Do we make preparations at the stage of laying electrical wiring?

I would like to share my experience, which I gained during the construction and laying of communications. I am not a professional in this field, so the information provided may be incomplete or inaccurate.

I, like many, am faced with a dilemma, what to do if the construction of a house/apartment (choose the one you need) needs to start today, but there is no money and/or time for the design and implementation of a smart home system in general and lighting automation in particular.
Answer: it is necessary to establish such communications that will allow the implementation of smart lighting functions in the future without the need to “familiarize yourself with the rake.”

Reading forums and talking with friends who tried to implement automation in an ordinary apartment, I noticed several common problem areas:

1. In apartments/houses built without taking into account the possibility of introducing lighting, control of smart devices can only be implemented (there are exceptions) using wireless battery-powered elements. There are relays for controlling the lamp that can be placed in the socket box. But for this, the socket box must be deep and not only a wire with a phase, but also a neutral wire must come into the socket box, so that such a relay or button can be powered. And here a problem emerges, and not just one.

   Firstly, deep socket boxes are extra work of gating and no one does it just like that, so you shouldn’t expect yours to be any different

   Secondly, usually only a phase is connected to the switch and an extra wire under zero can most often appear only by accident. For example, if the electrician-installer did not have a two-core wire on hand for a single-key switch and he used a three-wire one. In the case of a smart switch, you will have to limit yourself to wireless devices that run on batteries, which creates an additional problem like “the battery is dead.” If mechanical switches are simple and reliable, then with “smart” devices not everything is so wonderful. In the case of a smart lamp, you will have to leave the mechanical wall switch always on and use a separate remote control, which also has batteries. We leave the issue of diagnosing the reasons for the inoperability of lighting control in such a combination outside the brackets of this article. You reader, of course, don’t see this as a problem. And if you live alone, then checking the batteries, for example, is not a problem. But if not only you, but also your family members use this benefit, then a non-working switch, due to which, for example, your grandmother cannot turn on the light in your absence, can bring a lot of “pleasant” emotions. And when you come home in the evening and try to change the battery, you may find that you have run out of fresh batteries and you have to wait until tomorrow, when the store opens or when the batteries are charged. With the growing number of such devices, the scale of the disaster is only growing.

2. When choosing products from well-known manufacturers, you are choosing a fairly well-functioning and reliable system (conditional assumption), but the downside is that you have to choose a closed ecosystem, which may not be cheap and does not want or do not like to work with devices from other manufacturers. And over a long time horizon, it may not be available for purchase for replacement and renewal. This leads to increased acquisition and replacement costs.

3. By choosing open protocols like HomeAssistant, OpenHub, etc., you solve the vouchsafed problems of closed ecosystems, but you also lose access to their strengths: smooth operation and professional technical support (although this is not always the case). The whole world is before your feet with all the ravines, hummocks and cow dung. Even if you have implemented the High Availability principle, a cluster of redundant servers, gateways and other things, then sooner or later you will be faced with the inability to turn on the light due to the failure of one of the many elements of the system or during a period of reconfiguration or maintenance. After the third communication with the conditional grandmother, the balance of emotions between negativity from dissatisfied household members and positive emotions like “I did it after all” most often goes into the negative zone.

You, reader, will of course object that this is not a problem because “he who walks can master the road.” And I agree with you on this, and I myself also chose the path of freedom and open protocols. But how to solve the problem of reliability and uninterrupted operation so that the comfort of using the system does not suffer due to imperfect technology.

The answer is simple: this requires implementing redundancy of control loops and minimizing the number of critical points of failure that can lead to inoperability of the lighting system.

This simple idea haunted me. But how to make it so that you can control the light both from a regular mechanical wall switch, and with digital buttons or through the algorithms of a smart home controller, etc. At first, I viewed this idea as a pipe dream, and the prospects for a smart home were put off for an indefinite future. But when studying the range of electrical devices, a device such as a pulse relay came into the focus of my attention. It comes in both the form factor of a circuit breaker for mounting in a panel on a DIN rail, and in a compact format for installation in a junction box or socket box.

