Rank #3 in Best Reptile Heat Lamps 2026: 10 Ranked, and One Lumens Figure That Doesn't Add Up
DERNORD 100 W Mercury Vapour UVB Heat Bulb, E27
Price and rating as shown on Amazon when we collected them. Both change.
The DERNORD Mercury Vapour Bulb Tortoise is a 100 W self-ballasted mercury vapour lamp on an E27 screw base, sold for £30.99 and rated 4.4 out of 5 from 203 ratings. It takes third place in this guide to reptile heat lamps.
What holds it back is not the bulb but its spec table. The same listing gives it a "Voltage" of 220 volts and, a few lines further down, an accepted voltage of 100 to 240 volts at 50 to 60 Hz. It also fills in three control fields — Touch, Push Button and Infrared — for a bulb that screws into a holder and has no buttons, no remote and no app, and it describes the one bulb's light as "Warm white, cool white (with a slight bluish tint)". An "Incandescent Equivalent" of 100 watts for a lamp that draws 100 watts says nothing either. None of that makes the DERNORD a bad bulb; it means those fields were filled in from a template, and the numbers worth reading are in the bullets. Everything on this page is taken from the Amazon listing and its customer reviews, not from testing of our own.
How those 203 ratings break down
An average hides its own shape. This is the spread behind the 4.4 stars.
Specification
Exactly as published on the Amazon listing, field for field.
| Price | £30.99 |
|---|---|
| Rating | 4.4 out of 5, from 203 ratings |
| Light Type | Mercury Vapour |
| Wattage | 100 watts |
| Bulb Base | E27 |
| Voltage (as listed) | 220 Volts; accepted voltage 100 to 240 Volts, 50 Hz to 60 Hz |
| Control Method (as listed) | Touch; Controller Type: Push Button; Connectivity Technology: Infrared |
| Light Color (as listed) | Warm white, cool white (with a slight bluish tint) |
What buyers actually say
Quoted from customer reviews on Amazon
Verified purchase“Bright and produces heat. Perfect for my tortoise”
Verified purchase“For making tortoises very happy under their light basking with confidence s”
What it is up against
The rivals it was ranked against in Best Reptile Heat Lamps 2026: 10 Ranked, and One Lumens Figure That Doesn't Add Up.
Questions people ask
How much does the DERNORD mercury vapour bulb cost?
The listing shows £30.99 for the 100 W bulb, with a rating of 4.4 out of 5 from 203 ratings.
What wattage is the DERNORD bulb?
100 watts. The listing repeats that figure as the wattage, the power consumption and the light source wattage, and also gives an "Incandescent Equivalent" of 100 watts — the same number as the bulb's own draw.
Does the DERNORD bulb need a separate ballast?
No. The second bullet describes it as a self-ballasted mercury vapour bulb that provides the benefits of natural sunlight, which the listing calls one of the most important aspects in keeping reptiles healthy.
How should it be mounted?
The fifth bullet says the 100 W bulb should be mounted vertically in a fixture so it points straight down rather than tilted, which the listing says reduces damage from overheating and increases its burn life.
What does the thermal reset feature do?
The first bullet says a "THERMAL RESET" controls the temperature; you let the UVA UVB lamp cool for around 15 to 20 minutes and then it restarts.
What do buyers say about the DERNORD bulb?
The listing carries 4.4 out of 5 from 203 ratings. The reviews shown on the listing call it bright and say it produces heat, and describe tortoises basking under it.
Comments
Reader comments are not checked against the manufacturer's claims above.
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