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  • Author Author: M_B
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The great CNMB boss question

M_B

Following on from my recent blog post about my most common question (terminal blocks for the CNMB din rail enclosure), I was reminded recently of another common one.


The CamdenBoss CNMB DIN rail enclosure has a base which clips to the DIN rail (it can also be wall or panel mounted). On this base is a pair of mounting bosses which can be used to secure the lower PCB to the base. I am regularly asked about these bosses, namely what size screws to use. The simple answer is – you generally don’t need to use them. This is because the PCB is held in position from above (when sitting on the rail) by pillars running down the inside of the body of the enclosure. As long as you sit the PCB on top of the edges of the base (see image below), the PCB will be held securely.

 

image


If however, you want to secure the PCB to the base, we have stock of some screws which you can use. The part number is CNMB/S.

  • Following on from an inquiry earlier this week, I must tell you the boss can be useful after all - when using a heavy PCB. For example on a wider lenclosure, such as a size 6 CNMB, with components like transformers, chokes etc. If you don't screw down the PCB, the PCB might be pressing against the top part of the box and effectively "floating" above the base. If the box is box gets knocked about, there is a danger that the momentum of the PCB floating around causes sufficient force to pop the front off the box. Compare that with the scenario of the PCB being screwed down. Now the PCB is effectively tied down to the DIN rail (the base is firmly clipped on). No floating, no force pressing against the lid.