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Terminal blocks - no fusing down?

M. Joshi

Whenever transitioning from a preceding supply cable protected by a higher current circuit breaker or fuse, I always fuse down before connecting the appropriate lower gauge wire.

 

What I wonder is then how such distribution blocks like these Weidmüller AWPD 35 4X6/6X2.5 are safe:

 

336b015b6f6025bb0464050c14dff2fc-huge-weidmuller-awpd-35-4x6-6x2-5.png
35mm² to 2.5mm²
  • 0

    We also need to remember that there are two parts to protection against overcurrent:

    (a) Protection against overload current; and
    (b) Protection against fault current.

    Now, (a) requires “fusing down” but this is entirely possible if the overcurrent protective device is installed downstream of the reduction in current carrying capacity, but upstream of the point at the circuit is potentially subject to being overloaded, e.g. the point(s) of utilization.

    and (b) does not necessarily require “fusing down” at all, provided that the requirements for thermal constraints in fault conditions are met.

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