Distribution transformer location

Status
Not open for further replies.
G

guggemos

Member
Location
Richmond, California
The oil filled distribution tramsformers on our project are located such that the radiator fins are <2-ft to the surrounding rebar reinforced concrete block walls. I thought the xfmrs had to maintain minimum 3-ft clearance to tha walls. XFMR1 = 13.8kV-4.16kV, 10MVA. XFMR2 = 4.16kV-480V, 2500kVA.
Not only does this fall under the NEC Art. 110 but also OSHA.
 
Smart $

Smart $

Esteemed Member
Location
Ohio
guggemos said:
The oil filled distribution tramsformers on our project are located such that the radiator fins are <2-ft to the surrounding rebar reinforced concrete block walls. I thought the xfmrs had to maintain minimum 3-ft clearance to tha walls. XFMR1 = 13.8kV-4.16kV, 10MVA. XFMR2 = 4.16kV-480V, 2500kVA.
Not only does this fall under the NEC Art. 110 but also OSHA.
Click to expand...

The fins are not the enclosure (of live parts). Code doesn't specify distance for adequate cooling, the manufacturer does.

I'm not sure there is any OSHA violation either. Is the space you are referring to a path for egress?
 
charlie

charlie

Senior Member
Location
Indianapolis
Who owns the transformers? If they belong to the serving electric utility, the NESC offers little in the way of guidelines for clearance. If this is in California, they have their own version of the NESC. :)

Rule 152A2 states, "The installation of liquid-filled transformers shall utilize one or more of the following methods to minimize fire hazards. The method to be applied shall be according to the degree of the fire hazard. Recognized methods are the use of less flammable liquids, space separation, fireresistant barriers, automatic extinguishing systems, absorption beds, and enclosures.

The amount and characteristics of liquid contained should be considered in the selection of space separation, fire-resistant barriers, automatic extinguishing systems, absorption beds, and enclosures that confine the liquid of a ruptured transformer tank, all of which are recognized as safeguards.​
 
H

hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
I've always been told a minimum of 10' from a building, but have not heard of a minimum from a retaining wall. Quoted a replacement feed to a building where the existing transformer was about 2' from the building wall, checked with the building department, and they would require it to be moved out to
10' before they would pass it. Quoted it that way and did not get the job, sure hope the other contractor knew to check, or they would be crying at the end of the day! Big bucks to move it.
 
G

guggemos

Member
Location
Richmond, California
Distribution Transformers Location

Distribution Transformers Location

The xfmrs are client owned (power plant). The path around the radiator fins is an egress to inspect the equipment (fans, secondary bus duct, etc.). Don't the fans qualify as electrical equipment thereby requiring work space?
 
Smart $

Smart $

Esteemed Member
Location
Ohio
hillbilly1 said:
I've always been told a minimum of 10' from a building, but have not heard of a minimum from a retaining wall. Quoted a replacement feed to a building where the existing transformer was about 2' from the building wall, checked with the building department, and they would require it to be moved out to
10' before they would pass it. Quoted it that way and did not get the job, sure hope the other contractor knew to check, or they would be crying at the end of the day! Big bucks to move it.
Click to expand...
The 10' comes from the distance that must be maintained by an enclosing fence... but the code is rather vague on walls. See 110.31.
 
Smart $

Smart $

Esteemed Member
Location
Ohio
guggemos said:
The xfmrs are client owned (power plant). The path around the radiator fins is an egress to inspect the equipment (fans, secondary bus duct, etc.). Don't the fans qualify as electrical equipment thereby requiring work space?
Click to expand...
I'll buy it, but can you cite a code reference which specifically requires it??? i.e. without having to "stretch" the interpretation to include, inspection and maintenance thereof. I know there are such requirements, but the space required seems always to be for accessing exposed live parts, or those behind enclosure doors.
 
Status
Not open for further replies.
Top