Mike Dolt Enterprises
Mike Dolt Enterprises
User: mphillipps, Location: Delmarva, USA
Asked on: Saturday, April 16, 2011 at 3:49 pm EDT
Answered on: Tuesday, May 14, 2024 at 4:15 am EDT
Question: I was asked to check if a bedrooms receptacles had proper grounded. My 3 pronged plug in tester showed 2 amber lights indicating the receptacle was wired correctly. I then did a fallow up test checking voltage across hot and neutral. It read ~120 volts. Next, I read across hot and ground. It read 87 volts.I've not seen this before. How can it be explained?
Your observations indicate a potential issue with the grounding system in your bedroom receptacle. Here's an explanation: Grounded Receptacle
A grounded receptacle typically has three prongs: hot, neutral, and ground. The ground prong provides a low-resistance path for electrical current to flow back to the electrical panel, protecting against electrical shocks.
3-Prong Tester
When you tested the receptacle with a three-prong tester, it showed two amber lights. This usually indicates that the receptacle is wired correctly, with a hot wire connected to the brass terminal, a neutral wire to the silver terminal, and a ground wire to the green terminal.
Voltage Tests
However, your subsequent voltage tests revealed unusual results:
Hot to Neutral
Reading ~120 volts is expected, indicating that the circuit is supplying the correct voltage to the receptacle.
Hot to Ground
Reading 87 volts indicates that there is a difference in electrical potential between the hot wire and the ground wire. This suggests that the ground path is not properly established.
Possible Explanation
The discrepancy between the tester and voltage readings suggests that the ground wire in the receptacle may not be properly connected or may have high resistance. When the tester checks the continuity of the ground wire, it may find a weak connection, but when you measure the voltage, the resistance in the ground wire limits the flow of current, resulting in a lower than expected reading.
Implications
A weak or improper ground connection can compromise the safety of the receptacle and increase the risk of electrical shock. If the ground wire is not functioning as intended, it cannot provide a reliable path for fault currents to flow, potentially leading to dangerous situations.
Recommended Actions
Verify Grounding System
Use a multimeter to measure the resistance between the ground prong of the receptacle and the electrical panel. A reading below 1 ohm typically indicates a good ground connection.
Inspect Ground Wire
Check that the ground wire is properly connected to the green terminal in the receptacle box and that there are no loose or damaged wires.
Call an Electrician: If you are not comfortable working with electrical systems, it is recommended to contact a qualified electrician to assess and resolve the ground fault issue. They can ensure that the receptacle is properly grounded and safe to use. Flag for review