Enclosure IP ratings allow you to select the right product for the application. But what do the numbers mean? And how can you be sure you have made the correct choice? Chris Lloyd, general manager for Spelsberg els UK, explains
IP – International Protection – or Ingress Protection as it is more commonly known, is a set of ratings designed for determining the level of protection offered by an enclosure against solid objects and water.
Defined by the international standard EN 60529, these ratings were initially developed as a way to classify enclosures, and now provide a convenient way to compare levels of sealing.
This standard describes a system for classifying the degrees of protection provided by electrical equipment enclosures, and is displayed in a standard format, such as IP56. The first digit is the protection against contact with dangerous parts and solid bodies; while the second is the level of protection against the harmful ingress of water. In some cases there may be a third digit which relates to the protection of an enclosure against external mechanical damage – this classification is covered by EN 50102, not EN 60529.
To indicate that tests are not applicable to the product, the letter ‘X’ is used in place of the first or second numeral. It is also used in standards to indicate that such protection is not required for the range of products covered. For example, IP4X specifies that protection against the 1.0mm probe is required and that there is no requirement for the protection from the ingress of water. According to current IEE Wiring Regulations – BS7671 – an enclosure which is readily accessible must maintain an IP rating of IP4X for horizontal top surfaces, in order to prevent small items falling through and coming into contact with live equipment.
For the purpose of most applications the rating system goes up to IP68, which provides complete protection from ingress when fully submerged (though statically fixed) in water up to 10m in depth. A specialised IP69K rating is available, however, for applications needing protection against dust, high temperature and high pressure water. Products with this certification are therefore suitable for use where equipment must be carefully sanitized.
The adoption of this classification system is a uniform way for describing the protection provided by the enclosure, with the IP rating ensuring that the project specifier knows that the product is protected from particles, dust or water in the environment where it will be installed.
While the rating system reliably indicates the level of protection an enclosure supplies, it is very common to see enclosures being over specified. Not only is this often more expensive, but it can also mean the enclosure is less suitable for the application.
Reducing condensation
Ventilation or pressure compensation devices can reduce the possibility of internal condensation caused by changes in air temperature and humidity. Where significant heat is generated in an enclosure, ventilation is generally employed to permit the equipment to operate within its designed performance characteristics. To minimise enclosure size and cost it is common to employ natural ventilation, using louvres and/or vents as required. Suitably located louvres and/or vents can provide protection against the ingress of heavy dust and occasional drips of condensate falling from above.
Drainage holes may be sufficient to disperse the condensate, but these apertures may reduce the IP rating. If correctly designed, however, drainage holes can enhance the weatherproof capabilities of an enclosure.
Enclosures need to be properly designed for the application, and most enclosure suppliers should be able to help with this. Spelsberg, for example, has in-house design and manufacturing expertise and can ensure that every aspect of the design is considered before suggesting one of the 4,000 items in the standard range – or providing a bespoke, engineered solution.
This ensures that issues such as ventilation and drainage are catered for and non-standard cable entries are accommodated while still maintaining the required IP rating for the installation.
Moulded enclosures
It should be noted that IP ratings are for ingress only, and that tests are comparative and conducted with fresh water. They therefore don’t indicate the enclosure’s ability to withstand the effects of corrosion from salt water, chemicals, acid rain and other special environments as well as the normal expected weather conditions.
Enclosures in moulded materials are available for use in harsh environments and generally provide good resistance to corrosion and chemicals. To avoid deterioration, careful consideration is required when choosing moulded enclosures as some materials do not perform well with dilute acids, certain chemicals or when exposed to ultra violet light (direct sun light). There is a vast range of moulding materials now available, so specifiers must consult the manufacturer for information on the ability of these to withstand hostile environments.
Standard or bespoke?
There are many important consideration when specify electrical enclosures or junction boxes. At best a poor specification choice will lead to unnecessary cost. At worst it could lead to catastrophic failure once installed.
It’s always best to speak to an expert who can help to specify either a standard enclosure or a bespoke version created to your individual design requirements.
Spelsberg els
T: 01952 605849
