Why Do I Have Lower Voltage Readings?
Ed in Kansas asks; Why is there only 48volts between the neutral and ground on an electric outlet? How to Identify the Cause of a Low Voltage Condition of an Outlet.
Low Voltage on an Outlet
Electrical Question: Why is there 48volts between the neutral and ground on an electric outlet?
- While re-tiling our kitchen, I pulled all outlets away from their boxes in order to tile right up to the box. On one outlet I noticed a dim led in my circuit tester on the ground side.
- I put a voltmeter on it and noted that there is about 48volts neutral to ground. Hot to Neutral is 120volt, but the Hot to ground is about 60volts as well.
- None of the other outlets on this circuit have this problem.
- This outlet has been working, but I am not convinced it is OK now that I have discovered this anomaly.
- I also swapped the circuit breaker with another and the problem remains, so it is not the circuit breaker.
- I was thinking of replacing this outlet with a GFCI outlet, but my guess is that it would continually trip. What do you think is the problem?
Additional Comments: Good job!
Background: Ed, a Homeowner from Prairie Village, Kansas.
Thanks for your Electrical Repair Question Ed.
Low Voltage Readings at an Electrical Outlet
Application: Troubleshooting a Low Volt Problem with an Outlet Circuit.
Skill Level: Advanced. This electrical wiring project is best performed by a Licensed Electrical Contractor or Certified Electrician.
Tools Required: Basic Electricians Pouch Hand Tools, Voltage Tester or Volt Ohm Meter.
Estimated Time: Depends on the type and age of the electrical wiring and the access to the circuits and wiring to be evaluated.
Precaution: This is a project that should be performed by a Licensed Electrical Contractor and typically requires specific tests of the electrical circuits.
Notice: Repairs to Home Electrical Wiring should be done according to local and national electrical codes and installing new or replacement electrical parts or equipment may require a permit and inspections.
How to Identify the Cause of a Low Voltage Condition of an Outlet
Check the Circuit Ground Wire Bond at the Panel
A low voltage condition such as this is typically an indication that the circuit ground wire may not be properly bonded at the panel, or the ground wire may not be attached or properly spliced at a connection point within the circuit.
Check the Ground Wire within the Circuit
If the ground wire is properly bonded at the panel location then additional tests should be performed.
NOTE: A low voltage condition such as this is may be caused by a fault with the neutral wire. The process explained below will help to identify the location of the faulty wire or a connection is causing the low voltage condition. Voltage tests are made at each outlet that is on the same circuit as the affected outlet.
The following is an example of a method used to identify a low voltage problem on an outlet:
- Check for loose or faulty wiring connections at the power source before the outlet with low voltage.
- Use a good quality non-digital meter that will not produce inductive readings. The test leads should be placed on the circuit wire, not the outlet.
- Take voltage readings at all of the outlets that are on the same circuit.
Electrical Tests and Observations
- If you get 120 volt readings on the tester between the hot-to-ground you will need to shut off the circuit and make a continuity test for each wire leading from each outlet that is connected to the problem outlet.
- Pay special attention to the test readings of the ground wire, and look for loss of continuity, which will indicate a problem with the wire, or a faulty connection or splice.
- The continuity test is best accomplished using a spare insulated wire that is attached to one wire at a time at the problem outlet enabling a loop back test to the source outlet where the tester is located.
- Note: Your checking for Continuity with the circuit power Off. A full continuity reading with no resistance for each wire will indicate a normal condition. Keep in mind that a continuity test is a low-voltage test and the circuit may act differently when 110 to 120 volts is restored. If there is a problem between two locations then you may have a damaged cable inside the wall.
- Damaged cable occurs during the nailing process of framing, cabinet installation, or drywall installation.
- If you get 60v (or 0v) hot-to-ground, your problem is located before the outlet and you may have a broken ground from the power source to the affected outlet.
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