Guide to BS EN1303:2015 Digit 8

Guide to BS EN1303:2015

The security of any door assembly is a combination of many factors including the door construction and physical environment surrounding the door. However, the cylinder is probably the most vulnerable element in the assembly and is therefore subject to severe requirements of resistance to physical attack and other aspects of security such as key control.

BS EN 1303:2015 is the European Standard which establishes assessment and test criteria for a cylinder to quantify its resistance to physical attack, durability and key security. BS EN 1303:2015 classifies cylinders for locks using an 8 digit coding system. Features assessed include durability, fire resistance, key related security and attack resistance. The resulting 8 digit code can be used to directly compare the performance of one cylinder range against another.


Digit 8 - Attack Resistance: Five grades of resistance against drilling and mechanical attack are identified in accordance with table below:

See requirement of key related security 4.8.6 a


Clause Requirement Test Clause Parameter Grade Unit

0 A B C D
4.9.2 Resistance to drilling 6.9.1 Time
- 3/5 5/10 3/5 5/10 Min.
4.9.3 Resistance to attack by chisel 6.9.2 Blows - 30 40 30 40  No. 
4.9.4 Resistance to attack by twisting 6.9.3 Twists - 20 30 20 30 No.
4.9.5 Resistance to attack by plug/
cylinder extraction
6.9.4 Force
- - -







4.9.6 Torque resistance of plug/cylinder 6.9.5 Torque - 20 30 20 30 Nm