Should I ground my body when working with 200V+?

Do not ground yourself to anything. The only safe way you can work like this is to be flying or hanging by a rope which is very unlikely.

As all others already mentioned, don't ground yourself, isolate yourself or the circuit ... or even both

• never work on life systems > 50VAC (especially untrained)
• You could isolate the circuit by using an transformer, so the only risk is touching 2 different live parts (Phase & ground for example). If you just touch one nothing should happen
• use proper protection like a RCD (german FI)

the mentioned wristbands usually have 10MOhm so the current would be 0.02 for 220V and combined with your internal resistance low enough to not die.

Mains electrical person here.

There is no reason to work on a 230V -> 5V converter.

They are common as dirt, and you can buy one literally more places than you can buy eggs. Every gas station, liquor store, smoke shop, five-and-dime aka dollar store, apothecary, grocery.

Their common-ness does NOT make them a good choice for hobbyist hacking. You found out why.

Hobbyists should never be opening up an AC mains power supply. The items are commodities. Simply obtain a UL-Listed AC mains supply that gives the low voltage output you want to work with, and don’t open it up or tamper with it.

If you want to work with high voltage but low current AC, such as a Jacob’s Ladder, then obtain a UL-listed, isolating, 24 volt AC power supply, preferably one with intrinsic current limiting, and an appropriate step-up transformer to kick it up to your high voltage. That makes it an isolated “service” which means if you touch one leg of it and building earthing, nothing happens. Even if you touch leg-leg, as long as your high voltage is limited to 5 milliamps (due to current limiting on the low voltage side), it is rather unlikely to harm you.

EVERY AC mains shock is death brushing against your shoulder

Every single time you experience an AC shock, it is because the conductances (1/resistance) of the various current paths just happened to be too little to kill you that day.

However, these ad-hoc current paths are highly variable. If they didn’t kill you today, they can’t count on doing the same tomorrow. The humidity in the air might change. Your skin might be sweaty.

A stun is as good as a kill, if you’re unlucky. The picture postcard example is electrical drownings. But you can also be killed falling off a ladder, or collapsing (face-planting) into the mains AC equipment you are working on.

Stay on your side of the wall wart

For hobbyists, there is so much rich and fertile ground to be worked in the low voltage DC space, that there really isn’t any reason to fool around in AC mains. And if you look at the countless electronic projects in kit form, or made in low volume (many things on Kickstarter for instance), it’s the same refrain: a complicated ingenious low voltage DC product, coupled with a commodity wall-wart that is UL-Listed. Even though the project/kit makes not attempt to UL-List.

(And BSI, TUV, ETL etc. are valid NRTL substitutes for UL; however CE is not, unless it’s built and sold at bricks-n-mortar retail inside the EU proper. Everywhere else, CE means Chinese Excrement, because there are no consequences for faking it).

Needless to say you void the UL listing when you open one up.

Some people deride that ubiquitous wall wart and wish every product had an AC line cord or socket on the device. OK, that makes the UL listing vastly more complicated. Now the device’s internal power supply must grind through the much tougher White Book rules applicable to AC mains. If you notice, the first Mac Mini shipped with a power block. That’s because Apple was able to push the power block through the lengthy and complex UL listing process without revealing to UL what the product was. The Mac Mini itself could breeze through quite late, since it was entirely low voltage. *So, do you want your kit manufacturer or Kickstarter small-volume builder to really have to grind through that expense and delay? No.

To sum it up:

• Definitely do NOT ground yourself, as this is likely to increase current (The wrist bands many people working with pcbs wear are used to protect the circuits from esd)
• Review your basic knowledge about working with electric components
• Whenever possible do NOT work with live wires, setup your measurements before turn on measure, turn off, change measurement setup, repeat (In most cases you don't need to mess with your system while it's connected)
• If you insist on working with a live wire:
  • make sure you have a RCD in you system to at least protect you to some degree
  • Try using only one hand
  • Try to isolate yourself (e.g. using a mat)
  • Have a second person close by, in case you mess up badly and need help (Person should actually first aid and how to turn your stuff of before touching you)
• If you do this for your work (college or industry) there is most likely someone responsible workers safety, speak to them

Generally I always recommend to not work with live wires

No you shouldn't. The current will probably pass through your heart and kill you. See this link for the origin of this picture and some useful facts. https://www.mikeholt.com/mojonewsarchive/ET-HTML/HTML/EletricalShockHazard~20020326.htm

https://www.mikeholt.com/mojonewsarchive/ET-HTML/HTML/EletricalShockHazard~20020326.htm

You need to review basic electrical safety with your professor assuming you are in college. If in the workplace someone didn’t do a good job interviewing you and you need to ask for training. Electricity can kill you by causing your heart to stop and afib and it can literally cook you and cause your muscles to lock up as it is shocking you. You also need to know what to do if your buddy is getting shocked otherwise both of your could die vs only one. This is serious stuff. Anyone who works on electrical items even on their house must learn electrical safety

Edit: getting shocked at 220v is an incident that you must report in writing and is not your fault. Leadership needs to be aware so they can take the appropriate corrective action. This could be a problem with how you were instructed and the professor needs training on how to teach safety. You should have been tested and passed on safety before anyone let you on that project near high voltage. Your question confirms you were not tested on safety. If you are trying something out you saw on YouTube, please report it to YouTube so it can be removed. None of us here want you or anyone else hurt.

220VAC can often cause severe permanent injury or death. Stop working with those voltage levels until you have professional training.

In an official communication, OSHA has stated that they consider all voltages above 50V to be hazardous. Just like with car accidents, not every electric shock above 50V will severely maim or kill you, but as explained in the OSHA link, the likelihood of injury increases drastically as you go above 50V.

Stack exchange is the wrong place to learn about safety in life-or-death scenarios. Take a course from a trained professional.

You ask about additional precautions regarding shocks:

• wear no metallic jewelry, including rings, bangles.
• if you have a wristwatch, use a leather band, not metal.

Metal-backed wristwatch is somewhat hazardous. Your skin is damp underneath, making skin resistance lower. A cheap plastic-shelled watch is an improvement.

Grounding oneself, while working on live electrical equipment, would be an open invitation to disaster.

Insulating oneself from ground would be the only way to ensure total safety.

That's why rubber mats are provided on the door side of control panels. Electrical maintenance personnel are also provided with rubber shoes and rubber gloves and tools like pliers are also well insulated.

In spite of such protection the bigger danger is touching a live point with one hand and ground with the other. The best precaution against such an eventuality would be to always keep one hand in ones pocket while dealing with live equipment.

Such basic precautions should not be ignored even when use of GFCIs is mandatory.

Wrist Bands are to protect equipment from you(ESD) not you from from equipment. Best you can do is to not work on live equipment and use RCD if you really have to (Also, isolation transformers are a good thing, but you have some learning to do as they have some subtle issues of their own).

The wrist bands (if they are good ones and not some random ebay junk) have a large series resistor in the connection to ground (typically 1 Mega ohm) precisely to minimise the dangers inherent in contacting a power line while earthed. This resistor allows the static to dissipate quickly (The human body is figured to be a 100pF cap for ESD purposes) while limiting the current in the case of contact with a high voltage supply to a level unlikely to kill.

You really do NOT want to be firmly earthed if you contact a high voltage source.

Grounding won't protect you against shocks when touching live wires! Quite the opposite, the better you are grounded, the higher the resulting current through your body will be.