it MUST be protected by an RCD (Residual Current Device). You should always take steps to protect the cabling from damage, or use armoured cable. Mains lighting is excellent for security lighting.
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Why do light bulbs always blow when you switch them on, and why do they blow fuses?
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An ordinary incandescent "light bulb" consists of a thin tungsten filament in a glass envelope containing an inert gas. The filament has a relatively high resistance, and thus gets hot - hot enough to give out useful amounts of light as well as lots of heat - when current is flowing through it. The inert gas prevents the hot tungsten rapidly oxidising, as it would in air, or rapidly evaporating, as it would in a vacuum. It does, however, reduce efficiency, by conducting heat away from the filament. (Different gases and pressures are selected for different applications: for example, krypton and xenon are advantageous because they convect less and prevent evaporation better than argon/nitrogen, and therefore allow a hotter, more efficient, filament to be used while maintaining lamp life. Note that quartz halogen bulbs are different again: here, evaporated tungsten is re-deposited on the filament, thus allowing it to be hotter still while maintaining its life).
Tungsten, being a metal, has a resistivity which increases as its temperature rises. Therefore, when you switch on a lamp, it presents a much lower resistance than normal to the passage of electricity, and so your beefy electricity supply will drive through a great deal more current than normal while the filament heats up, putting it under thermal stress as it expands. This on its own encourages the filament to give up and break, but it is exacerbated by the fact that any thinned section will incur extra stress, as it will heat up more quickly than the rest of the filament (being thinner), present a higher resistance, and thus dissipate even more than its fair share of the (increased) power. This will tend to thin it further, rapidly, and hence lead to a point of failure.
How do you deal with it? Well, using a rotary on/off dimmer, where you always have to switch on the lamp at its lowest brightness, will help a lot. A dimmer will reduce the maximum available light output slightly. You can also fit negative temperature coefficient thermistors in series with the bulb. These have a resistance/temperature characteristic with the opposite slope to that of the filament, so give a "soft start" until they themselves warm up. Again, you will lose a little brightness, and waste a little energy in the hot thermistors. I am not aware of any "off the shelf" products containing thermistors, probably because they need to be selected for the wattage of lamp required.
It should be noted, however, that it is probably counterproductive to try to keep a light bulb alive for too long. This is because the thinned filament will be taking less current, so the light output will be reduced, and the tungsten that has evaporated from it will be deposited on the inside of the glass, reducing efficiency by blocking some of the light.
As regards blowing the fuse, this is never directly due to a broken filament falling onto the lead-out wires, and thus presenting a much lower resistance, but is due to the gas or vaporised filament in the bulb becoming ionised. The high temperature and large electric field (full mains voltage across a very small gap) which occurs when the filament breaks can cause the gas to go into a conducting state, and the plasma will "spread" until it shorts out the lead-out wires, because it presents a much lower resistance than the filament. This causes a "pop" due to rapid heating, and has been known to cause the envelope to explode. Light bulbs usually have built-in fuses to deal with this, but as they are built down to a price, they aren't always effective.
If you plug in a new light bulb and it only lasts a few seconds, leaving a white pattern on the glass, this is because it has cracked at some point, letting air in. When energised, the filament has oxidised to white tungsten oxide, which condenses on the glass in a pattern corresponding to the flow of air inside as the lamp is switched on.
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I want to wire up additional lights but I'm not sure about the best way to get a supply to the switches. Can you advise?
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If you look at the lighting ring main in your loft, you will see that you have a power feed that loops onwards to each light fitting from the fuse box. The last fitting is where you should pick up your power and feed on to the first of your new fittings.
You then feed a pair of wires down to the switch, red being the switch feed and black the switch return. The fitting should then be connected across the 2 black wires, as the switch return (usually identified with red electrical tape) is live when the switch is on. (The 2 reds will be joined.)
The feed on to the next fitting should then be connected to red (live) and black (the neutral) from the last fitting and so on.
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How do I take a feed off two currently existing electricity sockets to create two more?
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It is possible to end up with 4 separate sockets (single 1 gang or double 2 gang)
The present wiring will run in a loop (ring main) from the fuse box to each socket in turn and then back to the fuse box. You may have one of these rings for the kitchen, upstairs and downstairs. You will have to find the wire that feeds into the first of your sockets, the other wire should then be fed between the two sockets you have.
This wire will need to be disconnected at one socket and diverted to the new socket site. A new wire will then run from this point to the second new socket and from there to the original socket that the wire was removed from. This will complete your ring main once more.
