Electricity, like other benefits of civilization, is available to every person today. We can no longer imagine life without lighting, television, computers and refrigerators. But this phenomenon should be handled carefully, since sometimes unpleasant surprises await us. One of these is a short circuit between electrical wiring wires. The result, at best, is the operation of circuit breakers and the absence of a 220 V network in one of the residential premises. How to find a short circuit in the apartment wiring (short circuit)? Every educated person can do this.
Types of short circuits and their manifestations
Electrical networks distributed by wiring along the walls of the house can be single-phase or three-phase. Three-phase ones also have varieties - four-wire with a neutral wire or three-wire without it. If the load is symmetrical in all phases, only 3 phase wires can be used. If not, a neutral wire must be present.
According to the latest standards, input is carried out through five conductors - a ground wire is added to the 4 above. Thus, in a single-phase network there is only one short circuit in hidden wiring - between the phase and the neutral conductor. For 3-phase networks there are different types of short circuits:
between two phase conductors; between one of the phases and the neutral core; between phase and ground; between the neutral and grounding conductors.
Now we can define a short circuit. This is a short-term or long-term contact of two current-carrying conductors having different potentials. In this case, the current strength between the closed conductors increases many times.
If the circuit breaker on the electrical panel does not work in time, the conductors begin to overheat, leading to the melting of the insulation with its subsequent fire. The result is a fire. In addition, connected appliances and even people may be harmed if they try to extinguish a fire with water without turning off the power.
Wiring check
Testing conductors using a multimeter is functionally provided in most digital devices of this class. To set the dialing mode, just set the switch to the position marked with the “Buzzer” icon and prepare the measuring chain shown in the figure.
If current flows through the piece of wire being tested, the multimeter will produce an audible signal (buzzer). Naturally, to test a section of a circuit several meters long, you will need an additional wire used to expand the measuring circuit.
Another option for testing phase and neutral linear conductors of considerable length involves twisting them at the remote end of the electrical wiring.
In this case, to check the circuit for an open circuit, it is enough to connect the multimeter's test leads to the free contacts of those ends of the electrical line that are located closer to the device.
Causes of short circuit
The reasons for the occurrence of such emergency situations are very diverse.
Damage to the insulating layer is the most common occurrence during renovation or remodeling. For example, a nail caught in the insulation and driven into a wall. Violation of insulation due to water ingress - for example, from neighbors. The connections of conductors protected with insulating tape during installation suffer the most. Aging of cables, especially in old buildings. At that time, the wires did not have such high-quality insulation as they do now. Over time, it begins to deteriorate, which leads to short circuit. Exposure to rodents who like to taste electrical wiring, risking their lives. Such phenomena occur in private houses, the basements of which are favored by mice and rats. The network load is too high for the wiring, for which the current-carrying conductors are not designed. The result is overheating and destruction of the insulation. A faulty electrical appliance that, when connected to the mains, creates a short circuit.
Possible consequences
Consequences of a short circuit in an electrical panel
A short circuit is a negative phenomenon that can lead to a fire and breakdown of household appliances. But other problems caused by the defect can also be identified:
- Melting veins. If they explode, they can cause harm to human health.
- Ignition of insulation. Relevant for low-quality insulating layers or made of flammable materials.
- Equipment breakdown.
To prevent all negative consequences, you need to find the short circuit in time and eliminate it.
Methods for localizing wire short circuits
How to independently find a short circuit in the wiring of an apartment? There are several ways to do this. In addition to modern devices, you will have to connect your sensory organs - vision and smell.
Visual inspection
This is the first thing to do. Quite often, this method allows you to immediately detect a short circuit. With a high probability you will find the short one in the most vulnerable places. Such as: electrical panels; distribution boxes; sockets, light switches; open electrical wiring locations; lighting devices; network extenders; plugs and power cables of devices.
As a rule, a short circuit is accompanied by crackling, light and smoke effects that leave marks on sockets, switches and walls. Such phenomena are accompanied by the appearance of smoke, the smell of which will also help you navigate.
Multimeter
Quite often, the affected part of the network is detected using this device. How to find a short using a multimeter? To do this, the tester switches to resistance measurement mode, selecting a range that is capable of measuring megaohms. If the network is single-phase, the resistance is measured between two conductors - phase and zero. If it is three-phase, you will have to measure the resistance between the phases, each phase and zero, phases and ground.
The best place to search is in junction boxes. From them the wires, as a rule, diverge in the form of rays. Therefore, you will have to sequentially ring all cable linings. You can speed up detection by looking at the electrician's notes on the electrical wiring diagram for your apartment. This information can be useful because the actual wiring often does not match the one shown on the drawing.
