Wisconsin Administrative Code › Public Service Commission › Chapter PSC 114 - Wisconsin State Electrical Code, Volume 1 › Subchapter III - Omissions, Changes or Additions to NESC-2017 › Part 3 - Safety Rules for the Installation and Maintenance of Underground Electric Supply and Communication Lines › 31 - General Requirements Applying to Underground Lines › Section PSC 114.317 - Outdoor location of oil-insulated padmounted transformers near buildings

Current through June 24, 2024
[Follows NESC 316, p. 250] (Addition) Following NESC
						316, add the following section:
317.
					 Outdoor location of oil-insulated padmounted transformers near buildings.
A. Noncombustible and Combustible Walls
For the purposes of this section, combustible walls are
						walls of Type No.V buildings as determined by Wisconsin Building Code
						(Construction Classification IBC Chapter 6). All other walls are considered to
						be non-combustible.
B.
					 Noncombustible Walls
Padmounted oil-insulated transformers may be located
						directly next to noncombustible walls if the following clearances are
						maintained from doors, windows and other building openings.
1. Padmounted oil-insulated transformers
					 shall not be located within a zone extending 6.1 m (20 ft) outward and 3.0 m
					 (10 ft) to either side of a building door. See Figure PSC 114-317B1.
Click Here To View
						Image
Figure PSC 114-317B1.
2. Padmounted oil-insulated transformers
					 shall not be located within a zone extending 3.0 m (10 ft) outward and 3.0 m
					 (10 ft) to either side of an air intake opening. Such transformers may be
					 located within said zone beneath an air intake opening provided there is not
					 less than 7.6 m (25 ft) diagonal separation between the transformer and said
					 opening. See Figure PSC 114-317B2.
Click Here To View
						Image
Figure PSC 114-317B2.
3.
a.
					 Padmounted oil-insulated transformers shall not be located within a zone
					 extending 3.0 m (10 ft) outward and 0.9 m (3 ft) to either side of a building
					 window or opening other than an air intake. See Figure PSC 114-317B3a.
Click Here To View
						Image
Figure PSC 114-317B3a.
b. For second story windows, the transformer
					 shall not be located less than 1.5 m (5 ft) from any part of the window. See
					 Figure PSC 317B3b.
Click Here To View
						Image
Figure PSC 114-317 B3b.
C. Combustible Walls
1. Padmounted oil-insulated transformers in
					 sizes up to and including 100 kVA shall be located according to the provisions
					 set forth in Subsection B for noncombustible walls.
2. Padmounted oil-insulated transformers in
					 sizes above 100 kVA shall be located a minimum of 3.0 m (10 ft) from the
					 building wall in addition to the clearances from building doors, windows and
					 other openings set forth for noncombustible walls.
D. Barriers
If the clearances specified in PSC 114.317 cannot be
						obtained, a fire-resistant barrier may be constructed in lieu of the required
						separation. The following methods of construction are acceptable:
1. Noncombustible Walls
The barrier shall extend to a projection line from the
						corner of the padmounted transformer to the furthest corner of the window, door
						or opening in question. The height of the barrier shall be 0.3 m (1 ft) above
						the top of the padmounted transformer. See Figure PSC 114-317D1.
Click Here To View
						Image
Figure PSC 114-317D1.
2. Combustible Walls
The barrier shall extend 0.9 m (3 ft) beyond each side of
						the padmounted transformer. The height of the barrier shall be 0.3 m (1 ft)
						above the top of the transformer. See Figure PSC 114-317D2.
Click Here To View
						Image
Figure PSC 114-317D2.
E. Fire Escapes
1. Padmounted oil-insulated transformers
					 shall not be located within a zone extending 6.1 m (20 ft) outward and 3 m (10
					 ft) to either side of the point where a fire escape meets the ground. See
					 Figure PSC 114-317E1.
2. Padmounted
					 oil-insulated transformers located beneath fire escapes shall have a vertical
					 clearance of not less than 3 m (10 ft) from the top of the transformer to the
					 bottom of the fire escape. See Figure PSC 114-317E2.
Click Here To View
						Image
Figure PSC 114-317E1
Click Here To View
						Image
Figure PSC 114-317E2