It’s not advisable. According to OSHA 1910.147(c)(5)(ii), “Lockout devices and tagout devices shall be singularly identified; shall be the only devices(s) used for controlling energy; shall not be used for other purposes….”
Combination locks can be unlocked using a code or a combination of numbers. Codes like this can be available to and known by multiple people at the same time. Thus, any one of these people can unlock the padlock at any time, even when it is not safe to do so. This, in essence, defeats one of the main purposes of LOTO procedures, which is to restrict access to hazardous energy.
For lockout tagout purposes, combination locks can fall short because they do not provide adequate protection against accidental or unintended re-energizing. This can put maintenance employees in danger. Padlocks with keys are far easier to keep under control and are more suitable for lockout tagout purposes.
It’s best to use padlocks that are specifically designed and made for lockout tagout procedures instead of using combination padlocks.