When connecting modern electrical appliances to the mains, most consumers use protection in the form of devices from overloads and leakage currents. This can be a residual current device (RCD) connected in series with the machine or a differential machine that combines the functions of a RCD and a simple machine. Depending on the type of heater (flow or boiler), its power, the number of electrical appliances, a general UZO is installed in the house on an electric panel or a separate one (on the power cable of the water heater).
UZO and diffavomat
Why does an RCD work?
When the boiler is turned on, an RCD can work, or the machine can turn off the electricity in the whole house. We will understand why the RCD periodically or constantly works on a home water heater:
- When a simple circuit breaker or a differential circuit breaker trips, the cause may be a short circuit inside the boiler or in its wiring or a network overload (if a lot of electrical appliances are included in the apartment). An anchor with shelves, a mirror can be clogged into the wall, violating the integrity of the wiring.
- An important role is played by the correct selection of RCDs according to the rated current and leakage current. If the device is improperly selected, it is often triggered.
- When the RCD is turned off, the cause may be a violation of the integrity of the heating element or the wiring inside the heater, leading to leakage of electric current to the boiler body. If there is an earthing circuit in the outlet, the power is immediately turned off. In the absence of grounding, the device turns off after a breakdown of current from the housing per person.
- Incorrect RCD connection in the electrical panel. If the job was done by a layman, then the possibility of a mistake is likely. Sometimes “ground” is connected to “zero”, which causes the device to trip.
- Malfunction of the shutdown device itself. The test button may sink or the switch may have mechanical defects. In this case, it will be triggered by the slightest vibration. In Termex heaters, the protective device is often faulty due to its poor quality.
- Sometimes the shutdown occurs after a period of time and heating the water. The reason may be a slight deformation of the boiler body and its contact with the "phase".
Troubleshooting Methods
Let's start by checking the difavtomat or RCD. At least 1 time per month, you need to press the "test" button to create conditions for current leakage and check its operation. If the circuit breaker does not trip during the test, it must be replaced.
Unfortunately, low-quality products enter the consumer market and RCDs are no exception to the rule. There are cases when blackening appears on it, when it is shaken, the detachment of the insides is noticeably audible, the indicator does not light (usually “green” lights up when the state is off, and “red” when it is turned on). You need to visually inspect the device, you can disassemble. If there are charred elements inside, then you should not try to make it, most likely the operation took place with increased load.
Burnt elements on the RCD
If there is no external damage to the machine and triggered during testing, you need to check the quality of the connection in the terminals of the electrical panel, the absence of moisture on the device and inside it, check the degree of heating in the working position.
Replacing the residual current device
When selecting a new product, the buyer must focus on the main characteristics:
- Voltage: 220 V (if you have a single-phase network), 380 V (with a three-phase network). In appearance, they differ, having 2 and 4 connectors in the upper and lower parts, respectively.
- The rated load current must be calculated either for all electrical appliances located in the apartment (if there is one RCD on the input wiring), or for the maximum load of the water heater (device for the boiler). Usually, a product with a slightly higher load current is purchased - from 16 to 100 A. When installing in an apartment, you focus on a current of up to 30A.
Individual RCD for a water heater
- An important point is the leakage current at which the machine trips. A range from 6 to 500 mA is available. In high-quality boilers, the manufacturer can indicate leakage currents (for example, 2 mA), then a separate RCD for the heater is selected at 10 mA. For a common device in the apartment, 30mA will be enough. Old wiring can be an indicator of large leaks, so this factor must be considered.
- The last characteristic that must be taken into account is what type of electricity this device protects from. For an apartment or a small house, they buy products of the type AC (protection against leakage of alternating current) or A (protection against leakage of alternating and pulsating direct current).
Advice! It is necessary to remember the rules for installing an RCD - the total current of all leaks of the home electrical network, taking into account all electrical appliances, should not exceed 1/3 of the rated current of the machine. In the absence of information for electrical appliances, a 0.4 A leakage load current is taken at 1 A. For a mains cable, leakage per meter is about 10 μA.
Make sure that the machine is working or replaced it with a new one, but with turning on the water heater it works anyway. Then move on to the next step.
Water heater check
First you need to inspect the heater surface - power cord, mechanical damage. If these are not found, you need to disassemble the boiler from the bottom side, where the pipes and electronic filling are located.
Water heater check
We disconnect the grounding on the boiler and connect through the RCD. In this case, it will not work if there is a leakage of current to the heater body. Now, with a voltage indicator, we check the protruding parts of the unit (pipes and the housing itself). Typically, with a damaged Ten, leaks are detected throughout the enclosure. Whoever has a multimeter, you can measure the voltage between the place where the leak is detected and the ground wire.
If leaks are detected on the body, turn off the boiler power, disconnect the terminal clamps from one or two heating elements (in some designs of water heaters). To detect in which of the two Tenes there is a leak, measure the resistance between the heating element and its body. Where resistance tends to infinity, the heating element is not damaged. In a faulty Ten, the resistance will have a finite value (about 450 kOhm).
Defective item must be replaced. Remove the flange and remove it from the socket. We buy a new one, designed for the same rated power (for example, 700 watts), install, connect the ground, use it.
Replacing a defective item
If everything is in order with the heating element, carefully check the integrity of the wires with a continuity or by measuring the resistance between the ends. The cause may be damaged wiring.
Important! Do not try to use the boiler in addition to protective devices, especially if the family has small children for whom a small current can become fatal. Call a specialist at home in case of lack of competence in the matter considered. The financial side of the issue is not as important as human life.
