Tag: Ghost Voltage

Dear Mr. Electrician: I got some phantom voltage readings between neutral and ground with my digital volt-ohm meter while I was changing an outlet in my house.  What do I do? NOTE: Some text links below go to applicable products on Amazon.  As an Amazon Associate, I earn from qualifying purchases.  Using my links helps to keep this website FREE. Answer: The term “Ghost” or "Phantom” voltage often explains abnormal voltage readings using a digital volt-ohm meter on household wiring.  I do not believe in “Phantom” voltage readings.  I believe the readings are actual voltage in the circuit due to a tiny amount of current leaking to the earth's ground. It is important for safety and for the proper functioning of your home appliances to find out what is causing the voltage leak and correct it. CAUSE OF PHANTOM VOLTAGE This can happen from some appliances such as older electric dryers or electric range circuits that were originally wired with three conductors instead of the now required four. When those circuits were installed, the National Electrical Code permitted using the insulated neutral wire (Also known as the grounded circuit conductor) as the equipment grounding conductor.  However, in many installations, the bare ground wire was used as the neutral instead.  This caused a small amount of current to be added to the grounding conductor.  The neutral was needed for the light inside the appliance and maybe the controls. A three-wire outlet is no longer permitted for new range and dryer installations.  Four conductors are required to pass inspection. Another possible cause of your phantom voltage reading is an electronic switching device such as a wall timer or electronic dimmer.  Many of those devices require a neutral conductor to operate.  However, many existing wall switches do not have a neutral conductor inside the electrical box to connect to.  Consequently, the uninformed installer will connect the ground wire to act as the neutral conductor.  Although this will allow the device to operate correctly, it also creates a hazard by adding voltage to the ground. Some devices were approved to be connected to an equipment grounding conductor under old rules in the National Electrical Code.  They are no longer permitted to be installed this way, and the code has been updated to require a neutral conductor in every switch box when installing new wiring. You can try to identify where the grounding problem is by having someone slowly flip off each circuit breaker one at a time while you monitor the voltage reading with a Category III or IV digital volt-ohm meter.  The voltage reading should change when the culprit is turned off. In our modern society, electronic controls and microprocessors are in just about everything electrically operated.  The electronics require very good quality electricity, which your power company supplies.  However, things inside of your home can cause that electricity to be less than perfect.  Motors are known to cause some issues.  Loose connections and faulty circuit breakers are another cause of power quality issues.  Sometimes, the problems associated with electrical wiring in a...