Managing electrical equipment clean-up after extreme weather events

22 June 2022


Extreme weather is on the rise in the United States. According to the NOAA National Centers for Environmental Information (NCEI), “in 2021, there were 20 weather/climate disaster events with losses exceeding $1 billion each affecting the United States.” This far exceeds the 1980 to 2021 annual average of 7.7 yearly events.

Extreme weather events, like tornadoes and hurricanes, are usually short-lived but can leave devastation in their wake. Hurricane-force winds of 75 mph or more can severely damage, even destroy, large buildings and mobile homes. Tornadoes can also destroy large buildings, uproot trees, and hurl large structures farther than several football fields. Damaged paths can be anything from one mile wide to 50 miles long. Both hurricanes and tornadoes produce winds so strong they can cause storm surge flooding.


Such high winds can knock down power lines and rip cable housing out of the ground. Flood waters and fires caused by these extreme weather conditions can also damage both above ground and underground wiring and cabling. Once a storm dissipates, it's time to survey the scene and figure out exactly what is broken and what can be repaired, what needs to be cleaned and what needs to be replaced. These things can all be done through testing and inspection.

Check the grounding

One of the most important things to check after extreme weather savages an area is grounding. Grounding gives electricity the most effective way to return to the ground via an electrical panel. It is a direct electrical connection to the earth, a connection to a specific point on an electrical or electronic circuit, or an indirect connection that works because of capacitance between wireless equipment and the earth. A system with faulty grounding can have catastrophic results that not only could lead to a loss of equipment, but even worse, loss of life due to electrical malfunctions.

Ground resistance testing is affected by the weather. The test item is not easily managed like a motor or electrical circuit, which can be dried, cleaned, placed in a controlled environment or some other adaptation to accommodate easy or standardized testing. When it comes to ground resistance testing, the test item is a complex interplay between the grounding electrode and its soil environment.

Grounding can be checked using one of Megger’s many handheld ground resistant testers.

Test insulation resistance

Insulation resistance testing is another big one. This type of testing is crucial after extreme weather, especially if an area is ravaged by flood or fire. It helps to ensure safety. By performing an insulation resistance test you can eliminate the possibility of having a life-threatening short circuit or short to ground. This test protects against compromised wiring and defective equipment. It also helps to protect against fire or electric shock. As such, an insulation tester is a prime recovery product after catastrophic events and insurance companies require this type of testing be performed before they pay for any damages caused by flood or fire.

Insulation resistance testers can be used to test switchboards and electrical controls, transformers, cables, and wiring, as well as electrical tools. However, before any testing can begin, especially in the case of flooding, electrical windings must be dried out, with a maximum temperature for drying at 194 °F.  This helps prevent further damage to the test item, such as rapid thermal deterioration of the insulation and high vapor pressures from the steam produced at excess temperatures. Drying out can be done by placing windings in an oven with suitable temperature control and good air circulation, or by circulating a low voltage current through the windings until the insulation resistance has reached a value of at least 100 000 Ohms.

Ground resistance and insulation resistance testing are crucial after extreme weather has swept through an area. These tests help easily identify where serious issues lurk. Insulation resistance testing is of particular importance because it protects both people and systems, helping to prevent serious injury and ensuring the safe and reliable working of electrical equipment. Testing for ground helps to identify faulty grounding and electrical malfunctions that can cause catastrophic equipment losses and, in the most extreme cases, loss of life. These are two tests are, therefore, essential and should never be overlooked or ignored.