Master Lock No 410

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Master Lock No 410

Master Lock 410 LOTO
Master No 410.jpg
Name Master Lock 410 LOTO
Manufacturer Master Lock
Lock Type Padlock, Cylinder
Lock Design Pin tumbler

The 410 LOTO is a plastic-body padlock made by Master Lock.[1] It is designed and marketed to electricians and maintenance workers who need to lock out and disable equipment while performing maintenance.

The 410 LOTO is notable as being one of few 6 pin locks manufactured by Master Lock. It has also achieved notoriety among locksport communities as a well-known practice lock for learning tension control and recognising counter-rotation while picking security pins.


Principles of operation

See Pin-tumbler (Principles of Operation)

The 410 LOTO is a 6-pin core containing 5 spools and 1 lightly serrated pin[2], in random positions. The keyway is physically restricted by the plastic body to rotate only clockwise, but the core is able to rotate counter-clockwise using a tension wrench underneath the body. The lock can be permanently damaged by rotating the core 180° clockwise, as this can drop the key pins out of the lock or into the lock body.[3]

The lock is available with two possible keyways. It is not usually possible to know which a lock will come with until it is opened.

The 410 LOTO uses a ball-bearing locking mechanism to detain the shackle, making it immune to the shackle bypass techniques common on older Master Lock padlocks.

Disassembly instructions

The 410 LOTO cannot be disassembled non-destructively. However, it is possible to take it apart relatively easily, while keeping it mostly intact. The plastic lock body can be split using a tool wedged down the shackle hole in some cases, or can be cut along the seam using a rotary tool to weaken the seal.[2]


The 410 LOTO design prevents any shim bypass, either by core or by locking mechanism. However, the padlock is made of plastic and does not have a hardened shackle, and as such is vulnerable to many brute force or heat attacks. It is vulnerable to the following:

See also


  1. BosnianBill. Master Lock Lock Out Tag Out (LOTO) Training Locks (YouTube)
  2. 2.0 2.1 Faffler, Billy. Master 410 Picked and Gutted (YouTube)
  3. F3rdNami5h. Master Lock 410 LOTO Picked and Gutted (Reddit)
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