A healthy basking spot in the terrarium is the heart of every species-appropriate reptile habitat. Modern UVB metal halide lamps (HID lamps) offer a particularly effective combination of light, heat, and UVB radiation – perfect for all reptiles. But proper installation is essential!
In this guide, we’ll show you step-by-step what you need to consider – from lamp positioning to the electronic ballast (EB).

Choosing the right UVB lamp
Metal halide lamps come in different wattages (e.g. 35 W, 50 W, 70 W, 100W, 150W). The choice depends on:
• Species (e.g. desert vs. tropical)
• Animal size (juvenile vs. adult)
• Climate of origin
The higher the UV requirement and the larger the terrarium, the higher the wattage should be. For specific lamp recommendations per species, check our Reptiles Expert Matrix or our dedicated blog articles here.

Optimal distance to the basking spot
The distance between the lamp and the basking spot is crucial for effective UVB exposure: see Reptiles Expert Matrix.
Important: UVB must not be filtered through glass or plastic!

Mounting the lamp
Metal halide lamps are operated in a specialized ceramic socket and installed securely above the basking spot – either inside the terrarium (e.g. with mesh cover) or outside, if there is a clear line of sight.
• The socket must be heat-resistant and firmly screwed in.
• The UVB lamp with built-in reflector directs the light onto the basking spot. The entire animal should be illuminated.
• The lamp must not be mounted at an angle or suspended loosely – always install it to shine straight down. Otherwise, health issues may arise, such as eye infections.

Proper connection of the electronic ballast (EB)
Metal halide lamps require an external EB to regulate the current and operate the lamp. Without an EB, the lamp won’t start!
• The EB is mounted outside the terrarium – e.g. on the wall or underneath the terrarium in a well-ventilated area. Heat buildup must be avoided! It is often placed on a wooden beam above the terrarium or on the terrarium cover.
• It must be kept dry and not exposed to warm airflows from heat lamps.
• Pay attention to the cable length between lamp and EB. Ideal is 1–1.5 meters.
• Route cables safely to prevent damage from bites or heat.

Safety & maintenance
• Check UVB output regularly (e.g. with a UV meter).
• Replace the lamp about every 12 months – even if it’s still glowing!
• Regularly check the EB for heat development.

Conclusion
A properly installed UVB metal halide lamp creates the perfect basking spot in your terrarium: natural light, effective UVB, and healthy heat – all in one. Make sure to maintain proper distance, secure mounting, and clean installation of the EB – and nothing will stand in the way of your reptile’s sunbath.