How To Repair Mouse Chewed Wires?

Chewing wires and cables is mice’s favorite activity. But chewed wires can have deadly effects on the house’s electrical systems. So, how do you fix chewed wires? That’s what we will share today. 

To fix a chewed wire, separate the wires from the damaged area, cut the chewed part, slip a small shrink tube over each wire and large tubes over both, solder the wires, and shrink the small tube and then the large one. Protect the wires and use deterrents for prevention.

This step is common and simple. The step depends on where the wire is damaged. Follow this article till the end to know how to fix a chewed wire and how to prevent it from happening further. 

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Understanding the damage caused by mice chewing on wires

Rodents like mice, rats, and squirrels have enduring teeth growth for which chewing things is their pastime. 

Since the household wires are easy to access, the rodents will chew them and even build nests close to them for faster access. 

Experts claim that the offspring and single pair of rats can only turn to half-billion rates over 3 years. Mice are also fast breeders. 

One or two of them may not worry you, but one can become a hundred quickly. 

When these rodents chew your household wires and expose them inside the insulation, it can cause serious accidents. 

The bare wires and other wires bundled together will become extremely hot after exposure. 

The heat will inflame the insulation and wood framing. 

Rodents chew the protective cover around the ground wire, power-supply wires, and electrical cords attached to the electrical appliances. 

It can disrupt the electrical current and increase the risk of short circuits, electrocution, and fire hazards whenever you turn on the appliance. 

When the rodent chews wires and damages the insulation, there is a high chance of neutral touching the live wire and causing a short circuit. 

A spark from the exposed wires is more dangerous than everything else as it can start a fire at any moment. 

Loose wiring in the attic, crawlspaces, and walls are common areas where rodents can reach and chew the wires. 

Squirrels and mice nesting near the junction box and loose wire connections cause excessive heating, short circuits, tripped breakers, and overloading.

Signs of mice infestation 

Bite marks on the insulation and exposed live wires signify mice infestation.

It is difficult to spot rodent damage in the wires unless the appliance stops working or causes a bad short circuit. 

However, identifying the signs of infestation can help you find out the issue beforehand and solve it:

  • Rodent dropping is a common sign. It will be 1-2 cm long and dark brown, like a raisin. When the dropping ages, it will turn white and dusty.
  • The walls and floors will have grubby marks suggesting that the rodent has been climbing and rubbing against them.
  • You can see rodent nests made from property materials, like wire insulation, food packaging, and paper.
  • They leave footprints and trails by their tails.
  • Watch for burrowing signs around your property. 
  • You can hear scratching, squealing, and skittering sounds nearby. 
  • You will suddenly experience power outages, tripped breakers, flickered lights, and failed appliances. 
  • Check the wires, and you will find bite marks. 
  • You spot a rodent chewing on the wires.

Techniques for repairing wire insulation 

If you have a rat or mouse infestation, you will see damaged insulation in the wires at one point. 

You should repair the wire insulation first to prevent the wires from contacting the wrong materials and causing serious damage. 

Here are some ways to fix wire insulation:

Method 1

If the wire damage is minor, stick an electrical tap over the exposed wire part and wrap it around. 

Peel the tape end from the roll and center it properly over the cable with the exposed wire. 

Press it well on the exposed section and wrap the tape tightly. 

The method is ideal for minor chewing. 

But you must replace the wire insulation if the rodents have damaged the cable badly. 

Remember that the electrical tape can wear out over time. 

So, replace it with a fresh layer regularly. 

Common wires whose insulation can be taken care of with electrical tape are phone or laptop chargers, power cables of electrical appliances, and headphone cords.

Method 2

First, look at the electrical wire closely and observe the damage level. 

If the inner wire is chewed, repair the wire before the insulation. 

If the wire is fine and only the insulation is chewed, slide a heat-shrink tube over the damaged insulation. 

Use a blow dryer to shrink the tubing over the wire and wrap the tubing with electrical tape.

Method 3

For heavy-duty appliance cords, paint liquid tape over the damaged insulation area. 

Let the liquid tape dry for some time. The product’s label will mention how much time you need to give the tape to dry out completely. 