If the network section is not subject to short circuits, there will be no resistance between the conductors. Otherwise, the multimeter will show a specific value or 0, and it may change periodically.
Unfortunately, during such a test, a small potential difference, about 9 Volts, is applied to the conductors. Broken insulation can easily withstand such voltage. But at 220 Volts, it can no longer isolate the wires; they are short-circuited. Therefore, you cannot always trust the tester's readings.
Determining a faulty device
If, when several devices are connected to the network, the circuit breaker knocks out, the reason may not be in the electrical wiring, but in one of the devices. It is quite easy to detect. To do this, all devices in the apartment are disconnected from the network. Then the machine turns on. If it does not knock out, we find the faulty device by connecting the electrical equipment in series. As soon as the faulty one is connected, the machine will immediately work.
What to do if it shorts: emergency actions
If there is a power outage in your home, you should make sure that there is an emergency at home.
Smoke and the acrid smell of melted plastic will tell you about problems. It is necessary to turn off the machines, unscrew the plugs on the electrical panel, and disconnect electrical appliances from the sockets. It is better to put out an open fire by covering it with a blanket or thick cloth.
If you have a powder (car) or carbon dioxide fire extinguisher, be sure to use it to extinguish the fire. Do not pour water on the fire!
The causes of serious electrical faults are varied, but in most cases are known. The occurrence of a short circuit is associated with improper operation and violation of clause 2.1.21 of the PEU rules during installation of electrical wiring.
Methods for eliminating short circuits
Once a faulty outlet, switch, or section of electrical wiring has been identified, you can begin to restore the network to working condition. With sockets and switches, everything is simple - you will need to install new devices, fortunately they are sold in a wide range. Don't try to repair them - new ones are very inexpensive.
Eliminating the found sections of wiring with a short circuit is a little more difficult. You will need to find the location of the grooves in which the wiring is hidden. It should be remembered that the cables are laid strictly in horizontal and vertical directions, this will facilitate detection. Sometimes grooves are detected visually - especially during renovation, if wallpaper is torn off the walls.
To determine the location of the wiring, you can use improvised means or devices specially designed for this purpose. Then the wires are freed from the plaster, alabaster and removed. After this, a new cable is laid. The joints must be twisted and carefully insulated.
Using improvised means
Testing wires with a multimeter is not the only possible option for testing them for continuity or breakage. You can verify the serviceability of any linear conductor without the help of this universal device.
To carry out such a check you will need:
- a regular battery (preferably a 4.5-volt square one);
- a 3.5 Volt light bulb, with which the linear section of the wire being tested is checked (monitored);
- a pair of connecting wires and a gripping type connector (the so-called “crocodile”).
After preparing all the necessary elements, a simple measuring chain is assembled on their basis, consisting of a test light, a battery and the conductor being tested. If the circuit is correctly assembled and if the tested area is in good condition, the control light will light up. The absence of a glow even though all circuit elements are working properly indicates a break in the conductor itself.
When testing in this way, the same principle is used as when checking with a multimeter turned on in the dialing mode.
Some useful tips
If your building is of considerable age, it is best to completely replace the old electrical wiring. A short circuit can occur in any other place, since the insulation of the conductors has already lost its desired properties. If you find that any of the switches or sockets begin to spark, it is better to replace them immediately. It is in such places that areas of increased probability of short circuits arise. If for some reason circuit breakers and RCDs (residual current devices) are not installed, this defect must be eliminated, otherwise the consequences could be disastrous. This omission is observed in old buildings. If new electrical wiring is installed, the cable cross-section must be generous so as not to overheat the conductors during heavy loads. To do this, you must clearly understand which electrical appliances will be connected and where.
By strictly following all the above recommendations, you can eliminate a short circuit in the wires on your own, without having special education or skills for this.
How to check a car battery with a multimeter
If you suspect that the battery is not working well, then again, a multimeter will help you. So, arm yourself with a multimeter configured to measure voltage (20V):
- Disconnect one terminal and connect the red contact to the positive and the black to the negative. Normal voltage should be between 12.4 - 12.8 Volts. It is important to take measurements at least an hour after stopping the engine.
- Measure the voltage under a load equal to twice the capacitance. For example, if the capacity is 75 Am/hour, then the load should be 150 Am. If the voltage drops below 9 Volts, it means something is wrong with your car’s battery (undercharging or failure). After disconnecting the load, the voltage should be restored within 5-10 seconds.
