Earthing or grounding (toma de tierra)

What earthing is for

Every appliance with a metal casing and every socket is connected to the earth through the green and yellow cable. If an internal wire touches the casing, the current finds an easy path to the ground instead of through your body. That leak trips the RCD (diferencial). Without an earth, the casing stays live until someone touches it.

It is also essential for the surge protector, which diverts voltage spikes to earth.

What it consists of

• Earth rods driven into the ground or a buried copper conductor, usually under the building’s foundations.
• Main earth line to the meter room and the fuse box.
• Protective conductor on every circuit, to each socket and appliance.

It is governed by ITC-BT-18 and, for homes, ITC-BT-26.

How to tell if you have it

Earthed sockets have two metal side clips. A green and yellow cable should reach the fuse box. But having the cables does not guarantee the earth works: the earth resistance has to be measured with an earth tester and continuity checked to every point.

Is it compulsory?

Yes. The REBT requires installations to be earthed, and it is one of the first things checked when issuing a boletín or rewiring an old flat. Many old flats in Seville have none. If taps or the washing machine give you a shock, the earth is probably missing or broken.

Guide price

Installing or improving the earthing costs an estimated 250 to 600 euros plus VAT, depending on access to the ground. See electrical safety in Seville, Spain.