How can be, that cable witch is less than 1mm2 can handle larger load than 17 AWG?
Or my computer cable has different measurement system used? Or listed 16A mean peak only?
It can't be.
16A/250V on your photo is just plug rating, not whole wire rating. Check other end of wire - it may have 10 or 20A rating :)
And how i can actually calculate max cable load by cable area (mm2)?
You can use some table. Table you mentioned (AWG Sizes and Current Limits) has a note:
Current (Ampacity) The current ratings shown in the table are for
power transmission and have been determined using the rule of 1 amp
per 700 circular mils, which is a very conservative rating. For
reference, the National Electrical Code (NEC) notes the following
ampacity for copper wire at 30 Celsius: 14 AWG - maximum of 20 Amps in
free air, maximum of 15 Amps as part of a 3 conductor cable; 12 AWG -
maximum of 25 Amps in free air, maximum of 20 Amps as part of a 3
conductor cable; 10 AWG - maximum of 40 Amps in free air, maximum of
30 Amps as part of a 3 conductor cable.
Or AWG Sizes and Current Limits table is wrong?
These are many tables, maximum currents are calculated with diffrent rules. There are NEC standards, IEC standards, cable manufacturers standards, some local rules in many countries in the world. I think IEC is not bad idea for reference, but you can use any other reliable organisation or company.
Here is wire calculator based on "IEC 60364-5-52: Low Voltage Electrical Installations (2009)" standards (low voltage is < 1kV in IEC nomenclature).
General question - does installed 1mm2 cable will be good enough for that load ?
For 8 camera power supplies (probably not more than 50W total) and 190W TV - this is more than enough. These camera power supplies have 3A/220V rating, but 3A is peak current.
If you have a lot voltage converters connected to one UPS - turning them on all at once may cause very high pulse current and your UPS may have problems with startup.
Maybe it doesn't matter for 8 small camera power supplies and 1 big TV, but you should know.
3A on your camera power supply is pulse current for charging converter input capacitor.