14/04/2020

Which residual current device (RCD) should I install?

Close-up of a row of electrical terminal blocks with blue wires connected, in an industrial setting.

Which RCD should I install? Are you a PV installer and wondering which type of RCD to install in which situation? Check out the tips below!

What does an RCD do?

An RCD protects people against electric shock. In PV systems, a separate combined RCD (alumat) is often recommended. If you connect the inverter to an existing circuit, a fault can cause all circuits to trip—problematic if, for example, the boiler stops working. A separate RCD prevents this from happening.

Which type of RCD do you need?

Residential: 30mA, 100mA or 300mA type B alumat
Non-residential / 3-phase inverters: 300mA type B Always check the manufacturer’s datasheet to determine the correct type.

Most inverters come with internal leakage current detection. However, an external RCD is still essential to provide additional protection for cables and to prevent dangerous situations.