Hi:
It was built by someone who retired. A pair of band heaters go around a metal tank with various plumbing attached. Water and nitrogen/air will flow through it. Water leakage is not expected and pressure is barely above atm. There is also a tube heater on one of the pipes going to the main tank. Heaters run on 208 single phase. 20A circuit for the bands, and 3A for the tube.
The maker wrapped the tank with fiberglass braid fabric thermal insulation. Then layer of metal tape wraps around the whole thing. I have no idea what covers the studs of the band heaters. I suspect only a thick layer of the fiberglass fabric.
The tank was grounded with a heavy wire tying back to the power source ground. The high temp leads from the band and tube heaters were run about 6-12" in open air into a metal junction box where they tied to power. The tank sits unbolted and the junction box bolted to a heavy metal shelf plate.
Our electrical inspection guy recommended only one absolutely necessary improvement before it can pass an electrical safety inspection (must meet OSHA and NPFA electrical safety requirements): The open air wires have to be protected with conduit or some mechanical shroud.
I plan to put BX flex-armor conduit around the tube heater wires, which will involve devising a custom fitting to fasten the BX to the tube heater.
Second, I plan to run 1/2" EMT conduit from the junction box to the heater. The inspection guy thought it would be OK that there is no way to fasten the conduit to the heater tank, so it would just butt against the outer layer of tape.
I think he assumed that the tank was fastened to the shelf. I discovered it isn't. Now I think the heater needs to be bolted to the shelf so that it can't move relative to the conduit and shear or tug on the wires.
But what else bugs me is the unknown protection for the band heater electrical input studs.
What do you think is required/recommended to protect those studs? Must a junction box be fastened over the band heaters' studs, and the conduit fastened to that box? This would entail a major rework of the insulating tape and fabric, plus substantial additional mechanical engineering.
Or is it reasonable to just bolt the tank to the shelf and run the conduit to butt against the outer tape covering? I don't feel satisfied by this. The problem is there is no way to ensure grounding of the metal tape, which could go live if the band heater bolts punch through the fabric.
I'm inclining toward the more thorough re-work, though that will not make the end user happy. But I'll have to put my name on that inspection form.
Thanks for input.