Oikodomisis

What Is an Electrician's Certificate (YDE): When Is It Mandatory, What Does It Include, and Why Does HEDNO Require It?

If you've ever rented a house, bought property, or tried to change the name on your electricity bill, you've almost certainly come across the phrase: "You need a new electrician's certificate."

The bureaucracy can certainly feel frustrating. It often looks like just another paid formality. In reality, the so-called YDE certificate, formally the Responsible Installer Declaration, is one of the most important safety documents for any home.

Let's see what exactly this technical file is, why HEDNO (the network operator) forces you to provide it, and what the electrician you call actually checks.

1. What exactly is YDE? (It's not just a piece of paper)

Many people think that the certificate is a simple declaration signed by the electrician. In fact, it is a complete technical file that captures the "x-ray" of your electrical installation.

A proper YDE certificate file includes five core documents:

  1. The Responsible Declaration Form: The central document where the licensed electrician states under his signature that the installation has been tested and is 100% safe.
  2. Panel One-Line Drawing: A technical diagram showing exactly which fuses are on the panel, what size they are and how they connect to the leakage relay.
  3. Installation Plans: Drawings of the house (living room, bedrooms, etc.) showing the exact locations of all sockets, switches, lights and fixed appliances (eg water heater, kitchen).
  4. Control Protocol: A check-list where the installer visually checks whether the regulations have been observed (eg correct distances of sockets from the sink in the bathroom).
  5. Measurement Form (The most important): The table with the numbers resulting from the special measuring instruments (how much the insulation withstands, in how many milliseconds does the relay drop, how much resistance does the ground have).
Illustration for 1. What exactly is YDE? (It's not just a piece of paper)

2. When is the issuance of a new YDE mandatory?

Illustration for 2. When is the issuance of a new YDE mandatory?

The law is strict and clear. You must call an electrician for a new YDE in the following cases:

Initial Connection

When a newly constructed building gets electricity for the first time (after construction).

Certificate Expiration

YDE has an expiration date! For residences it expires at 14 years and for business premises at 7 years (or even less, depending on use).

Change of Name / Provider

If you rent a property and want to transfer the electricity account into your name, HEDNO checks its database. If the existing YDE has expired, the account-holder change cannot proceed.

Change in Delivery Features

If you request an increase (e.g. from single-phase to three-phase current), power reduction, or change of use (e.g. conversion of a warehouse into a residence).

After Major Renovation

If you changed the cables, the panel, or added new heavy lines (e.g. for a heat pump or an electric car charger), the old YD is no longer valid, as it does not reflect reality.

3. Why does HEDNO insist on this? (Limits of Liability)

It is reasonable to ask: "If I am paying the bill, why does HEDNO care whether my internal wiring is old?"

The answer lies in the division of responsibility. The public distribution network belongs to HEDNO, but HEDNO's responsibility ends at your supply meter. Everything downstream of that point, inside the property, is the owner's responsibility.

HEDNO supplies your property with significant electrical load. If your internal installation has leakage currents, short-circuit risk, or inadequate grounding, there is an immediate danger of electric shock or fire. The YDE is the legal document that confirms a licensed professional has inspected the installation and considers it safe to energise.

Illustration for 3. Why does HEDNO insist on this? (Limits of Liability)

4. How Is the Inspection Carried Out? (Beware of the "5-Minute" YDE)

Illustration for 4. How is the check done? (Pay attention to the "5-minute" YDE)

Issuing a YDE is not something that should be done over the phone or in five minutes with a quick glance at the panel. A careful professional follows a real inspection process.

First comes a visual inspection of the main panel, with the power isolated, to check conductor tightening, signs of overheating, and whether the cable cross-sections match the breaker sizes. Then the electrician uses a dedicated installation tester to perform insulation tests, residual-current-device trip tests, and grounding measurements. In other words, a real YDE is based on measured values, not on guesswork.

If all the tests pass, the electrician draws the floor plan, fills in the numbers on the forms, signs them, stamps them with his trade association and gives them to you to file with your provider.

Summarizing

The Responsible Installer Declaration (YDE) is the closest thing your home has to a formal electrical health certificate. Yes, it is a bureaucratic step and it has a cost, but it is also the legal safety mechanism that protects occupants from poor workmanship, failed grounding, and ageing concealed wiring. Do not look for someone to "just sign"; insist on a proper inspection.

Related Articles

YDE Cost and Validity (2026 Guide): How Often It Must Be Renewed in Homes and Business Premises Changing the Electricity Account Holder: Which Documents You Need and When a New YDE Certificate Is Required Construction-Site Power: How the Initial Connection Works and How It Is Converted to a Permanent Supply The New ELOT 60364 Standard (formerly KEHE and HD384): What Changed in Internal Electrical Installation Rules

Preview