Download - Electrical Thumb Rules - 6
Electrical Thumb Rules You MUST Follow (Part 6)PostedNOV 29 2013byJIGUPARMARinENERGY AND POWERwith2 COMMENTS
Electrical Thumb Rules You MUST Follow, Part 6 (On photo: View in the Transformer Room in the underground area during White House renovation on March 26, 1952 - via trumanlibrary.org)
Continued from:Electrical Thumb Rules You MUST Follow (Part 5)
12 electrical thumb rules to follow:1. Transformer earthing wire / Strip size2. Motor earthing wire / Strip size3. Panel earthing wire / Strip size4. Electrical equipment earthing5. Earthing wire (As per BS 7671)6. Area for transformer room: (As per NBC-2005)7. Span of transmission line (Central electricity authority)8. Max. lock rotor amp for 1-phase 230V motor (NEMA)9. Three phase motor code (NEMA)10. Service factor of motor11. Type of contactor12. Contactor coil1. Transformer earthing wire / Strip sizeSize of T.C or DGBody EarthingNeutral Earthing
55 KW506 mm GI Strip
Go back to Rules
3. Panel earthing wire / Strip sizeType of PanelBody Earthing
Lighting & Local Panel256 mm GI Strip
Control & Relay Panel256 mm GI Strip
D.G & Exciter Panel506 mm GI Strip
D.G & T/C Neutral506 mm Cu Strip
Go back to Rules
4. Electrical equipment earthingEquipmentBody Earthing
LA (5KA,9KA)253 mm Cu Strip
HT Switchgear506 mm GI Strip
Structure506 mm GI Strip
Cable Tray506 mm GI Strip
Fence / Rail Gate506 mm GI Strip
Go back to Rules
5. Earthing wire (As per BS 7671)Cross Section Area of Phase, Neutral Conductor(S) mm2Minimum Cross Section area of Earthing Conductor (mm2)
S 200 HP11.1511111
Go back to Rules11. Type of contactorTypeApplication
AC1Non Inductive Load or Slightly Inductive Load
AC2Slip Ring Motor, Starting, Switching OFF
AC3Squirrel Cage Motor
AC4,AC5,AC5a, AC5b,AC6aRapid Start & Rapid Stop
AC 5aAuxiliary Control circuit
AC 5bElectrical discharge Lamp
AC 6aElectrical Incandescent Lamp
AC 6bTransformer Switching
AC 7aSwitching of Capacitor Bank
AC 7bSlightly Inductive Load in Household
AC 5aMotor Load in Household
AC 8aHermetic refrigerant compressor motor with Manual Reset O/L Relay
AC 8bHermetic refrigerant compressor motor with Automatic Reset O/L Relay
AC 12Control of Resistive Load & Solid State Load
AC 13Control of Resistive Load & Solid State Load with Transformer Isolation
AC 14Control of small Electro Magnetic Load (72 VA)
Go back to Rules
12. Contactor coilCoil VoltageSuffix
24 VoltT
48 VoltW
110 to 127 VoltA
220 to 240 VoltB
277 VoltH
380 to 415 VoltL
Go back to Rules