What's the difference between a socket with earth and one without?

The "schuko" socket (with the two side earth contacts) has been the standard in Spanish homes for decades, but sockets without earth are still installed by mistake in places where the regulations require it.

Where earthing is mandatory

The REBT requires an earth connection on all general-purpose sockets in a home, and especially strictly in the kitchen, bathroom, utility room and any damp area, where it is also combined with the circuit's residual-current protection. There are practically no reasonable exceptions left in housing: every new socket must have earth.

Why some old installations don't have it

In installations more than 30–40 years old it's common to find sockets without earth, because at the time it wasn't mandatory or the installation was done before it became widespread. It isn't just a cosmetic problem with the socket: if there's no earth at the socket, there's no earth conductor in the cable up to that point either, so replacing the accessory isn't enough, the cabling must be reviewed.

What to check before quoting a partial renovation

Before pricing "changing a few sockets", it's wise to check with a voltage tester or multimeter whether there is an earth conductor in the box. If there isn't, the item stops being a simple accessory change and becomes a cabling job, with its corresponding cost.

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