Fitting Downlights

Once you have decided that you wish to install Downlighters in your room it is important for you to decide several things:

Question

• 1. How many Downlights do I want? Or need?
• 2. Should the Downlights be 12v or 230v?
• 3. Do the Downlights need to be fire rated, acoustic rated or IP rated?
• 4. Can I do the work myself or should I get an electrician in?
• 5. What is the best process from start to finish for actually fitting the Downlights?
• 6. Do I need any special tools?
• 7. Can the existing lighting circuit support the extra light fittings?

Question: How many Downlights do I want? Or need?

Answer

This very much comes down to personal preference. Personally I prefer to fit more than is required, and then divide then up onto different switches. This will create different lighting effects. For example if you are putting the downlights into a kitchen you could have the downlights that are placed over the worktops on one switch and the other downlights that are illuminating the rest of the kitchen on another switch possibly a dimmer. This then means that you have good task lighting where needed and controllable mood lighting elsewhere.

However there are still some important factors to remember.

Without having any technical information about your particular room, use the following "Rule of Thumb". This best describes a kitchen, but can be adjusted for any room in your house.

Firstly make sure the Downlights that are going to be closest to your walls are no more than 600mm into the room. The reason for this is that 600mm is the standard measurement for the depth of your floor cupboards. This will mean that once the Downlights are fitted, no shadows will be created over the area that you are working.

You should now work out the position of the other lights by spacing them at intervals of between 900mm and 1200mm. From these figures you should now be able to calculate how many fitting will be in a row and how many rows you will need.

top

Question: Should the Downlights be 12v or 230v?

Answer

This has been a long standing debate with no particular winner. I hope the below information helps.

Low voltage (LV or 12v) downlights are wired to a transformer, which is then wired to the mains supply. Although the transformer wastes approximately 10% of the power through stepping down the voltage to 12v this is more than compensated by the improved performance of low voltage downlights.

Due to a thicker filament, the halogen 12v bulbs (size MR16) are more efficient than the halogen 230v (size GU10) equivalent. The thicker filament also means that the bulbs are more robust.

Another advantage of 12v is that low voltage bulbs use halogen gas, which provides a much whiter and brighter light with higher clarity than the more traditional mains voltage incandescent bulbs.

Mains voltage downlights are wired directly to the mains without the need for a transformer.

The mains voltage (230v) downlights are generally cheaper, and can be simpler to install, as there is no need to install a transformer.

As an electrician I would advise my customers to use 12v Downlights in Kitchens and bathrooms where you generally need more light, but can be reduced using low wattage bulbs or dimmer switches if needed. The use of 230v Downlights in other areas would then be perfectly acceptable.

top

Question: Do the Downlights need to be fire rated, acoustic rated or IP Rated?

Answer

Ceilings provide an important barrier that helps to prevent the spread of fire and noise between the floors of a building. Installing recessed downlights punctures this barrier and can reduce the effectiveness of this safety barrier.

Installing fire rated downlights helps to protect your premises from the effects of both fire and noise pollution and aids compliance with new building regulations governing the installation of downlights. Made from intumescent materials, fire rated downlights seal the gap between the ceiling and the fitting to offer up to 90 minutes protection against the spread of fire into the void spaces within your ceiling / loft space.

Fire rated downlights are more expensive than non-fire rated downlights. However, the worst decision you can make is to buy cheaper models that look exactly the same only to find out from the electrician fitting them, that building regulations require fire rated downlights for that situation. Then fire hoods will have to be bought and you would now find that you have spent more money in the long run.

Personally I feel it is best to always go for the safest lights on the market. Fires cost lives, surely that is worth a few pence more to fit fire rated downlights.

Having the right IP rated downlights is also a very important factor. Please see "What is IP Zoning" to see whether you will need an IP rated downlight. Water and electricity do not mix. Again IP rated downlights cost a fraction more but by paying a little extra you could save yourself from being electrocuted, or causing the contacts in the fitting to corrode. This could lead to a short circuit and possibly a fire.

top

Question: Can I do the work myself or should I get an electrician in?

