G10Q 2D 4-Pin 21W 835 Cool White Fluorescent Lamp – 3500K

The G10Q 2D 4-Pin 21W 835 Cool White Fluorescent Lamp is a compact square-shaped replacement lamp designed for compatible 2D fluorescent fittings requiring a 21W 4-pin lamp.

Producing approximately 1350–1375 lumens with a balanced 3500K Cool White (835) colour temperature, this lamp provides broad, even illumination from a compact flat design.

It is commonly used in compatible bulkhead lights, ceiling fittings, corridors, stairwells, apartment common areas, commercial lighting and emergency lighting applications.

This lamp is particularly useful as a replacement for older or difficult-to-find 21W 835 4-pin 2D fluorescent lamps, including compatible GE and other manufacturer equivalents.

Key Features

• 21W 2D fluorescent / CFL lamp
• GR10q / G10Q 4-pin base
• 835 colour code
• 3500K Cool White
• Approximately 1350–1375 lumens
• CRI approximately 80+
• Compact flat / square 2D design
• Broad and even light distribution
• Suitable for compatible electronic control gear
• Suitable for residential and commercial applications
• Ideal replacement for compatible 21W/835 4-pin 2D lamps
• Replacement option for compatible GE and other 21W/835 lamps

Technical Specifications

Compatible & Equivalent Lamp References

This 21W 835 GR10q 4-pin 2D fluorescent lamp may be suitable as a replacement for equivalent lamps where the original fitting requires:

21W • 835 • 3500K • GR10q / G10Q • 4-Pin

Common replacement and cross-reference numbers include:

GE Lighting Cross-Reference

A particularly useful replacement reference is:

GE F212D/835/4P – 21W – GR10q 4-Pin – 835 – 3500K

GE reference 29327 is also associated with the F212D/835/4P lamp format.

If your existing lamp is marked:

F212D/835/4P

or

GE 29327

check that the base and physical dimensions also correspond with your existing fitting.

Other Replacement References

Other documented 21W/835 replacement formats include:

Athalon F21/2D/835/4P

and

Duralamp GR10Q/4PIN/21W/35K

The most important replacement specifications remain:

21W • 835 • 3500K • 4-Pin

Important: Manufacturer references are provided as a replacement guide. Always confirm the wattage, base, pin configuration, colour code and physical dimensions of your existing lamp before ordering.

Common Applications

The 21W 835 4-pin 2D fluorescent lamp is commonly used in compatible:

• Bulkhead lights
• Ceiling fittings
• Hallways and corridors
• Stairwell lighting
• Emergency lighting
• Apartment and body-corporate common areas
• Commercial buildings
• Offices
• Retail environments
• Hospitality applications
• Utility areas
• Wall-mounted fittings
• Enclosed exterior fittings

The compact square-shaped design provides broad illumination while requiring considerably less length than a conventional linear fluorescent tube.

How to Identify the Correct Replacement

Before ordering, check the markings printed on your existing 2D fluorescent lamp.

For this product, look for:

21W + 835 + 4-Pin + 3500K

You may also find markings such as:

21W/835/4P

F212D/835/4P

GR10q

G10Q

or a manufacturer-specific catalogue number.

If one of these markings appears on your old lamp, also compare the physical size and pin arrangement before purchasing.

What Does 835 Mean?

The 835 colour code is an important identifier when replacing fluorescent lamps.

8 = CRI approximately 80+

35 = approximately 3500K colour temperature

Therefore:

835 = CRI 80+ / 3500K

This is particularly useful because customers may find 835 printed on the old lamp without seeing “3500K” written anywhere.

Searching the manufacturer's lamp number together with 21W/835/4P can also help identify the correct replacement.

GR10q / G10Q 4-Pin – Important Compatibility Information

This product uses a 4-pin 2D lamp base.

A similar-looking 2-pin 2D fluorescent lamp is not automatically interchangeable, even if it has the same wattage and appears physically similar.

For this product, check:

✓ 21W

✓ 835

✓ 3500K

✓ 4-Pin

✓ GR10q / compatible G10Q-labelled fitting

✓ Correct physical dimensions

Do not choose a replacement based solely on the square shape of the lamp.

835 / 3500K Cool White Light

The 835 / 3500K Cool White colour provides a balanced white appearance between warmer 2700K–3000K lighting and cooler 4000K lighting.

It is particularly suitable for:

• Offices
• Hallways and corridors
• Apartment common areas
• Commercial interiors
• Stairwells
• Retail environments
• Hospitality areas
• Utility areas
• Bulkhead lighting
• General-purpose ceiling lighting

If maintaining the same light appearance as your existing installation is important, look for 835 or 3500K on your old lamp.

Need Help Finding the Correct 2D Lamp?

If you're unsure whether this 21W 835 4-pin 3500K lamp is the correct replacement, send NZ Lights a clear photo of your existing lamp showing the printed markings and base.

We can help identify the correct wattage, colour code, pin configuration and base 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 fluorescent and CFL lamps
• 2-pin and 4-pin 2D lamps available
• Single and bulk quantities available
• NZ-based support
• Fast nationwide delivery
• Daily dispatch from Christchurch, New Zealand