Outdoor Transformer Clearances

[gadero]

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

 

[rbulsara]

Normally the local utility companies have some standards that they go by, ask them to provide you a copy.

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.

 

[tinfoil]

The CEC and OESC (in Canada) stipulate minimum 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.

 

[RajT]

Industry practice in Europe is to provide 1800 mm ( 1200mm min) clear access all round

 

[gadero]

Thanks for the responses.

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.

 

[alehman]

The following link is a private utility company standard. It is fairly typical of those I have seen working within the U.S. See page 105.

http://www.alliantenergy.com/docs/groups/public/documents/pub/p012675.pdf

 

[Electic]

In my area this is governed by a state administrative code at 8', with an exception granted for alley located free standing garage structures. The issue becomes, who's problem is it if a property owner builds too close to the existing utility transformer?

NESC 152 A requires installation of liquid filled transformers to "minimize" fire hazards without giving particulars.

 

[tinfoil]

@Electric

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.