I have a 4 gang switch box in my house that I built in 1999.

When facing the switches, the switch on the far left I would like on the far right. I must disconnect wiring and then reconnect the switch in order to move it in the 4 gang box, from one side to the other.

The switch is a non-grounding type. What code applies? If I take it out and move it over, do I need to install a grounding type?

For clarification, this is not a "repair."

The real question is, do you consider the grounding of switches an important safety improvement?
If so, is it less important if it is an old switch?

I don't have all my old code books with me, but.... I think that before 1999 it was permitted to have switches installed without grounding as long as plastic faceplates were used. Once a metal faceplate was installed than the yoke of the switch required grounding.

This was changed in 1999. Often plastic faceplates were replaced with metal, so the code was changed to require grounding.

You also needed plastic screws

Yes, the new switch must be of the grounding type and connect to the EGC for the circuit it controls. Reinstalling a non-compliant switch would not be appropriate. With that being said, you would not be required to change any of the other switches in the house unless you remove one of those as well.

Make sure you get a permit too...

Since you probably had to disconnect or remove the other three switches to move the one to the right... Well what about all four?

All I can say is in 1995 when I built my house and when the switches started to have a green screw. I asked Hillsborough.
The response was I guess you should use the connection if it is there. "But it is not required."

BTW,
I have not seen plastic trim screws come with the plates in quite sometime.

Imagine going to get your tires changed on your car. You decide to change just the front two tires. Now, would it make sense for the installer to put tires of similar condition and wear back on the car? Wouldn't it make sense for the NEW tires to be NEW or at lest in better condition / safer?

At the same time, I shouldn't be required to change the back tires becuase they are existing. I and the installer are both aware the back tires are now not as good or up-to-date as the front tires, but they eventually will be when you decide to change those tires some day in the future.

This is how I read the new and existing building codes. It would be inappropriate to reinstall an unsafe or non compliant material, device, or equipment, but nothing in the code requires an existing non-compliant material, device, or equipment to remain in service.

Bryan, Don't worry, he is in my county, I have my stop work all ready to go...(LOL)

Just rotate the tires Nick...