What Is the Length of the RX-PT8 Tube? Complete Size and Installation Guide for Commercial Growers

One of the most common questions growers ask when evaluating the Koray RX-PT8 (also known as the PT8T) for their growing operation is about its physical dimensions. The size of a grow light tube determines whether it fits your existing racks, how many units you need per shelf, and how to plan your growing layout for maximum coverage and efficiency. This guide provides a thorough breakdown of every dimension that matters, along with practical installation advice drawn from real-world commercial deployments.

Whether you are designing a new vertical farm, upgrading an existing plant factory, or setting up a small indoor growing operation, understanding the RX-PT8’s dimensions will help you plan your installation with confidence. Let us cover every measurement, spacing requirement, and layout consideration you need to know.

The Core Dimensions of the RX-PT8

The Koray RX-PT8 grow light tube has a total length of 1200mm (approximately 47.2 inches, or roughly 4 feet). This is the same standard length as a conventional T8 fluorescent tube, which means the PT8 is designed as a direct modern replacement for the fluorescent tubes still widely used in commercial growing racks around the world.

The cross-section of the tube measures 33mm wide by 35mm tall. This compact rectangular profile is one of the slimmest in its class, allowing the PT8 to fit into tight shelf gaps and multi-tier growing systems where every millimeter of vertical space counts. Despite this small physical footprint, the PT8 packs impressive optical performance thanks to Koray’s proprietary secondary optics technology, which concentrates the light output downward for maximum efficiency.

The 1200mm length is not arbitrary. It is specifically chosen to match the most common shelf widths in commercial growing racks. Standard hydroponic shelving systems typically use shelves that are 1.2m wide, and the PT8 spans these shelves perfectly, delivering uniform light from edge to edge.

Why 1200mm Is the Ideal Length for Commercial Growing

The 1200mm tube length has become the industry standard for commercial growing operations for several practical reasons. First, it matches the most popular shelf dimensions used by growing rack manufacturers worldwide. Second, it provides an optimal balance between light coverage and handling convenience. A tube that is too short would require more units per shelf, increasing wiring complexity and cost. A tube that is too long would be difficult to handle, ship, and install in confined spaces.

The Koray RX-PT8 at 1200mm hits the sweet spot. It covers a wide swath of growing area with a single unit, and its slim 33x35mm profile means multiple tubes can be installed side by side on a single shelf without wasting space. This is particularly important in vertical farming operations where shelf height is limited and every centimeter of vertical clearance between tiers matters.

How Many PT8 Tubes Do You Need Per Shelf?

The number of RX-PT8 tubes needed per shelf depends on your target PPFD level and the depth of your growing area. Koray has published detailed PPFD mapping data that provides clear guidance.

For a standard 1.2×1.2m growing area, the recommended configuration is 6 PT8 tubes mounted at 0.3m (30cm) height above the canopy. This setup delivers an average PPFD of 300 μmol/m²/s across the entire area. The total power consumption for this configuration is approximately 133W per square meter, which is highly efficient for the light levels delivered.

If your shelf is 1.2m wide and 0.6m deep, you would typically use 3 tubes spaced evenly across the width. For deeper shelves (0.8-1.0m), you may want to add an additional row of tubes to ensure uniform coverage at the back of the shelf. The key principle is to maintain consistent spacing between tubes so that the light overlap creates uniform PPFD across the entire canopy.

Mounting Height and Its Effect on PPFD Coverage

The recommended mounting distance for the RX-PT8 is 0.2 to 0.3 meters above the plant canopy. This range provides the best balance between light intensity and coverage area. Here is how the PPFD performs at different distances for each spectrum variant.

At 0.15m (15cm), the V3 spectrum delivers 416 μmol/m²/s at the center, while the F175 spectrum delivers 365 μmol/m²/s. The F4K seedling spectrum delivers 270 μmol/m²/s. These high values are ideal for demanding crops that require intense light, such as fruiting plants or fast-growing leafy greens.

