Prof. Dr. Thorsten Jungmann (last updated 2025-09-03)
1 What does it look like?
A multiple socket-outlet (German: Mehrfach-Steckdose) consists of a plastic housing with several integrated protective-contact socket-outlets, possibly with a cover or an integrated child-protection device (protection against contact). At the side or at one end is the permanently connected supply cable with a plug for the mains supply. In some cases, a switch with an indicator light as well as fuses or surge protection are integrated.
2 What can it do?
It allows you to connect several electrical devices to a single socket-outlet. In addition, by means of a switch or integrated surge protection, it can switch or protect the connected loads together.
3 How does it work?
Inside, the contacts of the individual socket-outlets are connected in parallel to the supply cable. When the multiple socket-outlet is plugged into the mains socket-outlet, the mains voltage is present at all socket positions. Switches interrupt the contact on both poles (L/N). In this way, devices can be switched on and off centrally.
4 What does it look like inside?
Inside there are metal bars or contact strips that distribute the line conductor, the neutral conductor and the protective conductor to all socket positions. The supply cable is permanently connected and leads to the mains plug. Optionally, switches, fuses or protective components (e.g. varistors) are built in.
5 What role does it play in teaching?
The multiple socket-outlet is suitable as an example of the parallel connection of loads and illustrates the topics of current division, cable cross-section and overload. It also shows how additional functions such as switches or protective circuits are implemented in practice.
6 What role does it play in practice?
Multiple socket-outlets are widespread in households, offices, laboratories and workshops. They make it easier to connect several devices, but they also involve dangers: overload (the classic: three waffle irons on one multiple socket-outlet), heat build-up and fire risk if used improperly. High-quality versions with a sufficient cross-section, child protection and surge protection are recommended.
Symbols
- Letter code in schematics: X