UNDERGROUND CONDUIT SYSTEMS for Primary and Secondary Conductors (Rev. 6)

Transcription

1 May 2014 UNDERGROUND CONDUIT SYSTEMS for Primary and Secondary Conductors (Rev. 6) Engineering & Asset Management No. 242 Rocky Mountain Power Utah Wyoming Idaho This procedure and related documents are posted on the web at:

2

3 Underground Conduit Systems for Primary and Secondary Conductors for Rocky Mountain Power Power Delivery no. 242 Author: Ken Shortt, Ryan Anthon Approval: Paul Radakovich (through R5), Douglas Marx (R6) Authoring Department: Rocky Mountain Power Operations Approved File Location: Pdxshrn104\shr04\Eng\Publications\DIS\POL File Number-Name: 242-RMP Underground Conduit Systems.docx Revision Number: R6 DRAFT Revision Date: 5/13/14 Document Security Category Confidential Restricted External Critical Infrastructure Information (CII) Internal Revision Log 0 1/28/11 Initial issue. 1 2/3/11 Edits by Ken Shortt 2 2/21/11 Edits by Ken Shortt, revisions to backfill req s in trench figures, per rule 321 in the NESC 3 3/10/11 Extensive edits to text, figures and tables. 4 3/28/11 Addition of Section 4.9 by Michelle Darger and edits to figure /15/11 Extensive edits and additions by Ken Shortt 6 5/13/14 Updates to allocated pad areas in Figures 3.3.2, 12.1 and 12.2 by Ryan Anthon Modification of this document must be authorized by PacifiCorp engineering publications, (503)

4 Underground Conduit Systems for Primary and Secondary Conductors for Rocky Mountain Power Power Delivery Policy no General Purpose Changes or Conflicts in Requirements Definitions Application Underground Requirements Customer Responsibilities Conduit Installation Requirements Trench and Backfill Requirements Pad Boxes, Padvaults, Flat Pads, and Secondary Boxes Padboxes (Box Pads) Padvaults (Vaults) Flat Pads Secondary Boxes Clearances, Firewalls, and Enclosed Spaces Working Clearances National Code Clearances Firewalls Power Company Equipment in Enclosed Spaces Installation Guidelines Trenches and Backfill Trenching Call Before You Dig Backfill Installation Guidelines Conduit, Conduit Proofing, and Conduit Sealing Installing PVC Conduit Installing Conduit to Energized Equipment Installing Conduit through Pavement Pull Line, Proofing, and Sealing the Conduit Joint Use Separation Transition from Overhead to Underground Equipment Bases General Information Site Selection Modification of this document must be authorized by PacifiCorp engineering publications, (503) i

5 7.2 Site Preparation Height above Final Grade In Residential Subdivisions Leveling Equipment Base Location Barrier Post Protection Joint Use Bonding Wire Three Phase Sectionalizing Cabinet Equipment Base - Customer Responsibility Pad Box Dimensions Three Phase Sectionalizing Cabinet Excavation Three Phase Sectionalizing Cabinet Customer Installs Pad Box Power Company Installs Pad Box Single Phase Sectionalizing Cabinet Equipment Base - Customer Responsibility Pad Box Dimensions Single Phase Sectionalizing Cabinet Excavation Single Phase Sectionalizing Cabinet Customer Installs Pad Box Single Phase Sectionalizing Cabinet Power Company Installs Pad Box Single Phase Transformer Equipment Base Customer Responsibility Pad Box Dimensions Single Phase Transformer Excavation Single Phase Transformer Customer Installs Pad Box Single Phase Transformer Power Company Installs Pad Box Secondary Box Customer Responsibility Pad Box Dimensions Secondary Box Excavation Secondary Box Customer Installs Pad Box Power Company Installs Pad Box Concrete Flat Pads - Customer Responsibility Flat Pad Dimensions Three Phase Transformers Excavation, Flat Pad Three Phase Transformers Padvaults - Customer Responsibility Padvault Dimensions Excavation Padvaults Customer Installs Padvault Power Company / Padvault Clarification Modification of this document must be authorized by PacifiCorp engineering publications, (503) ii

6 List of Figures Figure Primary, Secondary, and Service Conductor Schematic... 2 Figure Typical Primary and Secondary Equipment... 3 Figure Fiberglass Conduit... 6 Figure Electrical Grade PVC... 6 Figure Fiberglass Sweeps... 6 Figure Fiberglass End Connections... 7 Figure Field Altered Sweep - Damaged PVC... 7 Figure Typical Mandrels... 8 Figure Primary Trench Figure Secondary Trench Figure Joint Use Secondary Trench Figure Joint Use Primary Trench Figure Fiberglass Pad Box Figure Pad Box Installation Figure Typical Padvault Figure Typical Padvault Installation Figure Three-Phase Transformer on a Flat Pad Figure Flat Pad Installation Specifications Figure Secondary Box with Pedestal Figure Installed Secondary Box with Pedestal Figure 4.1 Working Clearances to Pad-mounted Equipment Figure 4.2 Clearances between Oil Filled Equipment (Transformers) and Structures Figure 4.3 Typical Firewall Figure Typical Primary Conductor Trench Figure Typical Conductor Trench Figure Acceptable Backfill Figure Unacceptable Backfill Figure Applying Glue to Conduit Figure Seating the Conduit Figure 6.2 Installing Conduit to Existing (Energized) Equipment Figure 6.3 Installing Conduit through Concrete Figure Conduit Plug and Pull Line Figure Conduit Proofing Figure Plugging the Conduit Modification of this document must be authorized by PacifiCorp engineering publications, (503) iii

