Using mac mini nearly for 3yrs. From few weeks i feel electric stock over it surface and on keyboard too. I Tested with current tester it showed electric flow

I don't understand, if you have a current tester it will show you the current, that's what I am asking.

Take your Mac to an Apple Store for diagnosis.

The Mac Mini is not grounded, it uses a double insulation and therefore does not have a connection to earth.

As you are unable to explain how you tested and what the measurements were of this "power flow", take the Mini to an Apple Authorised Service Centre for proper testing.

OK, not logic board then, some ground loop in your wiring it seems.

i called my electricion and will check my house earthing properly & replay

As previously stated, the Mac mini is NOT connected to earth, therefore as regards the Mac, the house earthing is irrelevant.

If you are paying an electrician to check, test, & inspect your household

or residential/business internal power situation, that same person should

be able to test the power leaking from your Mac Mini, and tell you what

it is, and how much power, AC or DC, with his professional instruments.

A good $10 multi-meter (or $2. from China, in the US) could show it.

A double-insulated appliance without a grounding wire should not leak

power; and will not have a ground to earth connection. However if the

metal outer case is capturing leaked electricity from the logic board or

power circuitry inside, then it is no longer insulated. It becomes an Apple

problem and too bad you couldn't have tested it when only 10 days old.

Then they could've taken it back into stock & given you another; unless

the Apple store you patronize does not allow returns with the first 2 wks.

You could try to measure the power leaking by using a multi-meter probe

on the case (perhaps a screw or metal housing) and the other probe on

a known ground (to electrical earth or known good grounding wire.)

Electricity can be fun, entertaining, and positively shocking...

Good luck & happy computing! 🙂

And a connected peripheral with a ground connection is a potential path.

Such as the original poster's supplied 'grounding action via' hand, for example... 🙂

Indeed

Once more.

What were the results of this test?

The return line is often known as the neutral line, it should be 0v, but often is not. Which may be a fault condition but at 1-2v is not serious.