Protection from direct contacts: IPXXB or IP2X?

THE QUESTION
On the electrical standard, we often read that the assemblies and/or the electrical equipments in general shall provide a degree protection against contact with live parts at least IPXXB or IP2X according to IEC 60529. What do these codes means and which differences exist between the degree protection IPXXB and the degree protection IP2X?
 

CONSIDERATIONS
Let’s start from the arrangement of the IP Code. The code of the degree protection is composed from the following parts: 
–    Code letter (International Protection) IP;
–    First characteristic numeral (numeral 0 to 6, or letter X);
–    Second characteristic numeral (numeral 0 to 8, or letter X);
–    Additional letter (optional) (letters A, B, C, D); 
–    Supplementary letter (optional) (letters H, M, S, W). 

The first characteristic numeral indicates that: 
–    The enclosure provides protection of equipment against the ingress of solid foreign objects; and simultaneously
–    The enclosure provides protection or person against access to hazardous parts by preventing or limiting the ingress of a part of the human body or an object held by a person. 
The second characteristic numeral indicates the degree of protection provided by enclosures with respect to harmful effects on the equipment due to the ingress of water. 
The additional letter indicates the degree of protection of person against access to hazardous parts. 
Additional letters are only used: 
–    If the actual protection against access to hazardous parts is higher that the indicated by the first characteristic numeral;
–    Or if only the protection against access to hazardous parts is indicated, the first characteristic numeral being then replaced by an X. 

Let’s analyze the two degrees of protection IPXXB and IP2X. 

According to EN IEC 60529, an equipment marked IPXXB is protected against access with the finger, or rather the jointed test finger of 12 mm diameter, 80 mm length has adequate clearance from hazardous parts. 

According to EN IEC 60529, an equipment marked IP2X is protected against solid foreign object with diameter ≥ 12,5 mm, or rather the object probe, sphere of 12,5 mm diameter does not fully penetrate. Moreover, the mark IP2X also ensures protection against access to danger parts. In particular an equipment marked IP2X is protected against access to hazardous parts with the finger, or rather the jointed test finger of 12 mm diameter, 80 mm length has adequate clearance from hazardous parts. 
 

CONCLUSION
The degree of protection IPXXB shall be chosen when the danger is the access to hazardous parts (direct contact). This degree of protections represents necessary and sufficient condition to protect from direct contacts. 
The degree of protection IP2X shall be chosen when the dangers are both the ingress of solid foreign object (with diameter ≥ 12,5 mm) in the electrical equipment and the access to hazardous parts. This degree of protection ensures the same protection from direct contacts offered by IPXXB. This degree of protection represents sufficient condition to protect from direct contacts. 

Regarding direct contacts, the degree of protection IP2X is equivalent to degree of protection IPXXB.