Originally Posted By: jhorton This post was automatically imported from our archived forum.
I recently bought a Greenlee voltage checker. One of the pens you put near a wire and it flashes and beeps at you. Found it EXTREMELY handy wiring my new home.
Used if today and got a couple of hits that concern me. First I was checking outlets and for no reason put the meter up to a light switch that worked. It went off. It had a decorative metal face plate so that concerned me. I checked further and noticed it went off all up and down the wall in large area. Much to large for it to be an electric wire in the wall. After some digging I found a metal return air duct was behind the wall. I then started checking all the metal vents and ductwork in the attic. It all checked hot. The only thing that didn't show voltage was the return air grill.
My question is could there be static voltage present that would cause it to read? I know wiring 3 way switches you have enough induced voltage on wires that are not connected to show up as hot with this tool.
I had a regularmeter but I couldn't find a ground within reach of of my leads and I was not about to remove any covers at that point to access a ground wire. (I am going to buy some longer leads)
Then in the basement I had the same thing happen on the fuse panel. The box itself appeared to hot. Having used this meter in my house I am building and playing with it I know my panel will not trigger it unless you are right on top of a breaker and then only near the switch.
This leaves me wondering about this Voltage Checker. I played it safe and will just disclaim these areas. But if the meter is not right then I need to know! Anyone else run into anything like this?
-- Jeff <*\\><
The man who tells the truth doesn't have to remember what he said.
Originally Posted By: Bob Badger This post was automatically imported from our archived forum.
Jeff I would look to see the voltage range on your non contact voltage checker.
You may have bought yourself a voltage checker with a very low threshold which makes them IMO to sensitive for line volt use.
I have a Fluke with a 90 volt minimum voltage to operate.
This is much less likely to show voltage around a switch.
That aside I could not feel comfortable leaving this house with out getting a more definite answer, if this stuff was live obviously it needs fixing.
Your in a tough spot, tell them to get a sparky and it turns out your checker was wrong. , don't tell them, and your checker was right.
Originally Posted By: jhorton This post was automatically imported from our archived forum.
It’s supposed to check down to 50 volts. I checked some 12-4 wiring in the house that it tripped on. There was 48-49 volts that showed on my meter. It was induced voltage as the wires were not connected to anything yet but the common was hot.
I warned the lady living in the house of what I found. I wish I had had a better way to check it because it really made me nervous. But as I said, I didn't have long enough leads with me and I wasn't about to touch that unit or the panel after that. Will stress to the new owner that needs to be checked immediately.
-- Jeff <*\\><
The man who tells the truth doesn't have to remember what he said.
Originally Posted By: jpeck This post was automatically imported from our archived forum.
Jeff,
Sounds like you found some things which were not grounded.
The metal switch plate cover needs to be grounded (required for safety), if not grounded, it could easily pick up the induced voltage from within the switch and set off the voltage detector. Had the metal cover been grounded, that would have grounded out the static voltage signal.
Same for the electrical panel. May not have actually been grounded.
The metal a/c and heating duct could have a piece of NM cable laying on it for enough of a distance to induce the 'phantom' voltage described by Joe T. not long ago on another thread.
The metal duct work would normally be grounded by virtue of being connected to a grounded air handler / furnace, however, there may have been a vibration isolator section installed (should be in many cases with metal duct) between the air handler / furnace and the metal duct, that would break the ground to the metal duct from the air handler / furnace.
Originally Posted By: jhorton This post was automatically imported from our archived forum.
Ah Haaa! This is an old house, built in 1949 and it is a two wire system! No grounds make perfect sense!
I had all the clues but just didn't put it together. Will tell the owner that and still suggest an Sparky just in case. But now that makes sense!
Well on second thought......
It was only one switch plate. But the duct work was behind it. So it might be from a short in the HVAC unit afterall. Well I will try to find out what they find out. Always something to learn.!
-- Jeff <*\\><
The man who tells the truth doesn't have to remember what he said.
Originally Posted By: rray This post was automatically imported from our archived forum.
I had a whole house whose walls and ceilings were reacting to my voltage tester. Even the door knobs were conducting electricity, but only when they were touching the walls.
It was vacant at the time, so I had the opportunity to really look aruond.
When I got to the attic, I found roof leaks everywhere, wet blown-in cotton insulation, and live electric wires laying on the insulation right there at the attic access. Didn't go no further.
When I followed up with my Client later, specifically to ask about the electrical problem, he told me that the combination of roof leak, wet insulation, and live electric wires were causing the metal in the plaster walls to conduct electricity throughout the house. Fixing the roof, replacing the insulation, and terminating the live wire properly corrected the problem. That was a first for me.
Originally Posted By: dspencer This post was automatically imported from our archived forum.
On this subject I just did a test on a wire that ran my test pen crazy, until I touched the ground wire… then it goes completely off. I meter bulb tested it and no power. So what is tripping my pen. I bought a new one and retested and same results until I removed the ground from the panel box or touched the ground would my pen stop.
My pen says it reads as low as 50volts... This house is mixed with knob-tube wiring...