At 0.2m (20cm), the V3 delivers 316 μmol/m²/s and the F175 delivers 275 μmol/m²/s. This is the most commonly used mounting distance in commercial operations, providing strong light levels with good coverage width.

At 0.3m (30cm), the V3 delivers 210 μmol/m²/s and the F175 delivers 185 μmol/m²/s. This wider spacing is suitable for seedlings, microgreens, and other crops that do not require maximum light intensity. The wider coverage at this distance means fewer tubes may be needed for light-loving crops.

Comparison with T8 Fluorescent Tubes

Many growers upgrading from fluorescent T8 tubes wonder how the RX-PT8 compares in terms of physical fitment. The good news is that the PT8’s 1200mm length matches the standard T8 tube length exactly, and its 33x35mm cross-section is comparable in size to a T8 tube’s 26mm diameter. In many cases, the PT8 can be installed in the same mounting positions previously occupied by fluorescent tubes, though the wiring will need to be updated to accommodate the PT8’s integrated AC120-277V driver.

The performance difference, however, is dramatic. The Koray PT8 delivers over 40% higher PPFD compared to previous generation tube lights while consuming significantly less power. The F175 model saves 24% electricity compared to the old version, and the V3 model saves 33%. When you factor in the longer 35,000-hour lifespan (compared to roughly 10,000-15,000 hours for fluorescent tubes), the return on investment becomes very clear.

Daisy-Chaining and Wiring Considerations

The RX-PT8 supports daisy-chain wiring, which greatly simplifies installation. In the standard configuration, you can connect up to 10 PT8 tubes in a single daisy chain. If you are using the centralized power supply version, this number doubles to 20 tubes per chain. This means you can power an entire shelf of lights from a single power connection, reducing wiring complexity and installation time.

The daisy-chain capability also makes system expansion straightforward. If you decide to add more growing capacity, you can simply connect additional tubes to the existing chain without running new power lines, as long as you stay within the 10-tube (or 20-tube) limit. The tubes operate on AC120-277V input with a power factor greater than 0.9, ensuring compatibility with standard electrical systems worldwide.

Planning Your PT8 Installation: A Step-by-Step Approach

To plan your RX-PT8 installation, start by measuring your shelf dimensions: width, depth, and the vertical clearance between tiers. Next, determine your target PPFD based on the crops you are growing. Leafy greens and microgreens typically need 150-300 μmol/m²/s, while fruiting crops like tomatoes and peppers require 400-600 μmol/m²/s or higher.

Once you know your target PPFD and shelf dimensions, use the PPFD data at various distances to calculate the number of tubes and mounting height needed. For most commercial leafy green operations, 6 tubes at 0.3m height provides the ideal combination of coverage and intensity. For higher-light crops, reduce the mounting distance to 0.2m or choose the V3 spectrum for maximum output.

Finally, plan your electrical layout. Map out the daisy-chain connections for each shelf, ensuring you do not exceed the 10-tube limit per chain. Account for the power supply location and wire routing. The IP66 waterproof rating of the PT8 means the tubes can handle the humid conditions typical of commercial growing environments, so you do not need to add protective enclosures.

Conclusion: The Right Size for Commercial Growing

The Koray RX-PT8’s 1200mm length and 33x35mm compact profile make it one of the most versatile and well-sized grow light tubes on the market. Designed to fit standard commercial growing racks, delivering high PPFD output with Koray secondary optics, and supporting efficient daisy-chain wiring for up to 10 tubes, the PT8 is engineered for real-world installation convenience without compromising on performance.

With three spectrum options (F4K for seedlings, F175 for general use, V3 for maximum efficiency), IP66 waterproof protection, 35,000-hour lifespan, and CE/RoHS/FCC certifications, the RX-PT8 series is the trusted choice for commercial growers who need reliable, high-performance lighting that fits perfectly into their existing infrastructure.

For detailed PPFD maps, spectrum charts, and custom lighting plans, visit www.koraylights.com or contact Koray Lighting’s engineering team for a consultation tailored to your specific growing operation.