Once the liquid has dried, wrap the liquid tape with regular electrical tape. 

Methods of splicing and reconnecting chewed wires 

If the wires are badly chewed, you may have to splice and reconnect the wires or buy new wires. 

If you can splice and reconnect the wires, here are two simple methods to do it:

Things required:

Step 1: Inspect the wire and plan things

Before planning anything, you should inspect the wire closely. 

If the chewed cord is too old, it will break eventually, even after the repair. 

In that case, replace the whole cord (Southwire 9703sw8808 16/3 3-Foot Power Supply Replacement Cord, Heavy Duty SJTW Weather Resistant Jacket, UL Listed, Black). 

Take help from a professional in cord replacement. 

If the rodent has chewed the cord near the cord end, close to the plug, cut the cord, and replace the plug (2xPCS 15 Amp 125 Volt, Straight Blade Plug, Plug, Straight Blade, Grounding, 3-Wire Male Extension Cord Replacement Electrical Plugs End, Black). 

If the chewed part is at the center, cut out the chewed area, and splice the two cords together. 

If the chewed part is close to the appliance, you should replace it. 

Read on if you need to splice and reconnect the wires.

Step 2: Cut, separate, and strip the wires

Find the chewed portion, cut it off, and plug off the cord with a wire stripper. 

Pull and separate the wires about 1-2 inches from the downside. 

Strip 1 inch from the two wires ending with a wire stripper. 

Twist the wire ends tightly, so they are no longer loose or frayed.

Create a loop on each wire by wrapping them around a screwdriver.

Step 3: Attach the plug

Open the replacement plug cover to access the prong terminals. 

Another plug option is Leviton Commercial and Residential Thermoplastic Polarized Plug 1 – 15P 20 – 16 AWG 2 Pole 2 Wire.

You need to remove a screw or slide off the cover for some plugs.

Loosen the screw on the large prong, loop the neutral wire around the screw, and tighten it. 

Repeat the same process with the other prong of the plug. 

Close the plug cover and install the screw.

Step 4: Splice the cord

Begin by cutting the chewed part from the cord with a wire stripper. 

First, put a small shrink tube over each wire and then a larger one over both wires.

Slide a 4-inch heat shrink tube (Gardner Bender ⅜ in. D Heat Shrink Tubing Black 3 pk) over one wire. 

Another heat shrink tube option is MCIGICM 127pcs Heat Shrink Tubing 2:1, Electrical Wire Cable Wrap Assortment Electric Insulation Heat Shrink Tube Kit 7 Sizes.

Separate the wires 2 inches on the downside. 

Strip 2 inches from the end of the wire ends from all 4 wires with a wire stripper. 

Step 5: Solder seal wire connectors 

Slide Solder Seal wire connectors over one of the wires. 

For solder seal, try Kuject 12-PCS Solder SEal Wire connectors, Self-Solder Heat Shrink Butt Connector Solder Sleeve Waterproof Insulated Electrical Butt Splice Wire Terminals for Marine Automotive Boat Truck Wire Joint.

Twist the 2 matching wires together.

Shift the connector to the middle solder to align it with the middle of the splice. 

Step 6: Heat the solder ring

Use a heat gun and heat the middle solder ring to melt it. 

For a heat gun, try Wagner Spraytech 2417344 HT1000 Heat Gun Kit, 3 Nozzles Included, 2 Temp Settings 750°F & 1000°F, Great for Shrink Wrap, Soften Paint, Bend Plastic Pipes, Loosen Bolts and More.

Now, heat the other two rings to melt and shrink them. 

Rotate the connector to apply the heat evenly everywhere. 

Repeat the twisting process and melt with other wires. 

Step 7: Shrink the heat shrink tube

Use the heat gun to move the shrink tube over the connectors and apply heat to the tube until it shrinks properly. 

Rotate the cord, so apply the heat evenly. 

You can also use electrical tape instead of a heat shrink tube over the connectors to cover them. 

Safety precautions when repairing wire insulation 

Following certain safety precautions can help you in preventing electrocution and fire hazards. 

