MegOhm Test or Insulation Resistance Test:
Testing Wires For Lightning Damage
How do I know if there has been damage, is there a way to test the wires in the walls? The way to test for this is called an insulation resistance test, also known as a MegOhm test or sometimes referred to in the trades as “Megger Testing”
The electrical resistance of the insulation on a conductor or in a piece of equipment can be tested and measured by isolating the conductor from ground, applying a high voltage over time, then measuring the results. In most residential situations Master Electricians use a 300 to 500 volt DC test over 10 minutes. When this test is performed by electricians it is a very reliable test. This is recommended. Do not attempt this test on your own.
Performing a megohm test is crucial after a water loss or a lighting strike claim. An Experienced Public Adjuster can provide more guidance on if this should be performed. But an Electrical Engineer or a Master Electrician are the experts and they would be the ones to perform this Megohm Test:
If you have had a major strike and your insurance company has not told you about this process, then request this test be performed. MegOhm testing is really the only way to know if damage has occurred, and even then it is not a perfect testing process. You can’t be sure by visible inspection alone, and you can’t visibly inspect most of the wires in a home. Lightning has many unknown paths, it has a super high voltage and travels very fast. If your home has been hit tell your insurance adjuster you want it tested!
If you have a lightning strike you may have an insurance claim and your home may not be safe. The wiring in the wall may not spark a fire today but could burn down your home in the future with little to no warning.