Low-voltage electricity should be isolated and earthed, or otherwise made safe where it is appropriate to do so. Electrical isolation to small premises can be achieved by isolating electricity at the consumer unit or fuse board.
It may not be possible for personnel to isolate and make safe the electricity supply using normal methods. In this situation, assistance will be required from the relevant electricity supplier or competent person to make the electricity supply safe. Until this is confirmed, personnel should operate at a safe distance.
It should always be assumed that the low-voltage system is live or that there may be a residual current hazard present, until the relevant electricity supplier or competent person confirms otherwise.
If there is threat to life and it has not been possible for personnel to isolate the electricity at the consumer unit, the following steps should be taken:
- Contact the electricity distribution network operator (DNO) to request urgent assistance, such as remote isolation of the power; the DNO can be contacted by dialling 105 in Great Britain or 03457 643643 in Northern Ireland
- If the DNO cannot be contacted, or if there would be a delay in them being able to isolate the power, a risk versus benefit assessment should be carried out to determine what life-saving actions need to be taken
- If there are no alternative actions available, consider removing the supplier’s main fuse, found on the supply side of the meter, with caution and preferably with the permission of the DNO
As there is the possibility of small quantities of asbestos being present in older fuses, appropriate personal protective equipment (PPE) and respiratory protective equipment (RPE) should be worn if the supplier’s main fuse is being removed.
All commercial premises should have electricity isolation points at the electrical intake. At larger sites, there may be isolation points that control areas of the site or separate pieces of machinery and equipment. Isolating any electrical supplies should be considered as soon as possible, taking into account any wider impact on other essential systems, installations or work processes.
If personnel need to deal with three-phase power supplies, they may need to request assistance from the electricity supplier, unless there are on-site engineers competent in dealing with, and controlling, this hazard.
If the electricity supply has been isolated, a robust system should be implemented to ensure it is not reconnected. This may involve the use of locks, signs or supervision.
Performing rescue of a casualty
If it can be determined that a casualty is in direct contact with low-voltage electricity:
- Carry out a risk assessment
- Pull the casualty clear, using electrical gloves or other dry insulating material