Siemens UL 489 - Mounting on Horizontal Surface -  Mounting Tolerances

5 – 3
5.1.2 Mounting on horizontal surface - 
Mounting tolerances
The circuit breaker must be mounted on a rigid, level surface, capable of supporting the weight of the breaker, cradle, and associated busbar
components. The maximum amount of offset in the mounting plane is 3/64“ (1mm).
Fixed-mounted breaker
(1) Mounting points
Cradles for draw-out breaker
NOTICE
Damage to finger clusters.
Improperly aligned bussing at the terminal connections may affect the position of the bus stabs. Misaligned bus stabs may
result in damage to the finger clusters during circuit breaker rack-in.

Do not distort the cradle terminal connections when connecting to the main bus.
 h max 3/64” (1mm)
(1)
0139
3/64” (1mm)