The residual differential (DR) which is also known as the residual differential switch (IDR) is a mandatory protective device in all electrical installations, but not all of them use it. Knowing how to install a DR should be something common, but many have doubts and knowing that we will teach step by step how to install a residual differential by a connection scheme, in addition to explaining what is a residual differential switch and what a DR is for, come on guys!
What is a DR and what is the application of DR?
In a very simple way, the residual differential (DR) is a protection device used inside electrical installations, it works as an automatic switch, which allows to de-energize the circuit whenever there is a current leak higher than what the DR is able to detect. By perceiving this leakage of electric current, the device also contributes to avoiding the increase in the value of the electric bill, as it does not allow unnecessary expenditure of energy due to leakage of electric current.
Therefore, its main objective is the protection of users against electric shocks, as it disarms immediately after detecting the leakage of current to the individual’s body, because in this way it significantly minimizes the serious consequences of electric shocks.
It is important to note that the DR protection device is mandatory in all installations, but especially in environments that offer greater risks of electric shock , such as, where there are electric or electronic showers and / or bathtubs.
Tips on how to install a dr
Now that we know what a residual differential device is and what it is for, we can explain how to do the installation, but first we need to take some care during the installation and pay attention to certain occasions.
- Before using the test devices, make sure they are working, test in trusted places with circuits that you know are active or not.
- We recommend that the general circuit breaker be turned off and that you inform everyone who is present at the facility that you will be working at that location, thus preventing anyone from turning the circuit on again while doing the work.
- Even at low voltage, an electric shock can be fatal under certain conditions. So, as a recommendation, have a padlock so that you can lock the meter and no one turns the circuit on without you being aware. Right after switching off, make sure that the location where the DR will be installed is de-energized.
- Do not install the DR device in a box for which it has not been designed or does not support the required number of components, do the sizing first!
- If you are unsure about the instructions given, do nothing.
Materials and tools
It is important to use the right tools, depending on your purpose, so use materials and tools of good origin and quality to minimize risks during installation, in addition to contributing to a quality and better finish installation. To do the installation you will need:
- Residual differential switch (IDR)
- Hang tags
- Stripping pliers
- Cutting pliers
- Screwdriver or “Philips”
- Test key
Installing the DR device
If you are adding the DR in a circuit distribution board (QDC), check the position of the other devices, where it is input and output, to maintain a standard of organization, reducing the chances of errors. The same should happen if a new installation is made in QDC.
Fix the devices according to your model, so that the residual differential device is fed from above and its outlets from below, maintaining standardization and respecting a certain order. The same should occur if more DR devices are installed.
With the help of stripper pliers, strip the conductors and power the device, there is no correct polarity for the DR, the only specification is where the neutral cable will be connected, but we always recommend maintaining a standard of supply for the components.
The diagram below shows the assembly of a circuit distribution board with a surge protection device (DPS) and a DR. So that the residual current is switched on right after the general circuit breaker, with the same phase being connected in the DPS and derived for the DR. The cables that leave the IDR are derived at the circuit breakers of the other circuits.
In this system, the neutral conductor is connected to a DPS and soon afterward it is also derived for the DR. The neutral leaves the Residual Differential and is connected directly to the neutral bus.
All conductors must be well fixed, make a test and lightly pulling the cables, in this way you check if they are really well attached to the terminals. Before closing the QDC connect the circuits and do the tests, to check if everything is right and if there is no irregularity.
The video below shows the step-by-step assembly of the scheme mentioned above. It is intended to show how to connect all the components and separate each circuit.