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

Aware that guidelines have recently been issued within the NHS to remove ‘child-proof’ inserts from electrical sockets in NHS properties, we at Crowthorne have serious concerns in regards to current use within containment laboratories as their purpose in these facilities has not been fully considered. These concerns, however, apply only to containment facilities and not to any other locations within hospitals etc.

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

However, in practice, air leaks are frequently found coming out of electrical sockets because 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 usually involves removing the socket and/or trunking and sealing the back box and cable conduit between the box/trunking and the wall structure. This method however, is both disruptive to laboratory operations and is not always possible to achieve. ‘Child proof’ type inserts have become an increasingly common way of trying to reduce risks associated with leaks as it reduces the open area of the socket and therefore the leak. However, not only does this rely heavily upon diligence by the lab staff  to fit the inserts every time a plug is removed from the socket but it doesn’t truly resolve the issue of the cables leaking at the point of entry as some residual leakage around the switch on the socket remains.

Crowthorne Limited and Crowthorne Hi-Tec Services Limited have many concerns about the immediate 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. In order to move away from the use of inserts, a method we are in favour of, we 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.


If you have any concerns over the guidance issued or wish to discuss a way forward without compromising your containment laboratory, please contact Crowthorne Limited (Farnborough) at +44 (0) 1252 37233 or +353 (0) 1824 3670 (Ireland).

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