Combi earth leakage circuit breaker

How do you protect yourself from fires in electrical installations? Which devices prevent fires? How do you find the right fire protection switch and what specification should you pay attention to? This eibabo® catalog contains combination RCCBs/line protection with a focus on fire protection. Did you know that about a third of the fires in Germany inside buildings have an electrical origin? Three quarters of this can be traced back to electrical devices or the electrical installation. How can you face this danger? Electricity is omnipresent and it is impossible to imagine our everyday lives without it. As a rule, the classic measures for protection against overload, short circuits and residual currents are considered sufficient and comprehensive fire protection is therefore also assumed. But this protection is not unlimited. In this article, we will bring you closer to the function of suitable fire protection switches and arc fault circuit breakers.

Source: eibabo®, ABB DS ARC1 C20 A30 fire protection switch Image: ABB DS ARC1 C20 A30 fire protection switch

What is a combination RCD/line protection with fire protection function?

If switches for fault currents and line protection are combined, this results in FI/LS combination switches. These protective switching devices combine the functionalities of residual current circuit breakers and miniature circuit breakers. What are these properties? A residual current circuit breaker prevents you from getting a dangerous electric shock if you touch something that is live. This switch provides personal protection that ordinary fuses and a circuit breaker cannot provide. A circuit breaker is an electromechanical device used to protect a circuit from excess current caused by either an overload or short circuit. So while a residual current circuit breaker only protects people from electric shocks caused by ground faults and a miniature circuit breaker is only used to protect against overcurrent, the combination of both switches offers comprehensive protection against both types of faults.

Good to know

An arc fault switch is an arc flash detection device. Its purpose is to detect the presence of dangerous electrical arcs and to isolate the affected circuit.

Added to this protection is another safety feature - arc flash detection. Devices with this capability are referred to as fire circuit breakers, arc fault circuit breakers, or AFDD. The abbreviation AFDD stands for the English term 'Arc Fault Detection Device'.

Why do I need a fire protection switch?

Fusing with an RCBO combination switch already protects against many dangers. But there is a kind of error that the classic RCBO combination switch does not recognize. These are arcs within a cable or connection. But what is an arc? An electrical arc occurs when electrical current crosses a physical separation between two conductive materials. If only little current flows, a short-term spark is produced. If the current is high enough, a continuous arc is generated. This can result in temperatures of over 6000°C and gaseous air turns into plasma. In principle, arcs are not a problem as long as they are generated in a controlled manner, for example in an electric motor or in a light switch. However, when accidental arcing occurs in a circuit, a fire can occur due to the intense heat from combustible materials. Common causes are:

Damaged insulation of current-carrying conductors
Faulty cable connections and line connections

These causes are often caused by improper handling. These include:

kinking, crushing and twisting of cables and lines
damage caused by screws, nails or drills
loose connections between two cable ends
Poor cable protection and mounting (damage from mechanical stress, movement or rodents)

To minimize the risk of fire from these faults, fire protection switches have arc fault protection devices and offer protection against serial and parallel arc faults. A serial arcing fault occurs between two parts of the same phase of a line. A parallel arcing fault occurs when the arc occurs between the phase conductor and either the neutral conductor or the earth conductor.

How does the arc fault protection device work on a fire protection switch?

Fire protection switches continuously monitor the waveform of the electrical current flowing through one or more circuits. Arcs affect this current flow. If the device detects an unusual signature in the wave, the circuit is broken. 'Normal' arcs that occur during the operation of electrical systems (e.g. in the electric motor) are recognized by the device as harmless. With these, the protective mechanism does not trigger. But beware! A fire protection switch does not recognize:

Phase-to-earth fault such as a residual current circuit breaker
Line-to-neutral fault like a circuit breaker
Overload like a circuit breaker

For this reason, the fire protection switches are usually available in combination with RCBOs or are combined with them in the control cabinet.

When should I buy a combination RCD/line protection with fire protection function?

Basically, we always recommend not to save on your own safety. Even if a fire protection switch is not necessary to protect all circuits, the damage in the event of a fire is usually higher than the additional costs for such a device. Of course, you have to weigh the risk yourself. In certain facilities and parts of the building, however, the use of a fire protection switch always makes sense. This can be:

Institutions with valuable goods (jewelers or museums)
Rooms with combustible contents (barns, laboratories)
oxidizing structures (chimneys, elevator shafts)
Buildings open to the public (hotels, retirement homes, youth hostels, hospitals)

If you decide against the installation of fire protection switches, please pay attention to the smell of burning from cables or sockets in everyday life. It doesn't have to be an arc fault, but if you smell burnt, you should always look for the cause. Also, if any cord or appliance feels hot to the touch, turn off the affected circuit immediately and, for permanent installations, contact an electrician.

for your safety

Fire alarms and smoke alarms are additional safety devices that you should never do without in your building. You will find high-quality and reliable devices in our shop. Use our intelligent search.

Beware of rapid 'clicking' noises and burn marks on electronic devices. Turn off the affected circuit and have an electrician check the system.

What types of fire protection switches are there?

As a global electronics retailer, the eibabo® technology store has an extensive range of fire protection switches. Available are:

stand-alone devices that you can install in series with a suitable protective device (miniature circuit breaker or residual current circuit breaker).
Device combinations that unite the fire protection switch with a combination RCD/line protection
Additional modules for other protection devices, which are usually only compatible with the protection devices of the respective manufacturer

What should I look out for when buying a combination RCD/line protection with fire protection function?

The choice of the right switch depends on the tripping characteristics, as is the case with classic RCBOs. There are, among other things, type B and type C combination switches. The main difference lies in the tolerance to the strength of the current surge, which leads to the disconnection of a circuit.

TIP:

Higher inrush currents can occur when lighting or motors are switched on. Your selected device must be able to distinguish these load peaks from actual errors.

Devices with B characteristics are typically used for normal household and non-critical commercial applications. These trigger at residual currents that correspond to three to five times the nominal current. Choose type C devices for commercial and industrial applications. These trip at five to ten times the nominal current.

Make sure you choose a reputable manufacturer. With no-name devices, reliable operation cannot be guaranteed and they deviate significantly from the specified values. In our shop you only get the best quality from leading manufacturers such as ABB, Doepke, Eaton and Hager.

Catalogue content:

In this eibabo® catalogue Circuit breakers and fuses > Earth leakage circuit breaker with auxiliary device you will find items from the following product groups: