A residual current device is an electrical product that controls the difference between the incoming and outgoing currents, and if the set parameter is exceeded, it disconnects the network. A must-have thing in modern electrics that is responsible for safety. But a few common mistakes when connecting a device can change its functionality. How to prevent this - further in the article.
The main mistake: installing one RCD per input
Many residents of apartments or private houses prefer to kill two birds with one stone: connect one common RCD and at the same time save money without installing products on each line requiring such protection, in separately.
Why such an installation is not entirely correct:
- When an RCD is triggered, it is difficult to determine which consumer the "phase" is hanging on: a refrigerator, air conditioner, hob or washing machine.
- The device can work even with a banal turning on of a powerful appliance, for example, four burners on the hob (consumption on average 5-7 kW).
Therefore, it is better to spend money and install an RCD on consumers who really require it: a boiler, a washing machine, etc.
Connecting "zero" after the RCD to the common bus
The problem that relates to the above paragraph. Some masters think that after the RCD, the neutral wire can be connected to the common bus, after which the conductors will be laid to their consumers. But this is not the case.
With such an installation, any switching on of the electrical device will be perceived by the protective device as exceeding the same current difference established by the manufacturer. Consequence: permanent tripping of the RCD. And every extra on / off - a decrease in performance.
Installation of an RCD without a circuit breaker
But this mistake can have serious consequences.
Important! RCD does not protect the network from short-circuit currents, but only from leakage, which can be dangerous to the life or health of users. RCDs should be installed exclusively in tandem with a circuit breaker.
You can also purchase another device - a differential machine, which is an ordinary bag and RCD "in one bottle". Such a device is more expensive, but it also performs 2 functions at the same time.
Installation of an RCD on a line with a protective "zero"
A certain caste of "master electricians" prefers not to delve too much into the protective lines of the object, but simply install the RCD in the shield, even if the working "zero" in it is connected to the protective one. In this case, you will have to refer to the regulatory documents - SP 31-110-2003.
This set of rules for design and construction at the end has a useful Appendix A, strictly regulating the use of RCDs. Clause A.4.3. states that the RCD cannot be installed on lines in which the neutral working conductor is connected to the protective one. Also, do not mount devices on the ground line. This is a serious violation and can lead to equally serious consequences.