Electricity loss through moisture condensation

The glass on the outside of fluorescent lamps are coated with a substance which causes the water to bead up on the surface. If this coating is missing, a film will form above 95% relative humidity that can make it difficult for the lamps to start. Before a fluorescent lamp starts, the impedence is on the order of a few Meg Ohms. Once it starts, the impedance drops to a couple hundred ohms. A liquid film of some kind that offers this continuous path from one end of the lamp to the other, loads down the high open circuit voltage required to initiate a current path through the cold high impedance gas.

Once the lamp starts, there is usually no significant electrical loss, even under water. In a plating facility, however, there may be an accumulation of acidic fume condensation on insulators that create a path for parasitic losses. Unfortunately, no one can predict the amount of impedence you would have in parallel with the lamp. Depends on the depth of the sludge and its makeup and surface area. Too many variables. Every fixture will be different.....

On the other hand, the lamp bases are generally steel or aluminum. If they deteriorate in the presence of acid fumes then they present a safety issue. That makes it easy to justify. Lamps with bases that crumble while trying to remove them present some electricution hazzards if they are changed while energized. Light fixtures made of steel also deteriorate rapidly around acid fumes. Protection of the plating tanks from iron or aluminum oxide debris may become the justification you need. Lumen loss is a null consideration because even a sealed fixture will get dirty but it may relieve you from the other issues mentioned.

Hope that helps!