Control Panel Modifications Increase Arc Flash Hazard Potential

Bob V.

New Member
Dec 30, 2016
We currently have a stand-off between engineering and maintenance groups in my manufacturing facility. Maintenance wants to put viewing windows into 480V control cabinets, so they can read error codes on VFD/inverter-drives, safety controllers, and the like. Engineering (myself and a few others) do not know of a safe way to do this, excepting for products available from reputable vendors such as Fluke.

Maintenance wants to use acrylic/lexan materials, and simply glue them to do the door. Engineering is struggling to find an industry standard that speaks against such a control panel door modification. NFPA 70E does not seem to address this issue.

Please help!

Hugh Hoagland

Staff member
Dec 30, 2016
Louisville, KY
This definitely breaks the listing of the equipment and the manufacturer’s design.

The approved products would only open when used and maintain the cabinet’s rating. Never modify any equipment in any way other than approved by the manufacturer or an engineering design. While the idea of not opening the cabinets is a very good one.

A better way might be to locate the information you want to read outside the cabinet. This could be done with a webcam or some other means but we always discourage modifications without thinking of all the safety consequences. Many fiber optics cameras are on the market now which could do this from outside the cabinet and avoid any unnecessary modifications.