Shutdown Maintenance Services

Servicing of Electrical Installations is one of ON Engineers’ fortes.

The ON Engineers team has extensive experience in preventive scheduled maintenance, calibration of protection relays, on-demand corrective servicing of High Tension (HT) switchgears and transformers, as well as Low Tension (LT) switchboards installed within a premise.

Our skilled engineers have carried out maintenance servicing of electrical installations such as government, commercial, retail, industrial and mission-critical buildings such as hospitals and data-centres and telephone exchanges. Our extensive experience in this area enables us to provide value-added services to many organisations in the public and private sectors.

The benefits of engaging ON Engineers for the Servicing of Electrical Installations are as follows:-

  • Maintenance of high voltage apparatus in accordance with Energy Market Authority's guidelines and manufacturers’ recommendations.
  • Safe and effective operation of an electrical system with minimum risk of breakdown and consequent interruption of power supply.
  • A comprehensive written technical report providing critical data and recommendations after maintenance servicing work, allowing management to have a better understanding of the condition of their electrical system and the areas that require their attention.
  • Advisory and actual services in follow-ups to the servicing, such as repairs and replacements.
  • Besides our pre-servicing, servicing and post-servicing activities, we value-add by offering online storage of servicing reports through our Online File Management System so that they are able to easily access these reports 24/7.
  • Follow-up with our clients to strengthen and maintain their servicing regime.

Activities involved in the service and maintenance includes activities such as:


  • AC High Voltage Test
  • Contact Resistance Test
  • Functional Test
  • Primary Injection for CT Ratio and Polarity Test
  • Secondary Injection Test for Relays


  • AC 50Hz high voltage test
  • AC VLF high voltage test
  • DC high voltage test
  • Dissipation factor test
  • Online and Offline PD measurement
  • OWTS test
  • Polarisation Index test


  • AC High Voltage Test
  • Dissipation factor test
  • DGA and oil quality test for transformer oil
  • Online and Offline Partial Discharge measurement
  • Reconditioning of transformer oil
  • Transformer Repairs
  • Voltage Ratio and Vector Group Test
  • Winding Resistance Test

The main Singapore Standard for Electrical Installation Maintenance is “SS538 : 2008 - Code of Practice for Maintenance of Electrical Equipment of Electrical Installations”


For enquiries, kindly contact us at : +65 6795 4666 or :