You can be reasonably sure that your electrical equipment is safe to work on if all sources of energy (electrical, mechanical, gas, pneumatic, hydraulic, pressure etc) have been securely isolated and any stored energy has been released from the equipment. You should always follow the procedure, as set down in the manuals provided by the equipment manufacturer, and any local safety rules. If you can’t find the manuals, contact the manufacturer and get them to send you manuals or download one online before you start work.
Equipment containing dangerous chemicals or other substances may have to be decontaminated before it is safe to work on. You should ask a competent person what to do in these instances.
It is important to ensure that there is no chance a source of energy can be deliberately or inadvertently reconnected to the equipment while being worked on. This can be achieved by applying a lock to each isolation device.
The person doing the maintenance should have all the keys to these locks in their possession. Warning notices should be posted at the points of isolation.
If work is to be carried out on or near exposed conductors, the conductors should be proven dead, using appropriate test equipment, before work commences.