mbrooke
Batteries Included
- Location
- United States
- Occupation
- Technician
I would guess heat. What kind of lights are they?
“ shoot low boys their riding shetland ponies”
Besides heat, UV light doesn't play well with most plastics. Are these wire-nuts getting exposed to direct light as well as heat? LED's would be a prime source; I don't know about HID's.HID is the worst, followed by LED. In general these wire nuts seem to self biodegrade.
Besides heat, UV light doesn't play well with most plastics. Are these wire-nuts getting exposed to direct light as well as heat? LED's would be a prime source; I don't know about HID's.
OP said "especially behind luminaires". Whatever he is experienceing is primarily because of heat. I see this often within HID luminaires, but is behind the lamp reflector where there should be no light or UV. But use the black connectors that are rated higher temp and they definitely last much longer. Guessing they are made from a different kind of plastic than most other connectors.LEDs do not put out UV. A white LED is a blue LED with a white phosphor coating (converts blue to white. A fluorescent is mostly UV again with a phosphor coating. A metal halide is a mercury vapor lamp (almost pure UV) with a halogen gas that converts UV to bluish-white. So only the fluorescents or especially metal halides eat plastic.
Guessing the wire nuts are PVC PVC plastic uses chlorine atoms to cross link the vinyl polymers. But the chlorine turns into hydrochloric acid when it breaks down which attacks the PVC and creates a self destructing chain reaction. That’s why white (natural) outdoor PVC plumbing breaks down in ten years. If you paint it, coat it, wrap it in a nylon jacket, or fill it full of something to block UV, it lasts quite a bit longer.
The fact that it is turning to powder is a big hint...that’s not overheating which causes it to peel and crack and melt. That’s clearly either chemical attack or UV.
What type of wire are you using for the field connection at the fixture? Standard wirenuts are rated at 105°C.OP said "especially behind luminaires". Whatever he is experienceing is primarily because of heat. I see this often within HID luminaires, but is behind the lamp reflector where there should be no light or UV. But use the black connectors that are rated higher temp and they definitely last much longer. Guessing they are made from a different kind of plastic than most other connectors.
Been a few times I seen HID luminiares have 90C supply conductors that fails, even if luminaire is marked for 90C supply conductors. Sometimes I would even use a high temp fixture wire in a FMC whip for those luminaires when installing new based on seeing such failures.What type of wire are you using for the field connection at the fixture? Standard wirenuts are rated at 105°C.