CL3 Laboratories and Safety Alert on Use of Inserts for Electrical Sockets

A fundamental requirement for all CL3 laboratories is that they must be sealed to permit fumigation under emergency conditions at any time i.e. without the need to enter the room. This includes sealing all service penetrations into the room such as electrical cables. The point of seal should be where the cable penetrates the inner skin of the facility as this represents the fumigation boundary.

In practice however, air leaks are frequently found coming from electrical sockets as they are flush-fitted into either walls or on surface mounted trunking which indicates that the cable penetration point is likely to be leaking. The best way to prevent this from occurring is to deal with the problem at source, which involves sealing the back box and cable conduit between the box/trunking and wall structure. This method though, is both disruptive to laboratory operations and not always possible to achieve. ‘Child proof’ style inserts have become an increasingly popular method of trying to reduce risks associated with leaks. This does however rely upon lab staff diligence to fit the inserts every time a plug is removed plus it doesn’t fully resolve the issue of the cables leaking at the point of entry as some residual leakage around the switch on the socket remains.

BPS Crowthorne has concerns about the implementation of a policy planning to remove all inserts without first sealing the cable entry points to the room and any other leak paths behind the socket plate. This is because the removal of inserts could render laboratories not only non-fumigatable but also not operational at containment level 3 without risk of prosecution by the HSE. BPS Crowthorne strongly recommend that all leaks through the electrical services are sealed and tested to confirm a full seal has been achieved before inserts are removed.