Put a wire nut on each end of each wire in their respective boxes.
Nothing else needs to be done.

You do not have to connect anything to them, just cap them off.

Remember to use a smaller wire nut suitable for a single wire of the appropriate gauge you are capping off. It helps them stay on when you pack them into the back of a junction box.

There is no junction box for the 'extra' set of wires. Doi just jam them into the junction box for the new fan along with the active wires? Right now they are taped up to the roof beam.

Should I cap off the connections at the switch too?

Buy a box and cap. Route the wire into that box. End of each wire must be capped with a wire nut. The safety ground wire must connect to the metal box.

Wire must be terminated in a box that is secured to a 2x4 or joist. Wire cannot be dangling freely.

A box needs to be secured (doesn't need to be to a stud or joist). Old work boxes can attach to the finished wall surface. The box only needs to be grounded if metal. Plastic boxes are common these days.

"Wire must be terminated in a box that is secured to a 2x4 or joist. Wire cannot be dangling freely. "

If neither end of the wire is on a junction box you can do nothing and leave the wire uncapped and hanging in space as you wish.

It is NOT part of the structures wiring.

If one end is on a box, then capping both ends ad ending th 'loose' end in another box is required.
The cable has become a portion of the building wiring.

So, for the wires in the attic, I can buy a junction box at HD, screw it into a roofbeam 2x4, cap the wires, and leave it at that? If the box is metal then I must fasten the bare copper ground to the box. If the box is plastic then no need to attach the ground.

Should I also individually cap the wires at the switch?

"Should I also individually cap the wires at the switch? "
if this is in another junction box, yes.

If you use a metal box upstairs connect the ground wire in the switch j-box and then ground the metal box in the attic (10-32 screw in the box).
If you use a plastic box in the attic no ground connection is needed at either end.

And remember to leave a note with the wires so the next person knows what they went to, in case they want to restore that function.

"And remember to leave a note with the wires so the next person knows what they went to, in case they want to restore that function."

The "next person" would be crazy to use an unknown abandoned cable with some type of "note".

One of guys I saw on TV had a great idea. Whenever abandoning a cable he nuts the conductors on both ends together. If some idiot decides to reconnect it, it will at least immediately trip the breaker rather than possibly intermittently connecting or energizing some random piece of non-bonded metal.

" Whenever abandoning a cable he nuts the conductors on both ends together."

Just push them out of the box and cut off cable conductors flush with the jacket n each end.

No parts required. takes about zero time.

If you tighten up the cable clamp with no cable present you can even close off the opening into the box.

Works well for internal clamps that do not take a round plug, and avoids spending money on a plug.

Sorry to hijack, but I'm trying to learn. I was certain we had our washer/dryer in the coat room when I was a kid, but I couldn't locate an electrical outlet there now. I need an outlet to connect the alarm system panel, so... I poked a hole in the drywall and found the metal box connected to a 2" x 4" with wires capped with nuts, just as westom describes. I'd like to connect an electrical outlet tomorrow, then repair the drywall. Seems pretty straight forward.

When I read lazy and brickeyee's comments about a note for the next guy, I got a little concerned. This wiring certainly was the source for the washer and dryer electrical connections. Anything specific I should consider before proceeding?

Thanks. E

" I poked a hole in the drywall and found the metal box connected to a 2" x 4" with wires capped with nuts"

Without tracing those wires you have no idea where they came from.

As a homeowner you can take a lot more chances than my license and liability insurance allow me to take.

Thanks brickeye - I guess I don't understand what chance I could be taking. Where could those wires possibly have come from?

My parents bought our home (the model home in our neighborhood) from the builder a few months before I was born. My family has been its only inhabitants. My mother did one renovation when she moved the laundry to the basement (sort of wish she hadn't done that), and the wires were capped and sealed into the box. They're the builders wires for the 120V outlet in the original laundry area.

Is the concern that the wires could have been incorrectly installed when the house was built?

I removed the plywood, uncapped the wires, read the voltage (120V) and connected them to a 15A outlet, wrapped it in electrical tape and screwed the outlet into the box. Here's a "before" image. The purple wire was live, the white neutral.

I appreciate your input. I have plenty left to learn and don't want to destroy the house.

Your mom shouldn't have covered over the box. All junction boxes need to remain accessible. She should have just put a metal or plastic blank plate on it if she no longer wanted an outlet there (NOT WOOD and then drywall!) . If she's done any other modifications to the electrical, then I would definitely take another look at it.

If you are sure that that is all that was done, then restoring it should be fine. However, if the modifications were done by some unknown previous owner then it wouldn't be a good idea to restore it without knowing exactly what's going on.

Greg, thanks for the clarification. And for what it's worth, my mom could do anything in the garden on her own - I once saw her lift a tree - but I'm sure she hired a contractor for the reno. She would never have touched an electric wire, so I have no idea how we ended up with something not to code.

I found the 120V and I'm glad it was there, although a little uneasy that it was covered over improperly. There was a dryer right next to the washer, so there was at one time, a 240 outlet up there too. My concern is that if they covered over the 120 incorrectly, they may have done the same with the 240. Do I need to look for this as well? The dryer is now in the basement.

Thanks for your help.

I'd definitely dig into the wall further to see if he buried the 240v box as well.
And if this guy re-did the basement laundry room, I'd be examining that as well. He obviously didn't know what he was doing because not burying junction boxes is a very basic aspect of electrical work that anyone with any knowledge about electrical codes should know. Especially if you get paid to do it.
The guy was a hack.

Hello, I am trying to cap off a plug outlet that I will not be using. I removed the receptacle and capped off each wire individually (without stripping first). I turned off the breaker before doing all of this but I turn the breaker back on and there is no power to any of the other outlets on that breaker. Where did I go wrong??