The relay, or residual-current device, is the most important part of your electrical cabinet.

In layman terms the relay is also known as a circuit breaker and as the name suggest, it protects against electrical shock in case of an error. This is measured by the device as when the amount of power going into the installation doesn’t match the amount leaving the installation.

If an error occurs in a wire or inside the cabinet, which is connected to a circuit breaker, and linked to a washing machine or another electrical device, the relay will register the error and will disconnect the power. Thereby decreasing the chance of an electrical shock. It is paramount that the relay works correctly, and it needs to be checked 1-2 times per year.

Newer versions of RDC doesn’t cut off the power as easily during a thunderstorm

A sudden overvoltage in the electrical grid due to a lightning striking close by, can cause the relay to turn off the power, even though it wasn’t caused by an actual error. Many have tried arriving home after a vacation and smelling rotten food from the kitchen due to the power being cut off from their fridge due to a thunderstorm.

It can be hard to protect against a sudden discharge due to a lightning striking in the area. The best thing you can do is make sure to have a newer relay installed that does not turn off the power as easily during a thunderstorm. This has to be done by an authorized electrician. A better version of the relay which is called “HPFI” in Danish has to be installed in every new building in Denmark from 1993 and forward. If you are on vacation and worried about your power turning off during a thunderstorm, it can be a good idea to ask your neighbor to check.

NB: The relay does not protect against lightning damage. The best thing you can do to protect against lightning damage is to turn off your power and unplugging electric devises during a thunderstorm. It is also possible to have a lightning rod or overvoltage protection installed. This is something that we are able to help with at PH-EL.

This is how you test your relay

Press the test button on your residual-current device, it is often marked with “T”. If the power doesn’t turn off, your relay isn’t working, and you should have it checked by your local electrician. It is not legal to change or repair your relay by yourself.

If in doubt, whether your relay is working or not, you can always contact PH-EL.

PH-EL is your local electrician

At PH-EL, we are experts at repairing and installing residual-current devices and we are always ready to come by and give advice to both private individuals and businesses.