Two-prong outlets are a sign of ungrounded wiring, common in homes built before the 1960s, often with cloth-covered cable. You have safe options short of a full rewire.
Can I just put a 3-prong outlet on an old 2-wire circuit?
Not by itself. A 3-prong outlet with nothing connected to the ground hole looks grounded but is not, which defeats surge protectors and appliance safety features. Home inspectors flag this as "open ground".
What are the code-approved options?
The electrical code allows these replacements for ungrounded outlets:
- Replace with another 2-prong outlet (where you can still find them).
- GFCI protection: a GFCI outlet, or a GFCI breaker for the circuit, lets you use 3-prong outlets on ungrounded wiring. They must be labeled "No Equipment Ground". This adds shock protection, but it does not provide a true ground for surge protectors.
- Add a ground: run an equipment grounding conductor back to the panel or grounding system, then install grounded 3-prong outlets.
- Rewire the circuit with modern grounded cable.
Is cloth wiring dangerous?
Cloth-covered cable from the 1940s to 1960s is not dangerous by itself, but the insulation gets brittle with age and heat, especially at light fixtures and in hot attics. Moving or bending it can crack the insulation. Have it evaluated, especially where you see fraying or plan remodeling.
What does it cost?
IES installs a GFCI outlet for $135, or grounds a 2-prong outlet location with a GFCI for $135. Larger grounding or rewire jobs are quoted from photos or a free estimate.
About these prices: rough starting-at prices from the IES price book. The final price depends on what we find on site, your utility and your city or county. Estimates are free.
Common questions
Can I replace a 2-prong outlet with a GFCI?
Yes. The code allows a GFCI outlet or GFCI breaker to protect ungrounded outlets, marked "No Equipment Ground". It protects people from shock but does not provide a true ground.
Are ungrounded outlets illegal?
Existing ungrounded 2-prong outlets in older homes are generally allowed to remain. Replacements must follow the code options above.
General information for California homes under the California Electrical Code (based on the NEC). Local rules and inspectors can vary. Not a substitute for an on-site inspection. Never work inside a panel, at the meter or on live circuits.