Every week we get a call that starts the same way. A strip light has failed after a season outdoors, or a bathroom install has gone patchy after six months, and nobody can work out why. Almost always, the answer comes back to the IP rating. Either the wrong one was specified, or the right product was installed in a way that quietly cancelled out its protection.
After more than twenty years supplying LED lighting across New Zealand, we’ve learned that IP ratings are one of the most misunderstood specs in the business. Here’s how we explain it to our trade customers.
What The Two Digits In An IP Rating Actually Mean
IP stands for Ingress Protection. The two numbers that follow are separate scores, not a single grade.
The first digit rates protection against solids, from 0 to 6. In practice, only the top two matter for lighting. A 5 means dust protected, so dust can enter but not in enough quantity to interfere with operation. A 6 means dust tight.
The second digit rates protection against water, from 0 to 8. A 4 covers splashing from any direction. A 5 covers low pressure water jets. A 6 covers powerful jets. A 7 covers temporary immersion to one metre. An 8 covers continuous immersion at a depth the manufacturer specifies.
So IP65 means dust tight and protected against water jets. IP67 means dust tight and able to survive being briefly submerged.
Why IP67 Is Not Automatically Better Than IP65
This is the point most people miss. The water scale is not strictly cumulative at the top end. A product tested to IP67 has been dunked, but that does not prove it can handle a pressurised hose. If a strip is going somewhere it will be washed down, look for a dual rating such as IP65/IP67, or ask what it was actually tested to.
We see this most often in commercial kitchens, cool stores and wash bays, where the real threat is a hose rather than standing water.
What The Ratings Look Like In Real Product
IP20 strip is bare board with no coating. It belongs indoors, in dry, sealed locations only.
IP65 strip usually has a silicone coating applied over the top face, leaving the underside exposed. It handles splash, spray and humidity well and stays reasonably slim and flexible.
IP67 strip is typically run inside a silicone sleeve or fully coated on both faces. It’s thicker and less flexible, and takes a little more care to mount straight.
IP68 strip is fully encapsulated, with the LEDs sealed into a solid extruded body. Our LED neon flex range is built this way, which is why it copes with unsealed outdoor locations, splash zones and areas where people will physically touch it.
Heat Is The Trade-Off Nobody Budgets For
Silicone is a decent insulator, which is helpful for keeping water out and unhelpful for getting heat away from the LEDs. A heavily sealed strip run at high output, with no path for that heat to escape, will run hotter than the same strip in an IP20 build. Over time that shows up as reduced output, colour shift and shorter life.
This is exactly why we recommend mounting sealed strip in aluminium rather than sticking it straight to timber or plasterboard. Our aluminium LED profiles act as a heat sink as well as a finishing detail. We covered the wider issue in our post on how to stop LED lights from overheating, and it applies double outdoors.
The other trade-off is optical. Thick silicone over widely spaced chips can accentuate dotting rather than hide it, so a high density or COB strip is usually the better starting point for sealed applications.
The Seal Fails At The Ends, Not The Middle
In our experience, IP rated strip almost never fails along its length. It fails at the cut, the solder joint or the end cap.
Cutting a sealed strip breaks the seal. Unless the cut end is properly re-sealed with the correct end cap and silicone adhesive, and the cable entry is sealed too, you have created an open door for moisture at the lowest point of the run. Water then tracks along the inside of the sleeve and corrodes the copper well away from where the fault appears.
If a run has to be joined on site, plan the joins for accessible, protected positions, and use IP rated connectors rather than heatshrink over a bare solder joint.
Rain Is Not The Only Thing Attacking An Outdoor Install
An IP rating says nothing about ultraviolet exposure, salt or temperature, and all three matter here. New Zealand sits under a high UV load, and cheap PVC sleeving yellows and goes brittle within a couple of summers on a north facing wall. Coastal sites add salt to the mix, which finds any exposed solder pad. Our outdoor LED strip lighting is selected with these conditions in mind rather than for a European climate.
For wet interior work, humidity and steam are the constant, not immersion. That’s the thinking behind our waterproof LED strip light range for bathrooms, showers and laundries. Bathroom zones under the wiring rules also affect what can go where, so have your registered electrician confirm the zone before the strip is ordered.
Don’t Forget The Driver And The Controls
A sealed strip fed by an indoor rated driver sitting in an exterior cavity is a failure waiting to happen. The power supply needs a rating suited to its own location, adequate ventilation, and a reasonable margin on its load. Our LED power supplies and control systems include outdoor rated options, and we’re happy to check driver placement at the design stage.
Getting It Right The First Time
Specify for the worst condition the run will see, not the average one. Mount in aluminium. Seal every cut properly. Rate the driver for where it actually sits.
If you’re weighing up a project and want a second opinion on the rating, give our team a call. We’d far rather help you get it right up front than replace a run in two years.
