ᐅ New Construction Drainage Installation

Hello everyone,

I am currently working on the electrical installation in my house. Since I come from an industrial background and have had little experience with building wiring, I now have a few questions about the implementation.

First, I would like to share my planning.

Because I am avoiding junction boxes 99% of the time, I have planned to use the following flush-mounted boxes for the installation:

Switches/buttons = deep flush-mounted box
Power outlets = standard flush-mounted box
Network = electronics box
Speaker connections = deep flush-mounted box
Cable/satellite = deep flush-mounted box
Room thermostat = deep flush-mounted box

I have planned the electrical installation conventionally, without using KNX. I have several reasons for this, which I don’t want to discuss here.

Now, I have the following questions:
The electronics boxes have a very large volume. Especially when placing two side-by-side in the TV area, this creates a very large opening in the 17.5 cm (7 inch) KS (calcium silicate) wall — especially when there is a socket for the satellite connection nearby.
Should the cavity be filled with mortar again before plastering, or is it fine to leave it empty?

Cable entry for deep flush-mounted boxes: To fully use the depth of the boxes, I want to feed the cables in from the back. Here too, I often need to widen the drilled hole or notch quite a bit to reach this point. Most of the time, this causes chunks of the calcium silicate blocks to break off (cavities inside the blocks). Should these cavities be filled beforehand as well?

I am a bit concerned about the structural integrity.

daddeln1988 schrieb:

Since I’m avoiding junction boxes 99% of the time, I have planned the following flush-mounted boxes for the installation.

That makes sense. Do you have electric roller shutters? Depending on where you place the switch later (we have ours by the door because it annoys me to walk to the window every time), it’s useful to install a junction box there. It will be plastered over later and won’t be visible. But it’s helpful when replacing the motor – just put a snap-on cover on it and don’t forget the empty conduit there.

daddeln1988 schrieb:

Switches/push buttons = deep flush-mounted box
Power outlets = standard flush-mounted box
Network = electronics box
Speaker connections = deep flush-mounted box
Cable/satellite = deep flush-mounted box
Room thermostat = deep flush-mounted box

Also use deep boxes for the power outlets. They cost just a few cents more but save a lot of hassle.
Consider using electronics boxes for the switches as well. Not using KNX is one thing, but there are plenty of alternatives with actuators you can hide behind the switches. Wiring those is still a real pain even with deep boxes. With electronics boxes you keep all options open.
The price difference is significant (around €3.50 vs €0.20 per box), but how many switches do you have in the whole house? At most 30-40… so it’s about a €150 extra cost, which I don’t want to miss anymore in our house.

daddeln1988 schrieb:

I planned the electrical installation conventionally without using KNX. I have several reasons for that, which I won’t go into here.

There’s nothing wrong with that.

daddeln1988 schrieb:

Now I have the following questions:
The electronics boxes have a very large volume. Especially in the TV area, when you place two side by side, it creates a very large hole in the 17.5cm (7 inch) calcium silicate wall. Especially when there is also a box for the satellite connection next to them.
Should the cavity be filled with mortar before plastering, or is it safe to leave it empty?

Use gypsum plaster and go for it. I just filled the entire hole with mortar and then inserted the box.
Plan LAN/satellite boxes separate from power outlets. For example, if you have 3 power outlets, 1 LAN socket, and 1 satellite socket, use a 3-gang frame for the outlets and a 2-gang frame for the data connections. LAN/satellite boxes aren’t the same size as power outlets, and it’s a nightmare to align everything perfectly in one frame. Two separate frames make it much easier (at least in my experience). Of course, the visual result has to suit your taste as well.

daddeln1988 schrieb:

Cable entry for deep flush-mounted boxes: To fully use the depth of the boxes, I wanted to route the cables at the very back. Here I often have to enlarge the drilled hole or chisel the groove quite far to reach this spot. Usually, part of the calcium silicate block crumbles (hollows inside the blocks). Should these cavities also be filled beforehand?

If half the block is missing afterwards, I would use mortar. Normally, though, nothing happens. We just drilled an angled hole through the block into the deep box to avoid chiseling so deeply.

I also come from an industrial background and had all your questions not too long ago.
A few more tips: With exterior walls, make sure to fully cover the box with plaster; otherwise, you can get black spots on the walls caused by air flow.
Are you building new or renovating? Don’t underestimate the amount of work for a new build. Particularly, doing something on short notice on site can take a lot of time.

There are airtight boxes available for exterior walls. You shouldn’t try to save money on the 12.35€ cost.

Also, it’s best to use standard-depth boxes everywhere, unless the walls are too thin in some areas.

The cables don’t need to be inserted deeply; it’s actually better if they come out as far forward as possible, giving you more flexibility when wiring.

We are building, and have been doing so for almost one and a half years. The shell of the building, including the roof, has been completed entirely by ourselves.

Yes, where the roller shutter switches are not located at the window, junction boxes are planned. That’s why it’s only 99%.

In the exterior walls, I fixed the boxes with plaster and then foamed around them.

No, unfortunately I have a few more switches and buttons. In the kitchen, living room, and dining room alone, there are 20 pieces. This is also due to the exterior lighting, outdoor outlets, and switchable indoor outlets.

Don’t forget the outlets for the access points when setting up the LAN. Ideally, they should be installed in the ceiling or at least at the top of the wall. The exact locations in the house depend on the floor plan.