Why some light switches do not have a ground wire?

At home I am trying to change or update the light switches and up to now, none of them have a ground wire, they have only 2 wires, in some they're both black, in some in black one white, and just 2 screws/holes on the switch? is this normal or should I worry about it? THANK YOU!
Why some light switches do not have a ground wire?
Light switches didn't used to be grounded until around 1987 or so. Even now, most inspectors don't require a ground wire for a snap switch. #1 Switch with 2 screws-simple snap switch. Romex application may have one cable coming into box with 2 wires in cable. This is permittable to use White wire as hot line, black should be return, switched. #2 Switch with 3 screws,( not counting the green grounding screw), 3way switch. Switches from more than one location. Be sure to remember which wire is on common, ( this is usually the odd color screw). Replacing outlets and switches is easier than it sounds. Use common sense and be careful.
Why some light switches do not have a ground wire?
These are just %26quot;dumb%26quot; switches. They just stop the power, or let it complete the circuit. They are perfectly normal. You might come across 2 way switches, that will confuse you to no end.
This is normal most of the time. Many light switches do not switch the positive wire, they switch the neutral wire. Just wire them up the same as the old ones. That is the code around here.
Didn't use to ground switches unless they were within reach of ground. i.e., earth, plumbing, concrete floor.



It is acceptable to send hot down on the white and switchleg back on the black.
USA This is normal. Until the 1970s, metal boxes were used for switches and receptacles in the walls. The ground wire was attached to the box, and the metal strap holding the switch to the box provided a ground for the switch. Then in the 1970s, plastic boxes were invented. You cannot ground a plastic box, and if the box is not grounded, the switch cannot be grounded. So, they added a ground screw to the switches. If you install switches in plastic boxes, they need to have the bare ground wire hooked to the green ground screw at the top/bottom of the switch. If the switch is in a metal box, the metal strap will ground the switch to the box and you don't have to do anything special.



As far as the switches having two screws or holes for wires, this is normal for single pole switches, where you can turn the light on from only one switch. Sometimes, there will be two black wires and sometimes one black and one white. This is also normal, and nothing to worry about.



If you are replacing switches, make sure you note how the existing switches are hooked up, and hook up the new ones the same way. If you are not 100% sure how to do it, please call a licensed electrician.