24v heading to the lights instead of 12v

[kylewbenson]

Howdy all. I'm hooking up a new water heater and decided to steal the power from the lights on the wall just above the bed. The water heater requires 12v, which is what I was expecting from the lights but instead I'm geting 24v. The light connection is series parallel, so the voltage drop is not being split between the two lights. Is this an issue, or am I missing something? I must admit I'm definitely a novice electrician.

[DKB_SATX]

You should check voltage other places, especially at the fuse panel. The easiest way to get 24v is to have 2 12v batteries wired in series instead of in parallel, or to have something wrong w/ a converter. At the time you measured this were you plugged in and running off the converter? Or just off the batteries?

Inland Andy has mentioned that ancient Univolts were designed to output 12v on some circuits and 19v on the ones that ran fans, and 24v is close enough to 19 for a beat-up ancient Univolt to stray that far from design specs, I guess.

[TG Twinkie]

I would check to see how the batteries (if you have more than one) are connected. If you have 24 volts and turn on a 12 volt light, it would burn out almost immediately.
If you have batteries. Disconnect the shore power, then read the voltage. Make sure your meter is on the DC setting.

[M2HB]

Originally Posted by DKB_SATX

You should check voltage other places, especially at the fuse panel. The easiest way to get 24v is to have 2 12v batteries wired in series instead of in parallel, or to have something wrong w/ a converter. At the time you measured this were you plugged in and running off the converter? Or just off the batteries?

Inland Andy has mentioned that ancient Univolts were designed to output 12v on some circuits and 19v on the ones that ran fans, and 24v is close enough to 19 for a beat-up ancient Univolt to stray that far from design specs, I guess.

I'll bet the batteries are in series, but that is just a guess.

[Wazbro]

I have a cheap meter from Harbor Freight that reads 18V when two other meters both read 12.5V.

[Phoenix]

Agree with M2HB; can't imagine how else to get 24-volts. Need to correct this ASAP, and BEFORE turning any 12 volt devices on, as most will probably be damaged.

[kylewbenson]

These are great ideas. Many of which I had not thought of. Currently, as we've been gradually restoring it, there are no batteries--though I totally would have guessed they were in series as well.

Everything is original, so I'm going to replace that converter and see if that's the issue. Though, the lights, and other 12v-ers seem to be doing just fine. Couldn't hurt to replace a 46 year old converter.

I'll double check and make sure I didn't have the multimeter set to AC.

[DKB_SATX]

Most old converters aren't designed to provide proper voltage without a battery in the circuit, so that may be a big part of the issue. If it's an original converter or something using similar technology, a new converter would be a pretty good use of $130 or so anyway, and that would likely provide a little over 13v whether batteries are installed or not.

[ROBERT CROSS]

Time for a new converter.....Call Randy for the straight scoop.

Bob