Answer

Firstly you should read " Part P - What is it? " as this will answer whether or not you can legally carry out the work you wish to do. Some people will always have a go, no matter what their level of competence is.

Electricity is dangerous and could kill you. I will always suggest to get an electrician in to do the work required, but if you are determined to do some electrics yourself please remember to be safe at all times and follow some basic safe isolation procedures before proceeding:

• Locate / positively identify correct isolation point or device
• Check condition of voltage indication device
• Confirm that voltage indication device is functioning correctly
• Switch off installation / circuit to be isolated
• Verify with voltage indicating device that no voltage is present
• Re-confirm that voltage indicating device functions correctly on known supply / proving unit
• Lock-off or otherwise secure device used to isolate installation / circuit
• Post warning notice(s)

top

Question: What is the best process from start to finish for actually fitting the Downlights?

Answer

• Decide where you wish to place your chosen downlights measuring out the ceiling and marking the central point of the light. Now drill a small pilot hole through the ceiling.
• Now you have marked out the positions of the downlights it is a good idea to check above the ceiling to ensure that there are no joists / wires / pipes in the way. You should be able to see a small pinprick of light coming through the ceiling where you drilled the pilot holes. If you are unable to view the ceiling from above it gets trickier. The best way is to determine which way the joists run and what the spacing of them are. You could then use an old wire coat hanger bent at a 90⁰ angle to the width of the downlight. Insert the wire through the hole until the 90⁰ bend is through. Now twist the wire a full 360⁰ and hopefully it will not bump into any obstructions.
• In the instructions or on the box of the downlights it will say what the cut-out for that downlight will be. For the best results I will generally use a hole saw (a type of drill bit) to the correct size of the downlight which can be purchased very cheaply from most DIY stores. Alternatively the use of a plasterboard saw (Pad Saw) can be used which eliminates the need for a drill and hole saw. For this method you will need to draw a circle on the ceiling to the correct size as a guide for when you start to saw.
• Hopefully now you have produced a clean cut hole in the ceiling, got the plaster out of your eyes and shaken yourself outside to stop you looking like Casper the ghost!
• Once the wiring has been pulled through the hole the downlight can be wired. To fit the downlight into the hole hold the two springs back against the sides of the downlighter and push up into the hole. The springs then lie flat on the top of the ceiling holding it in place

top

Question: Do I need any special tools?

Answer

This all depends on what you have in your tool box already! Please see the below list of what tools I have used in the past for fitting downlights. Some of them you might not need but can often prove useful.

• Chalk line
• Tape measure
• Pencil
• Pad saw
• Hand drill
• Hole saw (type of drill bit)
• Small drill bit for pilot hole
• Screw drivers

top

Question: Can the existing lighting circuit support the extra light fittings?

Answer

Lighting circuits are usually on 6 amp circuit breakers often know as MCB’s (Miniature Circuit Breakers). To calculate how many Amps are loaded onto the lighting circuit a simple calculation is made. UK voltage is 230 volts, now assume that each light on the circuit is 100 watts, and you have got 12 lights on the circuit.

The calculation would be:

Total Watts ÷ Voltage = Amps

So taking the above information the calculation would be:

1200 watts ÷ 230 volts = 5.22 amps

So now we can see that the above described lighting circuit is using 5.22 amps meaning that the circuit breaker of 6 amps is not being overloaded.

Now to confuse things a little but very helpful on lighting circuits when you are wishing to add more lights. On lighting circuits once you have worked out the amps you can now apply a thing called Diversity, which for lighting circuits is 66% of the total load. So to work out this calculation we can do the following sum:

5.22amps ÷ 100 × 66 = 3.45 amps

So now we can see that we are able to add more lights to the circuit now that diversity has been applied to it.

Remember to carry out your calculations before you start any work!