MV Switchgear — Live-Cleaned, Insulation Resistance Improved

The brief

A Perth distribution facility had been deferring its switchgear cleaning maintenance for two years because the only window for shutdown was a planned outage that kept getting pushed. Dust accumulation on insulators and busbars was reaching levels that the reliability engineer was uncomfortable with.

The ask: clean the equipment without shutdown. The site had an existing safety case for live cleaning of LV equipment, but had never extended to MV. We worked with the asset owner’s electrical authority to develop the procedure and run the work.

The work

We approached this the way we approach every live electrical job — slowly and with extensive risk assessment.

Pre-work. Site walk-through with the asset owner and electrical authority. Risk assessment, safety case extension to cover MV with our specific equipment and procedure. PPE requirements: arc-rated suits, face shields, voltage-rated gloves, hot-stick technique for any contact with the panel.

IR baseline. Insulation resistance test on each of the three panels before any cleaning. Recorded for handover.

Cleaning. Pellet feed at low pressure (60-70 PSI) — much lower than industrial cleaning. Worked from top of each panel down, with a 60-degree spread nozzle. Particulate captured by a HEPA-filtered vacuum positioned at the base of each panel.

IR retest. Insulation resistance test after each panel. All three panels showed measurable improvement in IR — typical when accumulated dust has been carrying surface conductivity.

Documentation. Per-panel photo log, IR test sheets, and cleaning record signed by the asset owner’s representative.

The result

• All three panels cleaned in a single day
• Zero shutdown of the facility’s MV system
• IR readings improved across all three panels (8-15% improvement on each)
• Safety case now formally extended to cover annual MV switchgear cleaning
• Site has since contracted us for annual cleaning across all six switchrooms

The annual contract is now in its third cycle. Industry talk at the asset owner’s parent group has the same approach being trialled at two sister sites.