Reptile & Amphibian Forums

I've lurked long enough to know there are people here working extensively with plastics.

I'm planning on building a 4x2x2 for a lizard, with an interior mounted incandescent fixture for basking lights.

Will the heat cause problems if using XPVC? The basking area will be 110-120F.

I realize XPVC is great for snake enclosures and racks, fine with belly heat and RHPs. But what about basking lights? What will it do to the material?

I will have more than adequate ventilation, so heat will not build up inside.

Thanks in advance.

I understand at least one company selling PVC cages is now including some sort of nylon spacer on the ceiling to prevent melting of the PVC.

I don't forsee building any plastic cages for diurnal, sun-loving lizards but if I did I would use some sort of barrier between the fixture and the plastic. Maybe something as simple as a couple of layers of cement board or tile backer.
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Currently keeping:

6.10 Gonyosoma oxycephalum (Javan, mixed colors)

0.0.4 Rhynchophis boulengeri

1.1 Philodryas baroni

1.1 Lampropeltis triangulum multistriata

0.0.1 Rhamphiophis rubropunctatus

0.0.2 Morelia viridis (Aru & Merauke locale types)

1.0 Rhodesian Ridgeback

Oh wow, I wasn't even thinking of the surface where the fixture meets the PVC. I was thinking more of the focal point of the bulb beams. That's a good point.

Here is something I was just about to do but ordered an RHP instead:

Vision sells a mesh top with a cutout for a ceramic light fixture for their Visionariums.

If you cut out a 3 1/2 inch hole in the celing of your plastic cage, mount the mesh and fixture over the hole, you now have a light fixture in the cage with no worries about melting the plastic.
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Mark

Hi Mark,

Sorry I should have specified that I am looking to stack these enclosures, I have several terrestrial, diurnal lizards. As such the fixtures would be located inside the enclosure.

It seems like a lot of keepers house Bearded Dragons and Uromastyx lizards in commercial PVC cages so I'm inclined to think there is a way to do this.

You might spend some time browsing and asking questions on some of the species specific forums, even if they are species you don't keep.
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Currently keeping:

6.10 Gonyosoma oxycephalum (Javan, mixed colors)

0.0.4 Rhynchophis boulengeri

1.1 Philodryas baroni

1.1 Lampropeltis triangulum multistriata

0.0.1 Rhamphiophis rubropunctatus

0.0.2 Morelia viridis (Aru & Merauke locale types)

1.0 Rhodesian Ridgeback

Chris, that's exactly what got me thinking, and I think we are talking about the same company, they make a "uromastyx" or bearded dragon enclosure.

I posed this question on another forum and apparently that company had the ceiling-melting problem as well, and had to send out a spacer like mark mentioned in his response below.

I guess that's why people have more success with the screen-hole-cutout-with-lamp-over-it scenario.

Thanks for your reply, I will keep at this and see what I come up with. I'm a few months out, but I'll eventually post results.

That's one of them. There was another company making PVCX cages that I think catered to the Bearded Dragon crowd, being breeders of that species as well as cage builders.

I think it can be done, you'll just need to take your time and run tests to see how things are working.

I like Mark's suggestion of a thermal mass source on the ceiling. You could also build a shallow plywood box that attaches to the ceiling and attach your fixture to that. Leave just enough room to fit in some radiant barrer insulation.

Adding thermal mass directly below the basking area also helps a lot. But then you have the additional problem of the PVCX cages being able to handle all the extra weight.
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Currently keeping:

6.10 Gonyosoma oxycephalum (Javan, mixed colors)

0.0.4 Rhynchophis boulengeri

1.1 Philodryas baroni

1.1 Lampropeltis triangulum multistriata

0.0.1 Rhamphiophis rubropunctatus

0.0.2 Morelia viridis (Aru & Merauke locale types)

1.0 Rhodesian Ridgeback

Yeah, that is tougher. Here is the theory that can work:

You don't bolt the lamp fixture to the cage top. Instead you mount it to a heat sink, then mount the heatsink to the cage ceiling. Aluminum makes a great heat sink.

Here is what I have done in the past:
I've done it with 50 watt bulbs in plastic cages (for snakes). Now I have fewer snakes, do community cages and use RHPs exclusively.

I purchased a ceramic single lamp fixture (the kind you find in an aquarium fixture for example), covered the exposed contacts with epoxy putty, and glued (epoxy) a piece of extruded aluminum (1/8 inch thick by 1 inch wide by 8 inches long) to the top of the fixture. I bolted the assembly to the top of the cage using spacers to separate the aluminum bar from the plastic.

The aluminum bar provides a great heat sink for the fixture. Most of the heat went there instead of the cage top. For a 50 watt bulb, no problem. This setup worked on HDPE which has a very low melting point, lower than PVC I believe.

>>Hi Mark,
>>
>>Sorry I should have specified that I am looking to stack these enclosures, I have several terrestrial, diurnal lizards. As such the fixtures would be located inside the enclosure.
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Mark

Mark, great reply. I will definitely rethink the design and see if there's something I come up with to diffuse the heat.

In my reply to Chris above, we mentioned a cage company with a similar design. On another forum, someone mentioned they had to incorporate a ceramic baking disk underneath the keyless light fixture to stop the melting from the MVB.

Thanks and take care,
Bill