Der Elektro-Tipp

The Elektro-Tipp - Customer information for electricians


Philipp C. Hensel

Dear Reader,

when it is humid and dusty, when, for example, strong sunlight causes high temperature differences between day and night, then power distribution solutions from specialists are in demand. In such difficult environments, trouble-free operation of systems should be ensured for years, better still, for decades.

The prerequisite for this is excellent housing quality with a high degree of protection. Given that rapid and significant temperature changes can result in condensation forming in enclosures, especially those with very tight housings, electronic equipment is prone to error ad failure in the long run.

To prevent these problems, we have developed special systems and accessories that keep the inside of the housings dry. In this way, we guarantee permanent operational safety for you and you for your customers.

With our simple selection table, you will quickly find the right product.


Philipp C. Hensel

Managing Partner of

Gustav Hensel GmbH & Co. KG


Electrical installation in difficult environmental conditions?

The right measures for high temperature differences: So that condensation is avoided in closed housings

Electrical installations must be set up in such a way that they can safely withstand the ambient conditions and stresses at their place of use. Temperature differences, e.g. due to climatic or operational influences, must also be taken into account. Temperature differences can occur in all protected and unprotected outdoor applications, but also indoors in special environmental conditions.

In all areas of the electrical installation, condensation can form in closed housings due to rapid temperature changes or major temperature fluctuations (day/night, change in weather, intensive sunlight, switching off the system). Particularly with a high degree of sealing, the risk of condensation accumulation increases, as excess air humidity cannot escape. In climates with particularly high humidity, the risk of condensation increases even more. Targeted measures are required to prevent consequences such as corrosion and malfunctions or even short-circuits or complete equipment/system failures.

What are the reasons for large temperature differences?

  • A cool night followed by a hot day
  • Weather change
  • Monsoons in tropical regions
Operating conditions
  • Different operating times of the installed units -> phases with a lot of power loss (waste heat) alternate with phases without operation (e.g. day/night)

Place of use
  • Outdoor applications: e.g. in the field of photovoltaics, water and waste water management, waste management, petrol stations and pipelines, telecommunications, mining and the building materials industry, etc.

  • Indoor applications: e.g. near large gates, in car washes and laundry rooms, in agriculture, in cement, glass and ceramic factories, in power stations/power distribution, etc.

Climate / Weather
Outdoor applications - petrol station
Indoor application

Special climatic conditions

High temperature differences and/or high humidity

What are the consequences of large temperature differences?

Especially for housings with a high degree of protection and thus high impermeability and low airflow between inside and outside

Warm air can absorb more water or water vapour than cold air. If the temperature in the housing drops, humidity is released at the condensation point in the form of condensation, which collects on the colder inner walls or built-in devices. The greater the temperature difference inside and outside the housing, the greater the risk of condensation.

There is a pressure difference between the inside of the housing and the environment.

  • Due to the resulting negative pressure in housings with a high degree of protection, outside air with humidity is sucked in because housings are not gas-tight.

  • If the temperature in the housing drops or if the air in the housing is completely saturated with water vapor, the humidity condenses and forms condensation on the inner walls and/or the built-in devices.
In addition, the temperature changes can have an impact on the units and thus shorten their service life.

Schematische Darstellung der Ex-Zonen
There is a pressure difference between the inside of the housing and the environment

Effects of condensation are multi-faceted:

  • Corrosion on equipment
  • Malfunctions
  • Electrical short-circuits
  • Equipment / system failures
  • This results in: Power outages, costly downtime, safety risks, to name a few ...

What do the product standards say?

  • The standard for cable junction boxes / small-type distribution boards specifies a hole for condensate drainage with a size of 5 mm (DIN EN IEC 60670-1, Chapter 12.3)
  • According to the standard for low-voltage switchgear, the relative humidity of 50 % of the ambient air must be taken into account, as well as occasional moderate condensation due to temperature fluctuations (IEC 61439, Chapter 7.1.1 (Table 15))

Hensel solutions for operational safety in the event of condensation

Provisions for water drainage should be made where condensation can occur within cable and piping systems and condensate can collect. Systems and accessories specially developed for this purpose by Hensel, which keep the inside of the housing dry and thus ensure the smooth and safe functioning of the electrical installation, provide a remedy.

Neue Kabelabzweigkästen und Verschaubungen für die Ex-Zonen 2 und 22 - mit vielen Vorteilen für den Elektro-Fachmann
Opening condensation membrane on cable junction boxes
Pressure equalisation  
Condensation membrane

Cable junction boxes DK / KF

An openable condensation membrane is standard for cable junction boxes. It is located at a low point in the cable junction box and, when opened, reveals a hole for the condensation to drain (Ø 5 mm).

Protection class IP 55 (with open condensation membrane)

Flexible Klemmentechnik

Ventilation flange Mi / FP

for ventilating ENYSTAR and Mi distributors at extremely high internal temperatures and where there is a risk of condensation.

Protection class IP 44

LES pressure equalising element

LES pressure equalising element

to reduce condensation and accumulation by equalising pressure. Prevents humid air from being sucked in from outside due to negative pressure. For pre-embossing M40 / M20.

Protection class IP 54

Insert cable + ventilate by equalising pressure
Insert cable + ventilate by equalising pressure

Combination ventilation gland KBM / KBS

reduce condensation that can form due to rapid temperature changes or intense sunlight, among other things, via a climate membrane in housings with a high degree of protection.

Protection class IP 66 / IP 67

Insert cable + ventilate by equalising pressure

Combination ventilation glands from Hensel are cable entry glands featuring a ventilation function and pressure compensation. A built-in climate membrane ensures that there is a balance between the air inside the housing and the ambient air. At the same time, the climate membrane prevents humidity from the outside from entering. Effect: The formation of condensation is reduced, accumulated condensation breaks down through the exchange of air.

Protective roof
Protective roof

Protective roof Mi / FP

provides protection against rain, snow and ice as well as condensation.

Protection class IP 65

Sealing compound
Sealing compound

WP (“waterproof”) cable junction boxes

with supplied sealing compound are suitable for outdoor installation and use in extreme application areas with risk of condensation and water penetration, as well as for installation in the ground, without traffic load.

Protection class IP 66, IP 68, IP 69

Hensel solutions for operational safety in the event of condensation

Ventilation flanges (Mi BF 44 / FP BF 18 / FP BF 27 / FP BF 36)

Protecion class

Suitable for box wall


300 mm

180/270/360 mm (FP)

Pressure equalisation



max. housing volume

Protection class

BM 20G

M20 x 1,5

28 l

IP 54

BM 40G

M40 x 1,5

122 l

IP 54

Combination ventilation glands



Sealing range

Protection class

KBM 20

M20 x 1.5

Ø 6 - 13 mm

IP 66, IP 67

KBM 25

M25 x 1.57

Ø 9 - 17 mm

IP 66, IP 67

KBM 32

M32 x 1.5

Ø 13 - 21 mm

IP 66, IP 67

KBM 40

M40 x 1.5

Ø 16 - 28 mm

IP 66, IP 67

Protective roof


Suitable for box wall (mm)

Height (mm)

Width (mm)

Depth (mm)

Mi DB 01





Mi DB 15





Mi DB 30

M32 x 1.5




FP DB 27

M40 x 1.5




FP DB 36

M40 x 1.5




Sealing compound + corresponding WP cable junction boxes


Net weight (kg)

GH 0350


GH 0500


GH 0850


GH 1200


You want more information? Contact us!

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