Can photocopying a text book for personal or for the use of others at work be considered an example for theft or fraud at work?

The photocopying of material which is not publicly available as open material without the permission of the copyright holder is against the law, usually treated as a civil matter, but in some cases can be classed as a criminal act. Doing so, particularly for multiple distribution to others, is classed as stealing someone's intellectual property and can be treated as theft.

(new person)

Yes, it can be.

If you photocopy it just to read yourself, for studying or something, then it's fine.

Though, if you claim it as your own/don't reference it, use it in a power point, as examples, etc., then it's not allowed, as that would be plagiarism (stealing information to use and claim it as your own) - which is also theft.

As the person above said, it's different if it's publicly available. Although, since it's from a textbook that is your own, it's violates copyright laws, and you would definitely need permission from the copyright holder if you were to distribute any part(s) of it.