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What are the common problems with an electrical panel dead front?
Sunday, July 3, 2022
The cover plate for an electrical panel is called a “dead” front because it's not supposed be electrically “live” and able to shock or, even worse, electrocute someone who touches it. The combination of the dead front and panel box is also intended to keep all the energized interior components untouchable and well-sealed to prevent any internal sparking or arcing from getting out. Here’s our list of things that can go wrong:
• Missing dead front - This is an obvious safety hazard, especially if there are children in the house, but we still occasionally see a panel with a long-gone dead front and dust-covered interior.
• Homemade replacement dead front - Any replacement dead front must be made by the original manufacturer specifically for that panel model, or a UL-approved alternate. A homemade dead front is never acceptable, no matter how carefully fitted. If you can’t find a matching dead front replacement, the entire panel needs to be replaced.
• Damaged or corroded dead front - Corrosion usually indicates another problem: either moisture intrusion from rain coming down the service mast, or a missing or damaged weather cover panel. The panel should be replaced if severe.
• Missing twistouts - Twistouts are the perforated metal rectangles in the dead front which are designed to be twisted away for an opening to expose each breaker switch in the front of the panel. There are plastic blanks manufactured to snap into the opening as an approved repair for a missing twist out.
• Pest infestation - Even a small opening in the dead front or box can allow wasps or small lizards inside the panel. The attraction is the small amount of heat generated by the breakers that make it a cozy, safe place to be in the winter in Florida. Mud dauber wasps that infest an exterior panel can be a big problem.
• Missing dead front screws - Even a single missing screw can allow a gap between the dead front and box, as shown below.
• Pointed dead front screws - Dead front screws protrude into the box, and a pointed one can puncture the insulation of a wire behind it and energize the dead front. Panels come with the required blunt-tip screws from the manufacturer, but sometimes they get misplaced and what’s laying arou nearby gets used instead. The worst are self-tapping screws, like the ones shown at right. A self-tapping screw caused a short circuit when it penetrated the cable behind and the unrepaired panel damage below. It does happen.
• Gap between dead front and box - No gap is allowed between the front of a panel box and the wall surface that the dead front of a recessed (flush-mount) panel will sit against in a regular wood stud (combustible) wall structure. But a 1/4” gap is acceptable in a noncombustible (steel stud or concrete) wall construction.
Also, the gap around the sides of the box cannot exceed 1/8” (NEC 312.3 and 312.4). The panel enclosure below, shown with the dead front removed, fails on both counts: it is almost an inch inset from the wall surface and the drywall was cut back too far around the box.
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Field Guide for Home Inspectors, a quick reference for finding the age of 154 brands of HVAC systems, water heaters, and electrical panels, plus 210 code standards for site-built and manufactured homes, and the life expectancy rating of 195 home components. Available at amazon.com for $19.95.
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