IP-classification

Good enclosure of electrical or electronic equipment intended to operate in difficult environments, where dust, corrosive substances, moisture or water can penetrate, is of the utmost importance in reducing the risks of electric shock, fire or explosion.

Minimum requirements are set out in documents such as product standards for electrical safety and in standards for equipment used in potentially explosive atmospheres. 
There are also encapsulation requirements applicable to products with high reliability requirements and where the entry of dust could cause problems. IP-classification testing is normally carried out in accordance with the global IEC 60529 standard or its European equivalent, EN 60529, which has also been adopted as Swedish Standard SS EN 60529.

Degree of protection against solid foreign objects (1 st number) 

IP 1X
The test for IP1X enclosures involves pressing a 50 mm diameter sphere with a force of 50 N against all openings in the enclosure. The item is approved if the sphere does not fully enter the enclosure and if there is a satisfactory distance from dangerous live parts and moving parts. 
IP 2X
IP 2X testing involves pressing a standardised 12 mm diameter test finger with a force of 10 N, and a 12,5 mm sphere with a force of 30 N, against all openings in the enclosure.  For acceptance, the sphere must not fully enter the enclosure and there must be a satisfactory distance between the test finger and dangerous live parts and moving parts   
IP 3X
IP 3X testing involves pressing a standardised test probe, in the form of a 2,5 mm steel wire, against all openings in the enclosure, with a force of 3 N.  For acceptance, the probe must not enter the enclosure.
 
IP 4X
IP 4X testing involves pressing a standardised test probe, in the form of a 1 mm steel wire, against all openings in the enclosure, with a force of 1 N. For acceptance, the probe must not enter the enclosure.    
IP 5X
Items to be tested for IP 5X enclosures are exposed to fine-grained circulating talcum powder in a dust chamber for 2- 8 hours, with the exposure time being determined by the test conditions for the specific item. This test is performed with a maximum depressure of 20 mbar inside the item under test, and with a maximum extraction rateof 60 volumes/hour. 

If specific product standards so permit, testing is performed without depressure for eight hours.
In addition to the dust test, a 1 mm steel wire is pressed with a force of 1 N against all openings in the enclosure.

For acceptance for Class IP 5X, dust must not penetrate into the item in such quantities, or in such a position, as to prevent satisfactory operation of the item or to present a safety risk. There must also be a safe distance from the wire to live or moving parts.
 
IP 6X
Items to be tested for IP 6X enclosures are exposed to fine-grained circulating talcum powder in a dust chamber for 2- 8 hours, with the exposure time being determined by the test conditions for the specific item. This test is performed with a maximum depressure of 20 mbar inside the item under test, and with a maximum extraction rateof 60 volumes/hour. 

Degree of protection against water (2nd number) 

IP X1
The enclosure is exposed to dripping water, with a flow rate of 1 mm/min, for ten minutes. 
Acceptance for Class IPX1 requires no water to have penetrated into the item in such a quantity, or in such a position, as to prevent satisfactory operation of the item or to present a safety risk

IP X2
The enclosure is exposed to dripping water during 4 x 2.5 minutes, with a flow rate of 3 mm/min.
The enclosure is tested in four fixed inclinations 15o from normal position.
Acceptance for Class IP X2 requires no water to have penetrated into the item in such a quantity, or in such a position, as to prevent satisfactory operation of the item or to present a safety risk

IP X3
The enclosure is exposed to water spray from an oscillating tube nozzle, with each spray jet giving a flow rate of 0.07 l/min, for ten minutes. Alternatively, a standardised spray nozzle, producing a spray of 10 l/min, may be used. If this spray nozzle is used, the exposure time is 1 min/m², with a minimum of five minutes. Regardless of the type of test equipment, water spraying is limited to ±60° from the vertical.
Acceptance for Class IP X3 requires no water to have penetrated into the item in such a quantity, or in such a position, as to prevent satisfactory operation of the item or to present a safety risk.

IP X4
The enclosure is exposed to water spray from an oscillating tube, with each spray nozzle giving a flow rate of 0.07 l/min, for ten minutes. Alternatively, a standardised spray nozzle, producing a spray of 10 l/min, may be used. If this spray nozzle is used, the exposure time is 1 min/m², with a minimum of five minutes. Water is splashed against the enclosure from all directions.
Acceptance for Class IP X4 requires no water to have penetrated into the item in such a quantity, or in such a position, as to prevent satisfactory operation of the item or to present a safety risk.

IP X5
The enclosure is subjected to a jet of water from a 6,3 mm diameter nozzle at a distance of 2,5 - 3 m from the item under test. The water flow rate is 12,5 l/min, applied for a time of 1 min/m², with a minimum of three minutes.
Acceptance for Class IP X5 requires no water to have penetrated into the item in such a quantity, or in such a position, as to prevent satisfactory operation of the item or to present a safety risk.
IP X6
The enclosure is subjected to a jet of water from a 12,5 mm diameter nozzle at a distance of 2,5 - 3 m from the item under test. The water flow rate is 100 l/min, applied for a time of 1 min/m², with a minimum of three minutes.
Acceptance for Class IP X6 requires no water to have penetrated into the item in such a quantity, or in such a position, as to prevent satisfactory operation of the item or to present a safety risk.
IP X7
The test is made by completely immersing the enclosure in water in its service position.
The enclosure is immersed to the depth of one metre with the duration time of thirty minutes.
Acceptance for Class IP X7 requires no water to have penetrated into the item in such a quantity, or in such a position, as to prevent satisfactory operation of the item or to present a safety risk.
IP X8
The test is made by completely immersing the enclosure in water.
Test conditions are subject to agreement between manufacturer and user.
Acceptance for Class IP X8 requires no water to have penetrated into the item in such a quantity, or in such a position, as to prevent satisfactory operation of the item or to present a safety risk.

Sources of information: www.sp.se/en