I am replacing a 20A 250V receptacle with a NEMA 5-20 and am seeing voltages I can't explain.

• Hot-ground: 122v
• Neutral-ground: 20v
• Hot-neutral: 95v

What could be the problem here?

Details

1. Turned off main
2. Removed 2 pole circuit breaker
3. Capped red wire
4. Installed 1 pole breaker and connected black wire
5. Turned on main
6. Remove old receptacle, discover there are only 3 wires - white, black, ground (this receptacle is labeled 20A 250V)
7. Installed NEMA 5-20 receptacle - black to brass, white to silver, ground to green as per instructions.
8. Read above voltages

Where did my red wire go?

I am certain I replaced the correct breaker. No voltage when I turn the breaker off.

The wire appears to be 12 gauge.

I am replacing a 20A 250V receptacle with a NEMA 5-20 and am seeing voltages I can't explain.

• Hot-ground: 122v
• Neutral-ground: 20v
• Hot-neutral: 95v

What could be the problem here?

Details

1. Turned off main
2. Removed 2 pole circuit breaker
3. Capped red wire
4. Installed 1 pole breaker and connected black wire
5. Turned on main
6. Remove old receptacle, discover there are only 3 wires - white, black, ground (this receptacle is labeled 20A 250V)
7. Installed NEMA 5-20 receptacle - black to brass, white to silver, ground to green as per instructions.
8. Read above voltages

Where did my red wire go?

I am certain I replaced the correct breaker. No voltage when I turn the breaker off.

The wire appears to be 12 gauge.

My outlet tester is inconclusive because all three lights appear to be lit.