The Narrow Flood Lamp – the development of a new design

The mercury vapour “true flood” lamp produces a wide diffuse beam of UV light but this does not penetrate far into the vivarium. The spot lamp, on the other hand, sends useful UVB a long way into the vivarium, but the beam is very narrow and its footprint, at the basking spot, may only be a few inches wide.

A few years ago, Westron Lighting Corporation introduced a lamp with a spreader lens moulded into the cover glass, similar to those used for halogen lamps, to create a beam wider than a spot lamp but narrower than a “true flood”.

There are several versions of this first lamp still found in use here and there (although manufacture was discontinued in 2004), all manufactured by Westron and sold under the brand name Active UV Heat Flood. The front glass of this lamp is completely clear –there is no semi-opaque internal coating– and has a characteristic hexagonal surface pattern. In the USA, this lamp was available from Wild Inside (UVHeat.com) both as an externally ballasted 60watt lamp and as a self-ballasted lamp in 100watt and 160watt versions, and T-Rex were distributing the 100watt and 160watt self-ballasted versions until early 2005. Some stocks may still be found.

T-Rex Active UV Heat 100watt Flood Lamp (discontinued version)

We measured the output of two of these old-style lamps, one brand new, and one that had been in use for about a year. The year-old lamp was still emitting a high level of UVB – 33uW/cm² at 12” – but we were surprised to discover that this was a fraction of that emitted by the brand new bulb.

Before burning in, the new lamp emitted 228uW/cm² at 12”. However, like the Active UV Heat Spot Lamp we tested, this burned in very sharply and after only 105 hours this figure had dropped to just 66uW/cm² at 12”. The results of the burn-in for this lamp can be seen in Fig.2. (Click on image to view full size version in new window)

The spread chart for this lamp, after burning in, is shown as Fig.3. It was somewhat disappointing to see that the “Flood” beam, after burning in, was no wider than that of the Spot Lamp. Its description as a Flood was somewhat debatable.

However, the one older lamp we tested certainly met the claim, made by the manufacturers, that after twelve months of normal use the output would still exceed that of a specialty linear UVB tube.

The manufacturer’s recommended minimum distance for this lamp - 6 inches - also appeared to be well within safety margins. Even the brand new lamp before burning in did not emit levels of UVB, at that distance, higher than those found in nature in direct sunlight. The heat produced at 6 inches might prove excessive in some vivaria, however, and we would once again emphasise the need for careful measurement of temperatures beneath the lamp.

Improving the Design

One problem has emerged over and over again, when dealing with the production of UVB lamps – that of decay. This problem, as we have seen, affects all types of lamp and is due to chemical reactions taking place on the inner surface of the lamp glass.

However, iguana rehabilitator Robert MacCargar works with the team at Westron Lighting Corporation. Calling upon his experience in designing and testing ultraviolet curing lamps (which are very resistant to decay) for the automotive industry MacCargar has recently taken the Active UV Heat Flood design further.

Westron are now producing lamps which are claimed to produce much more intense UVB light in a much wider and far-reaching beam, and to have an extremely low rate of decay. The new lamps look similar to the earlier design, with the spreader lens moulded into the cover glass, but have a milky appearance due to a fine magnesium coating applied to the inner surface of a new type of glass. MacCargar has named the new design the Mega-Ray Narrow Flood Lamp, and distributes a range of lamps with this design through his own company, ReptileUV.

The ReptileUV Mega-Ray

At the time these tests were conducted, there was no UK distributor for the ReptileUV Mega-Ray lamps, but they were available by mail order from USA from the company website, ReptileUV.com. (One UK distributor, South West Exotics, now exists: see our Links page for details)

Self-ballasted (SB) lamps (100watt and 160watt) are sold in both 110volt and “Euro” 220volt versions. An externally ballasted (EB) 60watt lamp is available with a matching ballast box (110volt only). There is also a Mega-Ray Zoo Lamp for specialist use, such as in zoos, in situations where high UVB levels are required at distances over 3 feet from the lamp, in very large enclosures.

