IP rating - Protection against Ingress

Sony Cybershot TX-5 (image taken
from Sony website).

Ever use products that failed because of water seeping into the interior? Or maybe sand jamming the moving parts? It is quite usual for products to be designed to be 'waterproof' or 'dustproof', but as an engineer, how do you know if they really are as they claimed, or what to look out for to know how 'waterproof' it is?

Engineered items are usually labeled as sealed against dust or water through a system known as IP rating. The IP code labeled on products and claimed in technical datasheet will provide users and buyers the degree of protection provided by mechanical casings and enclosures of electrical equipment against the following:

• protection against foreign objects (e.g. sand and dust)
• protection against effects due to ingress of water
• protection against access (accidental or intentional) by persons to hazardous parts inside the enclosure

So instead of the term 'waterproof', which provides no information of the nature of the product against water ingress, introduction of the IP rating provides a framework in which user can understand the level of protection afforded by the product against water intrusion.

A waterproof watch
(image taken from Globeoffer).

The details and classification of the rating, along with methods and tests to verify its compliance to a certain rating is outlined by the standard IEC60529, which unfortunately is not available to the public for free. The structure of the IP code is also provided within IEC60529 and it is fortunate that the code structure and method of interpreting it could be found easily from most websites, especially from suppliers of products which need to work under the aforementioned condition. 

IP code usually comprise of at least 4 characters, with additional optional characters to show additional protection. It started off with the mandatory characters 'IP', followed by 2 numerals after it. Each of the latter provides information on intrusion protection, with the 1st numeral providing level of protection against solid particle and the 2nd against water ingress. 

Sometimes additional characters will appear after the 2nd numeral. These characters are optional and rarely used, but will provide additional information regarding the additional type of protection and important details regarding the operation of the product. Subsequent articles will provide more information regarding the interpretation of the numerals and additional characters.

IP rating explained.