Can ESD protection shoes be worn at any conditions (in relations to electrical / electronic systems). I understand ESD protection shoes / overalls are used against generating static on the body. But is the protection good, when user standing near HV systems or user getting an electric shock. I was curious and would like to get some information. Thanks for the help.
ESD shoes are deliberately slightly conductive so that static build-up on a person is limited (if the floor is conductive and grounded, which it will be in a well designed ESD-safe facility). Static dissipative shoes that are stated to meet agency requirements have an "SD" mark. Here is a CSA marked shoe:
Work boots that are "shock proof" are made to have high dielectric strength and high resistance- with no upper limit (the CSA approved boots can withstand 18kV and pass < 1mA).
Typical logo for that kind looks like this (the Omega and CSA symbol, the green triangle indicates something unrelated):
You may be able to find shoes with both markings (depending on the standards that are met), but it's perhaps unlikely. The criteria for SD is\$10^6 \Omega < R < 10^8\Omega\$, and the criteria for shock protection is effectively R > 18^6 so there is a relatively narrow overlap. You should certainly not assume one is suitable for the other unless they bear genuine markings to indicate they have been tested.
Static electricity can reach a few thousand volts (and the SD shoes must not break over under those conditions) so there is no extra danger in working with SD shoes, wrist straps etc. provided that only reasonably low voltages are involved. See the standards documents for the test conditions.
This type of shoes are used for environments where they work with integrated circuits or PCBs very sensitive to the electrostatic of the human body. But these do not provide the protection for an electric discharge, for this other types of protection must be used. The use of shoes with ESD protection is often used a lot in the PCB factories as an example.