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Installation of 12v Lighting

Lumena 12v lights must be wired in parallel. If you are unfamiliar with parallel circuits, we tend to compare them to a ring road. Imagine a road leading up to a roundabout, this would be the power cable leading to the splitter. Like a roundabout, the splitter has multiple exits. Each exit will lead to the next place, either your final destination (a fitting), or another splitter, where the same rule applies.

When installing low voltage light fittings, a transformer is required. First, you will need to determine what size transformer is required based on the load to power. You will need the wattage of the lamps to power up and the total number of fittings. Multiple the two together to calculate the total load. For example, 3 fittings, each using a 5W bulb (3 x 5) = 15W. Therefore, a transformer exceeding this wattage is required, in this case 20W, also known as 20VA. For optimum performance, a transformer should ideally be loaded at between 50-80%. They can power less but if underloaded you may find that the the lamps do not last as long as expected, plus it is unnecessary additional expense. Equally, a higher load can be powered, however we recommend leaving around 10% to allow for power surges, start up current and also discrepancies in lamp wattage. A transformer must not be overloaded or the transformer will overheat and fail.

All cable joins must be 100% watertight. Accessories such as waterproof junction boxes, in-line connectors / plugs and heat shrink can be used – Wiring Instructions Available Here. Junction boxes can also be filled with a resin sealing compound such as Wiska Magic Gel for additional protection to connections. The number of fittings on one circuit should be kept to a minimum and cable runs kept a short as possible to prevent voltage drop and possible loading issues.

It is important that manufacturers guidelines are followed when installing 12v garden light fittings.

12V Plug & Play Systems

Plug and Play lighting systems are very simple, designed for quick installation with no tools required. This will also reduce installation costs. Simply plug the plug & play light fitting directly into the transformer / LED driver. Extension cables can be used when the fitting is located further away from the power source, as well as adaptors / splitters to power multiple fittings.

Customers can purchase a full range or plug & play garden lights and accessories from Lumena (12v Versa or 24v DConnect). Waterproof Transformers & Drivers (IP67-68), Extension Cables, Splitters & Junction Boxes, LED Lamps and Coloured Lenses are all available, plus more.

All Lumena 12v light fittings will be changing over to Plug and Play due to the simplicity of installation. Non plug and play items will also connect to these systems with the use of a cable converter. Consequently, this increases the amount of light fitting and accessory choices. For example, Dusk to Dawn Photocells and PIR Motion Sensors are compatible with the 12v system.

However, not all Plug & Play systems are compatible with one another. Lumena stock the Versa 12v Plug & Play Range alongside the DConnect 24v DC Plug & Play Range. Connectors cannot be used across both systems.

NOTE: Transformer / Driver required for all low voltage garden lighting circuits (sold separately).

12V Low Voltage Garden Lights VS 240v Garden Lights

A common question we are often asked is, “what is better, 12v or 240v”?

There are two main systems which can be used in a garden: 12v low voltage and 240v mains voltage. The system to be used will determine the types of light fittings which can be used. There are both pros and cons for both systems, and many factors which will help you make your decision. Here, we will educate you as much as possible about each garden lighting system to ensure you make the correct choice for your specific application.

12v Low Voltage Garden Lighting Systems

Low voltage lighting is particularly suited to outdoor environments. This is because it is designed to tolerate damp, outdoor weather conditions with no negative impact on the overall performance. Underwater lights should ideally be low voltage (12v) as it is much safer than mains (240v).

220-240v Mains Garden Lighting Systems

Mains voltage systems are a common choice as the standard UK household is 240v. In our experience many electricians are familiar with using 240v, and prefer to stick with . If replacing a previous 240v system, it is often thought that it needs to be replaced with the same system. With the use of carefully positioned waterproof transformers, available from Lumena, this is not necessarily the case.

Advantages

  • Safe – Low voltage systems are extremely safe and almost anyone with a basic knowledge of electrics can install them. If a cable was somehow damaged, such as with a garden spade, the voltage is not high enough to cause serious harm . A small shock may be felt but nowhere near as powerful as 240v mains.
  • Suited to damp environments – 12v systems are rarely affected by water, which makes them the perfect option for garden lighting. Sometimes, a small amount of condensation can appear inside the fittings due to a combination of moisture being trapped inside the fitting, heat of the lamp and cold air outside. If this water drips on the bulb holder or connection cables, a low voltage circuit will continue to function with no issues.
  • Cable Type and Position – Low voltage systems involve much less risk to safety. Therefore, the installation and positioning of cables is a much simpler task. As long as a high quality outdoor rubber cable is used, e.g H05RN-F or higher, the cable can be hooked up on fences safely, or even laid on top of the earth so that they are visible to gardeners etc. Lumena do recommend that cable is safely installed in conduit or water pipe wherever possible. This will protect the cable from animals and erosion from weedkiller and fertiliser. This is much easier than having to dig and lay the cable in armoured conduit 0.5m below ground, as recommended for 240v outdoor cable.
  • Maintenance costs – as a 12v system can be installed and maintained by an end user, installation and maintenance costs will be kept to a minimum. A qualified electrician will be required to install and 240v components, e.g. a waterproof outdoor socket, or to hard wire the transformer (if required).
  • Cable Runs – generally, mains voltage cable runs can be much longer that 12v based on voltage drop. Thicker cable will reduce the resistance, thus reducing the voltage drop, however for extremely long runs 240v will be required. Having said that, 12v systems can run from the mains cable periodically along the run.
  • Wattage of Lamps – with a mains system, there are no restrictions with the lamp wattage (load). This in turn will affect how bright the light can be and the types of lamps available. However, with 12v systems, the load is restricted my the maximum load of the transformer / driver used.
  • No transformer required –
  • Preferred by Electricians – Many electricians prefer to install 240v rather than 12v as a system they know and fully understand. Therefore they will probably complete the installation quicker and more confidently than if they were installing a system they are not used to.

