I need help identifying an installation problem with a Sonoff MiniR4M. I made the connection with parallel switches as instructed in the manual, however the device overheated and burned. the total power of the lights to which the device was connected was 190w and the electrical current was 1.5 amps. The only change I made to the installation was to use the neutral from another electrical circuit, but theoretically there would be no problem as they are all interconnected in the power panel. I can’t identify the problem.
On the contrary. I don’t want to go into details, but as a general rule you mustn’t do that. You have just found that out.
I say there’s no problem because I have more than 30 simple switches connected this way and two in parallel and I haven’t had any problems so far. But at that moment the problem occurred. I know that if I had an RCCB on all electrical phases this would be a big problem. I removed them after one burned out following a lightning storm and I had an interrupted neutral, with appliances burning out. The power distribution board in my house is like this. All neutrals directly connected.
Problem solved using a Sonoff ZB Mini L2, without the neutral wire. The problem is actually in the neutral, but I still don’t know what it is.
There’s no magic here. Just ask a qualified electrician for an explanation. As I said before, connections like yours are a no-go. Absolutely not! Doing so is like inviting chaos and danger to your doorstep.
In a nutshell, it looks like this. In an electrical circuit, the potential difference between two points causes electrons to flow from an area of higher potential to an area of lower potential. The greater the potential difference, the stronger the current flows through the circuit. Understanding this relationship is crucial to the design and analysis of electrical circuits. So the that the N wires converge and join at one point changes nothing.
If I may… Your switchboard is almost professional, but why are the L buses exposed like they’re on a nudist beach? The wiring in the wall box looks like it was done by a confused child. You’ve got yourself a real mess there, buddy.
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Why did S1 and S2 get together?
Answering the last question first, because it is a connection of switches in parallel, to turn the lights on and off at 3 points.
My house has 505 square meters of built area on 2 floors + attic and leisure area. It is a three-phase installation with two general power distribution panels, 1 for each floor + garden irrigation pump, artesian well pump + pool and whirlpool motor. It has its own solar energy generation system with 48 panels and solar water heating panels to power the boiler.
It is a very robust installation, it complies with local standards for sizing the electrical system, both in terms of wire gauge, number of electrical circuits, protection against atmospheric discharges and protection against electric shocks.
The lines in the distribution panel are completely closed by a cover. In Brazil, it is not mandatory to have an insulating cover on them, although some panels are already assembled this way.
Some of the wiring boxes were really full, they should have installed more conduits.
But in this investigation, I have already re-grounded the house and decided to re-ground the panels as well, changing the grounding system from earth-earth (TT) to earth, neutral - system (TN-S). which in my case would be practically interconnecting the ground and neutral combs of the panel, to equalize the potentials and improve the quality of the neutral. Here in Brazil, 4 different grounding schemes are allowed and each region has a preference for a form. I am a doctor, a thoracic surgeon, but I have never studied so much about electrical systems.
I have separated the structured cabling of the internet network and coaxial cables for the local TV signal, but if I were to do it again, I would perhaps separate the neutral and ground wires from the phase wires, to try to avoid inductance and reduce the chance of short circuits in the future.
In any case, we will install a power analyzer, since the potential difference between neutral and ground is varying from 12 to 20 volts throughout the day. It could be something internal, such as load imbalance between phases, harmonics in the power transmission frequency, or poor quality in the supply, with an unbalanced voltage step-down transformer and floating neutral.
The supply company inspected and replaced the connections of the external power standard, connected to the supply network. I also installed 3 more grounding bars on the ground, but it did not solve the problem. Anyway, still under investigation, but this episode helped me learn a little more and demand more from electrical engineers and technicians.
Photo 1 - Distribution board in my house
Photo 2 - Model of the distribution board that I will install
Photo 3 - Potential difference between the neutral and ground in the bedroom socket, which is repeated throughout the house.
Photo 4 - Grounding scheme in my house
Photo 5 - Change that will be made to equalize neutral and ground.
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