Minimum clearance of pad-mount transformer with fire-resistant barrier from building or opening

[katwalatapan]

Hello,

I wanted to inquire about the minimum clearance for a pad-mount transformer with fire-resistant barrier, from the building and/or any building opening.

According to the local utility requirements document, if a pad-mount transformer is to be located within 3 meters of a combustible surface/material of the building or within 6 meters of a window, door, opening, then a fire-resistant barrier is required to be constructed between the transformer and the opening/building.

Thank you.

 

[RonShap]

What kind of transformer is it?

There are some guidelines in the NEC (450.27 Oil, 450.23 FR3, etc) The regular oil in 450.27 is performance based.

The NEC is only involved if it is privetely owned. If it is a utility owned transformer, then you must follow what they say.

 

[stevenal]

http://www.fmglobal.com/fmglobalregistration/Vshared/FMDS0504.pdf

 

[tesladog58]

Also look at the NESC book for their guide lines, this is where the utilities get their standards for everything

 

[katwalatapan]

Thank you for the responses.

It is a 300 KVA, 3-phase, utility supplied transformer supplying 120/208V secondary. The transformer is supposed to be pad-mounted near the facility.

 

[7anoter4]

Since the oil quantity in a 300 kVA transformer is less than 100 gal, according to: NFPA 850
“Recommended Practice for Fire Protection for Electric Generating Plants and High Voltage Direct Current Converter Stations” ch. 5.2.4 Outdoor Oil-Insulated Transformers:
“5.2.4.6 For transformers with less than 500 gal (1890 L) of oil and where a firewall is not provided, the edge of the postulated oil spill (i.e., containment basin, if provided) should be separated by a minimum of 5 ft. (1.5 m) from the exposed structure to prevent direct flame impingement on the structure.”
I think "fire barrier" is not considered "fire wall" so this recommendation is a valid one.

 

[stevenal]

According to the local utility requirements document...

Sounds like you already have the very best guidance. What exactly is the question here?

NFPA 850 is out of scope, as this sounds like an ordinary commercial service.

 

[7anoter4]

From FM Global Property Loss Prevention Data Sheets
Table 6. Separation and Extent of 2-hour Fire Barriers for Protection of Main Building Walls
For Non-Approved transformer fluid [by FM] Fluid Volume less than 500 gal to Noncombustible Wall 5 ft.[1.5 m], to combustible wall also 5 ft.[1.5 m]. Remark : fire barrier mounted on the building; the distance is horizontal distance up to containment.