Contact Building and Energy
For licensing and technical enquiries
Contact us
Building and Energy general queries
Tel: 1300 489 099
Fax: (+618) 6251 1501
be.info@demirs.wa.gov.au
Oil-insulated high voltage (HV) combined-fuse switches Order 02-2015 issued to all persons working on and owners and operators of oil-insulated high voltage combined-fuse switches
Pursuant to s.18B of the Energy Coordination Act 1994, this Order dated 23 March 2015 is issued to and affects all owners and operators of electrical installations incorporating oil-insulated high voltage (HV) combined-fuse switches.
On 3 February 2015, electrical workers were engaged to perform maintenance on an 11kV oil-insulated combined-fuse switch. A violent explosion occurred caused by a high-current fault within the switch tank. Most of the insulating oil in the tank was vaporised instantly.
The type of switch involved is designed to permit a work practice whereby the three fuse cartridges immersed in the tank can be changed while the in-coming high-voltage bus bars at the base of the tank remain energised.
This accident is under investigation by EnergySafety and WorkSafe WA. While the investigation is not complete, it appears that there has been a short-circuit fault in the switch tank following the rupture and disintegration of a HV fuse within the unit.
Based on evidence obtained thus far from the investigation, I have formed the opinion that it is dangerous to carry out the above-mentioned work practice on HV oil-insulated combined-fuse switches, unless they are first completely isolated from the electricity supply.
Moreover, if one or more fuses have operated, they may have disintegrated, releasing conductive components into the switch tank. The act of operating the switch or earthing mechanisms may increase the probability of such components causing a short circuit with the live bus bars lower in the tank.
Therefore, safeguards are justified to protect those called upon to carry out electrical work repairs or other maintenance on such switches. My reasons for reaching this opinion are:
This Order applies to all HV oil-insulated combined-fuse switches produced by any manufacturer, including but not limited to the following:
Last modified: