Mega-Ray 100W Mercury Vapor UVB Bulb for ReptilesBearded Dragons & Red-Footed Tortoises
$48.95
100-watt Mega-Ray mercury vapor UVB + heat bulb for bearded dragons in 40-gallon tanks, basking turtles and red-footed tortoises — mount 12–20″ above the basking spot. Fits a standard 150 W ceramic clamp lamp.
🏆 Proven 10-Year Track Record– The original Mega-Ray design
📉 Slow UVB decay – independently measured at just 15% loss after a year (UV Guide UK)
☀️Natural Sunlight Simulation – Prevents metabolic bone disease
✍Self-Ballasted Design – No external ballast needed
🛡️ Magnesium Oxide Inner Coating – Mega-Ray’s translucent coating design
🇩🇪 Made in Germany – Free US shipping, 30-day returns on unopened bulbs, 6-month warranty
Satisfaction Guaranteed
- Free US Shipping
- Authentic Mega-Ray
- 6-Month Warranty
- 30-Day Returns (Unopened)
Why it costs $48.95
- The price is set by Mega-Ray, not by us. It is the same at every authorised seller, so there is no cheaper genuine bulb to find by shopping around. If you see one well below this, it is worth asking where it came from.
- Shipping is inside that number. US shipping is free and there is no handling fee. The price on this page is the price at checkout.
- Made in Germany, shipped from Mega-Ray’s US distributor. We are a small Tennessee store, not the manufacturer, and we do not pretend otherwise.
- We hold no inventory. Your bulb ships from the distributor’s current stock rather than off a shelf here, which is the only claim about freshness we can actually stand behind.
Compare all four Mega-Ray bulbs
Every Mega-Ray puts out the same UVB at its working distance. What differs is how far above the animal it has to sit. Measure from the bulb face to your reptile’s back, then pick the bulb whose range covers it. Not sure? Start with the wattage guide.
| 70W | 100WYou are viewing this one | 160W | 275WMost ordered | |
|---|---|---|---|---|
| Who it is for | Leopard and crested geckos, corn snakes, anoles, juvenile red-footed tortoises | Bearded dragons in 40-gallon enclosures, red-footed tortoises, basking turtles | Adult bearded dragons in 4×2×2 enclosures, monitors, iguanas, red-eared sliders | Zoos, breeders and tall enclosures. Not a consumer bulb |
| Working distance | 6–12″ | 12–20″ | 18–24″ | 30–48″ |
| Optimum distance | 8–10″ | 14–16″ | 20–22″ | 36–42″ |
| Closer than this is too close | 6″ | 12″ | 18″ | 30″ |
| Fixture required | Ceramic socket rated above 70 W | Ceramic socket rated above 100 W | Rated above 160 W. Most reptile clamp lamps stop at 150 W | Porcelain keyless lampholder rated above 275 W |
| Price | $48.95 | $48.95 | $48.95 | $51.95 |
Free US shipping on all four. Prices are set by the manufacturer, so nobody sells a genuine Mega-Ray for less.
Common questions about the 100W
Will the 100W fit my fixture?
It needs a ceramic socket. Ceramic socket rated above 100 W. Mega-Ray asks for a fixture rated above the bulb’s own wattage, and this is the single most common mistake we see — a standard reptile clamp lamp is usually rated to 150 W, which is not enough for the 160W or the 275W.
How far above the basking spot should it go?
Measure from the bulb face to your reptile’s back, not to the floor. The 100W works between 12–20″, and 14–16″ is the sweet spot. A screen lid takes out roughly 20–40% of the UVB, so mount closer to the near end of the range if the bulb sits above screen.
Can you still buy mercury vapor bulbs?
Yes. The US Energy Policy Act of 2005 prohibited the manufacture and import of mercury vapor lamp ballasts after January 1, 2008, not the lamps themselves. Mega-Ray bulbs are self-ballasted, so they have no separate ballast and were never covered. More on how self-ballasted bulbs work.
How long does it last?
Plan on replacing it every 12 months. UV Guide UK measured a self-ballasted Mega-Ray at about 15% UVB loss after a year and 17% after 18 months, which is slow for this lamp type, but output does fall steadily and a bulb can fail without warning. See the independent measurements.
What are the downsides of a mercury vapor bulb?
It produces heat and UVB together from one socket, so you cannot adjust them separately — and you cannot run it on a dimmer or a pulse-proportional thermostat, which will destroy it. It also needs the mounting distance above to be right, because you cannot turn the UVB down. In a tall or wide enclosure that single-point output is an advantage; in a very small one it is not.
Is it safe to use over my reptile?
At the distances above, yes. The 2014 independent test found no UVC at all and confirmed the glass blocks wavelengths below 295 nm. The risk with any mercury vapor bulb is mounting it too close, which is why the minimum distance on this page is a hard floor rather than a suggestion.
Still not sure? Email us and we answer within one business day.
