Letter 7014

Plating tank heaters

We recently did the electrical connections for a new plating room for one of our customers. The tank heaters plating are plating and my customer thinks it is the way we connected them. The heater manufacture says it a grounding problem. I am also told this is a common problem. We connected this equipment correctly, including proper ground connections. All grounds are common in the electrical panel. The only time the heaters do not plate is when the ground is not connected. What am I missing here?

Ron Byrd
SPEC - Cameron Park, CA

The problem isn't the grounding of the heaters, it's the grounding of the anodes, cathodes, or rectifier.

Electric heaters must be grounded for safety reasons, but this necessitates that everything else must "float", i.e., be isolated from ground; otherwise current will flow to or from the grounded heater to whichever side of the circuit is not grounded.

Ted Mooney, P.E.
finishing.com
Brick, New Jersey

Make sure the heater surface is non conducting. If it is an electrical heater, they are usually covered with a teflon surface. If this surface is punctured some how, an earth leakage will occur and trip the fuse if present. I have seen in the past that if the earth leakage system is not working, a small AC current flow is going through the chemical solution and starts a deposit on the heater.

Do not worry too much about the rectifiers, since those are DC.

Jelle Jüngeling
Meco Equipment BV - The Netherlands

+++++

We run heat and cool through coil pacs utilizing LP steam and a cooling tower. It negates the issue of electrical problems from electric heaters. I believe it's more efficient also. Solution temps must be maintained at specfic temps. Ambient temp plays a large role on which temps stabilize at and temps like to bounce up and down with the ambient temperature. So much where I live that the temps are computer controlled.

Victor L. Firman
Plating - St. Louis, MI, USA

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