How do you comply with NEC receptacle requirements in row homes with brick walls?

Question

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.

Answer 1

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.

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.

Answer 2

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.)

Answer 3

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.

Answer 4

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.