Electricity and water don’t mix, especially the sensitive electronics used in LED lighting fittings. Keeping water out of light fittings is critical for the long-term performance of exterior lights. The best manufacturers have learnt the hard way over many years how to achieve this.
They build and test to meet or exceed the designated fixture IP rating. When they fail, generally the fittings are not at issue, it is the installation and environmental factors that play the biggest part whether the fitting survives its design life, or not.
IP rating overview https://en.wikipedia.org/wiki/IP_code
The #1 cause of failure is the ingress of water up the supply electrical cable into the fixture, rather than the fitting gasket or potting failure.
Quality manufactures want their products to do what it says on the box, they want customers to be happy with their selection and specify the brand again. Exterior lighting manufacturing is an engineering step up from interior fixtures, it takes years of experience, fine tolerances and modern manufacturing technics to consistently keep water out, there are only a few world class manufacturers. Most specifiers can name only a handful of exterior manufactures but scores of interior.
Fittings are manufactured and tested in controlled environments, water testing and trial installation are performed by skilled experienced engineers, they actually read and follow the instructions. Site installations are another world, with various skill levels, environmental factors and equipment. The best are skilled, experienced, confident trades that understand the challenge, follow instructions and take pride in their work. No surprise these trades cost more than the “she’ll be right” contractors….
The second issue is the type and quality of installation – above ground, on the ground, in-ground. A wall mounted light fitting is easier to keep water out than an in-ground application with constant moisture in the soil at best, and worst case, sitting in water. If there is ever going to be an issue it will be with in-ground uprights.
LED Light fittings heat up when on and cool down when off, this creates a vacuum within the fixture, that can suck or “wick” moisture into the fitting over an extended time, this moisture condenses and pools within the fixture damaging the LED lamp and or control gear. Once the water is in it can’t get out.
Electrical Termination
Our exterior lights from LightGraphix and Meyer are factory terminated with round cable and IP68 glands, this short cable must be locally terminated to IP68. MLP supply RayGel branded IP termination kits which are quoted with exterior fittings and their correct use is mandatory to meet the warranty conditions.
RayGal overview on YouTube: https://youtu.be/YzqudlXHwGY?si=2HOncexFQ19GdMlc
Ideally don’t terminate outside, in many cases the factory can fit long cables up to 20mts eliminating the local electrical joint. Cables are pulled to a dry location for termination to the supply.
Installation
Modification
Another common failure is installers replacing the factory fitted round cable with standard building cable, the mechanical IP68 gland will only give a watertight seal if the cable is round and the correct diameter. The use of flat cable and silicon will not make a correct water tight seal. More silicon does not equal a better seal! It is a short term fix but will fail over time.
Take aways
- Use world class quality manufactures who have decades of experience
- Terminate the fitting to the supply with speciality IP rated connectors eg RayGal or ideally specify long cables and terminate in a dry location
- Ensure at both design and construction stages adequate drainage has been provisioned for in-ground uprights
- Use quality electrical contractors with experience of exterior installations especially in-ground uprights
- If you can’t I would suggest don’t waste your or your clients money and burden them with the ongoing maintenance hassles
