But they are not interested in your inspections being properly accomplished and when the welder is welding he has all the light he requires for his part of the job.
I personally carry three different styles of light on me during the day with three more in my box of spare tools in the truck or CRV. Haven't found a situation yet that I couldn't get adequate light on. Varying types of lens, colors, intensity, etc.
Cheapest one was $10 at the NRA Convention in Phoenix a few years back. It has been a great little light. All the others go up from there. My wife hates it when I go to Cabela's. But, I write most of my purchases off as business expenses.
Flashlights, Leatherman, wind speed/temperature gauge, boots, toolboxes (pistol cases), etc.
If I remember correctly, the lighting requirements when checking ducting/vents is equivalent to greater than 200 watt light bulbs. Takes quite a light to do that. But, you put it in (or out) and then look for leaks in a darkened area. I find it easier to go inside the vent and have a helper go around all the seams with the light. I don't have to darken a whole room are building that way. But, some are not accessible for getting into for a person, even of my challenged dimensions. And there are times it is easier to use the smoke.
Back on topic, There still seems to be a concensus that there are no lighting requirements in D1.1, or any of the D1, 14, 17 etc codes for that matter.
Have a Great Day, Brent