Access from above and below. Walls are typically hollow. Cut a rectangular hole where the new box is going to be, then go up in the attic and drill a hole down through the top of the wall, feed the wire into the hole in the attic, reach into the hole in the wall and pull the wire out.

Similar procedure for pushing a wire up from below.

Sometimes the wire itself isn't stiff/maneuverable enough, then you use something else first (wire coat hangers are useful at times) then attach the wire to the end of that to pull it through.

...or you could buy a fish which is what we generally use.

I understand that for wall switches. But how about outlet boxes that are normally chained horizontally?

Define "normally".

They are normally chained horizontally when the inside of the wall is accessible, or when somebody is willing to repair drywall after.

When the drywall is already there, and destroying it is not an option, they are not chained horizontally.

When these outlets were originally installed before drywall, they were chained horizontally. So if I want to move the outlet, it looks like I need to get into the drywall to do so...correct?

Say I want to move an outlet down on the wall about 3 feet. How would I do that from a drywall perspective?

You can drill through box holes and across stud bays with a long flex bit. It's easier if at least one of the boxes is going to be a 2- or 3-gang, so the hole is bigger.

The bit will have a hole in its business end with which you can pull back a steel messenger wire or fish tape, which you can then use to pull your cable.

Problem is, it's not easy to keep flex bits in the center of the studs, which is where you're supposed to be to protect the cable from nails driven into the wall. The first time I used one to go over 3 studs' worth, I not only wandered off center, I drilled right through the plaster wall into the next room!

When the top or bottom plate of the wall is accessable (from attic or cellar), it's usually easier to fish up (or down) and back down (or up).

Moving the recept down 3' depends on how it's wired now. If the cable to it is fished from below and nothing is daisychained from it, it's easy. If it feeds more recepts, you have a lot more work to do since you can't splice inside of walls. Usually you'll either have to pull a new cable to the next recept in the chain, or else leave the old box in place and put a blank cover on it. You can't bury a box that's in current use.

The more of this stuff you do, the more you think electricians are worth. :)

You are better off to ADD a box rather than MOVE a box for several reasons.
1. Old box leaves a hole to patch.
2. Cables in old box won't be long enough to reach new box.

Typical walls are not hollow. Most have fire breaks about half way down the wall. That means that at least once you will need to cut into the wall to drill though the fire break and fish down the romex if you are coming from an attic.

IF you have room to use a 36" flex drill, you may be able to drill through the fire break from above. Cut out for a receptacle in line with where you have drilled the holes. What I have often done is to tape the romex to the flex drill bit and push it to the receptacle hole at the bottom and then pull out the drill bit pulling the romex along. This is a little trickey but it can be done.

If there happens not to be fire breaks, use a fish chain to pull the romex down.

In a major remodel, drywall is usually the cheapest and easiest thing to "fix." Unless you are a wire fishing savant, I'd just cut holes where you need to and patch. You are going to be patching the old outlet holes anyway, so what is a few more?

Typical walls are not hollow. Most have fire breaks about half way down the wall.

I reckon that must be a regional thing. Either that or all the houses up here are built wrong.

I've run into those stupid "some idiot put a sideways beam here, right in my way!" scenarios maybe 2% of the time, and the bay next to it is almost always open. Who puts a 'fire break' in one cavity but not the rest of the wall? I think it's more like "Hey Bob! What're we gonna do with all these scrap pieces of 2x4?"

It's true, there usually are no 'dwangs' or 'noggins' - horizontal pieces between studs here in BC Canada either. Provided there's a plate at the top of the wall, I don't see how these 'firebreaks' do much apart from stopping you from retrofitting wires etc.

How big are your baseboards? In my old house with 8 inch baseboards, rather than disturb the plaster, I removed the baseboards, cut my outlet holes and the few inches of plaster that the baseboards hide, and run wires through the studs there. So much easier to cut holes when you can see what you are cutting! Then just replace with strips of drywall and the baseboards, and it's all hidden. It's A LOT of work to get it just right, but for saving my plaster it was so worth it!

Prior to the introduction of plywood sheathing, every external wall had some type of cross bracing.

Prior to the introduction of plywood sheathing, every external wall had some type of cross bracing.

Uh... My house (c.1905) has balloon framing - eg. nothing blocking the walls from the sill to the attic.

If you have totally hollow walls and a fire starts around any of those walls, the fire will suck right up that wall to the roof before you can say jack rabbit. In my area of Texas, homes have been built for a long time with fire breaks in every wall in the house.

My last home in Ohio (1969), built in 1921, had fire breaks.

"Typical walls are not hollow. Most have fire breaks about half way down the wall. That means that at least once you will need to cut into the wall to drill though the fire break and fish down the romex if you are coming from an attic. "

It means you need a longer drill bit to get through any fire-stopping from above (or below).

I have 'ship auger' bits up to about 5 feet long.
If there is not enough clearance in the attic a series of 24 inch bits and 24 inch extensions do the job.

If all else fails a 5 foot flex bit with a 4 foot extension (low RPM HoleHawg territory).

If the wall in question has a closet on the other side of the wall, openings as necessary can be made from that side and will be easier to patch. Try to imagine all the possibilities before cutting.