ᐅ Empty conduit pipes for electrical installation in the basement level
Created on: 19 Apr 2018 12:51
J
JumpYHello everyone,
I am helping with the construction of a new house for my brother. The house will be built by a prefab house company, but only from the basement ceiling upwards. The house will be a type of bungalow, and the company will handle all the installation and setup of heating, electrical work, etc., in the upper living area.
The basement is made of prefabricated concrete elements that are placed on the foundation slab. The ceiling is also a semi-precast element that is simply laid in place. Afterwards, the ceiling is poured together with the exterior walls.
We have created a plan in advance for how the basement should be designed. Only two rooms will have flush-mounted wiring, but all lighting fixtures—except those in the garage—will be flush-mounted. In the office room, the “main” installation wall with numerous connections will be built as a drywall partition to make it easier to install the boxes, etc. (The rest of the empty boxes are already embedded in the walls with conduits protruding.)
Now I need to order empty conduits very soon for the office and the hallway, as well as for all the lighting fixture boxes. The lighting boxes will be pulled upward into the ceiling, then routed toward the utility room into the distribution cabinet. All flush-mounted switches, roller shutter switches, room thermostats, etc., will also be situated there. Later, a home automation system will take over controlling heating and shutters; the standard light switches will simply be bridged in the distribution cabinet to allow for possible modifications or controls—since you never know what might be needed.
Can anyone with experience advise me on which conduit diameters and types I should use? I am aware of the challenges when pulling cables; I would generally not use conduits smaller than M20, but how much can really fit where? For example, do 2x twin CAT7 cables fit through an M25 conduit? What about twin satellite cables in an M20 conduit? I find it difficult to estimate this but don’t want to oversize everything unnecessarily.
Is it correct that power cables must be installed separately, but CAT7 and satellite cables could share one conduit if needed, and for example, roller shutter switches or room thermostats could also share a conduit?
I’ve been looking at the Fränkische conduit system but haven’t been able to clearly identify which is the “simplest” conduit suitable for concrete there. I have wholesale prices for various types—for example, one called “UNI-EFMPZ25” that costs only half as much as Fränkische’s but is also suitable for concrete and includes an optional pull wire. (Otherwise, Kati-Blitz.) Does anyone know this conduit, or will some say “nothing works but Fränkische”? That is the only alternative the wholesaler offers, but I definitely don’t want to spend 100 hours later just because the conduits have a terrible inner coating or similar issues.
Attached is a house plan in case anyone wants to take a look. I would be very grateful for any help. Then I could install the conduits next week, pour the concrete, and afterward start with the electrical installation. (Don’t worry, an electrician will perform the final inspection, but I’m capable of pulling cables myself 😉)
I am helping with the construction of a new house for my brother. The house will be built by a prefab house company, but only from the basement ceiling upwards. The house will be a type of bungalow, and the company will handle all the installation and setup of heating, electrical work, etc., in the upper living area.
The basement is made of prefabricated concrete elements that are placed on the foundation slab. The ceiling is also a semi-precast element that is simply laid in place. Afterwards, the ceiling is poured together with the exterior walls.
We have created a plan in advance for how the basement should be designed. Only two rooms will have flush-mounted wiring, but all lighting fixtures—except those in the garage—will be flush-mounted. In the office room, the “main” installation wall with numerous connections will be built as a drywall partition to make it easier to install the boxes, etc. (The rest of the empty boxes are already embedded in the walls with conduits protruding.)
Now I need to order empty conduits very soon for the office and the hallway, as well as for all the lighting fixture boxes. The lighting boxes will be pulled upward into the ceiling, then routed toward the utility room into the distribution cabinet. All flush-mounted switches, roller shutter switches, room thermostats, etc., will also be situated there. Later, a home automation system will take over controlling heating and shutters; the standard light switches will simply be bridged in the distribution cabinet to allow for possible modifications or controls—since you never know what might be needed.
Can anyone with experience advise me on which conduit diameters and types I should use? I am aware of the challenges when pulling cables; I would generally not use conduits smaller than M20, but how much can really fit where? For example, do 2x twin CAT7 cables fit through an M25 conduit? What about twin satellite cables in an M20 conduit? I find it difficult to estimate this but don’t want to oversize everything unnecessarily.
Is it correct that power cables must be installed separately, but CAT7 and satellite cables could share one conduit if needed, and for example, roller shutter switches or room thermostats could also share a conduit?
I’ve been looking at the Fränkische conduit system but haven’t been able to clearly identify which is the “simplest” conduit suitable for concrete there. I have wholesale prices for various types—for example, one called “UNI-EFMPZ25” that costs only half as much as Fränkische’s but is also suitable for concrete and includes an optional pull wire. (Otherwise, Kati-Blitz.) Does anyone know this conduit, or will some say “nothing works but Fränkische”? That is the only alternative the wholesaler offers, but I definitely don’t want to spend 100 hours later just because the conduits have a terrible inner coating or similar issues.
Attached is a house plan in case anyone wants to take a look. I would be very grateful for any help. Then I could install the conduits next week, pour the concrete, and afterward start with the electrical installation. (Don’t worry, an electrician will perform the final inspection, but I’m capable of pulling cables myself 😉)
Hi,
Using the Fränkische conduit will make pulling the cables much easier for you. You can fit either two 3-core NYM cables or one 5-core NYM cable plus a bus cable inside a 25mm (1 inch) conduit.
