Electrical shock from tap water: what to do, how to find the cause and eliminate it

There are many reasons why tap water shocks. This situation is abnormal and requires specialist intervention.And it’s not even about the level of discomfort that each family member experiences. At any moment, a small amount of tension in the tap water can increase and lead to more serious consequences than just a painful prick.

Possible reasons

Usually in such a situation, the first thing that comes to mind is the action of the nearest neighbors on the floor. Since time immemorial, the plumbing and heating systems have been used by unscrupulous residents to cheat on electric meters.

Today this situation is less common. Imagine the surprise of the residents when the water from the tap continues to produce electricity even in the absence of their neighbors in the house. Most often, household electrical appliances are the culprits.

The main reasons why tap water can shock:

1. Poor quality of grounding of electrical heating or hot water supply devices in the house.
2. Incorrect connection of electrical appliances.
3. Operation of powerful electricity consumers.

In all three cases, the reason is an increase in potential on the neutral wire. Under normal grounding conditions, excess voltage is cleared to zero.

If the grounding system does not work, or RCD protection devices are not used in the wiring diagram, then small but sensitive electric shocks will occur even with relatively good electrical equipment.

Some apartment owners who complain about constant micro-electric shocks from water taps or even heating systems forget to talk about unmetered sockets. Connected without grounding, often in violation of PUE standards, and used to power powerful electrical appliances such as heaters, electric ovens, washing machines and air conditioners.

When a powerful load is turned on, due to the voltage drop on the neutral wire, an increased potential will appear, different from zero. Its value can range from 2V to 25V.

Lack of grounding

Almost all old houses built at the end of the last century either did not have a grounding system or had a very formal grounding system. At that time, it was customary to save on materials, so grounding, at best, if there was any, was connected to a pipe buried in the basement.

Moreover, many home owners, due to their ignorance, believed that the “zero” in the outlet could be used as grounding, and when installing a new electric heater or water heater, they disconnected the grounding line of the electrical appliance to the neutral wire of the wiring.

As long as in high-rise apartments the most powerful electrical appliance was an iron, and water pipes, taps and heating communications were made of metal, there were no special problems. Except how quickly the pipes rotted, and the voltage in the network regularly “jumped.”

After 2 kW electric kettles, boilers and air conditioners came into widespread use, and steel pipes were replaced with plastic ones, the grounding problem resulted in the appearance of excess potential on water and electrical appliances.

Simply moistened with tap water, the skin of the hands has low resistance, and an electric shock even at microamps turns out to be very sensitive. The same potential may be present on the body of a refrigerator or washing machine if they are not grounded. Only due to the high resistance of the dry skin of the fingers, the electric shock is not felt.

Wiring fault

This happens if the wire is old (cracks in the insulation), or the cable is regularly shorted, the terminals on the contact (distribution) box, on the panel or in the socket are connected carelessly.

In this case, a barely noticeable flow of high potential occurs to the neutral wire. If the process occurs in a multi-core wire laid in a groove under the plaster, then the grounding line will already help. Any water heaterconnected to the water supply, will release increased potential into the water, flowing through a crack in the insulation.

Electrical fault

Most often, invited electricians indicate a malfunction of electrical equipment connected to the water supply or heating system. Worn water electrovalves, electric pumps, centrifuges, burnt heating elements remain the main reason for the appearance of excess potential in tap water. They can also cause current leakage.

Moreover, in some cases, in order to receive an electric shock, it is not necessary to turn on an electrical appliance, for example, a heating boiler. It is enough that the equipment is connected to electrical wiring and water supply.

Diagnosing the problem, where to start

Most master electricians, when asked why the faucet is electrocuted, suggest installing an RCD on the wiring branch that leads to the bathroom and kitchen.It is important to do this, but do not rush until the reason why the tap water is shocking has been identified. The RCD will simply turn off the branch if the potential drain current is higher than the safe norm. But this will prevent you from identifying the cause.

First of all, you need to check the household appliances connected to the water supply. The best way is to use a potential indicator. If, when you touch the body of the neon, the inside of it lights up, then this means that this device is the reason why the tap water produces an electric current.

