Blast/Fire Wall for Transformers

[asharma]

Can anyone tell me if there are any standards or guidelines giving the minimum safe distance vs capacity of the transformer beyond which blast wall/fire wall is not required. I need to find out whether there's a need of a blast wall between a building 3Meters away from a 2.5MVA 22kV/415V transformer. Thanks!

 

[jbartos]

Suggestions:
1. Check current local laws, bylaws, state and federal laws and regulations.
2. Item 1 may be circumvented by using dry-type transformers
3. NFPA 70-1996 National Electrical Code does not cover explosions, only fires in Article 450, and 450C deals with waults (it cites 4-inch concrete walls).

 

[GreyGoose]

look in the NFPA 850, Chapter 3 "General Plant Design". There are guidelines for minimum separation distances between structures for outdoor and indoor oil-filled transformers including firewall requirements. The guidelines are based on transformer oil capacity (volume), type of oil and transformer rating.
I would also advise following jbartos's advice of looking into any local, state, and federal laws that apply at your site and the NEC, Article 450 (Transformers).

 

[jbartos]

Suggestion:
NFPA 70-1999 National Electrical Code refers to NFPA 220-1995 Standard on Types of Building Construction (Type I and Type II Buildings) in NFPA 70-1999 Article 450-23 Less-Flammable Liquid-Insulated Transformers