Who supplies power at the berth

A ship at berth connects to the port's electrical installation, not to a utility. The port authority or terminal owns the shore connection point, and behind it sits a distribution network operator that maintains the cables and meters, plus a separate electricity seller that bills the energy consumed. The distinction between the two is the same one that governs every Spanish household, and it is the single most useful thing a master or port engineer can understand before plugging in.

The network operator and the seller are not the same company

In Spain, as across most of Europe, the electricity chain is split by law. The distribuidora owns and maintains the physical network: substations, cables, transformers, meters. It is a regulated monopoly with a defined geographic area, and it has no commercial relationship with the end user beyond delivering power and reading the meter. The comercializadora buys energy on the wholesale market and sells it to the customer, issuing the invoice and setting the contract terms. A ship or terminal can change seller without any physical work being done, because the wires stay with the operator.

This split is explained in detail for domestic and small commercial users in Spanish by the diferencia entre distribuidora y comercializadora guide, which sets out how the two roles divide responsibility for supply, faults and billing. The same logic applies at a port: the terminal's electricity contract names a seller, while the physical connection and any outage on the network side belong to the operator.

For a vessel, the practical consequence is that a fault at the berth may have nothing to do with the company named on the terminal's bill. If the shore connection point is dead, the first call is to the port or terminal operator, not to the energy seller. Only once the terminal confirms the supply is live does the question of metering and billing become relevant to the ship.

How do you find out which operator covers the area, and who to call?

Spain's distribution areas are public. The Comisión Nacional de los Mercados y la Competencia (CNMC) publishes the list of distribution companies and their zones, and each operator maintains a supply-point lookup. Given a CUPS code, the unique identifier for a supply point, the operator's website returns the distributor responsible for that address. Ports are no exception: a berth has a supply point, and that supply point belongs to one distributor.

For a ship, the CUPS is normally held by the terminal or the port authority, not by the vessel. That is the boundary to keep visible. The master does not contract with the distributor; the terminal does. What the ship needs is the terminal's escalation contact and, where shore power is metered separately, a clear reading of the meter at connection and disconnection.

If a berth loses power, the sequence is: terminal operations first, then the distributor's fault line if the problem is on the network. The seller is contacted only for contractual matters, such as a disputed invoice or a change of tariff. Confusing the two delays the response, because the seller cannot dispatch a crew to a substation.

How does the smart meter work, and how are readings taken?

Spain has largely completed its rollout of smart meters, which record consumption in hourly or finer intervals and communicate remotely over a power-line or radio network. The distributor owns the meter and collects the data; the seller receives the readings and uses them for billing. Manual reading visits are now the exception rather than the rule.

At a port, the same meter technology may sit behind a shore connection point, particularly where the terminal sublets power to tenants or vessels. Remote reading means the consumption profile is visible without anyone boarding. For a ship, that cuts both ways: it makes accurate billing possible, and it makes unexplained consumption visible. Taking a photograph of the meter display at connection and at departure remains standard practice, because it is the only record the ship controls.

Where a meter is not remotely read, the distributor sends a reader on a fixed cycle, and estimated readings may be used between visits. Estimated readings are a common source of dispute, and the remedy is a photograph and a formal reading request to the distributor through the terminal.

What does a ship actually connect to?

A vessel at berth connects to a shore connection point, sometimes called cold ironing or shore power. The connection point is part of the port's electrical installation. Behind it, the electricity has travelled through the public distribution network to a substation serving the port, then through the terminal's own installation to the berth.

Three parties matter. The port authority or terminal owns the berth infrastructure and the connection point. The distribution network operator delivers power to the port's supply point and maintains the network up to it. The electricity seller contracts with whoever holds the supply contract, usually the terminal or port authority, and bills the energy.

Shore power standards vary. Low-voltage connections at 400 V are common for smaller vessels, while larger ships may require high-voltage supply at 6.6 kV or 11 kV. The connector type, cable management and protection settings are agreed between ship and terminal before connection. None of this changes the commercial structure: the ship is a consumer behind the terminal's meter, not a customer of the distributor.

Why the distinction matters for cost and safety

Safety and cost both follow the same split. The terminal is responsible for the safety of the connection point and for the protection settings that isolate a fault. The distributor is responsible for the network upstream. The seller is responsible for the price and the contract. A master who knows which party owns which part of the chain can ask the right question in the right order.

On cost, the structure explains why shore power tariffs at a port rarely match a household tariff. The terminal buys energy under a commercial contract, adds its own costs for infrastructure and management, and resells to vessels. The underlying network charges and energy price are set by the distributor's regulated tariffs and the seller's contract, but the price a ship sees is the terminal's.

What a ship should record at every connection

The practical checklist is short. Record the meter reading at connection and disconnection, with a photograph. Confirm who holds the supply contract for the berth. Note the terminal's escalation contact for power faults, and separately the distributor's fault number if the terminal provides it. Keep the connection agreement, including voltage, frequency and maximum demand, with the ship's papers.

None of this requires the ship to understand Spanish retail electricity in detail. It requires knowing that the wires and the bill come from different organisations, and that at a port the ship sits behind the terminal, not in front of the distributor. That single distinction resolves most confusion about who to call when the berth goes dark.