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Electrical Area Classification Calculator

API RP 500/505 & NEC Article 500

Classification System

Classification Method

Release Source

Source Type

Ventilation

Ventilation Condition

Operating Pressure

Operating Pressure

psig

Higher pressure may increase classified area extent for some sources.

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Understand electrical area classification principles and code requirements

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Division vs Zone System

Division System (US Traditional):

Division 1: Normal operation hazard
Division 2: Abnormal conditions only

Zone System (IEC-based):

Zone 0: Continuous hazard
Zone 1: Normal operation hazard
Zone 2: Abnormal conditions only

Limitations

Extents are based on API RP 500 Figure recommendations - site-specific analysis may differ
Does not account for heavier-than-air accumulation in pits or below-grade areas
Consult qualified electrical engineer for final area classification drawings

Standards & References

API RP 500
Classification of Locations - Division System
API RP 505
Classification of Locations - Zone System
NEC Article 500
Hazardous Locations - Division
NEC Article 505
Hazardous Locations - Zone