Conduits for electrical installation in basement level

Hello everyone,

I am helping with the new construction of a house for my brother. The house is being built by a "prefabricated house" company, but only from the basement ceiling upwards. The house will be a kind of bungalow; all installation and setup of heating, electrical, etc. for the upper living area will be carried out by the company.
The basement consists of precast concrete elements, which are placed on the ground slab. The ceiling is also a semi-finished part, which is simply laid on. Afterwards, the ceiling is poured together with the exterior walls.

In advance, we created a plan for how the basement should be designed. Underfloor wiring is only to be done in 2 rooms, but the lamps, except for the garage, are all flush-mounted. In the office room, the "large" installation wall with numerous connections will be installed as a drywall wall to make it easier to install the boxes etc. (The remaining empty boxes are already cast into the walls, and tubes stick out.)

Now I have to order conduits very soon for the office room and the hallway and for all lamp boxes. The lamp boxes will be pulled upwards into the ceiling and then laid towards the utility room in the distribution cabinet. All flush-mounted switches, roller shutter switches, room thermostats, etc. should also go there. Later, a home automation system is supposed to take over the heating and roller shutter control; the normal light switches in the distribution cabinet will simply be "bridged" there to possibly allow changes or controls, you never know what might happen.

Can anyone with experience tell me which diameters and types of pipes I should use? I know the problems when pulling cables; basically, I would not use any pipe smaller than M20 anymore, but how much can I really get through where? For example, do 2x Twin-CAT7 fit through an M25 pipe, what about Twin-Sat in an M20 pipe? I really find it difficult to estimate this, but I also do not want to oversize everything too much.
Is it correct that power cables must be laid separately, but Cat7 and Sat could go in one pipe in an emergency, and for example roller shutter switches or room thermostats could also "possibly" share one?
Then I looked at the Fränkische Rohrwerke, but couldn’t quite figure out which is the "simplest" conduit suitable for concrete there. I have wholesale prices for different types; for example, I also have "UNI-EFMPZ25," which costs only half as much as the one from Fränkische but is also suitable for concrete and would have an optional pull wire installed. (Otherwise Kati-Blitz.) Does anyone know this pipe, or does anyone say directly that nothing works without Fränkische? This is the only external supplier my wholesaler offers, but I definitely don’t want to stand there for 100 hours later because the pipes simply have a crappy inner layer or something.

Attached is also a house plan, in case someone wants to take a look at it. I would be very grateful for any help. Then I could install the conduits next week, and then it could be poured, and afterward, I can start with the electrical installation. (Don’t worry, the acceptance will be done by an electrician, but I can also pull cables ;))

Hi,

take the Franconian one, it will help you a lot when pulling the cables. You can fit either two 3-core NYM cables or one 5-core NYM cable and a bus cable into a 25mm conduit.

Data and Sat cables must ALWAYS be laid separately from 230V lines. You can simply remember that NYM cables are NEVER allowed to be bundled together with data or Sat cables. The only exception to this rule is the green KNX cable as it has a corresponding test voltage and may be laid together with NYM cables.
Two NYM cables in one conduit (e.g. for roller shutters and thermostat) are absolutely no problem.

Thank you very much for the prompt feedback.

You mention 2x 3-core NYM, so would I be able to fit 2 pieces of 3x1.5mm² NYM or 1 piece of 5x 2.5mm² NYM?

I am currently considering which cross-sections would actually make sense; for lamps I assume 1.5mm², sockets then already executed with 2.5mm²? Three-phase power socket of course 4mm²/6mm² depending on cable length, but that’s surface-mounted anyway, so it doesn’t matter.

Regarding the cable cross-section, I wanted to consult an electrician again. I have read quite a bit now, many also recommend cable laying before pouring concrete, I only know it the other way around because the electrician usually comes later, when screed and concrete, for example, are finished, if someone else already installs the conduits. Otherwise, timing gets really tight.

Hello,

I tend to be a bit bolder in this regard. I pull the cables through the pipes before laying the pipes, that way there are fewer problems with pipes not being continuous. Masons are not very careful with the pipes in the floor slabs, they stomp on them quite a bit. Another advantage of the [fränkischen] is that they are much more durable.

You only need 2.5mm² for stove, cooktop, dishwasher. The rest you can usually do without problems with 1.5. The 2.5 are a pain to clamp in the outlets. And if you have cable lengths longer than 15m, you just use a 10A fuse. It's still 2.3kW which is enough for most devices. Especially since the sockets are only designed for a continuous load of 10A anyway (this is often ignored).

The basement floor mainly concerns the office room and the corridor. In the corridor, 1.5mm² is then clearly sufficient, but in the office with 5 sockets per supply line, one should probably better use 2.5mm². On the other hand, even with that, you don't get over 2kw; you just have to choose the circuit breaker accordingly smaller, I will check that again.

The pipes are relatively protected because the ceiling will be poured very soon, and the pipes won’t be damaged anyway. Since I am there permanently myself and know the company well, I will keep a close eye on them.

Can you possibly name a type among the Franconian ones? I am still not sure which type of pipes is really suitable now. (Concrete-resistant obviously, but there are 15 different ones again...)

So far, I've never had a problem with that, 1.5 has actually always been sufficient.

I usually use the FFKuS-EM-F. pipes.