Sometimes it is not only the flow of water when the tap is open that produces an electric shock, but also the mixer itself, metal objects, for example, a sink or the body of a water heater. It is clear that the water is electrocuted due to improperly connected household appliances.

Often, owners carry out diagnostics without instruments, touching household appliances connected to the water supply one by one with their hands. If it hits during contact, it means that this particular device is guilty of inducing excess potential in the water.

Sometimes they check with a wet hand. In this case, the faulty device produces a stronger electric shock due to reduced skin resistance. The method is not entirely safe, but for experienced craftsmen it is quite acceptable. You just need to do it right:

1. Touch the outer surface of your fingers, and only with one hand.
2. Wear shoes with rubber soles.

Refrigerators of old Soviet models often give electric shock (if anyone still has them). The reason is the lack of normal grounding and partial breakdown of potential to the housing. This method was usually used by refrigeration specialists. If, with a light, brief touch, the refrigerator produces an electric shock, it means that the compressor winding is burnt and is piercing the housing.

Sometimes household appliances produce weak currents.You won’t feel the blow with a dry hand, but if there are fresh scratches or wounds on the skin, the sensitivity increases. When you turn on a faucet in the kitchen or bathroom with a dry hand, it doesn’t seem to hit you, but as soon as you put your fingers under the water or close the faucet with a damp palm, you feel a noticeable electric shock.

The most desperate “specialists” check with both hands. With one hand, take hold of the end of the wire, secured with a clamp to a bare section of the metal pipe of the heating system in apartment buildings. The second one carefully touches household appliances connected to the water supply one by one.

In this case, the chances of identifying the culprit who gives the electric shock are higher than in the previous one. But at the same time, the risk of receiving a severe electric shock with serious consequences increases. There is no need to do this - it’s better not to take risks. After all, it is not known why a boiler or water heater is electrocuted. This could be excess potential, or worse, damage to the wiring. Then the phase hits the body of the device. A blow through two hands can lead to cardiac arrest even with a small current.

Therefore, the first thing to do is to restore normal grounding and check for the presence of increased potential on the body of the boiler, boiler or water heater. If everything is in order, you can proceed to a more detailed check.

Appliances

Most often the equipment is in good working order. Modern water heating equipment for domestic use undergoes special testing and certification of protection against electric shock. But sometimes even new appliances can cause electric shock in the water under the tap.

This usually happens when working water heater. The effective voltage usually drops from 220 V to 210 V, depending on the power of the heater.If, at the time of operation, you measure the voltage between the neutral wire and ground (done according to all the rules), then you can see that there will be potential between “zero” and “ground”.

Try using a multimeter to measure the voltage at the contacts in the socket of a boiler or electric speaker without touching the body of the device. And then between zero and the ground terminal. The device will show the presence of potential. You can verify that the water from the tap is electrifying at exactly this moment.

The water in the pipes plays the role of a grounding conductor, and since a small but increased potential (10-15 V) appears at “zero” after switching on, it will flow along metal and wet surfaces to the parts of the boiler or boiler in contact with the water flow. A person, having opened the tap, inevitably “crashes” into this circuit; the current flows through the palms and hits slightly, but noticeably. This is especially noticeable in private houses.

Broken wiring and extension cords

In the event that excess potential appears on the neutral wire due to the lack of normal grounding, tap water flows with a relatively small current. Most people feel little or no shock.

It’s another matter if the potential appeared as a result of direct flow of current into the water from the tap due to damage to the wiring insulation. In this case, it shocks very sensitively, regardless of whether the electric heater (boiler) is running or is simply plugged in.

This is especially true for lighting bathrooms. Due to damaged insulation, potential from the phase wire will flow along wet surfaces to the water. In this case, not only it hits, but also the cast-iron bathtub and the turned off mixer or shower tap.

Neighbors' fault

A situation may occur that water from the tap produces an electric current even when the water heating and lighting equipment is turned off and de-energized. This means that the increased potential for tap water appeared due to the actions of neighbors in the apartment building.

