Can You Run Electrical Wire and Ethernet in the Same Hole?

When wiring a home office, media room, or smart-home retrofit in a Toronto or GTA home, homeowners often want to fish ethernet cable through the same holes and stud bays as existing electrical wiring. The temptation makes sense — the holes are already there. The code and performance implications are more nuanced. This guide covers when ethernet and electrical can share a path, when they cannot, and what to do to keep both working reliably.

Can you run electrical wire and ethernet in the same hole?

You should not run ethernet and 120V electrical cable through the same drilled hole in a stud or joist, and you should not run them in the same conduit. Best-practice separation is at least 200 mm (about 8 inches) between parallel low-voltage and line-voltage runs to avoid electromagnetic interference. Brief 90-degree crossings are usually fine. The Ontario Electrical Safety Code and the underlying Canadian Electrical Code separate low-voltage communications wiring from line-voltage systems in specific ways — pushing them through the same hole together violates both mechanical protection and separation rules.

Why separation matters

• Electromagnetic interference (EMI). 60 Hz alternating current induces a signal on nearby data cables. At speeds above 100 Mbps (any modern Cat5e/6/6a/7), EMI causes retransmissions, packet loss, and reduced throughput.
• Insulation safety. Low-voltage cable jackets are not always rated to withstand contact with damaged line-voltage insulation. In a fault scenario, a damaged 120V conductor could energize the ethernet run and its connected equipment.
• Mechanical damage. Sharing a stud bore concentrates the cables and increases friction, chafing, and the risk that a nail or screw driven through the wall will damage both.
• Inspection and code. The OESC requires certain separations and mechanical protection for both cable types. Bundled runs raise inspector attention.

What the code actually requires

• Different conduit or raceway. Line-voltage and low-voltage systems cannot share the same conduit, junction box, or raceway in most residential installations.
• Separation of parallel runs. Best practice: keep parallel runs at least 200 mm apart. Some references allow shorter separations if the electrical cable is in metallic conduit that shields EMI.
• Different bore holes through framing. Drill separate holes for line and low voltage.
• Perpendicular crossings. Brief 90-degree crossings between a line-voltage cable and a low-voltage cable are generally acceptable and do not require distance if crossings are short.
• Different device boxes. Data outlets and receptacles share a wall plate only with proper divider partitions inside the box (“low-voltage plaster ring” or divided device box), never bare in the same box cavity.

Real-world routing patterns that work

• Drill a second bore in the same stud, offset vertically by 200 mm. Cleanest approach for parallel runs in the same wall.
• Route ethernet through a separate joist bay. If accessible from an unfinished basement or attic, easy to keep them apart.
• Use a low-voltage plaster ring at data outlets. Combined with a proper power outlet in the same wall gang plate (with a divider) is acceptable.
• Bundle ethernet with other low-voltage runs (HDMI extender cabling, security, coax) and keep the whole bundle away from electrical.
• Cross line voltage perpendicularly where required to reach a room, rather than running parallel.

Common wrong patterns we see

• Ethernet fished through the same stud bore as an existing 14/2 cable.
• Ethernet stapled tightly along a 14/2 run through a joist bay.
• Data drops installed in the same undivided device box as a receptacle.
• Cat5e run through a live electrical junction box for convenience.
• Ethernet in the same PVC conduit as a 240V feeder.
• Ethernet across a fluorescent ballast or motor equipment without separation.

None of these will typically start a fire, but all will degrade network performance and most will attract inspector attention.

Performance impact you may actually notice

• Gigabit speeds dropping to 100 Mbps automatic negotiation on the affected switch port.
• Voice-over-IP call quality issues.
• Streaming video buffering that improves when the coincidentally-shared power circuit is turned off.
• Higher packet retransmission rates visible in network monitoring tools.
• PoE-powered devices (cameras, access points) occasionally rebooting under load.

Cat5e can tolerate more nearby electrical noise than Cat6a; Cat6a can tolerate more than Cat7. Higher-category cabling has tighter twist rates and better shielding, but neither is a licence to ignore separation guidance.

When ethernet-plus-electrical retrofits get complicated

Retrofitting ethernet into a finished GTA home usually means fishing cable through walls that already have electrical in them. Options include:

• Route through unfinished basement ceilings and drop into the wall from below at a fresh bore.
• Route through unfinished attic and drop from above.
• Follow baseboard and cornice mouldings using surface raceway.
• Use MoCA over existing coax if fishing new ethernet is impractical.
• Use mesh Wi-Fi with wired backhaul on the accessible drops as an interim.
• Combine ethernet install with any other renovation opening the walls.

DIY vs licensed contractor

Low-voltage ethernet cabling is generally not subject to the same ESA notification requirements as line-voltage work, and many homeowners run their own ethernet without issue. But if the ethernet install involves anywhere near line-voltage cable, or if new receptacles or power runs are part of the same project, the electrical portion falls under an ESA notification and must be done by an ECRA/ESA-licensed contractor. See when do I need an ESA permit for electrical work.

Expert tip from our ESA-licensed electricians

The single most common home-office network complaint we help track down in the GTA is not a router problem — it is Cat6 that was fished through the same stud bay as a 12/2 kitchen counter circuit ten feet away. The homeowner insists their gigabit connection has never worked reliably; three days of switch-port investigation later, moving the run 30 cm over solves it. If you are planning any new data run in an older home, plan the separation up front. Extra 30 cm of drill work saves hours of network debugging later.

Related reading from ezsmart.ca

• How to Run Electrical Wire Through Finished Walls
• How to Install an Outlet Behind a Wall-Mounted TV
• Can You Splice Wires Outside of a Junction Box?
• What Is the Difference Between Romex, THHN, and UF Wire?
• When Do I Need an ESA Permit for Electrical Work?

Frequently Asked Questions

What separation is recommended between ethernet and power?

At least 200 mm (about 8 inches) parallel separation. Perpendicular crossings are usually acceptable.

Will ethernet next to power still work?

It may, but expect intermittent packet loss, retransmissions, and reduced throughput on high-speed links.

Can data and power share a device box?

Only with a listed divider partition between the low-voltage and line-voltage sections.

Does shielded ethernet cable solve the problem?

Better than unshielded but not a licence to skip separation. Follow the code and manufacturer guidance.

Can I run ethernet in the same conduit as 120V cable?

No. Line-voltage and low-voltage systems cannot share a conduit or raceway in residential installations.

Contact us

Adding ethernet and new power drops to a Toronto or GTA home office? Call ezsmart at 416-838-9006 or use our contact page. An ESA-licensed electrician will coordinate the electrical portion and keep the low-voltage runs cleanly separated.