Description
Description
✅ This is the right bulb if you keep a bearded dragon in a 40-gallon or similar tank, a basking turtle with the lamp on a stand above the dock, or a red-footed tortoise, monitor, iguana or uromastyx at moderate height — and the bulb face will sit 12–20″ above your animal’s back (14–16″ is ideal). It fits a standard 150 W ceramic clamp lamp. Free US shipping, 30-day returns on unopened bulbs, 6-month warranty.
Is the 100W the right bulb for you?
The 100W is the standard-enclosure bulb: 12–20″ from the animal’s back covers most 40-gallon tanks, most turtle setups with the lamp on a stand above the rim, and most 4×2×2 enclosures where the basking platform sits high.
| Bulb face to the animal’s back | UVB at that distance | Verdict |
|---|---|---|
| Under 12″ | Above the intended range | Too close — raise the lamp, or use the 70W |
| 12–20″ | ~150–200 µW/cm² at the near end, 50–70 at the far end | The 100W’s working range |
| 14–16″ | — | Optimum |
| Over 20″ | Below useful UVB | Step up to the 160W |
Animals: bearded dragons in 40-gallon and shorter enclosures; red-eared sliders and other basking turtles with the lamp 12–20″ above the shell on the dock; monitors, iguanas and uromastyx in the 100–160W band; red-footed tortoises, skinks and Chinese water dragons at the upper end of the 70–100W band.
Fixture: a ceramic socket rated above 100 watts. A 150W-rated ceramic clamp lamp is fine.
Screen tops: a mesh lid removes 20–40% of what passes through it. If the lamp sits on a screen, measure the distance and then treat the bulb as if it were mounted further away than it is.
Not sure this is the right wattage? See which Mega-Ray bulb your reptile needs →
Keeping a bearded dragon? Read the bearded dragon heat and UVB guide → — 40-gallon vs 4×2×2, mounting distance and fixture rating.
Keeping a turtle? Read the turtle UVB and heat guide → — which bulb for the basking dock, how far above the shell, and the water and fixture rules.
Keeping a tortoise? Read the tortoise UVB and heat guide → — which Mega-Ray suits each species, and 14–16″ from the bulb face to the top of the shell for the 100W.
New to mercury vapor bulbs? Read how they work, which wattage and how far away → — the self-ballasted design, the full distance table for all four bulbs, fixture rules and what independent testing measured.
🦎 From a customer
“I’ve trusted Mega-Ray since 2014 and the bulbs consistently outlast their promised life, as measured by my solarmeter.” — Sarah Carroll, verified owner, 5-star review, August 2026 · read the reviews
📉 Independently tested
UV Guide UK measured a self-ballasted Mega-Ray at −15% UVB after one year and −17% after 18 months of daily use, where other mercury vapor lamps in the same test series lost 60–70% in their first 100 hours. The glass blocks everything below 295 nm — no UVC — and the inner coating throws a wider beam than a standard PAR38. (F. Baines, UV Guide UK, 2006 and 2014.) We still recommend replacing every 6–12 months, or when your Solarmeter says so.
In the BIAZA UV-Tool (Baines et al., Journal of Zoo and Aquarium Research, 2016 — a peer-reviewed assessment of 24 reptile lamps co-authored by Chester Zoo, Marwell, ZSL, Durrell and Bristol Zoo), the Mega-Ray 100W and 160W are rated as able to provide a suitable UV Index for all four Ferguson zones, one of only five lamps in the table to do so. Read the paper. See every measurement, the methods and their limits, on our test-results page.
🔬 Technical Specifications
| Wattage | 100 Watts |
|---|---|
| Bulb Type | Self-Ballasted PAR-38 Narrow Flood |
| Working Distance | 12–20″ from the bulb face to the animal’s back (optimum 14–16″) — see the distance table above |
| Minimum Distance | 12″ from the animal’s back — never closer |
| Recommended Replacement | Every 6-12 months |
| Suitable For | 🐉 Partial sun/occassional baskers: (i.e. redfooted tortoises, skinks, chinese water dragons). Open/partial sun baskers: (i.e. bearded dragons, redeared sliders, monitors, some caimens) |
| Voltage | 120V (North America) |
Important Safety Information
- Must use wire dome fixture only – Plastic fixtures can melt
- Never closer than 12″ to the animal’s back — optimum 14–16″ (see the distance table above)
- Allow 15 minutes cool-down before moving if accidentally bumped
- Use with Solarmeter 6.5 for optimal UVB monitoring (recommended)
Allie Coronado (verified owner) –
What a wonderful seller and a durable and long-lasting bulb! Knowing that I am shopping locally, but also for quality is important to me and I couldn’t be happier with my purchase!
Sarah Carroll (verified owner) –
I’ve trusted Mega-Ray since 2014 and the bulbs consistently outlast their promised life, as measured by my solarmeter. I was impressed with the speed of delivery and care in packaging!
Maura Gilliam (verified owner) –
Excellent bulbs and seller. They arrived safe and sound. These bulbs truly last, and my reptiles love them. Would highly recommend and will absolutely purchase again.