Ungrounded outlet fix cost

Fixing an ungrounded outlet costs $150 to $600 per location, typically around $250. The cheapest legitimate route is a GFCI outlet with a label, at $150 to $400. Actually running a ground wire is $200 to $600 per location. Rewiring the circuit is $800 to $2,500.

An ungrounded outlet is the two-prong kind, or a three-prong one somebody swapped in without a ground behind it. The second is far more dangerous than the first, because it looks safe.

What it costs

The three legitimate options

A GFCI outlet, labeled. Code explicitly permits replacing an ungrounded two-prong outlet with a GFCI outlet, marked "No Equipment Ground". It protects people from shock, which is the main risk, and it protects every ordinary outlet downstream of it on the same circuit if those are labeled too.

It does not provide a ground. Surge protectors need one to work, some electronics specify one, and a few appliances will not be happy.

Running a ground. A separate ground conductor can be run from the outlet back to the panel or to the grounding electrode system. It gives a real ground and it costs $200 to $600 a location, mostly in access.

Rewiring the circuit. The complete answer, and the one that also replaces sixty-year-old insulation.

The one thing not to do

Do not fit a three-prong outlet to an ungrounded box and connect nothing to the ground screw. Do not use a cheater adapter with the tab under the cover screw unless the box is genuinely grounded.

Both create an outlet that looks grounded and is not. Anyone who plugs in a surge protector sees the green light and believes their equipment is protected. Anyone touching a faulty appliance gets the shock the ground was meant to divert.

A $10 outlet tester tells you in three seconds which outlets in a house are actually grounded, and in a house from before about 1965 the answer is often surprising.

What to check for in an older house

Two-prong outlets anywhere. Normal in pre-1965 wiring and a legitimate thing to address room by room.

Three-prong outlets in an old house that test ungrounded. Someone has already done the wrong thing. This is the priority.

Knob and tube wiring, visible in a basement or attic as individual insulated conductors run through ceramic knobs and tubes. It is ungrounded by design, it is usually 90 years old, insurers increasingly refuse to cover it, and it is a rewire conversation rather than an outlet one.

Aluminum branch wiring, in houses built roughly 1965 to 1973. Different problem, also serious, and the fix is copper pigtails with approved connectors at every device at $2,000 to $8,000.

Reversed polarity, where line and neutral are swapped. Common, cheap to fix, and the tester finds it.

Where to prioritize

If the budget is limited, do them in this order:

1. Any three-prong outlet that tests ungrounded, because it is actively misleading.
2. Kitchen, bathroom, laundry, garage, basement and outdoors, where water and people meet electricity.
3. Wherever a surge protector is plugged in, since it is doing nothing without a ground.
4. Wherever a metal-bodied appliance is used.
5. Everywhere else, over time or during a rewire.

Frequently asked questions

Is a two-prong outlet actually dangerous?

Less than it looks. Two-prong appliances are designed for it and are usually double-insulated. The real risks are three-prong equipment used with an adapter, and outlets someone has already converted without a ground.

Will a GFCI outlet protect my computer?

It protects you, not the equipment. A surge protector needs a real ground to divert a surge to. On a GFCI-protected ungrounded circuit, a surge protector's protection indicator will typically show that it is not grounded, which is worth looking at.

Does a house need rewiring just because it is ungrounded?

No. Ungrounded wiring in good condition, GFCI protected, is code-compliant and safe for people. Rewiring becomes the answer when the insulation is deteriorating, when there are too few circuits for how the house is used, or when it is knob and tube.

How do I know if my outlets are grounded?

A $10 three-light outlet tester, plugged into each one. It shows grounded, ungrounded, reversed polarity and open neutral. It is the single most useful ten dollars a homeowner of an older house can spend.

Will an inspector flag this when I sell?

Ungrounded two-prong outlets are usually noted and rarely required to be fixed. Three-prong outlets that test ungrounded are almost always written up, and often negotiated on.