Does neutral cable cause electric shock?

There are people and electricians who have already suffered an electric shock in the neutral cable. Electric shock is a major cause of serious and fatal accidents in the production, transmission, distribution or consumption of electricity. In this article, we will answer that big question, whether the neutral conductor causes electric shock or not.

What is Electric Shock?

Electric shock is a disturbance of nature and diverse effects that are manifested in the human body when an electric current circulates through the body. The consequences and changes caused by electric shock in the human body depend mainly on the duration and intensity of the electric shock. Electric shock can manifest itself basically in three different ways, which are:

  • Static electricity (constant electrical voltage)
  • Dynamic Electricity (electrical voltage in the alternating or continuous electromagnetic waveform)
  • Lightning strikes or electrical arcs

The human body behaves like an electrical conductor, even having electrical resistance. The resistance that the human body offers to the passage of the electric current is due to the outer layer of the skin, which consists of dead cells. This resistance of the human body is between 100,000 and 600,000 ohms when the skin is dry and has no cuts.

The damage and sequelae that are caused by electric shock are directly linked to the intensity of the current and not necessarily to electrical voltage . So the greater the intensity of the current that runs through the body, the greater the effect.

Other factors that determine the severity of the shock are the paths taken by the electric current in the human body, with greater gravity being the paths in which the electric current passes through the heart.

Paths traveled by the electric current in the human body.

Below we can see the risks and damages of a certain range of electrical current when passing through the human body:

  • Electric shock with an electric current up to 10 mA – Donate and muscle contraction
  • Electric shock with an electric current between 10 mA to 20 mA – Increased muscle contractions
  • Electric shock with an electric current between 20 mA to 100 mA – Respiratory arrest
  • Electric shock with an electric current between 100 mA to 3A – Ventricular fibrillation that can be fatal
  • Electric shock with an electric current above 3A – Cardiac arrest and severe burns

Does the Neutral cable cause electric shock?

In ideal situations the electrical voltage in the  neutral conductor should always be at zero volts or as close as possible. Neutral and grounding should not have a potential difference, but the impedance of the neutral cable is not zero, so there is always the possibility of measuring some voltage between neutral and ground. Electric shock in the neutral is an electrical fault, just like the broken neutral.

Naturally, the neutral does not cause electric shock, since the neutral and grounding have no electrical voltage. What causes an electric shock is the difference in electrical potential between two points, which provides a flow of electrical current through a person’s body. In cases where the electrical voltage in the neutral conductor is not zero or close to zero, it means that there is an imbalance between the phases.

The neutral conductor in ideal situations does not cause electric shock, if this happens it is a sign that some problem is happening in the electrical installation, for example, a broken neutral. If the house has a well designed and calculated electrical circuit, this voltage between neutral and earth must not exceed 5V. For the neutral conductor to cause electric shock, there must be a considerable difference in electrical potential, for example, between phase and neutral.

The Neutral cable causes electric shock.

Does the neutral cable cause electric shock when the load is in operation?

Another very common question is whether the neutral causes electric shock when the load is in operation. Because whenever a single-phase load is connected in phase and neutral, the neutral conductor starts to conduct the same electrical current that comes through the phase. We decided to set up an electrical circuit to answer this question in practice.

Below we have the assembly of a lamp cicuit , which we use a socket and plug to facilitate when making some tests with an electrical voltage detector and clamp meters. The electrical voltage detector is a device that informs the presence of electrical voltage in the circuit and when there is electrical voltage in the circuit, it emits an audible signal and turns on a red light. The clamp meter is a device used to measure electrical current.

The first test is for the electrical voltage with the load off, placing the electrical voltage detector on the phase cable, the detector emits an audible signal and turns on the red light indicating it has electrical voltage. Then, placing the detector on the neutral cable, the detector does not emit a sound and does not turn on a constant red light indicating the presence of electrical voltage, the neutral has zero potential, that is, a voltage of 0V.

The second test is for the current with the load off, placing the clamp meter on the phase cable, then the clamp meter informs that the electrical current is zero amps. Then placing a clamp meter on the neutral cable will also indicate an electrical current equal to zero amps.

Electrical current test with the load off, using clamp meters.

Now let’s do the same tests with the load on. The first test is for electrical voltage, placing the detector on the phase cable, the detector emits an audible signal and turns on a red light, indicating an electrical voltage. After placing the detector on the neutral cable, the detector does not emit an audible signal and does not turn on the red light then, the neutral continues without presenting voltage.

Electrical voltage test with the load on, using an electrical voltage detector.

The second test is for the current, placing the ammeter on the phase cable has a current of 0.4 amps. Then, placing the ammeter on the neutral cable, we have a current value of approximately 0.4A. Whenever a single-phase load is connected to neutral, it conducts the same current that comes through the phase, this is the principle of electrical circuits.

Electrical current test with the load on, using clamp meters.

For there to be an electric shock, it is not enough just to have electric current in the neutral, it is necessary that the neutral also has a potential difference in relation to the earth, that is, there must be an electrical voltage between neutral and earth. Using the voltmeter to measure electrical voltage between the neutral and the ground point of the electrical circuit, the electrical voltage measured was equal to zero volts.

Electrical voltage between the neutral and the ground point of the electrical circuit.

As we know that the impedance of the neutral cable is not zero, then there is always the possibility of some voltage between neutral and earth, that is, neutral with a voltage other than zero.

In any case, do not touch bare cables, cable ends or busbars of electrical circuits. Even the trained professional has no way of knowing just by looking if it is a neutral or phase cable.

Of the electrical faults, the broken neutral is quite serious as it can cause overvoltages in the sockets, causing a neutral cable to have a voltage equal to that of the phase and in this case touching a live part of the neutral cable is very dangerous. In the video below of the World of Electrical, we show what it is and what are the effects of the broken neutral.