I have this simple little project where I'm planning to build or more like compile a mv fixture from a parts that I have taken from few other fixtures that were missing other parts or otherwise in poor condition. There are few question that I'm wondering.

Sometimes you come along with old fixtures that has rubber seals that are usually hardened and crumbled or otherwise missing. Since these seals are usually just rubber mat cut in a certain shape, it would not be hard to made a new one. But what kind of rubber should be used? I guess it should handle moderate temperatures and UV radiation?

Also, I was wondering what to use to replace asbestos insulated wires? Not sure about this particulat project but the base I was going to use had wires that were had outer insulation that looked like some sort of grey fiber material. Not sure if asbestos but I would not wanted to take a change. In this particular project, I planning to use either 125w mv ir 80w mv if I can fit 80w ballast instead of the original 125w one. The lamp is going to be burned base up so wiring from lampholder to gear compartment is going to expose to heat from the lamp. What temperature rated wires should I use for that? I've also seen some modern hid fixtures using some sort of heat shield tube slipped around the lampholder wiring.

Depending on lantern size and lamp power, the big seal around the bowl perimeter may be far away enough to stay fairly cold. In this case someting like door/window sealing adhesive gasket might be sufficient, especially if the closed lantern body presses it in place so it cannot move even if the adhesive softens

Works for me in my Elba PVB-7A - huge deep lantern made of solid cast Aluminum for 2x250W Merc originally, running 1 150W SON-T (gear was replaced). It gets barely warm around the gasket



I dont think anyone put much thought into UV effects on the gasket when the old (~60s) lanterns were made either. The only thing that probably saved it was, that the UV did not penetrate much after the 1st layer of the material, so this slowed the destruction. (it could reach further in as the damaged surface turns into dust and falls off, but this is a slow process that takes years)

In some lanterns the gasket is fairly confined between solid surfaces that block most of the UV access to it anyway



The modern high temp material is wires with Silicon isolation in Glass fiber braid. The braid is also available as separate tube to slip over wires manually, sometimes it is impregnated with something to fill the empty space between the fibers

For not very hot conditions i seen also Silicon composite (2 layer) isolation without the sleeve - This is designed more towards holding reliably ignitor voltage than towards heat resistance, and in some other lanterns something that looks like XLPE, though im not sure whether it really is

Heat shrink tubing for those wires will work wonders, if your not going to replace them, try and get the stuff with adhesive inside it, and if your not sure if they are asbestos or not, assume the worst and treat them like they are asbestos, keep the dust to a minimum and wear an N95 or better respiratory protection and disposable nitrile gloves, wash it all with clean water and your tools that you used, do this outside, and I would recommend using a pair of old clothes and toss them once your done, (don't wash them and contaminate your washing machine, used coveralls are cheap or those tyvek single use one, even if you look goofy in them, they aren't that bad and you only have to wear it for a short period of time) And if your replacing them keep everything damp that your working on, water won't hurt it so long as you let it dry completely before powering it up.. And yes people might think this is overkill, but it's better then getting killed by asbestos.. 

And for gaskets if you want ones that last forever, get a wood stove gasket they are cheap you glue them down with waterglass ( sold in the same area) and it will take what ever UV you can shine at it, even a broken outer bulbs and a MV running till it goes EOL, the last one I bought cost me about $10 for 12 feet of it and the glue was only a few bucks and they come in a wide range of sizes and even hollow tubes which flatten out nicely, they are fiberglass so they won't rot, or melt, and you can cut them with a knife, and a word of warning about the glue, don't get it on the glass you'll never get it off..