Shock & short circuit hazards at electrical panel covers & cover screws:

This article discusses safety hazards involving the screws used at some electrical panels and suggests safety procedures for the electrical inspector, home inspector, or other professionals who examine residential electrical systems.

Safe electrical inspection procedures and safe use of volt meters, DMMs, multimeters, and similar electrical test equipment is discussed at the end of the article.

Electrical Panel Cover Fastener Screws & Electrical Meter Box Mounting Screw Hazards

[Click to enlarge any image]

• Looking: 
  
  Look carefully for evidence of burning, arcing, or other damage before touching or moving components. Eg.: sharp sheet metal screws in panel covers may short hot wires.

• Unsafe Electrical Panel Screws: 
  
  the electrical panel cover screws have been replaced with sharp pointed sheet metal screws
• Electrical Panel Access, Rats & Other Distractions: 
  
  (distractions from being careful) there are rats at your feet, or there is a rats nest of wires or other obstruction to safe cover removal - watch what you say.

At an inspection the author had encouraged a nervous buyer to accompany him into an ugly dark muddy basement to inspect the mechanical systems.

The client, a woman not properly dressed for an inspection, wore high heels and a tight skirt.

She was wobbling in the dirt floor in a dark crowded corner of the basement, terrified and already shaking in the dim light. The author, encountering a maze of wires in the way of the electrical panel, forgot to edit his thoughts, and muttered aloud: "geez what a rats nest."

The client screamed "RATS!!!" and ran terrified from the basement, falling towards the dark stairs.

• Distractions during an electrical inspection are themselves dangerous.
  
  A NE ASHI inspector reported that

As I just touched an electrical panel cover screw with my Milwaukee screwdriver I saw a tremendous flash of light - as bright as the sun. I was certain I was dead. As moments passed I realized I was still standing there, alive.

Am I alive? I asked myself. I learned that from behind me and my client, the real estate agent had chosen that moment to take a flash photograph of the proceedings. - to DF Randolph MA 09/2008

This distraction is more risky than it may appear. A sudden flash, a sudden shout or movement, could cause an inspector to lurch, touching an electrically live and dangerous component. It is important for the inspector to learn and practice calm, steady movements and to resist distractions.

How to Look for Unsafe Panel Cover Screws & for Evidence of Burning and Arcing When Approaching the Electrical Panel

• Look at the electrical panel before touching 
  
  the electrical panel cover; is there evidence of a problem such as
• Arcing, Overheating or Burnups:
  
  you see evidence of electrical failures such as burned or overheated components. In the photo at left the ground wires are clearly overheated - something is wrong. In this case a homeowner was badly shocked when he touched his metal workbench.
  
  See Case History:Loss of Neutral Shocks Homeowner for details.

The pair of photos whoen here illustrate (above) electrical arc flashover soot, and below, the repair - tape on the electrical wire, but the wire is still too close to the screw mounting hole for the panel cover.

• Look for improper and unsafe electrical cover screws, sharp pointed sheet metal screws, and look for electrical cables that pass too close to the screw openings in the electrical panel.

Sharp sheet metal screws:

If you find that a sharp-tipped sheet metal screw has been used (usually to replace a lost original fastener) you should be alert for pierced, damaged, short-circuited wires in the panel - both during removal and during panel cover replacement.

We will not reinstall a sharp-pointed screw in a panel cover if wires are crowded close to the screw opening.

Having seen more than one shorted and burned panel from precisely this cause, we warn clients about this unsafe detail. It is trivial to correct.

It's an easy fix: use a blunt tipped screw, or file off the sharp point of the SMS.

Before re-installing the cover of the electrical panel, check to assure that no electrical wires have moved close to the panel cover screw mounting holes where they might be pierced or damaged.

ELECTRICAL INSPECTOR SAFETY PROCEDURES describes important basic safety procedures, clothing, and equipment for home inspectors and electrical inspectors.

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Continue reading  at ELECTRICAL PANEL INTERIOR HAZARDS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• ELECTRICAL PANEL INSPECTION SAFETY
• SAFETY for ELECTRICAL INSPECTORS

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ELECTRICAL PANEL COVER SCREWS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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