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Reasons Why a Neutral Wire Has Voltage

Reasons Why a Neutral Wire Has Voltage
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Last Updated: 27 October 2020

If you have electrical appliances at home, you have heard the term ‘neutral wire’ or ‘neutral current’ while interacting with 3-phase circuits. The neutral wire is just as important as the live and the earth wire in powering your appliance or ensuring your safety. It is important for you to know its roles, what it looks like, how to troubleshoot one in case of excess current and can a wire carry a current and still be neutral?

What is a Neutral Wire and What Does It Do?

The neutral in any circuit is the conductor that connects the circuit back to the current source. It is often connected to earth at the main electrical panel, meter, street drop, or final step-down transformer of the power supply in a simple single-panel installation.

How Do You Identify the Neutral Wire and Does the Neutral Wire Carry Current?

The neutral wire is the white one. Its function is to take any unused electricity back to the circuit breaker or panel. That is why the neutral wire has voltage. It attaches to the silver terminal on your service panel. The neutral wire is hot and is only found in AC power as they allow the current to alternate by connecting the circuit to the power source. However, under varying circumstances, the voltage on the neutral wire can be too high, which poses the risk of overheating your appliance.

Why Does My Neutral Wire Have Voltage?

A Heavy and Unbalanced Load

Why Does My Neutral Wire Have Voltage

If you are wondering why my neutral wire has voltage, in a normal 3-phase system with the dominant loads being single-phase, it carries the unbalanced current. When the system changes (which is normal), the loads may become unbalanced, making your neutral wire have voltage. When sizing the loads and distributing them within a panel, only the full load current is considered, not when the load is on or off, and this may cause significant unbalances whenever the load is on or off. Other times, the diversity of the loads on your panel may cause a large imbalance in the system, though diversity rarely ever makes the neutral wire have voltage. If the diversity of the loads is the problem, your neutral wire may be undersized and can get burned out.

Harmonic Distortion

Suppose you are wondering why would a neutral wire be hot, excessive-high currents are another reason. You are having a problem with harmonic distortion, where the waves of your current are out of form. To determine whether you have this issue, use a true RMS meter rather than a normal ammeter or voltmeter and you should be able to detect unusual harmonics on the screen.

How Can You Fix This Problem?

How Can You Fix This Problem

A heavy unbalanced load is easy to resolve. The loads need to be powered from an appropriate phase that allows balancing by rewiring some of the loads on your panel. If a high diversity is making your neutral wire have voltage, use a power monitor to determine the extent of the load swings whenever a change in the system occurs, then rewire them for better balance.

On the other hand, if you have distorted currents, ensure that there aren’t any shared neutral cables, especially in branched circuits. If you cannot eliminate the shared neutrals, swap them with larger ones to avoid overheating. If neither of these options works, install a passive or active filter to reduce the distorted currents. The third approach to this problem is the use of transformers to reduce zero-sequence harmonics.

How to Protect Yourself as You Work on the Mains?

How to Protect Yourself as You Work on the Mains

Start by checking the wire code in your locality or state to ensure that you do not go too far out of your depth. Ensure that the floor and your hands are completely dry. Put on rubber-soled shoes and tools with rubber grips. Ensure that the mains current is off and put up a sign to ensure no one at home turns them on unknowingly. If you are troubleshooting neutrals, ensure that the system is de-energized using a tester, which will turn on if there is any current.

How to Use a Multimeter to Test the Voltage of Live Wires?

Turn your multimeter on and set it to display voltage (V) in the AC setting. The best multimeter also has two probes, the red one (positive) and the black (negative). Place the red one on the live cable and the black one on the neutral, and your reading should appear on the screen. If the screen reads 110-120V, then the fixture is live.

Conclusion

The information above is a basic guide on why your neutral has current. Anyway, it will be much better if you are highly advised to seek professional assistance for your safety. For further information, please post your queries in the comment section.

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