Running electrical wire through walls is a common task for do-it-yourselfers working on home wiring projects. While it may seem intimidating, with proper planning and safety precautions, it can be accomplished safely even by homeowners with minimal electrical experience. In this comprehensive guide, we will walk through the entire process step-by-step, from planning to execution, to help you successfully run wire through walls and add new wiring in your home.

Planning the Wiring Route

The first step is deciding where you need to run the wire and planning the optimal route.

Determine the Start and End Points

Decide where the wire needs to originate from and where it needs to terminate. Typically, this will be from the main electrical panel or junction box to the location of an outlet, switch or light fixture. Make sure to plan a route that minimizes the total length of wire needed.

Choose the Path of Least Resistance

Select the simplest path between the start and end points. The easiest route will be through unfinished areas like basements or attics. Running wire through finished walls or ceilings entails extra drywall work.

Avoid Obstacles

Plan the wiring route to circumvent potential obstacles like plumbing pipes, HVAC ducts, or wall studs. Trying to route around these can complicate the process. Consulting building plans can reveal hidden obstacles.

Map the Route

Sketch a map of the planned route including exact endpoints, path through each room, and location of any obstacles. This will serve as a handy reference during installation. Mark stud locations if running wire through finished walls.

Gathering the Right Supplies

Installing in-wall wiring requires having the proper supplies on hand including:

Wire – Use 14 or 12 AWG copper wire for 15 & 20 amp branch circuits. The amount needed will depend on the route length.
Wire staples or clips – To affix wire along framing in unfinished areas.
Fish tape – Flexible steel rod for routing wire through finished walls.
Wire strippers – For stripping sheathing when making connections.
Voltage tester – For safely checking if wires are live.
Junction boxes – For housing connections when splicing wires.
Wall plates – To cover junction boxes and outlets.
Drywall saw – For cutting outlet and junction box holes in drywall.
Drywall screws – For refastening drywall after cutting.

Safety Tips

Running wires carries electrical risks so preparation and caution is key. Follow these tips to stay safe:

Turn off the main breaker to cut power to the whole house. Use a contact voltage tester to confirm it’s dead.
Wear insulated gloves and eye protection for added protection.
Only work on one circuit at a time to avoid confusion.
Label all disconnected wires to simplify reconnecting.
Avoid kinking or excessively bending wire to prevent damage.
Make sure hands are dry when handling electrical wiring.
Take things slow and don’t rush. Attempting to work too quickly can lead to accidents.

Running Wire Through Unfinished Walls and Attics

The simplest wiring scenario is through open walls and attic spaces before drywall is installed. Follow these steps:

Secure the Wire

Run the wire along the sides of exposed wall studs or joists using wire staples or clips. Keep at least 12 inches from parallel runs.

Maintain Slack

Leave some periodic slack or loops of wire to account for wood shrinkage or shifting that could otherwise pull tight and damage the wire over time.

Protect the Cable

Position the wire to avoid contact with insulation or other potentially damaging materials. Use metal plates to protect where passing through metal studs.

Splicing

Wherever wire splices are needed, house the connections in a securely mounted plastic junction box fitted with a cover plate.

Outlets and Switches

Install outlet and switch boxes where required, fed by the new wiring. Consult codes for proper mounting heights.

Fishing Wire Through Finished Walls

Feeding wire through existing drywall is more challenging but can be done with some simple tools and techniques:

Choose an Inconspicuous Entry Point

To minimize drywall patching needed, drill access holes in corners or above trim where they will be less noticeable.

Hole Size

Drill holes just big enough for the wire – 1/2 inch for 14/2 NM cable or 3/4 inch for 12/2. Avoid oversized holes.

Use Fish Tape

Secure the end of a steel fish tape to the wire end and feed through the access hole. Have someone push from the other access point.

Utilize Wire Running Tools

Devices like wire running rods with specialized heads can help push wire through tight spaces in walls. Use fiberglass rods for metal studs.

Run Multiple Lines Together

When running multiple new wires, bundle and feed them all together through the same access holes.

