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Distribution cabinet fuses - protect you from electrical shocks
A circuit distributor, also called a distribution box or fuse box, contains components that ensure that the power is distributed safely and without interference in residential and commercial buildings as well as industrial plants. In our guide you will learn about the different types of fuses for distribution boxes and the basics of how they work.
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About fuse boxes
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Overview of selected distributor cabinet fuses and their functions
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Important when buying fuses for the distributor box
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Our practical tip: Detect defective fuse in the fuse box
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Frequently asked questions about distributor cabinet fuses
About fuse boxes
If the power fails unexpectedly at home or in the office, the first way to the circuit distributor is through. Electrical cables are inserted in distribution boxes for electrical installation, which distribute electrical energy into the individual circuits. The fuses inside protect against short-circuits and overload of electrical cables and devices. If the current is exceeded, the current flow in the fuse box is interrupted automatically.
Fuse boxes are available as surface-mounted and flush-mounted versions. They are divided into sub-distribution and main distribution. The main distribution follows directly on the transformer of the transformer station. The main distribution cabinets can be found either in the transformer station or in their vicinity. The cables of the main distribution system lead to several sub-distributors – the respective house connection of office, trade or apartment. Subdistributors are usually installed in the house connection room or in the basement and supply the individual circuits of a house with power from there. If there are several accommodation units, each apartment will have its own distribution list.
Meter cabinets or fuse boxes used in electrical installations are standardized. The standards refer to the size, installation series or DIN rails on which individual components can be mounted, their distances to each other and more.
Overview of selected distributor cabinet fuses and their functions
Numerous different electrical components are involved in the distribution of the current. These include, for example, contactors, terminals, relays, timers, miniature circuit breakers, ground fault circuit breakers and fuses. In some distribution boxes, electricity meters are directly integrated, while in other cases they are housed in a separate meter cabinet.
In the following we list some important fuses in fuse boxes and explain their function:
Line protection and residual current switch
Miniature circuit breakers (or miniature circuit breakers) interrupt the current as soon as fault currents occur or a short circuit or overload occurs.
Their shut-off mechanism is thermally triggered, i.e. by heating, or electromagnetically by a short circuit or by additional modules. Manual activation is also possible. For this purpose, the switch (toggle switch) must be turned over or the release button must be pressed.
RESIDUAL CURRENT circuit breakers (RESIDUAL current circuit breakers) are of fundamental importance for safety and protect against electric shocks when handling defective devices. They are released as soon as there are any abnormalities in the circuit. This is the case if a damaged or uninsulated device is touched and this could cause electric shock.
Melt, fine and NH fuses
Fuses have a fuse conductor that melts and is triggered if the rated current is exceeded. Such fuses are not repairable. After triggering, the fuse must therefore be replaced.
Fine fuses are device protection fuses with a melting wire that ensure that electrical devices are protected against defects if the rated current is exceeded.
LV HRC fuses are high-performance, low-voltage fuses used in large electrical installations (such as industrial installations) or in main distribution units, which are switched off in the event of a short circuit or overload current.
AFDD
Fire protection switches protect against cable fires. As soon as fault arcs are detected by loose contact points, for example, they switch off.
Poor insulation, cable wear, damage to electrical cables caused by construction work or cables with breakage and/or kinks could otherwise lead to fire.
Important when buying fuses for the distributor box
In our online shop you will find a wide selection of additional fuses and accessories for electrical installation in the distributor. Before purchasing individual components, the installation of the sub-distribution should be well planned. Check the number of circuits in the sub-distribution and consider how many fuses of one type are required.
In order for the sub-distribution to work smoothly, the basis must be correct – you need enough space for the planned and, if necessary, future power supply in the distributor. The following aspects play an important role in the selection of the backup elements:
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Product type: Micro fuse, RCCB, miniature circuit breakers, fuse monitoring and more
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Nominal current: Check the rated current of the components
- Number of poles: In our online shop you will find security elements with one, two, three or four poles
Four-pole switch disconnector
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Trigger characteristics: This information tells you under which conditions a switch is triggered; among other things, fast-acting, slow-blow and medium-blow variants as well as models of trigger characteristics B, C, D and others are available for selection
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Measured differential current: This value defines the maximum permissible differential value at which a shutdown occurs
- Fuse size: For installation without problems, a look at the fuse size is recommended
NH fuse
NH fuses are available in different sizes
Our practical tip: Detect defective fuse in the fuse box
Defective fuses can be identified by the fuse wire cut through – at least for models with glass housing. Ceramic models often have a protruding wire. If you are not sure, it is best to use a continuity tester. Defective switching fuses must be identified by means of a clearly marked switch position. If the reason for triggering is unclear, it is advisable to replace the model with an equivalent one.
Frequently asked questions about distributor cabinet fuses
What was the trigger characteristic?
There is a so-called trip characteristic for safety switches. From this, you can derive from when a thermal or magnetic triggering occurs.
What was to be observed when installing a distribution box?
First of all, there must be enough space in the sub-distribution and main distribution housing for all built-in devices. This also includes elements that will be retrofitted later. In addition, the box should be mounted at an easily accessible height in a room that can be accessed quickly and easily. Warning: The open door of the sub-distributor or main distributor must not block escape routes.
How many separate circuits are required?
3 circuits for²up to 50 m sockets, lighting, large and small electrical appliances – in every residential or commercial unit there are numerous electrical appliances, which have to be supplied with power via sockets. The number of separate circuits required depends, among other things, on the living area. For this purpose, there are guidelines for rough orientation:
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4 circuits for up to 75 m.²
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5 circuits for up to 100 m.²
Please note that the values must be adjusted to suit individual requirements. Powerful electrical appliances require their own circuit.