WiremanWireman · Old 2-prong outlets: safe upgrade options: troubleshooting for electricians · 2023 NEC ·
Old 2-prong outlets: safe upgrade options
Add a real ground, use GFCI protection with labels, or replace with a 2-prong. Never a bootleg ground.
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How it works
Two-prong receptacles come from wiring with no equipment grounding conductor, so there’s no low-resistance path to carry fault current and trip the breaker if a metal case becomes energized. You can’t create a ground by jumpering neutral to the ground screw. When a 2-prong receptacle is replaced, the code allows a few paths: connect to a real grounding conductor, use GFCI protection with the right labels, or install another non-grounding receptacle.
Every question and answer in this guide. Tap “Step by step” to walk through it.
- With the breaker off, pull the receptacle out. What wiring do you see?
- Metal box with metal conduit or armored cableTest: Measure hot to the metal boxExpect: About 120 V if the box has a ground path.
- About 120 VTest: Confirm a solid ground pathExpect: A low, steady reading, a few ohms or less.
- Low and steadyThe box is grounded through the raceway
- High, open or jumps aroundCan a grounding conductor be run to this box?
- YesAdd a grounding conductor
- No, not practicalWhich option fits?
- A GFCI receptacle at this spotUse a GFCI receptacle without a ground
- A GFCI breaker or first receptacle protecting the runGFCI protection for the whole run
- Put back a 2-prong receptacleReplace with a non-grounding receptacle
- 0 V or a few voltsCan a grounding conductor be run to this box?
- YesAdd a grounding conductor
- No, not practicalWhich option fits?
- A GFCI receptacle at this spotUse a GFCI receptacle without a ground
- A GFCI breaker or first receptacle protecting the runGFCI protection for the whole run
- Put back a 2-prong receptacleReplace with a non-grounding receptacle
- About 120 VTest: Confirm a solid ground pathExpect: A low, steady reading, a few ohms or less.
- Two-wire cable, no ground wireCan a grounding conductor be run to this box?
- YesAdd a grounding conductor
- No, not practicalWhich option fits?
- A GFCI receptacle at this spotUse a GFCI receptacle without a ground
- A GFCI breaker or first receptacle protecting the runGFCI protection for the whole run
- Put back a 2-prong receptacleReplace with a non-grounding receptacle
- Single wires on porcelain knobs or tubesKnob and tube wiring
- Metal box with metal conduit or armored cableTest: Measure hot to the metal boxExpect: About 120 V if the box has a ground path.