Earth and neutral conductor size and other safety codes for RMG in Bangladesh (Part 3 of 3)

[Part-1 and Part-2 of this article is published] Please check the categorized article in this blog

  1. Earthing cable sizes should be adequate with respect to the phase.


Phase cable size Earthing cable size
Below 4 rm Earthing not less than 3.243 mm2 or 14 SWG.But for the unavailability of this size it can be considered as 4 rm. So it should not be less than 4 rm
4 rm to 16 rm Same size of the phase
25 rm and 35 rm 16 rm
35 above Half of the phase cable size
In case of multiplication at LT panel As it is power cable like 240/300/400/500 rm. Then earthing cable size should be half of the total size. Say,if the phase cable is 6X300 rm then earthing cable will be 6X150 rm or 3X300 rm

Reference: BNBC-2006



  1. Neutral conductor should be of same size with the phase conductor.
  2. Inductive load/sockets (Machines and others socket loads) and lights cannot be connected in same circuits.
  3. Height and area of transformer room of particular KVA or generator room for particular KW is given in BNBC-2006. There are two tables mentioning this.
  4. CB should not have multiple inputs or outputs. No looping at CB terminals is not allowed. (Only 1 or 2 Exception always exists) (Violation may cause loose connections)
  5. One Bus-bar terminal should have one cable with actual size of lug. More than one cable should not be connected in same nut and bolts. No cable should be terminated without lugs. (Violation may cause loose connections)
  6. Rubber mat (insulation) should be present in front of the panel. The thickness should not be less than 5 mm. It should be solid and hard rubber. The length should be like -2 persons can stand side by side.

These above mentioned rules are from the 3 different codes. All have references. There are some other rules also. The rules and codes mentioned in the all three parts under this title are the most important. The existing factory can follow these codes to make their factory compliant. Before designing  a new factory or industry these codes should be kept in mind.

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