Electrical wiring - Converting 220 to 110

[JSorrell]

I have a 220 20 amp circuit feed for a hot water heater. It was old and way over sized for just bathroom sink use.
I just down sized it to a 2.5 gal unit which needs a 110 15amp circuit. When I installed a 110 duplex receptacle, the 220 line was 10 awg w/ 1 white, 1 black and gnd.
I installed the new single slot 110 15 amp Square D breaker where the double slot 20 amp breaker was. I used only one of the two black wires from the old breaker on the new 110 CB.
When I looked at the voltages I am puzzled. I read 100 vac between hot and neutral receptacle slot contacts. I see 19 vac between neutral and gnd and 120 between hot and gnd.
How do I correct this?
BTW: I tried using the other black wire (110 leg?) which was installed on old 220 20 amp CB and got the same reading.
Thanks in advance for your help.
Jay

[Rewired]

quote:Originally posted by JSorrell

I have a 220 20 amp circuit feed for a hot water heater. It was old and way over sized for just bathroom sink use.
I just down sized it to a 2.5 gal unit which needs a 110 15amp circuit. When I installed a 110 duplex receptacle, the 220 line was 10 awg w/ 1 white, 1 black and gnd.
I installed the new single slot 110 15 amp Square D breaker where the double slot 20 amp breaker was. I used only one of the two black wires from the old breaker on the new 110 CB.
When I looked at the voltages I am puzzled. I read 100 vac between hot and neutral receptacle slot contacts. I see 19 vac between neutral and gnd and 120 between hot and gnd.
How do I correct this?
BTW: I tried using the other black wire (110 leg?) which was installed on old 220 20 amp CB and got the same reading.
Thanks in advance for your help.
Jay

Jay,
First thing, you say at the receptacle you have 1 white, one black and the ground, but at the panel you have 2 blacks?
Is by chance, one of the black wires that went to the double pole breaker a white wire that was taped or painted black? If so that wire MUST be attached to the neutral buss in the panel (from the voltages you are getting it almost sounds like the neutral is not connected to anything at the panel). If you find one of the wires has been taped or painted black, it would not be such a bad idea to take all the tape off or somehow identify the wire as a "white" again.. Hope this helps a bit!

A.D