A situation when the lights suddenly go out in the apartment, and circuit breaker in the panel goes to the “off” position, familiar to many homeowners. This is a protective mechanism that works to prevent overheating of the wiring, fire or failure of expensive household appliances. However, if electricity goes out regularly, especially when you turn on any device, it becomes unsafe to ignore this phenomenon.
The first thing you need to do when you discover broken plugs is not to panic and try to immediately turn the switch back on. Circuit breakers (AB) have thermal and electromagnetic protection and require time to cool down or reset. If you turn on the machine immediately after tripping, it may break again or, worse, not work the next time due to sticking contacts.
In this article, we will examine in detail the main reasons why the machine turns off when you turn on the lights or household appliances. We'll look at the difference between a power overload and a short circuit, and help you determine whether the problem lies with the wiring itself or with a specific appliance.
Electrical overload: the most common cause
The most common reason for protection to be triggered is a banal network congestion. Each circuit breaker is rated for a specific amperage, such as 16A, 20A or 25A. This means that it can withstand the total power of all switched on devices not exceeding this threshold. If you turn on a powerful electric kettle, washing machine and hair dryer at the same time, the total current may exceed the rating of the machine.
In this case it works thermal protection. Inside the machine there is a bimetallic plate that heats up under the influence of current. When the rating is exceeded, it bends and mechanically opens the circuit. The peculiarity of the thermal release is that it does not operate instantly, but with a delay. You can turn on the appliances and the lights will go out after 5, 10 or even 20 minutes. This time is necessary for the plate to heat up to a critical temperature.
To understand which devices create a critical load, you need to know their approximate energy consumption. Modern energy-saving lamps consume little, but powerful heaters, boilers and electric stoves can “eat up” the entire safety margin of the wiring. If the machine breaks down precisely when several devices are operating simultaneously, there is only one solution: distribute the load or replace the machine with a more powerful one (only if the wiring allows it!).
The total power of devices on one line should not exceed 3.5 kW for a standard 16A machine. Take this into account when planning the operation of powerful equipment.
Short circuit: instantaneous operation
If the machine knocks out instantly, literally in a split second, with a characteristic loud click, then the electromagnetic release. This is a sure sign short circuit (KZ). Unlike an overload, a short circuit occurs when the phase and neutral conductors come into direct contact, bypassing the load. The circuit resistance drops to almost zero, and the current increases to enormous values.
The causes of a short circuit may be hidden in the walls or in the sockets. This could be damage to the wire insulation during drilling, aging of the insulating layer in old houses, or a manufacturing defect in an electrical appliance. Often a short circuit occurs inside the machine itself or at the junction of the wires in the distribution box, where the contacts have oxidized or the twist has loosened.
How to distinguish a short circuit from an overload by external signs?
When a short circuit occurs, a cracking or popping noise is often heard, and a burning or melted plastic smell may appear. The machine turns off immediately, and turning it on again without eliminating the cause is impossible - it will turn off again instantly.
Diagnosing a short circuit requires caution. If, after knocking out the machine, you smell a burning smell from the socket or see a melted switch body, further independent experiments are dangerous. It is necessary to call an electrician who, using megohmmeter or a multimeter will ring the circuit and find the location of the short circuit.
Malfunction of the connected electrical appliance
Often the culprit of the problem is not the wiring in the walls, but a specific household appliance. If the machine goes off every time you turn on, for example, a microwave or iron, then the problem is localized there. The heating element inside the device could burn out, the internal cable could be damaged, or a breakdown could occur on the housing.
There is a simple process of elimination to test this theory. Unplug all devices from the sockets in the group where the machine knocks out. Then turn on the machine in the panel. If it holds the load without connected consumers, then the wiring is intact. After this, start turning on the devices one by one. The one, when turned on, will knock out the traffic jams again, is the hero of the occasion.
☑️ Diagnosis of a faulty device
Particular attention should be paid to devices with heating elements and electric motors. A burnt heating element in a washing machine often causes a current leak or short circuit. When the electric motor in a vacuum cleaner jams, it can create starting currents, which it automatically perceives as an emergency situation. It is better to entrust the repair of such devices to specialists from service centers.
Problems with the circuit breaker itself
The possibility of failure of the protective device itself cannot be discounted. Automatic machines, like any mechanics, have their own operating life. Over time, the internal contacts may burn out and the cocking mechanism may weaken. As a result, the machine can knock out even at currents that do not exceed the nominal value, or, conversely, fail to work where it is vitally necessary.
Another common problem is poor contact where the wire connects to the machine. If the terminal screws are loose, resistance will develop at the connection point, which will cause heat. Heat is transferred to the machine body and to the thermal release, causing it to trigger falsely. This often happens in old panels where the contacts have not been inspected for a long time.
It is also worth considering the temperature regime. Circuit breakers are sensitive to ambient temperature. If the shield is located in a hot room or in the sun, the rated current of the machine may be reduced. In this case, a 16A machine may trip at a current of 14-15A simply due to overheating.
If the circuit breaker is hot to the touch and knocks out without visible load, first check the tightness of the terminal screws and replace the switch itself.
Correspondence table between machines and cable cross-sections
One of the main mistakes when installing wiring is the discrepancy between the rating of the machine and the cable cross-section. If you put a powerful machine on a thin wire, if it is overloaded, the wire will burn out, and the machine will not even click. Below is a table for copper wires to help you understand what kind of protection your wiring requires.
| Copper cable cross-section (mm²) | Rated current of the machine (A) | Maximum power (kW) | Load type |
|---|---|---|---|
| 1.5 mm² | 10 A | 2.2 kW | Lighting |
| 2.5 mm² | 16 A | 3.5 kW | Sockets |
| 4.0 mm² | 25 A | 5.5 kW | Hob |
| 6.0 mm² | 32 A | 7.0 kW | Electric stove |
| 10.0 mm² | 50 A | 11.0 kW | Entering the apartment |
The use of machines with a larger nominal value than the wire cross-section allows is strictly prohibited by the rules PUE (Rules for electrical installations). This is a direct road to fire. If your 16A circuit breaker frequently breaks down, and the wiring is old (2.5 mm² aluminum), replacing the circuit breaker with a 25A circuit breaker will not solve the problem, but will only create a new, more dangerous one.
Leakage current and differential protection
In modern shields, along with conventional machines, they are often installed RCD (residual current device) or difavtomats. These devices do not respond to overload, but to current leakage. If the machine knocks out (or more precisely, the RCD lever turns off) when touching the body of the device or in damp weather, then the insulation is broken.
Electrical leakage often occurs in the bathroom or kitchen where there is moisture. Water entering an electrical appliance or outlet creates a path for current to reach the ground. The RCD detects the difference between the incoming and outgoing current and breaks the circuit, saving a person from electric shock. In this case, a regular machine may not even respond, since there is no short circuit.
⚠️ Attention: If you have an RCD installed and it trips, under no circumstances should you bypass it or replace it with a regular machine. This will remove your protection from electric shock. Look for an insulation breakdown.
Professional equipment is used to diagnose leaks, but sometimes the problem can be found visually. Inspect appliance plugs for cracks and sockets for signs of soot or moisture. If the RCD trips when a specific device (for example, a boiler) is turned on, most likely the heating element of the water heater has broken.