I don't understand why anyone thinks that just because a light is old it's no good..@diabolical666?? I was given a 15+yr old hydro farm 400MH..i think it's the same thing he has, built in ballast..works fine. I know enough that i took it apart,cleaned it and checked the wiring. Those old mag ballast light last forever..might need to replace a CAP here and there. I see a huge fear, or misunderstanding?, of electricity in the MJ growing community..I don't get it, it's pretty simple. Oh and once you get bit by 120 a couple times..it's not that bad..lol
I'm not arguing the other points, I don't use it much because it puts off too much heat and my T5 blows it away.
Its not so much that its a fact that it will be unsafe.
I was the only maintenance guy at a roll to roll print press factory until it closed. Other than a few machines everything in there was built in the 30's to the 50's. Trust me I love old equipment. Most anything older is built better than the new stuff. Though sometimes at a trade off of efficiency.
I think that the decision to use it comes down to a set of variables that are unknown and complicated so everyone errs on the side of caution.
I might use it, you might to. The person deciding needs to know if they are capable of that decision. The person needs to be honest whether they know enough to deem the light safe. Be sure you understand how amps, watts, and volts work so you are capable of knowing how it was originally wired and if it is still wired that way and correct gauge of wire and even the length of wire.
Next comes to your home situation. Part of the decision of should you use it. If you own your own home, pay your own insurance, then yes go ahead. If you live with someone or rent then is the decision to use it fair? I would say in that situation then all parties might need to be involves in using older questionable lights.
Then comes this part. At a time in history when cannabis is on the verge of being completely legal we have a due diligence. We do not need people that grow burning their house down. We need to go forth and be safe and diligent and show the world that growing can be a safe endeavor.
Now that is some serious thought about that light. Now hopefully the OP can now take all this info into account and make an informed and competent decision.