Symptoms
- Outlet has two vertical slots and no round grounding hole
- Three-prong plugs won't fit or need an adapter
- Common in homes built before the 1960s
Likely causes
- CommonOriginal ungrounded house wiringMany older homes were wired with two-wire cable that has no ground conductor at all.
- PossibleA grounded circuit with the wrong outlet installedSometimes a ground wire exists in the box but a cheaper two-prong outlet was installed anyway.
- PossibleA metal conduit or armored cable serving as the only ground pathSome older wiring methods used the metal conduit itself for grounding, which an electrician can test for even without a dedicated ground wire.
What to do
- Check a few other outlets in the house to see if two-prong outlets are widespread or just in one area.
- Avoid using cheater adapters (the little three-to-two prong plugs) as a permanent fix, since they don't add real grounding.
- For sensitive electronics or anything with a three-prong plug, consider whether that outlet actually has a ground path available.
- Have an electrician test the outlet box with a circuit tester to see if a ground wire is actually present but unused.
- If a ground is present, the outlet can simply be swapped for a proper three-prong grounded outlet.
- If no ground is present, options include running new grounded wiring, or installing a GFCI outlet labeled 'No Equipment Ground' as code allows in some cases.
- Decide based on cost and what you're plugging in, since surge protectors and many electronics work best with a real ground.
Tools and parts
GFCI outlet for ungrounded circuitsSearch: “GFCI outlet no ground label”
When to call a pro
Call an electrician to test for an existing ground and to install GFCI protection or new grounded wiring where it matters most, like near water or for electronics.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.