It says not to grind over steaming pots on the label of the pepper grinder. Is this so you don't get burned or for some other reason?
There are two possibilities I can see:
- The steam can wet the pepper in the mill and cause it to cake in the grinding mechanism
- There's an over-protective lawyer worried someone will scald themselves and blame the grinder company.
Which of the two is your guess. Personally I use my grinder over steaming pots all the time and I've never had any problems, but YMMV.
I think all hand-held grinders have this warning of not grinding over steaming or boiling-hot contents.
The grinding action could splash the hot contents and scald your hands. If hot oil is involved - temporary or long-term blindness. You might accidentally slip your hands into the hot pot.
No legal dept of a manufacturer would want that to happen to their customers. To them users are idiots tending to sue.