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Glossary
Distribution board for operation by ordinary persons (DBO) in accordance with EN 61439-3
DBO. In accordance with EN 61439-3, a DBO is a distribution board intended to be operated by ordinary
persons. This is a switching device combination for distributing electricity in applications in residential premises
and other locations where they are intended to be operated by ordinary persons.
Distribution boards intended for operation by ordinary persons (DBO) are manufactured and tested in
accordance with EN 61439 Part 1 and Part 3. Part 3 of standard 61439 defines the specific requirements
for distribution boards intended for operation by ordinary persons (DBO).
A switching device combination that permits operation by an ordinary person must include a type plate
which states EN 61439-3 (VDE 0660-600-3) as the applied standard.
Unique features of such a switching device combination include:
1 They are intended for operation by ordinary persons, including switching actions and replacement of fuse
inserts. They are applications in residential premises or household applications in functional buildings.
2 The output circuits contain circuit breakers intended for operation by ordinary persons. For further information
refer to section 8 of EN 61439-3.
3 The maximum rated voltage to earth is 300 V AC.
4 The maximum rated voltage (Inc) of the output circuits is 125 A: the maximum rated voltage of the
switching device combination (InA) is 250 A. The FWB, FWQ distribution board is intended for a maximum
infeed current of 125 A (rated voltage InA max. 125 A).
5 The switching device combination is intended for distributing the electricity, but may also contain controllers
and signalling devices.
6 The switching device combination is closed and fixed in place.
7 The switching device combination can be intended for internal and outdoors installation (wall distribution
board: indoor installation). The minimum protection class of a DBO for internal installation must be IP2XC.
The minimum IK code for mechanical impact must be IK05 for internal installations. The minimum
pollution degree is 2.
For further information refer to EN 61439 Part 1 and Part 3.
Protection class / IP protection level
The protection class is stated for all switching device combinations with the IP code in accordance with IEC
60529 and proven in accordance with EN 61439 regarding
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protection against the touching of active components and penetration of closed foreign objects,
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the penetration of water.
The protection class is important for the protection against electric shock. The protection class applies to
sheaths, covers and enclosures. The protection class is stated with two IP protection level index numbers
and an optional additional letter.
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The first index number (0-6) indicates the protection against the penetration of closed objects and the
touching of dangerous components.
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The second index number (0-8) indicates the protection against the penetration of water.
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The additional letter (A-D) indicates the protection against the touching of dangerous components.