Data and satellite cables must ALWAYS be installed separately from the 230V power cables. A simple rule to remember is that NYM cables should NEVER be run together with data or satellite cables. The only exception is the green KNX cable, which has a specific test voltage and can be installed alongside NYM cables.
Having two NYM cables in one conduit (for example, for blinds and thermostat) is completely fine.
Using the Fränkische conduit will make pulling the cables much easier for you. You can fit either two 3-core NYM cables or one 5-core NYM cable plus a bus cable inside a 25mm (1 inch) conduit.
Data and satellite cables must ALWAYS be installed separately from the 230V power cables. A simple rule to remember is that NYM cables should NEVER be run together with data or satellite cables. The only exception is the green KNX cable, which has a specific test voltage and can be installed alongside NYM cables.
Having two NYM cables in one conduit (for example, for blinds and thermostat) is completely fine.
Thank you for the prompt response.
You mentioned 2x 3-core NYM cable, so would that mean I can run either 2 pieces of 3x1.5mm² NYM or 1 piece of 5x2.5mm² NYM?
I’m currently considering which wire cross-sections make the most sense. For lighting, I assume 1.5mm² is sufficient, while sockets should be wired with 2.5mm². For the heavy-duty power outlet, of course 4mm² or 6mm² depending on the cable length, but since that will be surface-mounted, it doesn’t really matter.
Regarding cable cross-section, I plan to discuss this again with an electrician. I’ve read quite a bit lately; many recommend running cables before pouring concrete. I’m used to it being the other way around because electricians usually come later, after screed and concrete are done, especially if someone else installs the conduits beforehand. Otherwise, the schedule becomes pretty tight.
You mentioned 2x 3-core NYM cable, so would that mean I can run either 2 pieces of 3x1.5mm² NYM or 1 piece of 5x2.5mm² NYM?
I’m currently considering which wire cross-sections make the most sense. For lighting, I assume 1.5mm² is sufficient, while sockets should be wired with 2.5mm². For the heavy-duty power outlet, of course 4mm² or 6mm² depending on the cable length, but since that will be surface-mounted, it doesn’t really matter.
Regarding cable cross-section, I plan to discuss this again with an electrician. I’ve read quite a bit lately; many recommend running cables before pouring concrete. I’m used to it being the other way around because electricians usually come later, after screed and concrete are done, especially if someone else installs the conduits beforehand. Otherwise, the schedule becomes pretty tight.
Hello,
I tend to be a bit more daring in this regard. I pull the cables through the conduits before installing the conduits themselves, which reduces problems with blockages. Bricklayers aren’t very careful with the conduits in the floor slabs; they tend to stomp on them quite a bit. Another advantage of the Franconian type is that they are significantly more durable.
You only need 2.5mm² (approximately 13 AWG) wiring for the stove, cooktop, and dishwasher. For everything else, 1.5mm² (approximately 15 AWG) is usually fine without any issues. The 2.5mm² wiring is a pain to connect inside the junction boxes. If your cable runs are longer than 15m (50 feet), you can use a 10A breaker instead. That still provides about 2.3kW, which is sufficient for most appliances. Especially since the outlets are generally only rated for a continuous load of 10A, something that is often overlooked.
I tend to be a bit more daring in this regard. I pull the cables through the conduits before installing the conduits themselves, which reduces problems with blockages. Bricklayers aren’t very careful with the conduits in the floor slabs; they tend to stomp on them quite a bit. Another advantage of the Franconian type is that they are significantly more durable.
You only need 2.5mm² (approximately 13 AWG) wiring for the stove, cooktop, and dishwasher. For everything else, 1.5mm² (approximately 15 AWG) is usually fine without any issues. The 2.5mm² wiring is a pain to connect inside the junction boxes. If your cable runs are longer than 15m (50 feet), you can use a 10A breaker instead. That still provides about 2.3kW, which is sufficient for most appliances. Especially since the outlets are generally only rated for a continuous load of 10A, something that is often overlooked.
The basement floor mostly concerns the office room and the hallway. In the hallway, 1.5mm² (approximately 16 AWG) wiring is more than sufficient, but in the office with 5 sockets per feeder line, it’s better to use 2.5mm² (approximately 14 AWG). On the other hand, even with this size, you won’t exceed 2kW, so you just need to choose a circuit breaker accordingly. I will review this once more.
The conduits are relatively protected because the ceiling will be poured soon, and after that, the pipes won’t be exposed to damage. Since I’m on site permanently and know the company well, I will keep a close eye on them.
Could you possibly recommend a type for the Franconian conduits? I am still unsure which type of pipes is really suitable. (Concrete-resistant is clear, but there are about 15 different variants of those...)
The conduits are relatively protected because the ceiling will be poured soon, and after that, the pipes won’t be exposed to damage. Since I’m on site permanently and know the company well, I will keep a close eye on them.
Could you possibly recommend a type for the Franconian conduits? I am still unsure which type of pipes is really suitable. (Concrete-resistant is clear, but there are about 15 different variants of those...)
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