I know that string grounding makes my guitar more silent, but by grounding my strings, I am connecting my self to the amplifier and the grid. This can be dangerous, especially with vintage amps that are not always grounded. So, is it safer to ground my guitar stings or not?
Some degree of hum is common with many type pickups when they pick up a 60 cycle hum from other electrical appliances in the environment. Single coil pickups are particularly susceptible whereas "Hum-Buckers" are specifically engineered to minimize this type hum.
But unwanted noise such as humming or buzzing that changes when you touch the strings may very well indicate a problem in your guitar or amplifier or somewhere else in the electrical supply chain that needs to be rectified for your safety.
If you are getting a hum or buzz through your amplifier when your guitar is plugged in, this could be a sign of a faulty ground somewhere in the system. It could be in your amplifier, your extension cord, your A/C supply circuit, your instrument cable or a loose ground wire on your guitar.
If you have 3 minutes to spare, the video below does a great job demonstrating potential ground issues.
If you want to be sure the electrical circuit in the house (venue) is properly grounded, you might want to throw a polarity checker in your equipment bag (Less than $5.00 US).
One easy and inexpensive route to silencing your guitar while adding an extra measure of safety is the use of a universal fused string ground like the one pictured below. It's around $20 US and has a fused circuit that will disconnect the strings from the grounding circuit and protect the player in the even too much voltage is sent through the guitar from a faulty ground in the equipment chain. To read more about it click here: Fused String Ground
Good luck and be safe!