G10Q T5 Circline 40W 840 Cool White Fluorescent Tube – 320mm

The G10Q T5 Circline 40W 840 Cool White Circular Fluorescent Tube is a specialist circular replacement lamp designed for compatible fittings requiring a 40W Circline fluorescent tube.

Producing a clean 4000K Cool White (840) light, this circular fluorescent lamp provides bright, broad and even illumination around its ring-shaped design.

With an approximate 320mm outside diameter, this lamp is suitable for compatible circular ceiling fittings and specialist fluorescent fixtures where the correct wattage, base configuration and physical dimensions are essential.

This lamp is particularly useful for replacing older or difficult-to-find 40W 840 Cool White Circline fluorescent tubes. As circular fluorescent lamps can look very similar while having different connectors and diameters, customers should compare the existing lamp carefully before ordering.

Key Features

• 40W circular fluorescent lamp
• T5 Circline design
• G10Q base
• 840 colour code
• 4000K Cool White
• Approx. 320mm outside diameter
• Circular / ring-shaped fluorescent design
• Bright and even light distribution
• CRI approximately 80+
• Suitable for compatible Circline fluorescent fittings
• Ideal replacement for compatible 40W/840 circular fluorescent lamps
• Suitable for residential, commercial and specialist applications
• Hard-to-find replacement fluorescent lamp

Technical Specifications

Replacement & Search References

This 40W 840 Cool White Circline fluorescent lamp is intended for compatible fittings requiring the same key specifications:

40W • T5 • G10Q • 840 • 4000K • Approx. 320mm

Customers searching for a replacement may encounter descriptions such as:

Important Compatibility Information

40W Circline lamps are not all interchangeable.

Different manufacturers have produced circular 40W fluorescent lamps with different:

• Base / connector configurations
• Outside diameters
• Tube diameters
• Control gear requirements
• Colour temperatures

For this NZ Lights product, check:

✓ 40W

✓ T5 Circline

✓ G10Q

✓ 840

✓ 4000K Cool White

✓ Approx. 320mm outside diameter

Do not choose a replacement simply because the old lamp says 40W or because the circular shape looks similar.

Important Note About OSRAM & Sylvania 40W Circline Lamps

Customers may encounter OSRAM FC 40W/840 or Sylvania T5 Circline Plus 40W/840 while searching for a replacement.

These are useful identification references for the broader 40W / 840 / 4000K Circline lamp family, but they should not automatically be considered direct replacements for this product.

How to Identify the Correct Replacement

Before ordering, inspect the markings printed on your existing circular fluorescent lamp.

For this product, look for:

40W + G10Q + T5 + 840 + 4000K + Approx. 320mm

Your existing lamp may show:

40W

40W/840

840

4000K

G10Q

or a manufacturer-specific model number.

The outside diameter and connector are particularly important when identifying a Circline replacement.

What Does 840 Mean?

The 840 colour code is an important identification number used on fluorescent lamps.

8 = CRI approximately 80+

40 = approximately 4000K colour temperature

Therefore:

840 = CRI 80+ / 4000K Cool White

This is useful when identifying an older lamp because the tube may simply have 840 printed on it rather than explicitly stating 4000K.

If your existing lamp says 40W/840, it indicates a 40W fluorescent lamp with approximately 4000K Cool White light.

You still need to confirm the base and physical dimensions before ordering.

840 / 4000K Cool White Light

The 840 / 4000K Cool White colour provides clean, neutral-white illumination particularly suitable for functional residential and commercial environments.

Common applications include:

• Kitchens
• Offices
• Retail stores
• Commercial interiors
• Apartment common areas
• Hallways
• Utility rooms
• Work areas
• Hospitality environments
• Public buildings
• General-purpose ceiling lighting

Compared with 827 / 2700K Warm White, 840 provides a noticeably cleaner and cooler-looking light.

If replacing only one lamp in an existing installation, check for 840 or 4000K on your old lamp to maintain a similar light appearance.

Common Applications

The 40W T5 840 Circline fluorescent lamp is suitable for compatible:

• Circular ceiling fittings
• Residential ceiling lights
• Commercial ceiling fittings
• Offices
• Retail stores
• Apartment common areas
• Hallways
• Hospitality environments
• Public buildings
• Utility areas
• Work areas
• Specialist circular fluorescent fittings

The circular shape distributes light around the complete ring, providing broad illumination from a relatively compact ceiling fixture.

How to Measure Your Circline Lamp

Physical size is extremely important when replacing a circular fluorescent lamp.

Measure straight across the complete lamp from the outside edge of the tube on one side to the outside edge on the opposite side.

For this product:

Outside Diameter: Approx. 320mm

Also compare the connector/base with your existing lamp.

Two Circline lamps can have the same 40W wattage and 840 colour code but still be incompatible because of different dimensions or connectors.

Hard-to-Find 40W Circline Replacement

Traditional fluorescent Circline lamps are becoming increasingly difficult to source as manufacturers discontinue older fluorescent ranges.

If your existing fitting is still operational and you want to replace the lamp rather than replace the complete fixture, matching the wattage, base, colour code and physical dimensions is particularly important.

Keep your old lamp until you have confirmed the replacement.

Need Help Finding the Correct Circline Lamp?

If you're unsure whether this 40W T5 G10Q 840 320mm Circline lamp is the correct replacement, send NZ Lights a clear photo of your existing lamp showing the printed markings and connector/base.

If possible, also provide the outside diameter of the existing circular tube.

We can help identify the correct wattage, base, colour code, colour temperature and physical size required for your fitting.

Why Buy from NZ Lights?

NZ Lights specialises in replacement lamps and hard-to-find lighting products for residential, commercial and professional applications throughout New Zealand.

• Specialist replacement lighting range
• Hard-to-find Circline and fluorescent lamps
• Large range of discontinued-style replacement lamps
• Multiple sizes, wattages and colour temperatures
• Single and bulk quantities available
• NZ-based product support
• Fast nationwide delivery
• Daily dispatch from Christchurch, New Zealand