DB (DISTRIBUTION BOARD)

DB – Distribution board is set of MCBs, ELCBs/RCCBs which are installed in a metal box & is used to distribute electrical power to different loads.

Classification of DB  –1) according to usage, 2) according to supply,

1)Classification of DB according to usage

  • LDB (Lighting DB) – It is used to distribute power to lighting circuits, 6A power points, exhaust fans etc. It is used for maximum 6A/10A current loads.
  • PDB (Power DB) – It is used to distribute electrical power /supply to power loads such as Geyser, Fridge, AC etc. All these items draw high current. MCBs of current rating 16A,20A,25A are used.
  • L&P DB – When DB is use for both lighting & power loads.
  • NDB (Normal DB) – It is used for normal AC supply where load is to be fed from normal power.
  • UPS DB – It is used for UPS supply where load is to be fed from UPS power.
  • Classification of DB according to supply
  1. 3- phase DB –

A 3 Phase DB consists of one no. three phase incoming MCB and a set of single phase outgoing MCBs. A 3 phase DB can be used for Lighting & Power load.  It can be arranged in two ways –

  1. Incomer – One TPN /4P MCB/ISOLATOR along with equal rating of ELCB /RCCB is used and outgoing– single phase MCBs – 4 nos/6 nos/8 nos/10 nos/12 nosper phase are used .  Such arrangements are called 4Way TPN DB/6Way TPN DB/8Way TPN DB/10Way TPN DB/12Way TPN DB. One no. neutral bar per phase & one no. earth linkper phase are fitted in the DB for neutral &earthing wire connections of each circuit.
  2. Incomer – One no. TPN /4P MCB/ ISOLATOR and outgoing single phase MCBs 4 nos/6 nos/8 nos/10 nos/12 nos SP MCBs per phase alongwith SP/DP ELCB per phase are used.  Such arrangements are called 4Way TPN DB/6Way TPN DB/8Way TPN DB/10Way TPN DB/12Way TPN DB. One neutral bar per phase & one earth ling per phase are fitted in the DB.
  1. Single phase DB –

A Single phase DB consists of one incoming and a set of outgoing MCBs. These can be arranged following way –

Incomer – One DP MCB and outgoing–  4nos/6 nos/8 nos/10 nos/12 nos  SP MCBs along with SP/DP ELCB are used.

IMPRTANT TERMS

  • SP – Single Pole (only one point isolation contact where one phase is connected).Application – Switching & protection is done in one phase only.
  • SPN – Single Phase with Neutral. Application – same as above.
  • DP – Double Pole (Two point isolation contacts where Phase & Neutral are connected). Application – Switching & protection is done in one phase & neutral only.
  • TP – Triple Pole (Three point isolation contacts where R,Y,B phase are connected). Application – Switching & protection is done in all 3 phases only.
  • TPN – Triple Pole with Neutral (Four point isolation contacts). R,Y,B phase & Neutral are connectedbut protection is given for 3 phases only, not for neutral.
  • 4P – Four Pole (Four point isolation contacts. R,Y,B & Neutral are isolated & protection is given for 3 phases & neutral)
  • 4/6/8.. Way TPN DB – In this, each phase has 4/6/8/.. MCBs that is why 4 Way TPN DB has 12 outgoing MCBs while 6 Way TPN has 18 MCBs & so on.
  • Phase– Live wire (from where current flows),
  • Neutral – where current returns
  • Earth/Ground – Point which is connected with earthling.
  • Insulator – Material which does not allow current to flow. It is used as a support in DB.