Every home requires a robust grounding system, but does that include the electric meter?
Grounding is a safety feature that protects people and electrical equipment from harm by giving electrical surges and spikes a path of least resistance. Circuits have a hot, neutral, and grounding wire. The hot wire brings the current from the source while the neutral wire returns it. This completes the circuit.
However, accidents can happen. The hot conductor can break, allowing the current to flow through an appliance’s metallic housing. Anyone that touches this metallic housing could fall prey to a deadly shock.
According to Neta World, it only takes 10mA to injure a person. Even when the voltage is low, electrocution can lead to death if the current disrupts the heart’s rhythm.
Grounding keeps the excess voltage from a surge or lightning strike from arcing into other conductive materials and overloading appliances. A conventional grounding system consists of the following:
- Grounding rod – This rod sends the excess current into the earth. Manufacturers usually make it out of copper because of the material’s exceptional conductivity. You will find the rod in lengths of 8 to 10 feet.
- Grounding Wire – This line runs between the service ground connection and the rod. Your contractor of choice may also favor copper here because of the material’s reliability and conductivity.
- Grounding Clamps – The clamp binds the grounding conductor to the rod.
Electric Meters And Proper Grounding
nSpek has published a meter box wiring diagram. An inspector may refer to a similar diagram when they visit your home. The picture shows a grounding electrode conductor running to the service drop, meter, and service disconnect.
This strongly suggests that an electric meter needs a ground wire, but is that true? This is what you should know:
- The safest option is to give all metering equipment a solid grounding system. But does that mean the meter requires separate grounding? No, it doesn’t if you install the meter near the utility transformer.
- What about a meter far from the grounded service entrance? You need to neutralize the potential between the earth and the enclosure, which means grounding the meter. Keep this grounding requirement in mind while adding the meter to the ground-fault protection or the service disconnect’s load side.
- You bond the equipment grounding conductor to the neutral conductor and service entrance’s grounding electrode conductors. Don’t expect the grounding electrode conductor to carry a current under most circumstances. It only comes into play when a fault occurs.
- If the neutral current is flowing along parallel paths on the equipment grounding conductor, you probably bonded the metering equipment to the equipment grounding conductor and the neutral. Don’t be surprised if you detect current flowing on the enclosure’s surface, possibly even the sockets.
- Call an expert if you have doubts about your ability to ground meters and panels. Otherwise, parallel paths (neutral current flow) can expose you to fire and electrocution hazards. Some laypeople have started fires because they created poor connections that resulted in overheating.
- Make sure the grounding wire is the correct gauge.
What Does The Law Say About Electric Meters And Grounding?
- Don’t tamper with the electric meter. If you have questions about the presence or absence of a grounding wire, call the utility company. The meter is their property. They will penalize you for tampering with the device.
- The energy provider will install the meter. They will include two live conductors and a neutral. A closer look should reveal an outdoor service disconnect on the load side. Inspect the point where the service entrance wires meet the overcurrent safety device for a service grounding point.
- You will most likely find the ground wire in the middle of the meter. Electricians typically connect it to the neutral bus bar bonded ground terminal. The other end of the wire runs to the grounding rod.
- It should be noted that a meter can work without a ground wire. While the grounding system is vital to your safety, it is not necessary for an electrical system’s operations. You are unlikely to notice any change in the power supply even when someone disconnects or breaks the grounding conductor. This is concerning because you won’t notice the wire’s absence until it’s too late.
- Even though you don’t technically need the ground, the NEC expects contractors to ground conductive materials with the potential to become energized.
- Check your local code for additional information. Some local regulations have a lot to say about meters and panels. Consider this guide from the Tennessee electrical code, which expects electricians to ground meter bases with a solid 4AWG copper conductor.
- They expect a clamp to connect the grounding conductor to a ½-inch rod. You must push the rod eight feet into the earth. Inspectors will scrutinize your work carefully before giving the electrical service the green light.
The local code should have the final say in this matter. In the absence of concrete guidance from the local authorities, a licensed electrician will rely on his understanding of the industry’s best practices.
How To Ground Electric Panels And Meter Bases?
- Call the power company. Ask them to remove the meter.
- Find the large ground lug. Use the large wire running to the electrical panel to identify it.
- Locate the hole at the bottom of the meter base and pull one end of your ground wire through it.
- Strip some insulation (½ an inch) from the wire before placing it under the ground lug. Tighten the lug.
- Make a shallow hole under the meter base by removing three inches of soil.
- Push a ground rod into the hole. Use a hammer to strike it. You only want a few inches of the rod to remain visible above the ground.
- Connect the ground rod clamp to the ground rod and tighten it.
- Strip the other end of the ground wire and position it under the ground rod lug (on the rod clamp) before tightening it.