When Mice and Squirrels Chew Electrical Wiring: A Hidden Fire Risk in Your Home
Hearing scratching in the attic or walls may seem like little more than an annoyance. But when mice or squirrels move into a home, the damage they cause can extend well beyond contaminated insulation, nesting material, and unwanted noise.
One of the more serious concerns is damage to electrical wiring hidden inside walls, ceilings, crawlspaces, and attics.
Rodents are natural chewers. When electrical wiring crosses the same areas where mice and squirrels travel or nest, the protective insulation around those wires can become another target. Once that insulation is damaged, what began as a wildlife problem can potentially become an electrical problem—and, in some circumstances, a fire hazard.
Why Do Mice and Squirrels Chew on Wires?
Rodents have continuously growing incisors, and gnawing is a normal part of their behavior. Inside a structure, they may chew on wood, plastic, stored belongings, insulation, PVC, flexible ductwork, and electrical wire coatings.
Electrical wiring is especially vulnerable because it often runs directly through the places rodents prefer to use.
Mice frequently travel through wall voids, basements, crawlspaces, and attics. Squirrels that enter through rooflines, soffits, fascia, or vents may find themselves surrounded by electrical wiring running across attic joists.
The rodent doesn't need to completely sever a wire to create a problem. Even removing a portion of its protective insulation can expose the conductor underneath.
What About Soy-Based Wire Coatings?
You've probably heard the claim that rodents are increasingly chewing electrical wires because manufacturers have replaced traditional petroleum-based materials with environmentally friendly coatings containing soy or other plant-derived ingredients.
There is some truth behind the origin of the story—but an important distinction needs to be made.
Manufacturers have incorporated renewable and plant-derived materials into some modern products, particularly within the automotive industry. This has led to widespread claims that soy-containing insulation smells or tastes like food to rodents.
However, there is not strong scientific evidence demonstrating that soy-based wire insulation causes rodents to chew wiring more frequently than conventional insulation. Rodents were damaging electrical wiring long before plant-derived materials entered modern manufacturing.
So while the increased use of renewable materials is real, saying that mice or squirrels chew modern wiring because it contains soy goes beyond what current evidence supports.
The bigger issue is much simpler:
If rodents have access to wiring, they may chew it regardless of what the insulation is made from.
How Chewed Wiring Can Become a Fire Hazard
Electrical insulation exists for a reason. It keeps conductive components separated from one another and from surrounding materials.
When a mouse or squirrel strips away that insulation, several problems can potentially occur:
Exposed conductors
Short circuits
Electrical arcing
Intermittent electrical failures
Tripped breakers
Damaged fixtures or equipment
Heat generation around compromised wiring
Increased risk of ignition around combustible materials
Attics can make this particularly concerning.
Wood framing, stored belongings, paper-faced materials, nesting debris and other combustible materials may be located close to electrical wiring. Rodent damage can also occur somewhere that a homeowner cannot easily see.
A wire buried beneath attic insulation may be damaged without producing an obvious warning until an electrical problem develops.
Electrical Fires and Attics: What the Numbers Actually Tell Us
It is tempting to see claims online suggesting that a specific percentage of house or attic fires are caused by rodents. Unfortunately, reliable national fire statistics generally do not provide enough information to assign a trustworthy percentage of attic fires specifically to mice, squirrels, or other rodents.
What national fire data does show is that electrical fires are a significant concern.
According to the U.S. Fire Administration, there were an estimated 26,400 residential electrical-malfunction fires in the United States in 2024. Those fires were associated with approximately 255 deaths, 800 injuries, and more than $1.5 billion in property loss.
Historical USFA data also shows why attic wiring deserves attention. In its analysis of residential electrical fires from 2014–2016, 13% originated in attics or vacant crawlspaces, making these concealed areas one of the more common locations of origin for residential electrical fires.
That does not mean rodents caused 13% of electrical fires. But it does illustrate why damaged electrical wiring in an attic should never be dismissed simply because it is out of sight.
Signs Rodents May Be Around Your Electrical Wiring
Homeowners should pay attention to more than simply seeing a mouse or squirrel.
Possible indications of rodent activity include:
Scratching or chewing noises inside walls or ceilings
Mouse droppings in an attic, basement, garage, or utility area
Squirrel nesting material in an attic
Gnaw marks on wood, plastic, pipes, or stored belongings
Damaged insulation
Nesting material near wiring
Visible tooth marks or missing insulation on electrical cables
Lights that suddenly flicker or behave unusually
Breakers that unexpectedly trip
Electrical symptoms should always be evaluated by a qualified electrician. Wildlife professionals can address the animal and its access points, but damaged electrical systems require the appropriate electrical professional.
Removing the Animal Isn't Enough
One of the mistakes homeowners can make with rodent problems is focusing exclusively on removing the animal.
Catching a mouse doesn't explain how the mouse entered the house.
Removing a squirrel doesn't repair the hole it used to enter the attic.
And neither one identifies everything the animal may have damaged while it was inside.
At Huntsman Wildlife, our approach is focused on understanding the entire wildlife problem: identifying the animal, locating potential entry points, evaluating areas where activity has occurred, and developing a plan to prevent continued access.
If evidence suggests wildlife has been active around electrical wiring, we can document what we observe and recommend that potentially damaged electrical components be evaluated by a qualified electrician.
Prevention Starts Outside the Home
The best way to protect the wiring inside your home from wildlife is to prevent wildlife from reaching it in the first place.
For mice, that means inspecting the exterior for small openings around foundations, siding transitions, utility penetrations, doors, garages, vents, and other construction gaps.
For squirrels, attention often shifts upward toward roof returns, soffits, fascia boards, roof vents, construction gaps, and other vulnerable areas along the roofline.
Wildlife exclusion addresses the source of the problem instead of simply dealing with the animal after it gets inside.
Hear Something in Your Walls or Attic? Don't Ignore It.
That scratching above the ceiling isn't necessarily harmless.
Mice and squirrels can damage insulation, contaminate attic spaces, chew building materials, and potentially damage electrical wiring hidden throughout the structure.
If you're hearing wildlife inside your home or finding evidence of rodent activity, Huntsman Wildlife can help identify what you're dealing with, determine how it's getting inside, and develop a plan to remove the wildlife and prevent future access.
Protecting your home isn't simply about getting an animal out.
It's about finding out what happened while it was in there.