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Watertight below sea level

Keeping substation basements dry.

Watertight below sea level

Roxtec cable seals are ideal for the expansive Middenmeer area in the Netherlands. The electrical substations are located five meters below sea level and need protection against water, rodents and electromagnetic disturbances.

The former seabed in Middenmeer is the new home to hundreds of wind turbines, gigantic data centers and numerous glasshouses for tomatoes and peppers. The 150/20 kV transformer stations of TenneT and Qirion are growing in between, connecting the facilities to the national and regional grids.

“We save money on using high quality seals from the start.”
Sije van der Veen, Qirion

Sealing is saving

The high, muddy ground water is a constant challenge for the power suppliers.    

“We use Roxtec seals because we know our basements will be dry and free from animals,” says lead engineer Sije van der Veen of Qirion. “We do not want rats, rust or humidity to damage equipment so we install the high quality from the start. It is much more economical than to try with putty over and over again.”

Watertight below sea level - Sije van der Veen, Qirion

Great support

Project coordinator Maureen van den Boogaard of construction contractor Joulz Energy Solutions agrees:

“Roxtec seals are always our first choice. It is very convenient to work with the products as well as with the representatives. They are very cooperative.”

Roxtec seals bring benefits besides the resistance to constant water pressure. By installing openable seals as spare capacity, Joulz Energy Solutions is preparing for cables from future wind turbines and for cables to additional data centers and glasshouses.

Reducing the risk

The Roxtec H4 200 UG™ seal enables the routing of cables in trefoil formation alongside an earthing cable through the same opening in the wall. It is a smart way to avoid looping cables and the risk of unwanted electromagnetic fields.

Roxtec GH transits are also used in the project with sealing modules providing protection against electromagnetic disturbances.

“We copy this concept for our new substations. And when we upgrade our old stations we change to Roxtec whenever it is possible,” says Sije van der Veen.

Why use Roxtec?

  • Proven protection
  • Electrical safety
  • Cable retention
  • Built-in spare capacity
  • Technical support onsite

Project facts

Involved companies

TenneT – national electricity grid owner
Qirion – regional electricity grid owner
Reddyn – electricity grid operator
Joulz Energy Solutions – contractor/installer


Sealing of power cables entering transformer stations underground

Sealing requirements

Watertight, Rodent barrier, EMI protection, Cable retention