RMP Underground Conduit System Installation Guide (Procedure 242)

ProcedureFigure 4.2 – Clearances between Oil Filled Equipment (Transformers) and StructuresTable 4.2 – Clearances between Oil Filled Equipment (Transformers) and StructuresClearance FromClearancein Front of(ft)Clearance toSide of (ft)VerticalClearancefrom (ft)Fire escape 20 10 n/aDoorway 20 10 n/aWindow that can be opened 20 10 n/aWindow that cannot be opened 10 5 10Air vent intake 20 10 25Air vent exhaust 10 10 25Combustible surface 8 n/a n/aNon-combustible surface 3 n/a n/aFire Hydrant (non metallic equipment) 4 4 n/aFire Hydrant (metallic equipment) 6 6 n/aNotes on Figure 4.2 and Table 4.2:• Distances are from the equipment.• If the building has a combustible overhang, the distance is measuredfrom the outside edge of the overhang.• Outside walkways or stairs attached to the building are considered partof the building. Minimum clearances must also be maintained fromwalkways used for exiting to a place of safety.• Distances less than those specified in Table 4.2 (but not less than therequired working space) may be allowed if approved by the appropriatecode enforcement authority. This may require alternate means of fireprotection per NEC Section 450.27 and NESC Section 152(A)(2),including fire barriers, fire-rated walls, sprinkler systems, oil-containmentmeans, or other measures. Use of alternate means of fire protectionmust be approved by the local code enforcement authority.• The final grade at the location of the transformer shall provide oildrainage away from the building. Otherwise, an oil containment meansis required.J:\Publications\FPP\DIS\PRO\242-RMP Underground Conduit Systems.docx R6, 5/13/14This document is posted online at rockymountainpower.net, and at engineering’s intranet site for distribution procedures.Modification of this document must be authorized by PacifiCorp engineering publications, (503) 813-5293. 19