Reasons why water shocks:

1. A broken or partially faulty ground loop from a neighbor. All excess potential enters the apartment through water, heating or water supply pipes.
2. Faulty (short-circuit) wiring in a neighbor's bathroom through the wall. It is found mainly in multi-storey panel buildings. Steel fittings, even without water, can conduct current from neighbors located 2-3 floors above or below the apartment.
3. Neighbors using water supply pipes as grounding.

The last option is scary, since there is a real danger of getting a strong electric shock when opening a water tap. In addition, such “ground” can cause corrosion of steel parts of water heating equipment and even failure of electronic circuit boards on a washing machine or heating boiler.

To make sure that water from the tap is emitting current because of the neighbors, it is enough to turn off the power to the apartment and measure the potential difference on the tap itself and the grounding bus (but not on the distribution board). As old steel pipes are replaced with polypropylene pipes, the threat has decreased, but not disappeared.

According to reviews, replacing with metal-plastic ones does not solve anything; in most cases, water from the tap still continues to give an electric shock. Until the grounding is put in order or potential equalization is completed on the neutral wire.

Short circuit in the wiring of the phase and ground conductors

The most dangerous and unpleasant situation is when current leakage occurs due to insulation damage and moisture ingress. Sometimes, in order for the water to begin to shock, it is enough to unsuccessfully drive a nail into the plaster of a wall or to pinch a wire with a galvanized profile when facing a kitchen or bathroom with plasterboard sheets.

This situation is considered one of the most dangerous. The potential on the neutral core will be greater in value than when turning on conventional household appliances. This means that the water under the tap will flow much stronger.

In addition, there is a risk that electric shock will occur not only from the tap water, but also from the heated towel rail and additional radiators for drying clothes, and any metal objects in contact with tap water.

There is no or poor contact on the grounding, grounding in the shield

If the water suddenly begins to generate electric current, then this is a good reason to check the condition of the input panel. Especially when it comes to wiring in a private house, where the flow of current through the ground loop is commonplace due to the poor condition of the electrical networks.

As long as the grounding works properly, the water in the kitchen or bathroom, as a rule, does not produce an electric shock. But over time, the contact point of the grounding bus on the distribution board rapidly rusts. After about a year, the contact periodically disappears due to a layer of rust, and the water under the tap and the metal parts of the water supply supply an electric shock.

The problem needs to be solved not only by repairing the grounding, but first of all by restoring the quality of the networks. Otherwise, the water in the shower and bathtub will shock every time a neighbor in the country turns on a circular saw or electric heater in the bathhouse.

How to get rid of electric shocks

It is necessary to put in order the existing grounding in an apartment or private house. There are many ways to check its quality, all of them are described in the PUE.

You can simply dig a 1.5-2 m steel pipe into the ground to its full depth. Water is used to improve contact with the soil.

Next, measure the potential difference between the pipe and the current grounding with the power supply turned off at the panel and in the on position. In the first case, the multimeter should show zero. If the device shows a potential difference or the water under the tap continues to emit current, then you need to go to your neighbors and check their electrical appliances.

If the grounding is working properly and there are no problems with neighboring equipment, the potential difference between the “ground” (with the packet switch on on the switchboard) and the pipe should not be more than 1-1.5 V.

Next step - install RCD devices on all electrical wiring branches leading to the bathroom and kitchen (where there is water). Check the quality of electrical wiring and all electrical appliances connected to the water supply system.

If a house or apartment does not have a built-in grounding loop, then it will need to be done independently or under an agreement with a private company at the expense of the housing association. Most likely, in such a situation, tap water produces electric current in many apartments, so residents will support the idea of ​​​​arranging full grounding.

Another option is to install a potential equalization system on the neutral conductor. It will not protect you from damaged wiring, but at least the water from the tap will stop giving you an electric shock due to unscrupulous neighbors or when powerful electrical appliances are turned on.

The situation when water flows from the tap does not look so threatening, but there is cause for concern.While the currents are small (microamperes), everything comes down to light injections. But if you leave everything as it is, the current can increase to milliamps, and this is already dangerous to health.

Tell us about your experience in dealing with current leaks through water, and how you managed to solve the problem. Save the article to your bookmarks so as not to lose useful tips.