This British Standard specifies performance requirements and test methods for thief resistant mechanically operated single-point lock assemblies (including locking plates, fixing screws, fitting instructions and cylinders where appropriate) that:
a) incorporate locks conforming to BS EN 12209 field of door application grades K. L. M. N. R. S and T. i.e. locks that can be locked from both sides with a key thereby only allowing key egress: and
b) are used in doors, window doors and entrance doors in buildings.
This standard does not cover thief resistant lock assemblies that provide keyless egress, i.e. lock assemblies that can always be unlocked from the inside without the need for a key.
NOTE 1 Thief resistant lock assemblies that provide keyless egress are specified in a separate standard. BS 8621. because they are sufficiently different in terms of what they offer for means of escape (from fire) and security.
NOTE 2 It is possible that lock assemblies conforming to this standard are not suitable for use on doors constructed from certain types of material, e.g. plastic or aluminium. The marking on the packaging of the lock assembly will provide this information in accordance with 7.2.
BS 3621:2004 history
2017BS 3621:2017 Lock assemblies operated by key from both the inside and outside of the door