Outdoor Transformer Clearances
Outdoor Transformer Clearances
(OP)
Are there any code required clearances for outdoor, pad-mounted, mineral oil-filled transformers from buildings, doors, windows, etc?
transformer....<1500kVA, 13.2kV or 4.16kV primary, 480Y/277 or 208Y/120 secondary
I've checked article 450 of the NEC. The article requires that safeguards be provided, but doesn't provide specific guidance. Also checked the NESC and come up with the same sort of criteria
Any suggestions or locations where I can find recommendations would be appreciated.
Thanks
transformer....<1500kVA, 13.2kV or 4.16kV primary, 480Y/277 or 208Y/120 secondary
I've checked article 450 of the NEC. The article requires that safeguards be provided, but doesn't provide specific guidance. Also checked the NESC and come up with the same sort of criteria
Any suggestions or locations where I can find recommendations would be appreciated.
Thanks






RE: Outdoor Transformer Clearances
More importantly liability and fire insurance underwriter have more restrictive requirments. I know FM (factory Mutual) has set guidlines for outdoors transformers. In absence of any other info, you may want to follow them.
Ask the insurance carriers of the facility you are working for.
RE: Outdoor Transformer Clearances
I believe you must be >3m (10') from a building, but 6m (20') away from any door or ventilation point. These distances can be reduced if you construct a blast-barrier, such as a cinderblock wall.
RE: Outdoor Transformer Clearances
Industry practice in Europe is to provide 1800 mm ( 1200mm min) clear access all round
RE: Outdoor Transformer Clearances
I was hoping to locate a standard with clearances listed. In my case, this is not a utility project. I will probably go to FM.
RE: Outdoor Transformer Clearances
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RE: Outdoor Transformer Clearances
NESC 152 A requires installation of liquid filled transformers to "minimize" fire hazards without giving particulars.
RE: Outdoor Transformer Clearances
We handle that problem by trying to educate the people who issue the building permits. It doesn't always work, but our records of correspondance are useful in proving that WE tried.