I’m putting together some junction boxes for domestic lighting using RS own brand DIN terminals in a suitable enclosure (home automation later would favour grouping the wiring into a limited number of JBs with space to accept relays later).

One thing that came to mind was to do with these:


They are the special DIN terminals that have a screw operated clamp to the DIN rail which claims to provide electrical continuity.

How might I decide if these would provide suitable and reliable continuity for the circuit CPC on say a circuit protected by a C10 RCBO? Or do you reckon they are just fine?

Points I’ve considered:

Reliability – these clamp to a plated steel rail – so providing the plating holds and the rail does not corrode, then OK Clamping action seems positive.

Contact resistance: haven’t attempted to measure yet, but I suspect it would be off the bottom of the range of my Megger.

Fault current – worst case scenario: hundreds of amps but no more than 1kA for a very short time.

There is a little leeway in that the circuit is RCD protected, but I feel it would be bad practice to factor that in as a key design consideration.

What do you folk think of such devices?

Many thanks,


1 Answer 1

  1. The link does not show any device.
  2. Ground connection via clamping to the DIN rail is industry standard since many decades, but the rail and clamp ratings must be considered.
  3. DIN rail corrosion is only a problem in aggressive environments like salt water, chemical industry etc., if the box has a low IP code. The plated rails normally do not corrode even after half a century. Furthermore, a closed junction box does have a slightly higher temperature thus lowering the possibility for corrosion.
  4. There are special types of DIN rails made of aluminum or copper to ensure low resistance. In some countries a normal steel DIN rail must not be used for the PEN, but can be used as pure PE.

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