We get asked a lot about connecting cables with garden lighting.
Firstly, when connecting to the mains you must always use or consult a qualified electrician.
A simple was of getting a garden lighting system set up is to get an electrician to run a swa armoured cable around your garden and also to place double outdoor sockets is various locations. The armoured cable should be run back to a switch or remote control that will operate the circuit. The circuit must be RCD protected. You can then plug in transformers or lights along the route to create your required lighting scheme.
Mains (230-240v) based garden lighting.
When connecting garden lights you have several options and depending on the voltage there are certain recommendations. For mains based lighting, I would recommend a junction box or high quality gel box. It should always be mounted above ground but if it is to be buried or left on the surface it must be resin/gel filled. Always use one gland per cable entry to ensure IP rating.
Extra low voltage (12v) garden lighting.
When it comes to connecting 12v or 24v systems you have a few options. Firstly, you can use junction boxes or gel boxes or you can also use heatshrink and crimps.
Junction box connection
From the 12v feed of your transformer you place a junction box, then depending on the number of lights, run individual cable runs to each light. When connecting low voltage lights, this methods work really well.
Make off the supply cable end and light feed end. Place and slide a 15-20cm lenght of heatshrink tube down the supply cable. Then using either red, blue or yellow butt crimps (depending on cable size) connect the made off ends, making sure the colours match. Then spread a couple of coats of quick drying liquid tape over the crimps and finally slide the heat shrunk over the connection ensuring no made off cables are visible and heat till it has tightly wrapped around the connection and the seal around the cable is water tight. For me heatshrinks are the best solution. It is also quick and simple. It provides a great waterproof connection that is easy to hide and discrete.