Unexpeced Voltage

[Anonymous]

There was a post last month regarding an unexpected voltage when a switch is off. I have the same problem on a kitchen light that I just rewired. It used to have two fixtures controlled by two switches. I replaced the two fixtures with one and checked the wiring and found approx. 2 volts on the circuit, even when off. What I thought was strange was that the voltmeter read 20 volts when set to one range and 2 when set to the lower range. I checked it with a circuit tester and it glowed slightly. For some reason it doesn't glow anymore, but it still reads 2 volts.

Question is what do I do? The post talked about "dirty wiring", but it sounded like it was somewhat common? Do I leave it as is and when I get time troubleshoot it? Thank you for your help!

[Wgoodrich]

What I call dirty wiring is very commonly in a home electricians or home owners will wire all the whites [grounded legs aka neutrals and true neutrals] in that box under one wire nut intermixing all the whites in that box with all different branch circuits in that box. This cause a back feed and imbalanced wiring system concerning unbalanced or return path current flow. Kind of like a healthy kid in a school room full of other kids that all have a cold. That healthy kid is being influenced by those around that one kid. Often that one kid comes to school the next day with that same cold.

Branch circuit true neutrals and grounded legs [120 volt white wires aka neutrals] are supposed to retain their integrity to their wiring deisgn only to that one branch circuit.

When intermixing all branch circuits whether 240 volt white true neutrals or 120 volt white grounded legs all connected together intermixes the flow of current between all these branch circuits by back feeds or any other easiest path back to the neutral bar of the panel.

This is an invite to overload a white wire's ampacity or to make a light bulb light dimmly or a hum in a motor that is shut off.

If one branch circuit loses its return path back to the panel then that branch circuit will try to find an alternative path to complete its circuit.

One loose connection hidden within your home somewhere will often create as much as 50 volts on a white wire trying to do the work of another branch circuit's white wire that has a loose connection creating a resistance to that circuits return path back to the panel neutral bar. The white wire that was joined to aht white wire of one branch circuit will not filter back through a white wire that has a path to ground and wire nutted connecting the white wires of two or more branch circuits.

Even though your switch is off you may have current flowing on that white wire you are testing because of the above back feed affect. This mistake is very common in dwelling wiring systems commonly due to level of knowledge and skills of that residential electrician that wired it not knowing he or she was doing wrong.

The only way to properly correct this wire mistake is to start at the panel and follow each branch circuit tracing to each box that branch circuit wiring travels and ensuring no white wire of one branch circuit is mixed with the connection of a second white wire of a second branch ciruict. Then repeat this tracing from the panel to end of circuit on every circuit in your home.

You are not alone. A very high percentage of houses are wire even today with the same mistake being made in wire nutting.

HOpe this helps you understand your quest for an explaination of this ghost voltage on a circuit that is shut off.

Good Luck

Wg