The ‘Classification Trap’: What D40 vs. D32 Means for AS 2293.3 Compliance

Decoding the “Alphabet Soup”: A Practical Guide to AS/NZS 2293.3 Luminaire Classification

I want you to picture an electrician, let’s call her “Jen.” Jen is on a maintenance job, replacing a failed emergency light in a long office corridor. The old fitting has a sticker: “Classification: D40.” She checks her van. She has two new fittings: one marked “D32” and one marked “D40.” The D32 is a brand she’s not familiar with, but it’s cheaper and her boss has been pushing to cut costs. The D40 is a trusted brand.

She hesitates. They look identical. What’s the harm?

She installs the D32.

Jen just unknowingly rendered that entire corridor non-compliant and exposed her company and the building owner to massive liability.

This isn’t a hypothetical. This is the “Classification Trap,” and it happens every day. It’s a mistake born from not understanding the most critical piece of information a manufacturer provides: the luminaire classification.

This “alphabet soup” (like C0:D80 / C90:D40) isn’t jargon. It is the engineering lynchpin that connects the product (governed by AS/NZS 2293.3) to the design (governed by AS/NZS 2293.1). 

As an expert who lives in this standard, let me be the one to finally translate this for you, simply.

What is the AS/NZS 2293.3 Classification?

When a manufacturer designs an emergency light, they must have it tested by a NATA-accredited lab. This testing (to the rigorous methods in AS/NZS 2293.3 measures the light’s performance, and the lab issues it an official classification. 

This code has two parts: the Letter and the Number.

The Alphabet (Class A to E): This is the “Shape” of the Light

The letter (A, B, C, D, or E) tells you the shape of the light distribution, or its “photometric curve”.  

Think of it like a nozzle on a garden hose:

• Class A/B: This is like a “jet” stream. It’s a very narrow, focused beam of light, designed to throw a long way. You might see this in a high-bay warehouse.
• Class C/D/E: This is like a “cone” or “shower” setting. It throws a much wider, more circular pattern of light.

In Australia, Class D is the most common classification you’ll see. It provides a broad, diffused circle of light that is ideal for illuminating open areas and corridors. 

The Numbers (1 to 800): This is the “Power” of the Light

The number after the letter tells you the luminous intensity of the fitting. In simple terms, this is its power, or how far it can “throw” that shape of light.  

A higher number means a more powerful light.  

• A D32 fitting is a Class D (wide circle) light with a “power” level of 32.
• A D40 fitting is a Class D (wide circle) light with a “power” level of 40.
• A D50 fitting is a Class D (wide circle) light with a “power” level of 50.

The D40 is significantly more powerful than the D32. This distinction is everything.

The “Pro-Level” Detail: Symmetrical vs. Asymmetrical Classification

This is the part most blogs get wrong or just ignore. You’ll often see two types of classifications.

Symmetrical (e.g., “D50”)

This is what you see on a “spitfire” or “satellite” fitting—the small, round lights. It has a single classification, like D50. This means it throws a perfectly symmetrical, circular “D-class” shape of light with a “power” of 50 in all directions. Simple.  

Asymmetrical (e.g., “C0:D80 / C90:D40”)

This is what you see on a long, “batten” style fitting. This code looks complex, but it’s simple when you understand why it exists. 

A long tube light doesn’t throw light in a circle. It throws a different pattern of light along its length than it does across its width. The code just describes this:  

• C0-180 (the C0 axis): This is the light distribution along the length of the batten.
• C90-270 (the C90 axis): This is the light distribution across the width of the batten.

So, a classification of C0:D80 / C90:D40 means :  

• Along its length (C0), it throws a D-Class shape with a power of 80.
• Across its width (C90), it throws a D-Class shape with a power of 40.

This is vital for a designer. In a long, narrow corridor, they will orient the batten so the powerful C0:D80 axis shines down the hallway, letting them use fewer lights.

How This Code is Used in the Real World (The AS 2293.1 Link)

So, why do we even have this code? Because it’s the input for the design standard, AS/NZS 2293.1. That standard has one goal: to ensure the light at floor level never drops below 0.2 lux. 

It gives designers two ways to prove this:

Method 1: The Spacing Tables (The Easy Way)

This is what 90% of designs use. AS/NZS 2293.1 has a series of tables (Tables E1 to E5, etc.). These are simple, pre-validated cheat sheets. 

A designer simply:

1. Picks a fitting with a Part 3 Classification (e.g., D40).
2. Knows the Mounting Height (e.g., 3.0 metres).
3. Looks at the table. The table says, “For a D40 fitting at 3.0m, the maximum allowable spacing between lights is 18.6 metres.”  

The design is done and is “Deemed-to-Satisfy”.  

Method 2: The Illuminance Calculation (The Hard Way)

For a complex area like a stadium or a weirdly-shaped room, the tables don’t work. Here, the designer must use special lighting design software. 

They import the “photometric file” for that exact fitting (a file provided by the manufacturer from their Part 3 testing) and place the lights in a 3D model. Then they run a simulation that proves the light level on the floor never, ever drops below 0.2 lux.

The “Classification Trap”: Why Jen’s Mistake is a Disaster

Let’s go back to Jen in that corridor.

• The Original Design: The designer used the spacing tables. He saw the corridor was 36 metres long. He used a D40 fitting at 3.0m, which allowed for 18.6m spacing. He put one at each end (18m spacing). The design is compliant.
• The Mistake: Jen replaces one of the D40 fittings with a D32.
• The Consequence: Jen doesn’t know that the spacing table for a D32 fitting at 3.0m only allows a maximum spacing of 15.0 metres.
• The Result: The system is now spaced at 18 metres, but the lights are only rated for 15 metres. There is now a 3-metre “black spot” in the middle of the corridor that is well below the legal 0.2 lux minimum.

In a fire, in the smoke, that black spot is where someone trips, falls, and becomes one of those 146,700 serious injury statistics.

Jen failed the system. Her boss is liable. The building owner is liable. All because of a single number on a sticker that they didn’t understand.

Conclusion: Respect the Classification. It’s Not a Suggestion.

That alphanumeric code is the single most important piece of data on an emergency light. It is a legal and engineering guarantee of performance.

When replacing a fitting, the rule is non-negotiable: you must replace it with a fitting that has an equivalent or better classification. Replacing a D40 with a D32 is a compliance failure. Replacing it with another D40, or a D50, is compliant. 

Don’t fall into the Classification Trap. Check the sticker, understand the code, and protect yourself, your business, and the people you’re paid to keep safe.