Stray voltage from float switch...

[a_kraker99]

A couple of my fish have looked a little stressed the past day and I read somewhere to check from stray voltage. I had some trouble figuring it out at first because I was using the AC setting on my voltmeter which was reading around 20-40 volts even with everything unplugged.

I decided to give DC a try and I got 0 volts. Started plugging things in 1 by 1 until I plugged my ATO float switch in. 12V DC 200 mA. I got a reading of about 10 volts in the tank. I can't figure out why it is leaking voltage. Maybe salt got into to switch itself? Or do these switches leak voltage from day 1? It is one of these. LINK (http://www.ebay.com/itm/New-Liquid-Water-Level-Sensor-Horizontal-Float-Switch-/250857517423?pt=LH_DefaultDomain_0&hash=item3a6845f16f)

[staindsoul]

edit: thought you were saying your meter setting was at 12vdc. but your ato, is 12vdc at 200ma. sounds like you have a bad float switch. replace it.

the 20-40vac is nothing but potential voltage. its the difference between the grounding conductor and that tank.

this may help. http://www.reefcentral.com/forums/showthread.php?t=2219254

[a_kraker99]

Thanks for the info. I guess I will try a different brand of float switch this time. Not sure why it went bad.
Is 12v at 200mA enough to harm livestock just out of curiosity? I am hoping maybe it is the reason I cant get my Frogspawn to grow. lol

[staindsoul]

Any current would be harmful. But just to verify you tested properly, where were theleads placed when you were testing for dc voltage?

You could also put the float switch in a container of water and do a continuity or ohm test to verify it does have a failure. Set your meter to ohm or ringing continuity. Place one lead in the water and one lead both wires, one at a time.

[a_kraker99]

I put the red lead in the tank water and black to an outlet ground. Also tested it in a separate container of water.
I got probably the cheapest piece of crap meter you have ever seen. it has AC and DC voltage, K ohms, something that looks like this " ->|- Check" (what is that?) and a continuity test. The continuity test only rings when I touch two ends of a good conductor like copper wire. I can't even put the 2 leads in water and have them ring. Not sure if that is normal or not.

[staindsoul]

That symbol is a capacitor test.

I don't think it is bad, now. You wouldn't want to use the receptacle ground for testing that vdc circuit. I haven't messed with a Ato yet. Can you get a meter lead on the terminals for the float switch of the Ato? For testing purposes. Or is it a plug style that you can't access?

Ideally to test that, you would want the float wired, the Ato on, one lead in the sump by the float, the other on the terminal with the wire on the Ato. Trying both positive and negative.

The 10vdc reading between the receptacle ground and tank wouldn't be a good reading. There is probably no current there. And You can't do a current reading with the meter options you listed.

[a_kraker99]

yes, I can access them. They are in a box with a relay that activates the ato pump. Do you have a different way I can test it then?

If I got a multimeter that can measure current can I test it that way?

[a_kraker99]

So are you saying that I can read DC voltage without there being any actual current just like you mentioned with the AC voltage? Electricity is confusing!

[staindsoul]

Ideally to test that, you would want the float wired, the Ato on, one lead in the sump by the float, the other on the terminal with the wire on the Ato. Trying both positive and negative.

Try it that way. I doubt you have any stray voltage from that.

[staindsoul]

So are you saying that I can read DC voltage without there being any actual current just like you mentioned with the AC voltage? Electricity is confusing!

Yes a meter is reading the voltage that is a potential circuit between the tank qnd grounding conductor. There can be a voltage potential with no current or circuit there. Think of a squirrel running on a high voltage wire. He is good till he touches a grounding conductor.

You don't need to be concerned with a voltage reading on vac unless it is nearing 105 volts or you have proper grounding probe installed then there is a problem. But that is a whole another story.

[a_kraker99]

So I had a spot where my ato wiring was worn and exposed a little but it is out of the water. I rewired it and now my stray voltage reading is 4 volts.

I wanted to see if there was current so I took a little 12v tester light, put the alligator clip on the ground and the probe in the water. It did not light up but I assume 4 volts probably isn't enough to light one of those anyway.

[a_kraker99]

okay, nevermind there was definitely current going into the tank. I think the lower voltage reading was due to things drying out a little bit. I dipped it back into the water and it spiked back up to 14 volts. I felt a slight tingle on my finger and confirmed it with the test light.

[staindsoul]

Pitch it and find a new one.

Do you run a gfi? It wouldn't have helped with the vdc, but it is a must.

[a_kraker99]

I am ordering a new one. I had 2 for insurance in case the other one hung up or something. For now I just put the bad one up on the mount higher so it doesn't touch the water but still protects from a complete overflow. I don't understand how one of those can fail. Everything is sealed well and it is plastic. Where would the voltage come from?