Running wires to exterior features and secondary buildings is a common necessity for building owners. However, leaving exposed wires running along the outside of a home or building is never a safe idea. To protect these wires from the elements, many owners elect to run them through an exterior wall with a conduit for an added layer of protection and simplified installation. A conduit provides a versatile tube for directing wiring, and it also protects the wires from harmful environmental conditions.
This article discusses how to run a cable through an exterior wall using a conduit, including the tools and steps needed to get the job done.
Table of Contents
Using Conduits With Electrical Wires
Electrical wires are never without some level of risk. Wiring is sensitive by nature and can quickly become damaged when exposed to the elements, resulting in lost connections. Exposed wires can also present health risks to building occupants. In addition to the shock risk, the National Electrical Manufacturers Association estimates that electrical problems cause over 67,800 house fires per year. Even sheathed wires can be cut or damaged over time, exposing the wires to the elements. To protect against these outcomes, many building owners choose to run their wiring through a conduit.
Conduits come in a range of styles and materials to fit the job at hand. Metal and plastic conduits are common and may be flexible or rigid depending on the needs of the application. Regardless of the type, a conduit can help protect wires, especially in exposed locations where environmental conditions present a higher risk. Some factors conduit can protect against include:
- Force: Conduit provides structural protection for wiring, preventing damage from impacts and crushing forces.
- Sunlight: UV rays can damage wiring and corrode sheaths over time. Conduit protects against this through UV protective surfaces and coatings.
- Moisture: Conduits are resistant to moisture and water, preventing water damage to wiring in outdoor environments. Some conduits are completely waterproof and can even be submerged.
- Corrosion: Corrosion from environmental chemicals, water and sunlight presents a risk to wiring. Conduits, especially PVC conduits, help protect against this.
- EMI: Certain metal conduits can help shield circuits from electromagnetic interference (EMI) in the surrounding environment.
On top of these protective benefits, most conduits have room for multiple wires. This extra space allows you to pull several wires through a single conduit, organizing your electrical wiring for improved accessibility.
Things You Will Need
Before beginning an exterior wall cable pass-through using a conduit, you will need to gather several tools. The tools you or your installer should have on-hand include the following:
- Noncontact voltage tester: Before working with any electrical components, you or your installers need to verify that the power to the circuit is completely turned off. A noncontact voltage tester is necessary to verify that no voltage is running through the work area.
- Stud finder: Stud finders are useful for locating wall studs in covered areas. You may need to know the location of the studs to determine secure attachment points for the conduit.
- Nonmetallic sheathed cable or SE cable: This is the cable you will use for the installation. Be sure to choose a cable that fits the needs of the installation.
- Cable connectors: Cable connectors are the attachment points for cables. These need to be installed at the junction box and at the device box to which the cable will be connected.
- Attachments: Depending on the needs of the installation, you or your installer may need a variety of attachments to hold cables and conduits in place. Cable staples and straps are used to hold cables in place during installation, while conduit hangers keep a conduit in place. These attachments may require nails or screws to secure. If the conduit or cable is being run along an area with no studs, you may also need drywall anchors.
- Hammer: Hammers are necessary when using nails and staples to drive attachments into studs and drywall.
- Drill: You or your installers will need a drill and an appropriately sized drill bit to create a hole in the wall for installing the conduit.
- Cable cutters: Cable cutters, as the name suggests, are for cutting the cable to length. This tool is necessary to ensure you don’t have excess cable coiled up inside the conduit.
- Cable ripper or utility knife: A cable ripper or utility knife is helpful for removing the insulating outer jacket from cables. These will be needed to remove the jacket from the ends of the cables to make connections to the junction box and the terminating device.
- Wire nuts: Wire nuts are wire connectors that help create safe connections at the junction box.
- Cable pulling equipment: Various cable pulling methods are available, each of which is suited to different conduit shapes and types. You or your installer may require a few different tools, depending on the method you decide to use. These tools may include string, a conduit piston, fish tape or other tools.
Installers may require additional equipment, such as ell pullers, trench diggers or shovels, depending on the specific needs of the installation. Building owners should discuss the needs of the application in detail with their installation specialists to avoid any delays due to missing equipment.
