When designing an outdoor lighting scheme, one of the first decisions is whether to use 12V low-voltage lighting or mains-voltage lighting, commonly referred to as 240V lighting.
Both have their place. The right choice depends on the size and layout of the project, the fittings being used, cable runs, installation requirements and how the lighting needs to be controlled.
For landscapers, electricians and garden designers, understanding the difference can make a significant difference to installation time, flexibility and the finished result.
What is the difference between 12V and 240V outdoor lighting?
The main difference is the voltage supplied to the light fittings.
A 12V lighting system uses a transformer or suitable power supply to reduce the mains electricity supply down to 12 volts before supplying the outdoor fittings.
A mains-voltage system, often referred to as 240V lighting, supplies suitable outdoor fittings directly from the mains installation without a 12V transformer.
Although 240V is still commonly used within the lighting industry as a description, the UK nominal mains supply is generally referred to as 230V.
Why choose 12V outdoor lighting?
12V lighting has become an extremely popular choice for professional garden lighting schemes, particularly for landscape lighting around planting, pathways and outdoor living areas.
Safer extra-low-voltage operation
One of the main advantages of a 12V system is the lower voltage present throughout the garden after the transformer.
This makes extra-low-voltage systems particularly useful in outdoor environments where lighting is positioned close to plants, paths and other areas people regularly come into contact with.
The mains connection and transformer still need to be selected and installed correctly, but the lighting circuit itself operates at a much lower voltage.
Flexible installation
12V systems can give designers considerably more flexibility when positioning fittings around a garden.
Spike lights can be positioned amongst planting, recessed lights can be incorporated into landscaping and additional fittings can often be incorporated into a properly designed system without having to distribute mains voltage throughout every part of the garden.
This can be particularly useful in gardens that may continue to develop after the original installation.
Ideal for landscape lighting
Modern 12V LED fittings can produce excellent levels of light while using relatively little power.
They are particularly well suited to applications such as:
- Spike spotlights
- Path and spreadlights
- Deck and step lighting
- Recessed uplights
- Planting and feature lighting
- Low-level architectural lighting
- Pond and suitable underwater lighting
A well-designed 12V system can therefore cover a significant proportion of a professional garden lighting project.
Easier to expand
Gardens rarely remain exactly the same. Plants mature, seating areas move, new features are added and customers often decide they would like additional lighting after seeing the original scheme working. Provided the transformer, cable and overall electrical load have been correctly specified, a low-voltage system can make future alterations and additions easier to plan.
What should you consider with 12V lighting?
Low voltage doesn't mean that a system can simply be installed without any planning.
Voltage drop
Voltage drop becomes particularly important on longer 12V cable runs.
Cable length, cable size, wattage and the number of fittings connected to the circuit all need to be considered when designing the installation.
Poor system design can result in fittings furthest from the transformer receiving insufficient voltage.
This is why choosing the correct transformer and cable sizes is just as important as choosing the lights themselves.
Transformer capacity
The total load of the fittings needs to be matched to an appropriately rated transformer or power supply.
It is also sensible to consider whether the customer may want to extend the system in the future rather than designing the transformer with no spare capacity.
Cable layout
The way the garden is divided into cable runs can have a major impact on performance.
On larger projects it may be more effective to create multiple lighting runs or zones rather than attempting to supply every fitting from one long cable run.
Good planning at the start of the project can make installation, fault finding and future additions much easier.
Why choose mains-voltage outdoor lighting?
There are also many situations where mains-voltage outdoor lighting is the most appropriate solution.
Ideal for building-mounted lighting
Outdoor wall lights, porch lights and other fittings mounted directly to a property are commonly designed for mains-voltage installation.
For an electrician working on the property, incorporating these fittings into the electrical installation can often be the most straightforward solution.
Useful for certain larger installations
For some large sites, long cable runs and higher-powered fittings, mains voltage may be more practical than distributing 12V over considerable distances.
Voltage drop still needs to be considered within any electrical installation, but it is generally a much more significant design consideration when working with 12V systems.
No 12V transformer required
A mains-voltage fitting does not require a separate 12V transformer.
This can make mains lighting attractive for applications such as wall lights or individual fittings positioned around buildings where an appropriate electrical supply is already available.
What should you consider with mains-voltage garden lighting?
Mains electricity outdoors requires careful installation.
Correct cable types, electrical protection, connections, ingress protection and the suitability of every component for its environment must all be taken into account.
Electrical work should always be designed and carried out in accordance with the relevant regulations and manufacturer's instructions, with appropriate electrical work undertaken by a competent person.
For domestic installations, Building Regulations requirements may also apply.
Can you use 12V and 240V lighting in the same garden?
Yes, and on many professional projects this is the best solution.
You don't necessarily need to choose one system for the entire garden.
For example, a project might use:
Mains voltage for:
Building-mounted wall lights and other suitable architectural fittings.
12V for:
Spike lights, recessed uplights, path lighting and planting areas throughout the garden.
This allows each part of the lighting design to use the system most appropriate for the application.
Are 12V lights less bright than 240V lights?
Not necessarily.
Voltage alone does not determine how bright a fitting will be.
Modern LED technology means a good-quality 12V fitting can produce excellent light output while consuming very little power.
Instead of concentrating purely on wattage or voltage, consider factors such as:
- Lumen output
- Beam angle
- Colour temperature
- Optics
- Position of the fitting
- Distance from the object being illuminated
For professional landscape lighting, where the light goes is often just as important as how much light the fitting produces.
Which system is cheaper to install?
There isn't one answer for every project.
A 12V system requires a transformer or power supply and needs to be designed correctly to control voltage drop.
A mains-voltage installation may require more extensive electrical installation work depending on the site and the existing electrical supply.
For trade customers, the better comparison is often not simply the initial price of the fitting.
Consider the complete project:
Product cost + installation time + cable + accessories + controls + future maintenance.
A system that is straightforward to install, maintain and expand can provide considerably better value over the lifetime of the project.
12V or 240V: which should you choose?
As a general guide:
Choose 12V when you need a flexible landscape lighting system around planting, paths, patios and garden features.
Choose mains-voltage lighting when you're installing suitable building-mounted fittings or the project design makes a mains-voltage circuit more practical.
Use both when different areas of the project have different requirements.
For many professionally designed gardens, combining the two gives the greatest flexibility.
Planning a garden lighting project?
At Lighting for Gardens, we supply 12V and mains-voltage outdoor lighting, together with transformers, cable, controls and installation accessories required to complete a professional lighting scheme.
Our team can also help trade customers select suitable products and work through the requirements of a project.
Whether you're lighting a single residential garden or specifying products for a larger landscaping project, getting the system design right before installation can save considerable time on site.
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