We tested seven lamps from the Mega-Ray range including three 60 watt EB lamps and two 100watt SB “Euro” lamps.

Externally Ballasted Lamps

The 60watt Mega-Ray EB lamp and ballast box are purchased as a kit; replacement lamps may then be purchased separately. At present these kits are only available in an 110volt version (the USA line voltage) and to operate them in the UK, with our 220-240volt mains electricity, we used a step-down transformer. There is no incandescent filament to produce additional heat, so the lamp is much cooler in operation. The lamps we tested seemed to produce less heat than a regular 60watt incandescent lamp. We set them up in 3-4ft vivaria and did not have the problems with overheating which had concerned us when considering the use of mercury vapour lamps in smaller set-ups. Because of the low heat output, it is possible to supplement the heat and light at the basking spot using regular basking lights or other heating devices under full thermostatic control. We found this to be a very satisfactory procedure with the lamps we tested.

The Output of the Mega-Ray Lamps on Test

ReptileUV state that output of individual lamps may vary somewhat within each range; the outputs are being standardised but it is still possible to request a specific output for a specific set-up, when ordering.

The three EB (externally ballasted) lamps were obtained for smaller vivaria where the basking spot for sun-loving “desert” basking reptiles – in this case bearded dragons – was to be sited about 12” from the lamp surface.

The two SB (self ballasted) lamps were obtained for a larger vivarium, also for bearded dragons, in which it was hoped that the lamp would provide the equivalent of a small patch of sunlight – a bright area of visible light, and high UVB (in the range of 150 - 350uW/cm²) over a wider area from 12” to 18” away.

Fig. 6 shows the output, at different distances, of these five Mega-Ray Narrow Flood Lamps after a minimum of 75 hours burn.

The results show that these lamps do indeed emit UVB at the levels specified. There was wide variation between the lamps but this was expected, since the lamps were labelled with their output as recorded prior to dispatch.

Readings at close range were higher than seen in nature, but at 12” (manufacturer’s recommended minimum distance) all the lamps produced levels of UVB resembling that found in natural sunlight (i.e., below 500uW/cm²; green zone on chart).

We plotted spread charts for both EB and SB lamps and found them to be very similar in shape. The spread chart for one of the EB lamps is shown in Fig.7. (below) These lamps produce a very wide, cone-shaped beam of UVB radiation projected along the axis of the lamp, with an even gradient towards its centre. The intensity of the UVB also falls away evenly with distance, but the beam extends a long way. The output is considerably greater than any other type of lamp, sold for use in the vivarium, which we have tested.

This beam certainly has characteristics of both “spot” and “flood” lamps and the term “Narrow Flood” seems very appropriate. This lamp is producing a roughly circular “footprint” about 30 inches across at a distance of 12 inches, within which is a gradient of UVB from 20 to over 150 uW/cm². Two and a half feet from the lamp, the centre of the beam is still 10 inches across, within which is a gradient from 20 to 27 uW/cm².

Fig. 8 shows one of the SB lamps, which has an even higher output than this, in use in the large bearded dragon vivarium for which it was supplied. In this set-up, the upper basking branch is not directly under the lamp, but close to the front of the vivarium. Since the beam produces a three-dimensional "cone" of UVB radiation, this puts the centre of the branch in the area receiving between 50 - 300 uW/cm². The lower branch, directly under the lamp, also receives good UVB coverage.

Fig. 9 (below) shows the spread chart for the EB lamp, emitting nearly 160 uW/cm² at 12 inches, in a large enclosure for a 4ft long adult iguana. He is heated, in addition, by a thermostatically controlled infra-red heat projector. Depending on where he sits, he can place his whole body in a UVB gradient between 20 and 175 uW/cm².

Decay – or Lack of it?

