IP rating conundrum constantly causes complete consternation

[teachergeezer]

IP ratings are fairly straightforward in terms of the 1st two digits. The problem comes when considering the 3rd, rarely used, digit. This is used to denote protection against mechanical impact, useful for some types of electrical equipment. A quick internet search reveals that several sites state the 3rd figure is simply 1 to 6 inclusive, however others state that the numbers 1 to 9 are used, with the exception of 4, 6 & 8. This can cause a problem if you specify IP ratings of xx5, when you cannot be sure what rating it will be.
As this is supposed to be a 'universal & international' system, and free from ambiguity, does anybody out there know what the correst system to use should be? Has anybody experienced problems with this confusion?

 

[plugwash]

afaict the third digit is an extra added by some manufacturers but not standardised.

if in doubt ask the manufacturer.

 

[kendor]

may be of use?

http://www.speckanalytical.com/products/Tips/IP Ratings.html

 

[plugwash]

i can't see how its just another set of definitions with no authoritive source quoted!