You should allow for ten outlets per ring main to prevent overloading. Once this number is reached a new ring should be created.
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How do I add an extra socket onto an existing single outlet socket?
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A socket adapter will enable you to change single outlet sockets to double or treble sockets. These are much safer than standard adaptors. Alternatively, you can run a spur from an existing socket to a new double socket.
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How do I separate two lights that are connected to one switch?
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Firstly, disconnect the link wire between the two lights. The light that has the switch wire from it is the light you will need to pick up a power feed from. This will have to be fed across to the second light (using the old link wire).
You will then need to run-in a new wire from this light to where you want the new switch to be.
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Can Halogen spotlights be fitted in a bathroom and if so, will they be affected by condensation?
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There are two main types of low voltage halogen spotlights. The most common is the fully enclosed type where the glass of the lighting element is enclosed in a half round sphere. These are not affected by condensation.
The second type can be compared to a car lamp and is most commonly used in living rooms. These spotlights should not be used in a damp area such as a bathroom. If the light is for use over the bath or in a shower cubicle a sealed unit must be used.
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How do I fit extra plug sockets?
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Sockets are fitted as part of a 'ring main' and this means that a cable goes from the fuse box in a circle to each socket and ends up back at the fuse box. To add more sockets you need to disconnect one of the cables at your existing socket, then run this to the new socket with a new piece of cable (2.5mm twin and earth) between the two sockets.
A ring main will usually have up to ten outlet points on it. Over this, a new ring main should be created. Additional sockets and cabling can be surface mounted in trunking, below the floorboards, or sunk into the walls.
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How can I wire an additional ceiling light and switch?
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Follow these simple steps:
1. Pick up the power from the Loop (3x red) and the Neutral (2x black).
2. Feed this to the new lighting point.
3. Run a pair of wires (1.5mm Twin and Earth) to the switch.
4. Join the 2x red to form a new loop.
5. The light fitting should then be connected across the two separate black wires.
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How do I re-wire a ceiling rose?
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Firstly, you will need to identify the wires at the ceiling point. You are likely to have three pairs of wires: 1. Power 'feed in' 2. Power 'feed on' to the next light in the ring 3. Switch wires. If you only have two pairs of wires, they will be the power 'feed in' and the switch wires.
The feed pair and the switch pair can be identified using a multi-meter. The connections are as follows:
1. All three Red wires joined together (this is the loop terminal in a rose).
2. Black wire from switch pair to live side of rose (identified by red tape).
3. Black 'feed in' and Black 'feed on' together (this is the neutral).
4. The light fitting is then connected across live and neutral.
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How do I install 2 way switching?
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You will need the following:
1. 2 x 2 way switches
2. Enough 1.5mm 3 core and earth cable to run between the two switch positions
3. Trunking or conduit to cover the cable or allow it to be sunk into the wall where needed
4. Earth sleeving
Here are the connections, once the cable is in place:
Original switch position:
1. Yellow to COM on switch
2. 2x red to SW1 on switch
3. Blue and black to SW2 on switch
New switch position:
1. Yellow to COM
2. Red to SW1
3. Blue to SW2
All earth wires with earth sleeve to earth point on back boxes (and switches if metal).
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Is the UK on 240V or 230V?
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Traditionally, the UK has had a 240V (+/-6%) electrical supply since the 1960s, when the various local supply voltages (ranging from 200V to 250V) were all brought into line with each other. Continental Europe had a 220V, and Ireland a 230V, supply.
As part of European harmonisation effort to ensure electrical appliances manufactured for use in the EU can be used in any of the countries, a common nominal voltage for the whole EU has been set at 230V. The transition is a two stage process:
- On 1 Jan 1995: UK became 230V +10% -6%, and Continental Europe became 230V +6% -10%;
- On 1 Jan 2003: the whole EU becomes 230V +/-10%.
For most consumers, their measured mains voltage has and will not actually change, because it already falls into these ranges: this was intentional.
The transitions shift the burden of responsibility from the electricity suppliers to the appliance manufacturers, to increase the tolerance to supply variation of their products. However, they will benefit by only needing to supply one model (apart from the type of plug fitted, but that is another story!) for all countries. Generally speaking, modern technology allows devices to remain affordable while being more tolerant to supply variations anyway. The heavy engineering of electricity supply is less amenable to tightening up on performance.
So, you may well still find that your supply is 240V, but it is now magically 230V compatible!
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