Most modern garden lighting uses a low voltage system comprised of 3 main components: a cable that distributes power to the areas to be lit; a mains to 12 volt transformer; the actual light fittings.
The most important things to decide on initially are the type of lighting (LED or conventional incandescent) and the size of the transformer, since this determines the amount of lighting (a combination of the number of fittings and their brightness) that can be run.
We shall examine the two systems (LED and conventional) more closely in a bit, but for immediate purposes it is only necessary to know that both use the same underlying ideas.
To assess the size of transformer needed, calculate the number of watts in total for all the individual light fixtures and buy a transformer that states it can handle that amount of power (for example, a pair of 20w spotlights plus 4 10w path markers produce a total load of 80w).
As with any mains powered device, the transformer must be situated indoors and the cable connected to it and then routed into the garden.
The cable itself applies a load to the system, in addition to the load created by the light fittings, which you should allow for when calculating the correct transformer size. This is typically stated on the packaging and increases in line with the cable length, which imposes an effective limit on the length of cable.
If your lights seem dimmer than expected and particularly so towards the far end of the cable then the cable is almost certainly over long. This is easily addressed by looping the cable back (if necessary attaching an extra section) and joining it close to the transformer. However, be certain that the two wires inside the cable are not cross connected – if you look carefully you should see a marking on one strand only which is used to help determine the correct polarity.
Once the cable is laid out and connected, simply attach individual low voltage garden lights by cutting and reconnecting the cable to incorporate the short cable length running to the light.
As mentioned already, both traditional incandescent and LED garden lights are widely available these days, bringing the added confusion of deciding which to buy and how to mix the 2 types.
LED lights consume an awful lot less energy and produce negligible heat. LED light is also brighter and more defined in comparison to regular incandescent light, which may be considered either a benefit or a bit hard on the eyes depending on what types of effect you want to obtain.
With few exceptions, you should not attach LED lights to a regular low voltage garden system, or the other way around. What will happen is that either the lifespan of your LED lights will be cut to just a week or so, or the constant voltage transformer (LED driver) will suffer a similar fate.
There are a few exceptions -some types of LED light are suitable for use on a conventional low voltage system, but these will state this on their packaging. Otherwise, to mix LED and incandescent low voltage garden lights you will need to lay out two separate cables – one connected to a regular 12v transformer and one to a constant voltage LED driver – and match the correct sorts of light fitting to the appropriate cable.
There are many benefits in running both types of garden lights; LED lighting has particular properties that enhance the range of possible lighting effects, and when used in tandem both types of lighting can be made to either contrast with or complement each other and so create effects that would simply not be achievable with just one or the other.