The relay is controlled by pulsed supply of 230V alternating current to the control contact. Control devices can be connected to the relay in parallel. Standard control is carried out by a bell button without latching, although there are impulse relays that can also work with standard lighting switches operating on a discrete principle. When using bell buttons, the number of points from which the lighting can be controlled is theoretically unlimited. Accordingly, the pulse relay can also be controlled by a smart home controller, which in turn reduces the requirement for the maximum switched load that such a controller can control, because it will only switch the AC control signal. And the failure of any control device does not lead to the inoperability of the control system. The only point of failure that disables the entire lighting system, in addition to the lamp itself, is the pulse relay itself.

Another advantage that we get when using a pulse relay is the ability to move the relay to the electrical panel and the ability to use standard inexpensive electrical and lighting components as part of the lighting system, costing from 200 rubles. for a switch/lamp versus 2000-10000 rubles. for smart devices.

This is what I was looking for. Now we need to figure out how to make it work. And here we come to the very foundation that I mentioned at the beginning of the article and which will allow us to implement any lighting control system: a classic system with mechanical switches, smart or hybrid using pulse relays. Answer: To do this, it is necessary to implement the appropriate electrical wiring diagram.

A short excursion into the wiring diagrams for lighting:
The classic wiring diagram, which has been used since the times of the USSR, implies, when laying a cable from an electrical panel, installing branch (soldering) boxes in places where the cable turns/branches embedded in the wall (see diagram No. 1).

This scheme minimizes the use of an electrical cable, connects several points in series, and when using corrugated pipes or special intra-panel cavities, in some cases allows for cable replacement without destroying the wall surface or finishing elements. The formation of a phase break and switching of the tap to the switch is carried out in a soldered box. The downside is the poor aesthetics of the junction boxes and the shutdown of all lights/sockets when the circuit breakers are tripped. In terms of smart lighting, we get all the disadvantages described at the beginning of the article.

“In response to people’s requests to remove the “socket” boxes out of sight, a scheme came up using recessed socket boxes and switching lighting cables in the socket box (see diagram No. 2). In this scheme, the cable from the panel goes into the switch socket box, where the switch is connected and switching the outlet to the lamp.

The advantages of this scheme: everything is good with aesthetics.
Cons: a little more cable and all the other disadvantages of the classic scheme, except for the lack of “separation” boxes.

In terms of smart lighting, it would seem that in this scheme it would be possible to provide for laying a cable with an extra core under zero to provide power to smart switches. But if you want to put a smart relay in a socket box to use it in conjunction with a mechanical switch or button, then you will have difficulty stuffing it all into the socket box, where two cables will go in instead of one cable when using scheme No. 1. And, if you need control from several points, you will be forced to limit yourself to using wireless buttons as additional switches. that is, not everything is smooth, but “smart lighting” can live.

And now we come to scheme No. 3 for organizing electrical wiring for lighting, which, in my opinion, is the most flexible and allows us to eliminate all the stated disadvantages. Flexibility is manifested in the fact that with such a wiring diagram you can implement any lighting control scheme: classic using mechanical switches or smart.

And most importantly, the lighting control circuit can be changed at any time by correcting the switching in the electrical panel and adding pulse relays and/or smart home controllers. The use of terminal blocks allows you to perform these corrections quite easily and more than once.

The only disadvantage of this scheme is the cost, because… You will need to lay a separate electrical cable from the switchboard to the switch and additionally from the switchboard to the lamp and provide a larger electrical panel that will accommodate all the equipment and wiring. Accordingly, there is more consumption of cables and components, and more labor costs for electricians for the installation itself. In the general estimate for electrical installation work, this is not a big increase to the estimate for electrical work, especially if we are talking about a standard apartment.

Conclusion

This article describes one of the solutions that can be used when implementing a smart home. I am sure that I did not open it for connoisseurs of the Americas. But my goal was to share my experience and try to highlight certain nuances and solutions that are not so obvious and can save time when choosing a path. I hope someone finds this article useful.