Does anyone know of light bulbs such as Hid mh 400 watt type have mogul sockets or bulb base that are not interchangeable? They have to be the same wattage and type and base size. Thanks
You can get the 1000watt metal halide lamps in "reduced jacket" that look just like a 400 watt-er. That'll screw you up unless you know.
If you're asking if there's anything "special" about a 400 watt metal halide socket, the answer would be no. You can change the ballast assembly and make an HPS into an MH if you want to. Just needs an enclosed lens for reasons peculiar to MH lamps.
We use alot of 400 watt MH fixtures for temp lighting. I can't recall the manufacturer off the top of my head but the mogul lampholders are pink instead of white. They take a specific lamp (rated to be in open air without a lens for safety purposes) and will not light a standard 400 watt MH lamp. Perhaps this is the situation the the OP is encountering.