We know that the explosion-proof system in North America is very different from that in China/IEC/EU regions. Not only do they implement different standards, but their explosion-proof markings are also very different.

1. The National Electrical Code standard is widely adopted in North America. There is a significant difference between the identification of NEC explosion-proof electrical equipment and the representation method specified by IEC. Generally, the explosion-proof type is not labeled, only the applicable category, zone, level, and temperature group are labeled.

2. The IEC and Chinese GB standards indicate their explosion-proof markings, explosion-proof structures, categories and levels of electrical equipment, and temperature groups.

The above two types of explosion-proof labels have their own advantages and disadvantages, but according to Chinese standards and regulations, NEC labeling is not suitable for China's national conditions.

for example

NEC500 represents:

The characteristic of this symbol is that for users, they do not need to know the explosion-proof structure type of the electrical equipment, but only need to confirm the environment in which it is used, the level of explosive hazardous medium, and the ignition temperature group.

NEC505 represents:

IEC and Chinese standards indicate: Ex+explosion-proof structure+category+level+group

For example:

For example:

Ex eb ⅡC T2 Gb
Indicating: Temperature group T2 for increased safety factories (allowing equipment to generate heat below 300 ℃).

Ex db ib ⅡC T6 Gb
Indicating: Explosion proof and intrinsic safety type, factory uses Class IIC gas, temperature group T6 (allowing equipment heating temperature below 85 ℃). Generally, electrical equipment with this explosion-proof mark is an explosion-proof electrical system.