Most homes have thermal insulation in their attic, roof, or loft, and it’s a great way to reduce heat loss. Reduced heat loss means smaller heating bills. But if you are concerned about the electrical wiring touching the insulation, you are not alone. When starting my career as an electrician, for safety this was one of the first things I learned. Can Insulation touch electrical wires? Here are some insights on this matter from my personal experience.
In general, there is no danger in thermal insulation touching wires, given that wires are electrically insulated. Depending on the thermal insulation type, you can use different techniques to wire around insulation. However, never let the thermal insulation contact uninsulated live wires.
How Can Thermal Insulation Safely Touch Electrical Wiring?
Modern electrical wires come with solid over-the-top insulations. This electrical insulation prevents the current from reaching the other surfaces of your house. So, the hot wire can touch the thermal insulation safely.
Must-Know Things About Electrical Insulation
The electrical insulation is made with non-conductive materials. Therefore, these insulators do not allow the electrical current to pass through. Most often, manufacturers use two materials for home electrical wire insulators; thermoplastic and thermosetting. Here are some details about these two materials.
Thermoplastic
Thermoplastic is a polymer-based material. With increased temperature, this material gets melted and becomes workable. Also, upon cooling, it becomes solid. Usually, thermoplastic has a higher molecular weight. You can melt and reform thermoplastic several times. However, this plastic does not lose its integrity and strength during this process.
DID YOU KNOW: High-performance thermoplastic will start to melt between 6500°F and 7250°F. To produce electrical wiring insulators, we don’t use these high-performance thermoplastics.
There are five thermoplastics that are used to produce electrical insulations. Here are those five thermoplastics.
| Type of Thermoplastics | Melting Temperature |
| Polyvinyl Chloride | 212 – 500°F |
| Polyethylene (PE) | 230 – 266°F |
| Nylon | 428°F |
| ECTEF | 464°F |
| PVDF | 350°F |
Thermosetting
Thermosetting plastic is made from viscous fluid resins, and the hardening process can be completed in several ways. Manufacturers use catalyst liquid, ultraviolet radiation, high heat, or high pressure for the hardening process.
Here are some common thermosetting plastic types.
- Cross-Linked Polyethylene (XLPE)
- Chlorinated Polyethylene (CPE)
- Ethylene Propylene Rubber (EPR)
Types of Thermal Insulations
There are four different thermal insulations that can be seen most often in America. Depending on the residential heating system and construction type, you can choose any insulation.
Loose-Fill Insulation
Loose-fill insulation contains unbonded materials. For instance, you can use fiberglass, mineral wool, or Icynene. Also, you can use cellulose or perlite.
TIP: Cellulose and perlite are naturally occurring materials.
Add the materials into your attic, floor, or adjoining walls to install loose-fill insulation. When choosing a synthetic material for loose-fill insulation, remember to check the R-value. This value might change depending on the temperature of your area.
DID YOU KNOW: Fiberglass loose-fill insulation might ignite at 540˚F.
Blanket Insulation
Blanket insulation is an excellent item for space between studs. They consist of thick fluffy sheets that can fill up the space between studs or any other similar space. Usually, these blankets have a width of 15 – 23 inches. And have a thickness of 3 – 10 inches.
Like in the loose-fill insulations, the blanket insulations are made from fiberglass, cellulose, mineral wool, etc. Depending on the built material blanket insulation will ignite between 1300˚F and 1800˚F.
Rigid Foam Insulation
This type of insulation is new to residential thermal insulation. Rigid foam insulation was first used in the 1970s. It comes with panel insulation made from polyisocyanurate, polyurethane, mineral wool, and fiberglass.
These rigid foam insulation panels have a thickness of 0.5 – 3 inches. However, if needed, you can get a 6-inch insulation panel. The standard size of the panel is 4 feet by 8 feet. These panels are suitable for unfinished walls, ceilings, and basements. The polyurethane panels will ignite between 1112˚F and 1292˚F.
Foamed in Place Insulation
Foamed-in-place insulation is also known as spray foam insulation. This type of insulation consists of two mixed chemicals. The mixture will expand 30-50 times compared to the original volume before starting the hardening process.
Foamed in place insulation is commonly made with cellulose, polyisocyanurate, or polyurethane. You can install these insulations in ceilings, unfinished walls, floors, and many other inaccessible places. At 700˚F, foamed-in-place insulation will ignite.
How to Install Thermal Insulation Around Wires and Cables?
Now you know four types of insulation that most American homes use. But did you know how to install these thermal insulations around wires? if not, don’t worry. In this section, I’m going to talk about it.
How to Install Loose Fill Insulation Around Wires
Among the thermal insulation techniques, this is the easiest method. There is no need for any early preparation. Blow the loose-fill insulation around wires.
TIP: Loose-fill insulations are commonly used in ceilings and attic floors. So, you might encounter light fixture wires.
How to Install Rigid Foam Insulation Around Wires
First, measure the spaces where you plan to install the rigid foam.
Then, cut down rigid foam insulation panels according to your measurement and apply suitable adhesive to the board.
Finally, install them behind the outlets and electrical wiring.
How to Install Blanket Insulation Around Wires
When installing blanket insulation, you’ll have to do some modifications. The blanket insulations are thicker than the rigid foam insulation. So they won’t fit behind the electrical wiring.
Method 1
First, place the blanket insulation and mark the position of the wires.
Then, split the blanket in half until it reaches the marked wire position.
Finally, run the wire through the blanket insulation. If you did it right, one part of the insulation will be behind the wires and the other will be in front.
Method 2
Like in method 1, place the insulation between the studs and mark the wire and outlet area.
Then, take a sharp knife and make a slit for wire, and cut off the outlet location on the blanket insulation.
Finally, install the insulation. (1)
TIP: Use a piece of rigid foam insulation to fill the space behind the outlet. (2)
Wrapping Up
Installing thermal insulations on wires and outlets is entirely a safe process. However, the wires should be electrically insulated. Also, selected thermal insulation should fit your basement or wall. If everything checks out, you can start the installation.
Take a look at some of our related articles below.
- How to run electrical wire in unfinished basement
- Why is the ground wire hot on my electric fence
- What gauge wire for light fixture
References
(1) insulation – https://www.energy.gov/energysaver/types-insulation
(2) foam – https://www.britannica.com/science/foam
Video References
Electrician U
Lowe’s Home Improvement
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