Why do some outlets in my house work but have no ground when I test them with a plug tester?

Your outlets are showing no ground because the circuits feeding them were wired without a ground conductor — this is extremely common in GTA homes built before the mid-1960s, and it's a safety issue worth understanding and addressing properly.

Most plug-in outlet testers have three indicator lights that tell you the wiring condition. When the tester shows "open ground" or "no ground," it means the outlet has hot and neutral conductors connected correctly, but the third wire — the bare copper or green ground wire — is either absent entirely or not connected. The outlet functions for powering devices, but it offers no fault protection. If a wiring fault develops inside an appliance and sends current down the ground path, there's nowhere for that fault current to go safely. Instead, it can travel through you, through metal plumbing, or cause a fire.

Why this is so common in Toronto homes

Two-wire ungrounded wiring (hot and neutral only, no ground) was standard practice in Ontario residential construction through the 1950s and into the early 1960s. In established Toronto neighbourhoods — the Annex, Riverdale, High Park, Leslieville, Cabbagetown, and much of Scarborough and Etobicoke's post-war housing stock — two-wire circuits are the norm rather than the exception. Knob-and-tube wiring, which runs through many pre-war homes, has no ground wire at all by design. Even aluminum-wired homes from the late 1960s and early 1970s often have incomplete grounding on some circuits.

You may find that some outlets in your home test correctly grounded while others don't. This is typical — many homes have had partial upgrades over the decades, where a kitchen or bathroom was rewired but bedrooms and living areas were left on the original two-wire circuits.

What your options are

There are three code-accepted approaches under the Ontario Electrical Safety Code for dealing with ungrounded outlets:

The first is full circuit rewiring — running new 14/2 or 12/2 NMD90 cable with a proper ground conductor from the panel to every outlet on the circuit. This is the most thorough fix and the only one that provides a true equipment ground. It's also the most disruptive and expensive, typically $300–$800 per circuit depending on run length and wall access.

The second is GFCI protection. A licensed electrician can replace the first outlet on an ungrounded circuit with a GFCI outlet, then feed the remaining outlets downstream from the GFCI's "load" terminals. This gives all those outlets GFCI fault protection, and they can be labelled "GFCI Protected / No Equipment Ground" per code. This is permitted under the OESC and is far less expensive than rewiring — typically $200–$350 per GFCI outlet installed. It does not provide a true equipment ground, so sensitive electronics and computers are better served by a properly grounded circuit.

The third option is GFCI breaker protection — replacing the breaker feeding the circuit with a GFCI breaker, which protects every outlet on that circuit. Cost is roughly $150–$250 for the breaker plus labour.

What you should not do is install three-prong outlets on two-wire circuits without one of the above protections in place. A three-prong outlet on an ungrounded circuit looks correct to a plug-in tester if someone has incorrectly bonded the ground and neutral terminals — a dangerous and code-violating practice that creates shock and fire risk.

Practical next steps

Have a licensed electrician assess your panel and circuits to map out which circuits are grounded and which aren't. If your home has knob-and-tube wiring, this conversation will also touch on insurance — many Ontario insurers now require K&T removal as a condition of coverage, and an assessment will clarify the scope of work involved. ESA permits are required for any new circuit wiring or panel work.

Toronto Electrical Repair can match you with a licensed electrician in your area for a free estimate — find local electrical professionals through the Toronto Construction Network directory at torontoconstructionnetwork.com/directory?trade=electrical.