Three (3) fundamentals are behind the “electrical classification” model for hazardous locations. These three fundamentals mirror our approach to other workplace hazards, and understanding these three fundamentals will help make a lot of sense out of NFPA 497/499 and 1910.307.
- Limit
- Confine
- Isolate
The most common protection method is using “intrinsically safe” equipment in a HAZLOC. This is one way we LIMIT the energy sources in the HAZLOC. Another way to LIMIT ignition sources is to use compressed air as a power source rather than electrical.
The next most popular protection method is to CONFINE the potential ignition source(s). This protection method is often times called “explosion-proof equipment.”
The least used protection method is ISOLATING the potential ignition source(s). This involves techniques such as pressurization and purging, oil immersion, hermetic sealing.
Our RAGAGEP(s) even dictate which protection methods can be used in which Class/Division.
| Division 1 |
Division 2 |
| Explosion-proof | Hermetically sealed |
| Intrinsically Safe | Nonincendive |
| Purged/Pressurized (Type X or Y)* | Non-sparking |
| Oil immersion | |
| *see NFPA 497 | Sealed device |
| Purged/Pressurized (Type Z) | |
| Any Class I, Zone 1 or 2 method (U.S. only) | |
| Any Class I, Division 1 method |