If you are repairing chewed wires yourself, here are some precautions you must follow:

  • The best way to prevent accidents is to turn off the breaker’s power and test for confirmation. Only shutting off the breaker won’t be enough as sometimes the appliance may have power due to the turned-on main panel. 
  • The electrical wiring will have an amp rating. While replacing the wires, check the amp rating of the circuit and then use the right wire size accordingly. For example, if you have a 20 amp circuit, you should use a 12-wire gauge
  • While splicing and reconnecting wires, make sure you make the connections tightly. Loose wires can contact the wrong materials or wires and cause fire hazards. 
  • Grounding and polarization are crucial. Grounding gives a safe path to current flow during short circuits, and polarization helps the current flow from the source through the hot wire and returns through the neutral wire.
  • It would be best to have an electrical or junction box, especially if you need to make a wire splicing. It will help secure the cables with cable clamps. 
  • Wear protective gear, like gloves, insulating sleeves, and safety glasses, and keep moisture away from you and the wires while working. 

Prevention tips to keep mice away from electrical wires 

Even if you can repair the chewed wires, you should perform preventive measures to keep the mice at bay. 

The best way to prevent them from chewing the electrical wires of your house is to stop them from entering or surrounding your house.

Common areas where rats and mice enter are:

  • Vents without hardware cloth
  • Spaces between the roof and framing.
  • Gaps in the weather stripping and under the garage doors
  • Ruptures in the bricks
  • The passage where the indoor wires lead outside and vice versa 

Below are some easy and effective preventive tips to keep mice away:

Seal your house 

Use caulk to seal every small opening around your house, especially the corners and cracks you cannot reach or never think of checking. 

If the opening is large, fill it with steel wool. 

Seal areas where the wire cables are going outside your house. 

Rodents can chew wires and make their way inside the house. 

Cover wires with steel

Covering wires with steel or hard plastic is a reasonable way to shield the wires. The mice won’t be able to chew them through. 

Use low-lying cords off the ground. Chewing is easier for the mice at the ground level.

Use deterrents or traps. 

Use traps to prevent the mice from eating your wires. 

For some people, traps are not an acceptable option. 

In that case, use special sonic deterrents to attract them to the traps.

Only mice can hear these deterrents so that humans and other domestic animals do not get disturbed.

Keep trash and food away.

The best way to keep rodents away is by keeping trash and food sources away. 

Remove the crumbs and clean your dishes immediately after eating. Clean your kitchen after making food. 

Do not leave any tissues, papers, or cardboard. 

Use locking trash bins to keep the rodents away from them. 

If the rodents fail to get any access, they will leave your house. 

Trim trees

Trees make it easier for the mice to reach your wires through the roof and attic.

Trim off the trees that make their way to your roof or attic to prevent them from entering your house and reaching the wires. 

Final thoughts 

It is annoying to see the wires getting chewed up by rats and mice. However, there are multiple ways to fix the chewed wires and their insulation. But, try to prevent this from further occurrence.

Hire professionals if you suspect rodents behind the damaged wires. They will examine the wiring problems and perform safe repairs by maintaining the local codes. Call pest deterrent professionals to get rid of rodents and prevent them from entering. 

Furthermore, attempt preventive measures to prevent mice infestation by sealing the entry points with caulk, protecting wires with hard plastic or steel, keeping the dishes and kitchen clean, and using deterrents.

Can mice chew through cement?

Mice and rats cannot chew through cement. They give up when they face concrete surfaces. So, setting electrical wires through cement is an effective way to stop rodents from causing any damage.

Why do mice chew wires?

Rats and mice chew wires to maintain their teeth, make their way through the obstruction, make nests, and receive food sources nearby.


Reference: Electrical Wiring WikipediaHome wiring Wikipedia.

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Arthur Smith

Howdy! I am Arthur Smith, an electrical engineer who is extremely passionate about electronics. I have lived in different parts of the US and currently reside in Wisconsin. I am one of those rare children who knew what he wanted to study and do in life right from the start. I was a curious child who wanted to know how switches work and how the AC works, and I would always observe my dad whenever he would handle the wires and fix things around the house. I currently work as an electrical engineer at a reputed company and write for this blog. And I read loads of books or play video games in my free time.

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