Working Principles of LEDs

Why Warning Light Spec Sheets Are So Confusing

Here's an honest confession from someone who fits this gear every week. Warning light spec sheets look precise, but half the codes on them come from completely different testing standards, written by different bodies, for different reasons.

Think of it like buying hiking boots. One brand rates waterproofing by hours in a puddle, another by a lab test with a hose, and a third just says "waterproof" with no detail at all. All three might be genuinely good boots, but you can't compare the numbers directly unless you know what each one is actually testing.

Light bars work the same way. Once you know the handful of standards that actually turn up again and again, you can compare products properly instead of just trusting whichever spec sheet sounds the most impressive.

IP Rating: The Two Numbers That Actually Matter

An IP rating, short for Ingress Protection, always has two digits, and each one tests something completely different.

• First digit, dust: ranges from 0 (no protection) to 6 (completely dust-tight). Most decent vehicle and marine lighting sits at 6.
• Second digit, water: ranges from 0 up to 9, covering everything from light splashing through to sustained high-pressure jets and full submersion.

So an IP67 rated light is fully dust-tight and can survive temporary submersion in water. IP68 goes further again, rated for longer or deeper submersion depending on the manufacturer's specific test conditions. Neither digit tells you anything about brightness, colour, or how the light performs electrically. It's purely about what the housing keeps out.

ECE R65 vs SAE: Two Rulebooks, One Confusing Word

Here's where most confusion actually happens, and it's worth getting straight once and for all.

There are two separate international standards for vehicle warning lights on the market, ECE R65 out of Europe, and SAE (commonly J595 or J845) out of the United States. Both use the word "Class" in their ratings. They do not mean the same thing.

ECE R65: Class 1 and Class 2

Under ECE R65, Class 1 means the light meets a single intensity level, tested for night-time use. Class 2 means the light has two switchable intensity levels, a brighter daytime setting and a dimmer night setting, so it doesn't dazzle anyone after dark. Class 2 daytime output is noticeably brighter than Class 1, roughly double, and switching between the two is a manual operator choice, not automatic.

ECE R65 also has a companion standard, R10, which covers electromagnetic compatibility rather than brightness. Seeing both R65 and R10 mentioned together on a spec sheet simply means the product has been tested for both light output and electrical interference.

SAE Class Ratings: A Different System Entirely

SAE ratings use their own separate classification for warning lamps, tested against different criteria to ECE R65. A product marked "SAE Class 1" is not directly comparable to an "ECE R65 Class 1" product, even though the words look identical on the page.

Flash Patterns and Synchronisation: More Than a Gimmick

Product listings love to boast about flash pattern count, twenty patterns, thirty patterns, more than you'll ever actually use in practice. It's a real feature, but it's rarely the one that matters most.

The feature genuinely worth checking is synchronisation, whether multiple light bars or beacons on the same vehicle can be linked to flash in unison. A synchronised pair of lights reads as a single, clear warning signal from a distance. Two lights flashing independently and out of sync can actually look messier and less noticeable, even though both units are perfectly functional on their own.

If you're fitting more than one light to a vehicle, ask specifically whether they synchronise together. That's the detail that separates a genuinely well-designed system from a pile of individually decent parts.

Voltage and Current Draw: What It Means for Your Vehicle

Two figures worth understanding here, and they're not as scary as they look.

Voltage Range

Most commercial and fleet lighting is rated for a range, commonly 12 to 24 volts, rather than a single fixed voltage. That range matters because it means the same product works whether it's fitted to a ute running a 12V system or a truck running 24V, without needing a different model for each.

Current Draw

Measured in amps, this tells you how much load the light places on your vehicle's electrical system. LED lighting draws dramatically less current than the halogen beacons it's replaced, which matters if you're already running a two-way radio, GPS tracker, and other accessories off the same battery. Lower current draw at the same brightness is a genuine win, not just a marketing line.

Exact current draw varies by model and should be checked on the specific product page or confirmed with us directly, since it changes with LED count and brightness setting.

Putting It Together: Reading MSL's Own Range

Let's apply this to gear you can actually buy today.

Notice what's genuinely useful here. It's not the flashiest number on the page, it's knowing which rulebook that number belongs to, and what it actually tested.

Still Not Sure Which One You Need?

Honestly, most buyers don't need to become spec sheet experts. That's our job. Mobile Systems Limited has supplied and installed vehicle and marine lighting for NZ businesses from Mount Maunganui for over 25 years, and we'll tell you plainly which rating actually matters for your specific vehicle and application, rather than leaving you to decode it alone.