Oikodomisis

Manual Mains/U/Z Switching at the Electrical Panel: Legislation, Safety and How to Install

In the previous chapter we saw the ultimate comfort offered by the Automatic Transfer Switch (ATS). But what if you're on a tight budget, or you've already purchased a simple, portable, jump-start generator that you want to use to power your entire home?

The first, instinctive thought of many is to make a ballad with two male plugs. They plug one into the generator, plug the other into any wall outlet in the living room and... the house has power.

As engineers, we need to sound the alarm: This practice is deadly dangerous, strictly illegal, and internationally known as "Suicide Cord". To manually power your home safely, there is only one legal way: The Manual Transfer Switch (I-0-II) in the electrical panel. Let's see why it is necessary and how exactly it works.

1. The Deadly Danger of Backfeeding

Let's explain why the "socket plug" patent is criminal.

When the electricity from DEDDIE is cut, the central cable that comes to your house "dies". If you send power from the generator to your outlets without isolating the house from the grid, the generator current will travel backwards (Backfeeding). It will come out of your meter, go to the neighborhood pole and go through the transformers.

Illustration for 1. The Deadly Danger of Backfeeding

The Danger to Man

The DEDDIE technician who has climbed the pole to repair the fault, considers that the cables are dead. Suddenly, the current from your generator hits him, resulting in serious injury or death. In such a case, the legal penalties are severe.

The Equipment Risk

If you have not turned off the mains and the DEDDIE current suddenly comes back on, the 400 Volts of the network will "collide" with the 230 Volts of the generator. The generator will literally go up in flames in a split second.

2. The Solution: The Toggle Switch (I - 0 - II)

Illustration for 2. The Solution: The Toggle Switch (I - 0 - II)

Legislation requires a physical, mechanical isolation of the two sources. This is where the manual Changeover Switch comes into play.

This is a switch that is placed inside your electrical panel, right next to (or instead of) the classic General Switch. It has a lever with 3 clear positions:

The mechanism of the switch is made in such a way that it prevents (I) and (II) from being pressed at the same time. You can't go wrong, no matter how rushed you are.

Position I (Network - DEDDIE)

The house receives electricity normally from the city. The generator input is mechanically blocked.

Position 0 (Closed / Dead)

The house does not get electricity from anywhere. It is absolute isolation.

Position II (Generator - H/Z)

The house is completely cut off from DEDDIE and is connected exclusively to the generator socket.

3. The Right Installation (How to set up the system)

The procedure must be done exclusively by a licensed electrician and involves two steps:

  1. The Change in the Panel: The electrician installs the I-0-II switch (single-phase or three-phase, depending on your supply).
  2. The Outdoor Outlet (Male Plug / Inlet): To connect the generator, the electrician will run a cable from the panel to the garden, balcony or garage (where the generator will be running). A CEE industrial socket will be nailed to the wall, but be careful: it must be a male socket (with prongs). So the connection cable you get will have a female plug on the end, eliminating the risk of electric shock if you accidentally touch the contacts.
Illustration for 3. The Right Installation (How to set up the system)

4. Step by Step: What to do when the power goes out

Illustration for 4. Step by Step: What to do when the power goes out

You have the installation ready. It is dark. The correct and safe sequence of actions is as follows:

  1. Close the "Heavy" Loads: Go to the panel and turn off the fuses of the water heater, kitchen and air conditioners. Your generator can't handle all of these, so don't start it with them connected.
  2. Change the Switching: Turn the switching switch from position (I), to position (0), and then to position (II).
  3. Put in front: Go outside, pull the cord and put in front of the generator. Let it work for 1-2 minutes to warm up.
  4. Connect the Cable: Plug the thick cable from the generator into the special wall outlet. The house (lights, refrigerator, sockets) gets power immediately.
  5. When PPC Returns: How will you know after you have electricity? The electrician usually puts a "bulb" (indicator light) in the panel, which is connected before the toggle switch. When the light comes on, it means the city power is back on.
  6. The Reset: Turn off the generator. Turn the panel switch back to position (I). You turn up the water heater. End.

Summarizing

Manual switching does require your own physical presence to start the system, but it is the safest, legal and most economical way (cost of parts around €60 - €120) to take advantage of a portable generator. It is the only practice that protects your equipment, you, and the technicians working on the poles in bad weather.

Next Step: Generators have exhaust fumes, make noise and need gas. Is there a greener and quieter way to have autonomy in our home? We close the Reserve category with the absolute trend of the time: Home Energy Storage vs. Generators: The future of backup and cost comparison.

Related Articles

Choosing a Generator for the Home: Diesel vs. Gasoline vs. Inverter (Quiet) How to Calculate a Generator's kVA: Sizing Guide to Lift Emergency Loads Automatic Transfer Switch (ATS): How the generator starts up on its own when the power goes out UPS (Uninterruptible Power Supply) Buyer's Guide: Line-Interactive vs. Online – What to choose for PC, Server or router

Preview