Any power grid rests on two pillars - short circuit protection and current leakage control. The first will save the wiring in the event of a malfunction, and the second will protect users. And if it is enough to install a circuit breaker from a short circuit, then an RCD is required to protect against dangerous potential. And how to properly mount it without grounding - we will understand in this article.
Why do you need an RCD at all?
Let's consider a typical situation. The most popular household appliance is a washing machine. And as a result of long-term operation, the insulation of any phase wire inside the machine is frayed, the bare core comes into contact with the body, after which the very dangerous one appears on it potential.
It is enough to touch the live body and the person acts as a conductor. But there is another problem - if the touch is unsuccessful, the arm muscles can contract and it will not be so easy to unclench them. The situation is dangerous and could end in disaster.
The residual current device compares the incoming and outgoing currents and in the case of a "runaway" (the person fulfilled the role of the load - he touched the body of the washing machine) simply disconnects this line. RCD will not work on short circuit or heating of conductors, only on current leakage.
Several options for connecting RCDs without grounding
It is important to remember that any RCD must be combined with a circuit breaker, since these are 2 completely different switching devices that perform different functions. But for reliable network protection, both packet traps and RCDs are needed.
Connecting one main RCD
The most popular option, in which only one residual current device is connected in the electrical room. This RCD must be connected immediately after the input circuit breaker: "phase" comes from the machine, and "zero" - from the zero bus. After the device, the phase and neutral wires are connected to other groups of circuit breakers.
The main disadvantage of this scheme: when the RCD is triggered, there will be no electricity in the entire dwelling.
Connection of several RCDs in one cabinet
The difference between this scheme is only that after the introductory RCD, several more of the same devices to protect individual consumers, for example, washing machine, water heater, refrigerator, etc.
The disadvantage of such a scheme is additional spending on the purchase of not one, but several RCDs. But there is also a significant plus - if a current leak appears in the network, then only one specific residual current device will work, leaving the remaining lines energized.
As for me, this is the most convenient and reliable connection option. And spending a few additional devices will pay off a hundredfold in the future.
Summing up
Both in the first and in the second case, the installation is carried out without a ground loop and this does not cause any individual difficulties. As well as the dangers in the further operation of the network. It is only necessary to correctly equip the electrical panel and correctly perform the wiring for individual groups.