Disadvantages

  • Transformers Required – At least one transformer will be required for a 12v garden lighting system to ‘transform’ mains voltage (240v) down to 12v. Depending on the number, location and wattage of fittings, additional transformers may be required, especially on longer cable runs. See “mixing 240v and 12v” below.
  • Wattage of Lamps – With 12v systems, the load is restricted by the maximum load of the transformer / driver used. It is important to know the exact lamp wattage of the system before purchasing the transformer to ensure the correct unit is purchased. Example: 10 x 4w bulbs = 40w so a 50w transformer is needed.
  • Cable Runs Shorter – Voltage drop is more of an issue with low voltage lighting systems. The longer the cable run, the more current is lost due to increased resistance. Therefore, after 30 – 35m of cabling,  lamps may end up dim or in severe cases not illuminate at all. Many factors affect voltage drop including the location of lights, the load and the thickness of cable. Read more about Voltage Drop here.
  • Cable Type and Position – Installing a 240v system, correctly following guidelines and regulations, generally is a much bigger job than installing low voltage systems and is usually more costly. All mains cables must be armoured, with the exception of the final 2m of rubber cable running to the fitting. Alternatively, it must be installed inside armoured conduit. As a safety precaution, guidelines recommend that cable based at ground level is buried at least 0.5m below ground. This prevents damage to the cable by animals, machinery and tools. Lumena recommend that all cable is safely installed in armoured conduit, including as much as possible of the cable attached to the fitting.
  • Tripping of Circuit Breaker – When a 240v lamp comes to the end of its’ life it will blow. Due to the sudden surge in current, this will often result in the circuit breaker tripping out. This  can be easily rectified by the flick of a switch, but if it is a common occurrence, it will become a little irritating. .
  • Water Ingress / Condensation Issues – 240v fittings are unforgiving when it comes to damp weather conditions, particularly GU10 bulb holders which are similar to a cup shape. Sometimes, a small amount of condensation can appear inside the fittings due to a combination of moisture being trapped inside the fitting, heat of the lamp and cold air outside. If this water drips onto the bulb holder or connection cables, a 240v circuit is very likely to trip, this is worrying and will potentially result in additional work and related costs trying to rectify the issue.
  • Maintenance Costs – as 240v mains systems must be installed by a qualified electrician, all maintenance work will also result in a call out charge. If there are ever any issues with the circuit tripping due to damage of a cable / water ingress etc, these costs will start to add up.

Some electricians can be hesitant to convert to 12v Lighting as it is unfamiliar to them. Also, some older low voltage lights were not of a high quality. We share the opinion of many of our trusted customers and trade professionals, and agree that high quality 12v Garden Lighting is the way forward !

Mixing 12v & 240v Lighting Systems

Mixing both 240v and 12v lighting systems is possible and fairly straight forward. Wherever a 240v feed exists, mains voltage outdoor lights can be connected via junction boxes.

To incorporate 12v garden lighting in the same area as 240v outdoor lighting, a waterproof transformer is required. All Lumena 12v Transformers are rated IP68 so are fully waterproof, although we do not recommend submerging in water in case of mains cable damage. Although our transformers are supplied complete with a 3 pin UK plug, this can easily be removed and the cable prepared as “open-end”. This can then be hardwired into a junction box with a mains 240v power feed. Anything located before the transformer will be 240v and anything after the transformer will be 12v. It is important to ensure the correct size transformer is selected, determined by the total wattage of fittings / light bulbs which will be powered.

Multiple transformers can be installed at various points around a 240v circuit. This also reduces the likelihood of voltage drop as the low voltage run will be substantially shorter.

240v Outdoor Lighting Installation

Lumena always recommend that 240v outdoor lighting is wired in parallel, the same as low voltage. We believe this to be a more reliable set-up. It also means that subsequent fittings will not be affected by any previous units on the circuit. This could be something as simple as a blown bulb, which would result in the power supply being interrupted part way around the circuit.

As with 12v, all cable joins must be 100% watertight. This is extremely important with mains garden lighting – water and 240v do not mix! If water is present in any of the cable joins, when the fitting is lit, the heat generated inside the fitting can act as a vacuum, pulling water up the cable and damaging the fitting. It is likely that this would void any warranty offered with the product. Waterproof junction boxes or inline connectors and heat shrink kits can be used. Wiska Magic Gel (resin compound) is a great addition for increasing protection to connections inside junction boxes. It is very important that the number of fittings on one RCD / circuit is kept to around a dozen fittings.  Anymore than this can cause issues further down the line, such as tripping / overheating etc. It is also more practical should an issue ever arise as the number of fittings to test would be much lower. It would cost a lot more for an electrician to test 50 fittings to find the one fitting with a fault rather than only 12 on that one circuit.

Manufacturers guidelines should always be followed when installing outdoor light fittings. For example, all in-ground lights must have adequate drainage surrounding them. This is particularly important in clay based soil beds.