Stray voltage

[cannarella]

Ok I consider myself electrical aware. I know the basics and am not terrified to take on my own wiring projects.

Ok so here is my problem. I have a small bathroom that I built that will hold my sump and stuff. I have a 15A power feed from another room that I built that comes into a GFCI plug. I then wire the hot, neutral, and ground to the 2 switches in the box. One switch goes to a fluorescent light on 14/2 dedicated cable. The other switch goes into the ceiling on 14/3 cable. The black is dedicated hot for a bathroom fan that will be on a humidistat switch and the red is on the switch for some future use. When I was going to install the fan I was checking the power on both the leads and the dedicated power (black) gave me 120V as expected. The switched power (red) when in the off position gives off 25V at the end of the run against the ground and neutral. I thought it was a bad switch so I replaced it with a new one. I checked the new switch with an ohm meter to make sure when in the off position there was no current. So I put everyting back together and I get the same results. Where is this coming from?

When I had the power off to change the switch I checked the continuity across all the wires to see if there may be one that is nicked. Well I got continuity across black-neutral, black-ground, neutral-ground. No continuity across anything to the red when the switch is in the off position. When the switch is in the on position I got continuity across everything. Is this something with the GFCI plug and the way it senses the faults?

I have gone back and checked all my connections and everything is correct and tight. What else can I check?

Andy

 

[Opcn]

It seems to me that if the switch is off then the red wire should be part of no complete circuit, so there should be no voltage to detect, in other less incorrect words, the red wire should test the same when attached to the switch that is off as it does when its not attached to any switch or wire and sitting on the floor.

 

[wrlk67]

If you have the bath fan already hooked up and are checking continuity across the black and white you will read continuity unless you are using a precision ohm meter. They cost about 200-300 dollars. The easier way to check is to disconnect the fan, lightbulb or any thing else that is connected to that circuit. You said that you got the circuit from another room, so you have to disconnect any loads connected in there too! Or you could just discconnect the feed coming into the GFI. As far as wiring goes the 25V is caused by stray currents on the ground wire, not uncommon in older houses and not a problem to your equipment. As for what it will do in the tank I can't help you with.

 

[cannarella]

Well the house is only 7 years old and all this wiring is new from the breaker box. The only place I have not checked is the breaker box. Will do that tomorrow.

Andy

 

[cannarella]

Any electricians out there? I have been doing some searching on stray voltage and have come up with possible induction? I am going to disconnect the hot (black) from the 14-3 wire and see if I still have any voltage on the switched (red)?

Andy

 

[RobinsonFam1]

hey andy, i will call a friend and let you know today ...one of them engineer guys......

BR

 

[cannarella]

Well I went and check some other areas of the house that were wired by the builder where an outlet was devided to one being switched and one being always on like I was wiring. With the switch to the outlet off I was getting 14 volts. I also found some answers on the net saying that this was normal. So I went ahead and wired up the fan and installed it. It works just fine.

Brandon, I would like to hear what you friend says though. I am going to ask are electrician here at work also.

Andy