House wiring problem

Sometimes the simplest tools are the best, like the good old Wiggy.

That is the difference between using a Digital Multimeter that can be safely used to determine the presence of line voltage on electrical wires namely a "low impedance" multimeter and the incorrect use of a high impedance multimeter which will incorrectly read "voltage" because of the capacitance effect being amplified by the length of the wiring in the circuit being measured...

Most cheap digital multimeters are intended to be used on small electronic circuits and circuit boards and not for use on testing long wiring runs like you would see in houses (feet compared to less than an inch/es on a circuit board)...

Since you don't do wikipedia (not even to use the referenced source materials for background verification of the articles) here is a reference:

On 4/2/2010 10:50 PM Evan spake thus:

Then explain why my cheap DMM gave *perfectly accurate readings* on my long wiring runs. I'm listening.

The 3 lite tester uses a lot higher current than a digital meter so it shouldn't show phantom voltage.

But it has its own problems. In particular, it can't test for sure there is a good ground. As with a digital meter, you should know the limitations of test equipment.

Are you absolutely sure it is 59.4V and not 59.4 millivolts?

Yes, I am absolutely certain. My Fluke makes it unmistakably plain.

Dave

Yes, *Please explain.* Otherwise you are just wasting all our time (and especially mine.)

Dave

So far, you seem to have one bad outlet, but only one. I'd fix it.

My own house was built only a year or two before the OP's ('48 or '49) and there isn't a ground to be seen except in the basement where BX was used.

nate

We had an Emerson radio with a plasstic case that was chipped, so the metal chassis on the bottom touched the metal table that the radio was on. The table touched the metal edging around the formica kitchen counter, and touching that anywhere along the 10 feet of it gave a small tingle. Wouldn't have happened these days.

But otoh, it made me strong. The electricity stimulated the growth of dendrites and chest hair, so now I'm the man I am.

I actually don't think it was a big problem, but otoh, for new construction all theese changes have cost very little.

In fact as the problem was described here, I think you only have to take the receptacle out and change the way the wires are connected. Or put a two slot receptacle back in.

Even if you have to do the whole house, how hard could that be?

If anything, a cheap digital VOM may be less likely to show a stray voltage. It isn't actually a case of misbehaving or misreading. The issue is digital VOMs have very high input impedances and hence present virually no load to the circuit being measured. In other words, they are taking a true measurement and NOT disturbing the circuit. The older analog VOMs had lower input impedances. And I wouldn't be surprised if some of the cheap $10 digital ones do too.

Still, I have to agree with David that the incidence of this occuring may be over reported. I have an excellent Fluke VOM and can't say I've seen this to be much of a problem. I would suspect that in at least some cases, something other than just having a true unconnected, floating wire picking up induced voltage is going on. Which is to say, somehow, somewhere, that wire is connected through some high resistance to some other live circuit.

It was not the floating ground directly that caused the problem. It was his total ignoring the general electrical flaws, many of wich he personally wired that was the most likely cause of the fire.

As a person and a boss, I greatly respected him. But he just did not understand mechanical things. He could pick up a first communion photo and name all the kids in the 30 year old photo.

I mixed photo chemicals to save a few pennies, but he would rip up any photo that could or should be better. He treated his employees and customers like family.

If I have to look up something on Wikipedia, it's likely that the pimply-faced 7th grader who wrote the article knows far more about the subject than I.

It all depends on how the wires are terminated. If one is solidly grounded and the other has no connection at all you have an antenna and a high impedance meter will register voltage. The amount of voltage will depend on how well the wire gets coupled to the fields around the house. Cheap really has nothing to do with it. Our $300 Fluke meters had the same problem. Guys who were used to the Tripplets we had called them "random number generators".

I do have to do the whole house. Every plug is this way. And, the AC compressor that uses 240? It's on *three different breakers*. If any of them are on, it comes on when called upon. I'm thinking that the problem must be in the service entrance, or the whole house wouldn't be bass-ackwards with 59 VAC between every slot and the GND terminal (which is not connected to anything.) I am thinking the person who said this was the same thing you woud see with an PC that had an RF filter and no ground knew what they were talking about. Wish I did. I can almost wrap my mind around everything but the three breakers for the AC. And no, I am not making this up. Whoever wired this house, or rewired it, had to have been either stupid, crazy or on drugs (pick two out of three.)

Dave (who is not happy right now.)

Yes, it can. Let's say there is a ground wire connected at the outlet but disconnected at the other end of a long piece of romex. There is a small amount of capacitance between that disconnected ground and hot as well a the same amount of capacitance between that ground and neutral. That would effectively create a voltage divider and show 50% of the voltage on the ground wire.

Hi, Proving whether it is real voltage is simpe, just hook up a light bulb. If it lights up it is real voltage if not, it is nothing.

On 4/3/2010 5:45 AM snipped-for-privacy@aol.com spake thus:

Well, OK, but I cannot believe that a DMM is going to pick up a false reading of *59 volts*. 59 millivolts, sure, but the OP insists that his meter is telling him there's 59 volts between each of hot & neutral and ground. This cannot be due to stray induced voltage.