Secure Wire

Secure wire to framing using special nail-on metal cable straps in finished walls once pulled through.

Fishing Wire Downward Through Floors

Wiring from an upper floor to a lower floor introduces gravity’s pull into the equation. Use these tips:

Drill at an Angle

Drill access holes downward at a 45 degree angle to prevent kinking when wires make the bend.

Lube the Wire

Cover the wire in a lubricant like wax or silicon spray to help it slide downward more easily.

Use J-Hooks

Secure J-hooks along joists leading to the access hole to guide wire downward and prevent tangling.

Feed Sections

For long vertical runs, disconnect the wires and feed one section at a time, reconnecting as you go.

Use Fish Rods

Attach an angled fish rod to the wire end and rotate to help feed sections around bends and through floors.

Installing Wires into Junction Boxes

Junction boxes house wire connections and outlets. Follow proper technique when installing:

Mount Securely

Attach junction boxes securely to framing using provided mounting brackets and screws. Use box extenders as needed.

Leave Extra Length

Keep at least 6 inches of extra wire in the box to allow for modifications down the road.

Strip Properly

Strip sheathing back between 3/8” to 1/2” using sharp wire strippers. Avoid nicking copper.

Make Tight Connections

Use twist-on wire connectors and tightly twist copper ends together for secure connections.

Close It Up

Close junction box covers securely once done to protect connections. Use cable clamps to anchor wire jackets.

Common Electrical Wiring Projects

Now that we’ve covered the core technique for feeding wires through walls, here are some of the most common wiring projects this applies to:

Adding Outlets and Switches

This is one of the most frequent uses of in-wall wiring – adding new outlets and light switches to existing rooms and areas.

Circuit Extensions

Need to tie new outlets and fixtures into existing circuits? Circuit extensions involve safely tapping into the existing wires and extending the branch circuit.

Kitchen & Bathroom Remodels

Kitchen and bath remodels often involve rerouting electrical to new appliance and fixture locations requiring new wiring runs.

Whole House Rewiring

Full rewiring jobs entail running all new wires for outlets, switches and lighting from the main panel throughout the home.

Electrical Service Panel Upgrades

Upgrading the main service panel to add more circuit breaker capacity often necessitates re-running feeder wires.

Adding Ceiling Fixtures

Installing new light fixtures, chandeliers and ceiling fans will likely require snaking wires through attics and ceiling cavities.

Smart Home Retrofitting

Retrofitting homes for smart tech requires running low-voltage communication cables through walls back to a smart hub.

FAQs About Running Wires Through Walls

Some common questions that come up around wiring through walls include:

Does New Wiring Need to Be Grounded?

Yes, for safety any new wiring run for outlets and lighting must include a grounding conductor, usually a bare copper wire.

Can I Use an Extension Cord Instead of Running Wire?

Extension cords are not meant for permanent installation – it’s always better and safer to run real wiring inside of walls.

What if I Encounter Asbestos During Wiring?

Stop work immediately and call an asbestos abatement specialist if you suspect exposed asbestos. Do not disturb it.

Do I Need to Get My Wiring Work Inspected?

In most areas, any major electrical work requires a permit and inspection by the local building department to ensure code compliance.

Can I Cut Holes in Floor Joists When Running Wires?

No, you should always drill holes for wiring at least 1.5″ from edges of joists – never cut notches that weaken them structurally.

Is There a Maximum Number of Wires Allowed in a Box?

Yes, junction boxes are rated for a certain capacity – crowding too many wires can overfill them, creating a hazard.

Conclusion

While running new wires and cables through walls takes planning and care, these tips will set you up for success on your next electrical project. Always exercise caution when working with electrical systems and call in a professional electrician if at any point you feel unsure or uncomfortable. Follow proper safety procedures, take your time, and soon you’ll find in-wall wiring jobs to be very manageable for an ambitious do-it-yourselfer. Just be sure to acquire any necessary permits and arrange for final inspections once complete.

How to Run Electrical Wire Through Walls