213859 / 825260300060
2019-08-07·BA00·III·en·05
Installation Conditions
7
Terminal Box Ex d
8252/1
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10
Installation Conditions
Clearance and creepage distances
- When installing components the clearance and creepage distances between the
individual components and between the components and the enclosure walls must be
sufficiently dimensioned.
- The creepage distances between the components must be tested and observed
according to the guidelines of the relevant operating instructions. The clearance
distances, depending on the rated operational voltage of the fitted terminals, must be
complied with.
- On all terminal boxes, the distance between enclosure cover and connection screws
of the built-in components (with the conductor connected) has to be observed: it must
at least have the value of the required creepage distances, for example
( 14 mm at 1100 V.
Distance between connection parts for intrinsically safe and non-intrinsically safe circuits
- Partitions used to separate connection terminals shall extend to within 1.5 mm of the
enclosure walls, or alternatively shall provide a minimum distance of 50 mm between
the bare conducting parts of the connection terminals when measured in any direction
around the partition.
- The minimum thickness of metal partitions must be 0.45 mm. They must be earthed
and have sufficient strength and stiffness to ensure that they will not be damaged
during connection work. Furthermore, the metal partitions must be equipped with
sufficient current-carrying capacity in order to prevent a burn out or disconnection of
the earth connection under fault conditions.
- The minimum thickness of nonmetallic, insulating partitions must be 0.9 mm. They
must have an appropriate comparative tracking index (CTI) and must be reinforced in
such a way that no deformation can occur.
- When fuses > 4 A are used, care must be taken to ensure that no inadmissible heating
at the terminals of intrinsically safe circuits can occur.
Covers for combinations of non-intrinsically safe and intrinsically safe circuits
- All live parts which do not conform to the "Ex i" degree of protection must be equipped
with an inner cover which meets at least the ingress protection rating IP30 when the
equipment is opened.
Intrinsically safe circuits
- In intrinsically safe circuits only insulated cables and conductors with a test voltage of
at least 500 V AC and a minimum quality of H05 are permitted.
- With regard to the insulation and separation of terminals and cables, it has to be
observed that the insulation test voltage is derived from the sum of the rated
operational voltages of intrinsically safe and non-intrinsically safe circuits.
- The diameter of single conductors/ finely stranded single conductors must not be
smaller than 0.1 mm.
Summary of Contents for 8252/1
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