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Many people from typical households have little knowledge of electrical wiring, which is why they might not be aware of potential hazards in their electrical systems. To reduce the risk of electrical shock and fire, you shouldn’t rush into connecting both the neutral and ground wire.
Let’s go over why the practice of connecting the two wires incorrectly can be unsafe.
Here’s What Happens if Neutral and Ground Are Tied Together:
Connecting both the neutral and ground wire in a sub-panel is dangerous because this would result in the ground wire potentially carrying electrical current. This situation can increase the risk of electrical shock. The neutral and ground wires should only be bonded (connected) in the main panel, where it is the designated bonding point.
Standard wiring comprises three wires: hot, neutral, and ground. For appliances to function, they need both the hot and neutral wires; the ground wire is a safety feature, not required for the appliance to operate. The hot wire delivers electricity to the appliance, while the neutral wire provides a return path for the current back to the electrical source.
Under normal conditions, the ground wire does not carry electrical current. Its purpose is to provide an alternate path for fault current, helping protect you if a short circuit occurs. Instead of current flowing through your body, it is directed safely back to the source through the ground wire.
If you connect the neutral and ground wires improperly, the ground wire can start carrying return current. This defeats the purpose of the ground wire because it is no longer just a safety feature; it becomes part of the circuit and carries current, making it a live wire.
A live ground wire increases the risk of shock because it may energize the metallic cases of appliances. For example, a refrigerator with a metal casing could become energized. If you touch it, the electricity could flow through your body, potentially causing a serious or fatal shock.
Can Neutral and Ground Be on the Same Bus Bar?
First, you need to identify whether the bus bar is in the sub-panel or the main panel. If it’s in the sub-panel, the answer is no: the neutral and ground wires should not be on the same bus bar.
According to the National Electrical Code (NEC), the neutral and ground should be connected together only at the main panel, not in sub-panels. This is because there should be only one return path for the electrical current, which is the neutral wire. If they are connected on the same bus bar elsewhere, it creates multiple return paths for the current.
Consider a sudden surge of electricity. In a correctly wired system, the excess current would flow through the neutral wire and trip the breaker, alerting you to a problem. However, if the neutral and ground are bonded in a sub-panel, the current could flow through both paths, potentially preventing the breaker from tripping. This leaves the fault undetected and increases the risk of electric shock if you come into contact with a metal appliance.
Why Do You Have to Bond the Neutral and the Ground Wire in the Main Panel?
Bonding the neutral and ground wire in the main panel is crucial for the circuit breaker to operate properly. Without bonding, a fault might not create a high enough current to trip the breaker, allowing the problem to persist unnoticed.
Bonding is the intentional connection of the neutral and ground, creating a low-impedance path back to the power source. This helps the circuit breaker detect faults and shut off the electricity quickly, protecting you and your home from potential hazards.
When a fault occurs, the bonded connection allows the current to flow back to the transformer through the neutral wire, not through the earth. This ensures a complete and reliable path for fault current, which helps the breaker trip as intended.
In other words, during a ground fault, relying solely on the earth as a return path could result in dangerous conditions. Bonding in the main panel ensures that the fault current flows directly back to the source, increasing the likelihood that the breaker will trip and cut off power, preventing the equipment from staying energized and reducing the risk of electric shock.
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