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I'm rewiring a Philadelphia row home, which like many others, has brick and cinder block for the side walls. There is no framing, just lath and plaster. I know some flippers will put in 2x3 studs to make things easier, but I'd prefer to avoid this for reasons of both cost and space.

What they Originally did was chisel away part of a brick and install the receptacles in the base trim. At the time they made small, narrow boxes, probably only 1 1/4" deep and completely flat on the front with wings made to nail into the trim. I have looked all over for these. I can't even find a picture of one. How are people handling this in renovations? The only other solution I can think of is that ugly plastic channeling that runs on the outside of the wall.

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I see two options. What I see in the US quite a bit is instead of running the plastic channels on the wall surface, people will use steel conduit. It gives kind of a rustic/industrial look. Receptacles would then be mounted in steel boxes on the wall surface as well.

example of surface mounted steel conduit

What is typical in Germany, where most walls are block and plaster, is that grooves are cut into the plaster, conduit laid into the grooves, and then the whole thing gets covered with plaster again. There are specific tools for this called wall chasers, they have a set of blades kind of like a dado set that let you cut a groove into the plaster. This would obviously be more work and much more messy than the first option. In addition to cutting the channel for the conduit, you would of course also need to chisel out holes for the boxes that would probably go through both the plaster and partially into the brick. As Harper points out, in the US, it is probably required by code to use conduit, and either way, it would be common sense to do so for protection of the cable, as well as future replacement.

wall chaser tool

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    Learn something new everyday; in this case a "wall chaser". I know they say that money can't buy happiness but it can sure mitigate unpleasantries which make life miserable. I couldn't imagine doing a whole house with a chisel! – MonkeyZeus Mar 4 at 15:22
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    I agree, I have decided that having the right tool for the job is basically always worth the money, it saves so much aggravation. Finding the right tool is sometimes a challenge though. – PhilippNagel Mar 4 at 15:24
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    Keep in mind that burying NM cable in mortar or plaster may not be legal in the US. – Harper - Reinstate Monica Mar 4 at 17:00
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    @Harper-ReinstateMonica correct, which is why I specified laying conduit in the groove. In Germany, there are cables rated for laying right in the groove without conduit, but the recent recommendation is to use conduit as well. They are also only supposed to run these horizontal and vertical from boxes, and at certain distances from corners, ceilings, walls, and doors and windows, so it is easier to find out where it's safe to drill. Obviously, it's not standard practice in the US, so steel conduit would be common sense. – PhilippNagel Mar 4 at 17:12
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Surface mount of some sort - "ugly plastic channelling" being only one of many sorts. Tasteful wood trim being the most easily accessed for a DIY less ugly / less modern-looking solution.

One reason you probably can't find those boxes would be that they are not going to have adequate space to meet code box fill requirements (and that's not a particularly recent part of code.)

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  • I wondered about that. Also, the cut-outs to feed the wire were on the corners so there was really no way to properly secure the wire in the box, other than it was a pretty tight fit. – mreff555 Mar 4 at 15:54
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    These days capping is available in fancy profiles, and in anodised aluminium construction too, making it blend somewhat better than the ugly white plastic stuff. A good carpenter given time and budget could come up with a nice dado or similar to do the job too. – Criggie Mar 5 at 6:55
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Just a short line from another Transpondian [UK here]

In the UK most older houses are brick & plaster. Only newer [& cheaper] constructions use what the US would call 'drywall', any decent modern build would use concrete 'cinder-block' & plaster so this is a very common situation.

Mounting on any trim, such as skirting, panelling or architrave is not allowed, so you have to surface-mount [unpopular] or chase the wall.

The standard method is to chase down into the brick & plaster - either old-style with a hammer & chisel, using a channel-cutter as mentioned by PhilippNagel, or more commonly using an SDS drill set to hammer only & using a large chisel/spade bit.

You can drop from the ceiling or come up from the floor, whichever is most convenient.
Later edit: I'm not certain whether to traverse horizontally is against code, but it is certainly frowned upon. People expect cabling above or below a socket & plan their picture hanging etc activities accordingly. They don't expect a wire horizontally. Using a cable finder is, of course, always recommended.

Once the drop is in, you then re-plaster.

Conduit is not required in the UK for such construction [though it is optional], only that metal back-boxes are embedded [plug & screwed] in the wall to carry the sockets & terminals. Any jointing must also be metal boxed. Back-boxes come in two common depths [25mm & 35mm; 47mm is less common, 35mm is 'standard'], depending on how much room you have to work with in the wall, single- or double-wall brick & whether you need sockets in-line on both sides of the wall.
UK Trade store link as example, presumably wouldn't fit US sockets so for illustration only.

enter image description here

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    Can also use an angle-grinder as the first part of chasing - cut two parallel lines then clear out with a hand chisel/SDS chisel. – Mike Brockington Mar 5 at 12:28
  • The difficulty here is that there is no guarantee that I will have power while doing this, and from what I can see there are no battery operated Chasers. I have Milwaukee M18 tools so I could get some chisels and a portable SDS drill but I'm wondering how difficult that is going to be. Have you done it before? I need to run about 16 channels, roughly 1 foot from the floor. – mreff555 Mar 5 at 12:44
  • It's not something I've done a million times, but I have a good 24v battery-powered SDS & large spade chisel which I have on several occasions used for such a task. I actually live in a very old house with 'pre-modern' wiring standards, so every time I redecorate a room I have some of this to do to greater or lesser degree. The upside, as you're re-plastering anyway to bury the cables, is the channels don't have to be perfect. SDS is 'good enough'. & certainly easy enough. – Tetsujin Mar 5 at 12:52
  • I just googled in the UK & you can get cordless wall chasers; to buy they are about the same price as a good SDS, 600 bucks-ish. They seem to all be 54v so won't have batteries interchangeable with most other tools. - one example tooled-up.com/… – Tetsujin Mar 5 at 13:07
  • @mreff555 I used to live in the UK and chased wiring by hand with a chisel & big hammer once or twice. With an SDS hammer & chisel you would be all set. Messy but very do-able. For short runs like 1' I think you're better off that way than with a grinder because of the dust. – UuDdLrLrSs Mar 5 at 16:51
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Yes those shallow boxes were ok once upon a time with the wires closer than allowed today. Today because of the 1-1/4” requirement most use conduit. I will use smurf tube or non metallic flexible tubing concealed in walls with shallow boxes this requires the splices or feeds to other devices to be made in a different location that will have enough volume for the additional wires and device for box fill.

The only other method is surface mount you mentioned you did not want that. The shallowest box I can remember using recently is 1-1/2 deep device box there are 1-1/4” round and square boxes but these need a mud ring or cover and would be larger than a device set in a trim board.

The trick I have used many times is to conceal a box in the ceiling for splices to other shallow boxes. The code definition for accessible (as applied to wiring methods) capable of being removed or exposed without damaging the building structure or finish or not permanently closed by the structure or finish. The code handbook for years has also stated removable panels designed to be removed are allowed most of the time I make a “picture frame” and screw the cover in place. The 1 area I have an inspector that will not allow this I use Velcro tabs , no tools needed to remove the decorative panel but tools are needed to remove the cover plate of the box.

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