The manufacturer claims that on average, the Mega-Ray lamp will only decay by 30% throughout its entire lifespan. This would make the product very different from some other UVB lamps and tubes we have tested, which have decayed by more than 50% within two weeks of everyday use. We charted the burn-in of four of the lamps. The burn-in chart for one of the EB lamps is shown in Fig.10. (Click on image to view full size version in new window) This lamp did not decay at all during the first 105 hours burn. The other three lamps decayed a little – between 5 and 8%.

One of the SB lamps was then tested regularly whilst in use in the vivarium, over a period of about nine months (3,000 hours of use). The results are shown in Fig.11(below; click on image to view full size version in new window). This lamp decayed approximately 5% in the first 65 hours but only lost about another 5-6% of output over the next nine months. These results suggest that the manufacturer’s claims may not be exaggerated.

The New T-Rex Active UV Heat 100watt Flood Lamp

The newest version of the T-Rex Active UV Heat 100watt Flood Lamp, now on UK shelves, is none other than Westron Lighting Corporation’s new 100watt, self ballasted lamp with MacCargar’s design. Until early in 2006, these were sold in identical packaging to the previous Active UV Heat Flood model, which was a little confusing. They could be distinguished, however, by their light milky magnesium coating. (Fig.12.) They are now sold in new packaging. (Fig 13.)

We tested one of these lamps throughout the burning-in period, and also plotted a spread chart for this lamp, which is shown in Fig.14. (below) Because we only tested one of these T-Rex lamps we are unable to comment as to how typical the output of this particular lamp might be, but this is clearly a remarkably different product from the previous version of the Active UV Heat Flood.

It has a much wider beam, vastly higher UVB output and showed little decay during tests. The results, not surprisingly, match closely those of the other new Westron lamps we tested. Its initial output, for example, was 294 uW/cm² at 12”. After 105 hours burn, this had decayed less than 4%, to 283 uW/cm². These levels of UVB may be found in natural sunlight.

Measurements closer than 10” gave readings higher than those found in nature (over 500uW/cm²) suggesting that a minimum recommended distance of 12”, as stated for the ReptileUV Mega-Ray lamps, would probably be suitable. With a lamp as powerful as this, it is particularly important that the manufacturer’s recommendations should be accurate in this respect. Unfortunately the information leaflet inside the box and the diagram on the side of the older box design were incorrect, referring to the older lamp model. However, the new boxes carry correct instructions and the insert leaflets should do so in the near future if they do not already.

Safety Precautions with High Output Lamps

For a lamp to produce high levels of UVB at a distance, it is inevitable that at very close range, levels of UVB will be hazardous. Just as with heat lamps, it is essential to keep reptiles – and their keepers- at a safe distance from the lamp.

However the zone in which un-naturally high levels of UVB occur, with all the lamps tested, was found to be regular in shape and close to the lamp surface. It should not be difficult to keep humans and reptiles out of this zone.

It is also important to provide a UVB gradient in the vivarium, in much the same way as we provide a heat gradient. In the wild, reptiles are able to move in and out of sun and shade at will, and this must be possible in captivity, as well.

The Mercury Vapour Lamps on Test

Back to the Mercury Vapour Lamp Index Page

Continue to the other MV Lamp Survey Reports:

Flood MV Lamps:

• The Zoo Med Powersun Flood Lamp
• The early versions of the Wild Inside/ T-Rex Active UV Heat Flood Lamp

Spot MV Lamps:

• The T-Rex Active UV Heat Spot Lamp

Spread Chart Summary: the characteristics of the beams of all the Mercury Vapour Lamps on test.

High UVB Output Mercury Vapour Lamps used in Zoos
The Osram Ultra-Vitalux and the ReptileUV Zoo Mega-Ray

The Use of Dome Reflectors with Mercury Vapour Lamps

The Use of Wire Mesh Guards and Screens with Mercury Vapour Lamps

Continue exploring the Lighting Survey 2005:

Introduction to Lighting Survey

Fluorescent Tubes

Compact Fluorescent Lamps

All these sections are also accessible from the side navigation bar.