The purpose of this electrical method statement is to define and implement correct practices for the precommissioning & commissioning of submain Distribution Boards SMDB.
By following the guidelines contained herein contractor shall ensure that the job execution complies with the project requirements and serves the intended function to satisfactory level of the client, also conforming to applicable standards and regulations.
Required Tools for SMDB Testing
- Portable Hand tools
- Step Ladder
- Insulation resistance tester
- Multimeter
Precommissioning Checks for SMDB
Ensure that the Sub main Distribution Board installation is complete and all mechanical & electrical comments on installation are completed & approved.
Also make sure that no damage has occurred between the period of mechanical completion & precommissioning.
Check the SMDB installation is free of any kind of construction debris and humidity etc.
Repair / replace damaged components, if any.
Ensure that the SMDB are properly tagged & identified location wise and service wise as specified.
Make sure that the wiring termination to the SMDB Sub main Distribution Board are complete, tight & secure.
Ensure that the outgoing cables from the SMDB are terminated in the respective distribution boards / equipment as per approved detail drawings and electrical layouts.
Check and ensure that the earthing of the SMDB has been completed and approved by client/consultant.
Ensure the availability of main power supply to the submain distribution board.
Also make sure that the incoming cables to the SMDB are properly tagged and identified as per cable schedule.
Ensure that the rating of the breakers (MCCBs) are as per approved shop drawings & schedules.
Make sure that the metering connections are proper & the meters are in healthy condition.
Check manually all the function of breakers in the SMDB.
Also check that the termination of the cables to the bus bars are tightened properly and as per torque as applicable.
Ensure that all manufacturer’s instructions are carried out as stated in test procedures of SMDBs.
Insulation Resistance Test For SMDB
Isolate all incoming & outgoing cables.
Apply a voltage of 500 volts DC between phase ‘R’ to Earth for 1 minute with phase Y,B & N shorted & earthed & record the values.
Repeat the test for other phases as well.
Commissioning Procedure for Sub main Distribution Board SMDB
Ensure that all the precommissioning checks are carried out successfully.
The incoming supply of the Submain Distribution Board shall be energized & the supply shall be measured for current & voltage.
Outgoing feeders shall be energized one by one & the supply shall be measured for current & voltage.
Check the metering functions for proper operation & correct readings.
Also check the earth leakage trip settings.
Check the circuit breakers on/off function.
Attachments
- Precommissioning check sheet for SMDB
- Commissioning check sheet for SMDB
- Risk Assessment
- Manufacturer’s instructions