You can find out if your electrical equipment is safe by carrying out suitable checks, such as inspection and / or testing. The level of inspection and / or testing should depend upon the risks. A simple visual inspection is likely to be sufficient for equipment used in a clean, dry environment. In addition, equipment that is more likely to become damaged, or is operated in a harsh environment, is likely to require more demanding electrical tests. 

Checks should be carried out often enough to ensure there is little chance the equipment will become unsafe between checks. It is good practice to make a decision on how often each piece of equipment should be checked, write this down, make sure checks are carried out accordingly and write down the results. You should change how often you carry out checks, according to the number and severity of faults found.

The best way to find out if specialised equipment is safe is to have it inspected and tested by a person with specific competence on that type of equipment. This may be the original manufacturer or their authorised service and repair agent. A reputable servicing company that deals with that type of equipment should also be competent to check its safety.

It is never absolutely safe to work on live electrical equipment. There are few circumstances where it is necessary to work live, and this must only be done after it has been determined that it is unreasonable for the work to be done dead. Even if working live can be justified, many precautions are needed to make sure that the risk is reduced ‘so far as is reasonably practicable’. See: Electricity at work: Safe working practices for more details.

The Electrical Safety Council has also produced a Best Practice Guide on safe isolation procedures