I need to move 2 outlet boxes up 2' from where they are. Can I use the existing boxes now as junction boxes to the new boxes?
Tere

I have several boxes on this run.

Legally - depends on local codes. Practically, yes. You can get a blank finisher to replace the duplex one on the existing jiffy box.

Make sure the new wire is secured to the old box by the existing clamp (if it has one) or a bushing.

This application is in the garage & TN code is non existent. I do want to be safe of course. Can I do the same with a light switch? We need a switch on the other side of the garage.

Sure you can.... Then just use a blank plate to cover the splice box.... BUT If your goin to fish a wire from that box to the new location why not use a three conductor wire and install 3-way switches so you can turn the light on or off from either location?

I had enough wire to just raise the outlets.

re the switch; my son in law said the way it is wired i would have to rewire the the whole thing.

Thanks for your input.