How to Run a Conduit Through an Exterior Wall
Once an installer has their tools and conduit on hand, they’re ready to begin the installation. Here is a step-by-step guide on running a conduit through a wall. Please keep in mind that any conduit installation should be done by or under the guidance of a trained professional.
1. Review the Plan
The first step to any installation should be a review of the plan for the conduit. Discuss your plan in detail with an installer well before the installation, and review it again immediately before the installation begins to address any last-minute alterations.
2. Turn Off the Power
Before beginning an electrical installation, make sure the power to the circuit is turned off. After turning off the correct circuit breaker at the service panel, the installer should use a noncontact voltage tester to verify that the circuit is turned off. If any voltage is detected, continue turning off circuit breakers until the reading is clear.
3. Install Connectors
After verifying that the power is turned off, the installation team can remove the cover of the junction box to install a cable connector for the new connection. They should also install a cable connector in the device box to which the new cable will connect.
4. Mark Studs
Use a stud finder to find and mark all the wall studs between the junction box and the device box. During this time, verify the run path for the conduit and make any last-minute adjustments if needed.
5. Drill a Hole
Drill a hole in the wall where the conduit will be installed. Be sure that the drill bit is large enough to create a hole that the conduit can fit through. This is also the time to drill any additional holes where the conduit will exit or enter the wall again.
6. Cut and Bend the Conduit
Cut the conduit to the right length for the installation. If the conduit is a flexible type, it will not need to be shaped. However, you or your installer will need to shape a rigid conduit using a bender or fittings.
7. Check the Hole
Check that there is enough space for the conduit to fit through the hole after it is shaped and widen it if necessary. Also, verify that no water is present that may impact the integrity of the conduit.
8. Slide in the Conduit
Once the conduit and hole shape are verified, begin sliding it through the hole in the wall. You may need an ell puller to help with 90-degree bends.
9. Install Supports
After the conduit is in place, install supports to attach it. In most cases, you will likely use conduit hangers. The first hanger should be 3 feet or less from the junction box, and any subsequent hangers should be 10 feet apart at most. If possible, install conduit hangers at studs with screws. If no stud is available in an area that needs to be secured, use a drywall anchor to attach the conduit hanger.
10. Pull the Wire Through
Pull the cable all the way through the conduit. For a straight conduit, a string, conduit mouse or fishing weight method may be used. For a conduit that has more angles and curves, fish tape is typically the best option. There are many cable-pulling methods, so choose the best one for your situation.
11. Cut and Connect the Wire
After pulling the cable through, cut the cable so it extends at least 8 inches from the front of both the junction box and the device box. After cutting the wire, use a cable ripper or utility knife to remove the outer jacket from the cable ends, then hold the stripped ends of the wires with the connecting wires at each box. Use a wire nut to complete the connection. After the connections are complete, replace the covers of the junction box and device box and turn on the circuit breakers to test the connection.
12. Seal Gaps
After verifying the integrity of the cable connection, use silicone caulk to seal any gaps between the conduit and the holes in the exterior wall.
Running Conduit Underground
In some cases, a conduit running through an exterior wall may also need to be run underground. This is common in cases where conduit needs to be run to a secondary building, such as a garage, workshop or maintenance shed. In these situations, you will need to dig a trench before the installation. For this segment of the installation, installers will typically do the following:
1. Contact the Local Municipality
Before digging any hole, the owner and installer will need to contact the local municipality to learn where existing electric, water and gas lines are.
2. Dig a Trench
After identifying where existing lines are, you and your installer will plan the route for the conduit and dig a narrow trench about 2 feet deep using a shovel or trenching machine.
3. Lay the Conduit
After the trench is complete, the installer will lay the conduit along the trench.
4. Fill the Trench
Once the wire is run, the installer will spread a layer of sand over the conduit to act as a warning for future diggers. They may also put red caution tape over the sand as an additional warning. Once these layers are set, the installer can top it off with soil.
Conduit is a valuable resource for protecting electrical wires in exterior wall installations. With a good installation team and quality conduit, building owners can rest assured that their wiring is secure. If you’re looking for quality conduit from a trusted supplier, AerosUSA has what you’re looking for.
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Learn more about our conduits and other product lines today. Contact AerosUSA to get started.