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Low Voltage or 240V Mains in the Garden?

Low Voltage Lighting in the Garden.

You’ve seen some lights you like but they are 12 volts. Your electrician tells you you’d be better off with 240volt lights. What do you do?

This is a question we often get asked, so we look at the issues to help you make up your own mind.


We all know that electricity can kill if not handled with care, so how can it be safe to use in the garden?

Mains (240 volts) lights should be safe when properly installed and maintained. But it does rely on the installation being in tip top condition. Your main defence is the RCD which will quickly cut off the power in the event of a fault and prevent electric shock.

But this raises some issues.

1)     Do you know that the RCD is working properly? And is the wiring OK? If your system hasn’t been checked recently it might not be, with possible dire consequences.


2)     RCDs are very sensitive – they must be sensitive to do their job properly – but this can lead to nuisance tripping. That is when your lights cut out for no apparent reason or they just won’t turn on. Low voltage is less susceptible to nuisance tripping.


Advantages of low voltage

Low voltage garden lighting has two layers of protection; overall protection from the RCD and the extra safety of being 12 volts instead of 240 volts, giving you peace of mind, especially important if you have children or pets.

Also, low voltage lighting is much less prone to nuisance tripping and is less sensitive to adverse conditions such as damp or accidental damage, making it ideal for garden lighting.

Many of the top garden lighting experts including Mike Shackleton, Julian Alder, David Jackson, Ian Kirkham and Rob Webber prefer low voltage, and some even insist on it.


12 volts versus 240 volts

There is a battle here between experienced garden lighting professionals who advocate low voltage and many electricians who opt for 240 volts. What’s going on?

The clue is in the word experienced. The garden lighting specialists have learnt from experience that 240 volts in the garden is more likely to be trouble, and that well designed low voltage systems are less temperamental, less likely to trip the RCD, and often easier to fix if you do get a problem.

By contrast, the experience of many electricians is that transformers have been the cause of much trouble and are best avoided. But often these were cheap transformers, installed in small, hot locations, where they overheated and packed up.

But good quality, IP rated transformers, specially designed for outdoor use, largely overcome these issues.


Advantages of 240 volts

With 240volt lights you don’t need a transformer, so there are some cost savings, and one less thing to go wrong.

And, in some locations it can be difficult to hide a transformer.

Cable voltage drop is not an issue for most 240v garden lighting installations.

Dimming 240v lights tends to be easier than low voltage dimming. However, most garden lighting isn’t dimmed.

Some light fittings are only available in 240v.


If the installation isn’t perfect, you will get problems.

Your safety is completely reliant on a high standard of installation and proper maintenance.

You are more likely to suffer from nuisance tripping of the RCD.

Cabling and connections tend to be more expensive - with much greater use of armoured cables in trenches. Digging lots of trenches can be very disruptive in a mature garden.

Regulations do not allow for the use of long unprotected 240v cables. This means that armoured cables are run to locations close to the lights.

Problems are usually harder to locate and more expensive to rectify.

With a 240v garden installation you need to be quite specific about exact positions of the lights early in the design process. There isn’t much wriggle room for changing your mind later.

Advantages of 12 volts


Less nuisance tripping of the RCD.

12v systems are less affected by damp and minor accidental damage.

12v cables can be run safely across flower beds, and along fences (which are considered temporary because they might be blown down), or up trees.

Problems tend to be easier to identify and cheaper to fix.

You can reduce the amount of trenching you need for armoured cabling, or in some cases even eliminate the need for trenches altogether.

There is less use of expensive 240v connections.

12v installations are easier to modify if you change your mind later. 



You need good quality transformers or led power supplies which cost money. But costs can be minimised if each transformer feeds a group of lights.

Long cable runs can suffer from volt drop.

Low voltage dimming can be difficult, so you need to be careful to get it right.

Sometimes there is nowhere to hide a transformer.

Some light fittings are not made in 12 volts.



The trend is towards low voltage garden lighting as more people recognise the considerable benefits it can bring.

But each installation is different. 240v is a good choice if you have nowhere to hide a transformer or if you want dimming.

There is nothing to stop you from having a mixture of low voltage and 240v lights.

Low voltage has so many advantages for garden lighting that we would always make it our first choice, and just use 240v in special situations.

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Posted by Lighting for Gardens on: Jan 7, 2020 11:20:00 AM