7 Figure Joint Use Separation Figure Joint Use Separation Figure Riser 8 from Pole Figure Riser 8 from Pole Figure Riser Too Close to Pole Figure 7.4 Positioning of a Pad Box Figure 7.5 Leveling the Equipment Base Figure Barrier Post Details Figure Barrier Post Layout and Clearances Figure Joint Use Bonding Wire in a Pad Box Figure 8 Three Phase Sectionalizing Cabinet Figure 8.1 Three Phase Sectionalizing Cabinet Pad Box Dimensions Figure 8.2 Excavation Dimensions - Three Phase Sectionalizing Cabinet Figure Top View - Three Phase Sectionalizing Cabinet Pad Box Figure Side View - Three Phase Sectionalizing Cabinet Pad Box Figure Conduit Placement - Three Phase Sectionalizing Cabinet Figure Hole through the Side of a Fiberglass Pad Box Figure 8.4 Top View - Three Phase Sectionalizing Cabinet Figure 9 - Single Phase Sectionalizing Cabinet Figure Single Phase Sectionalizing Cabinet Pad Box Dimensions Figure Excavation Dimensions - Single Phase Sectionalizing Cabinet Figure Top View - Single Phase Sectionalizing Cabinet Pad Box Figure Side View - Single Phase Sectionalizing Cabinet Pad Box Figure Conduit Placement - Single Phase Sectionalizing Cabinet Figure 9.4 Top View - Single Phase Sectionalizing Cabinet Figure 10 - Single Phase Transformer Figure Single Phase Transformer Pad Box Dimensions Figure Excavation Dimensions - Single Phase Transformer Figure Top View - Single Phase Transformer Pad Box Figure Side View - Single Phase Transformer Pad Box Figure Conduit Placement Single Phase Transformer Figure Conduit Placement - Single Phase Transformer Figure 11 - Secondary Boxes Figure Secondary Box Base Dimensions Figure 11.2 Excavation Dimensions - Secondary Box Base Modification of this document must be authorized by PacifiCorp engineering publications, (503) iv

8 Figure Top View - Secondary Box Figure Side View - Conduit Placement - Secondary Box Figure 12 - Three Phase Transformer Flat Pad Figure Dimensions of a Three Phase Transformer Flat Pad Figure Excavation and Conduit Placement - Three Phase Transformer Flat Pad Figure 13 - Switchgear and Three Phase Transformer on a Padvault Figure Padvault Figure Excavation - Padvault Figure Padvault Lid Figure Padvault is not set at the Proper Elevation Figure Conduit Entering the Padvault Figure Term-a-duct Used for Conduit Entering the Padvault Figure Grout Used for Conduit Entering the Padvault List of Tables Table 1.4 Conduit System Application... 3 Table Below-Ground Conduit Applications... 4 Table Above-Ground Conduit Applications... 4 Table Sweep Specifications... 5 Table 4.2 Clearances between Oil Filled Equipment (Transformers) and Structures Modification of this document must be authorized by PacifiCorp engineering publications, (503) v

9 Underground Conduit Systems for Primary and Secondary Conductors for Rocky Mountain Power Power Delivery Policy no General 1.1 Purpose This manual is intended to guide Rocky Mountain Power customers in the installation of primary and secondary underground conduit systems. This document covers most applications. This manual cannot address every possible situation. Consult the Power Company for solutions to unique circumstances to meet the intents of this manual. If additional information is required, or if the customer is not sure how to apply these guidelines, they should contact the Power Company at or via the internet at Changes or Conflicts in Requirements This manual is written with the intent to comply with all applicable codes, ordinances, and tariffs, as well as to implement common practices throughout the Power Company s service territory. Common practices are implemented to: meet or exceed minimum safety codes and municipal building ordinances, ensure fair and impartial requirements for all customers, use safe work procedures by following established Power Company standards, and facilitate the privacy and security of current and future customers and occupants. If a requirement in this manual conflicts with an applicable tariff, code, or ordinance, then other Power Company standards shall be used to design a solution that meets (or exceeds) the minimum requirements of the tariff, code, or ordinance. The Power Company will provide the standards, and should be consulted with questions on the applicability of any item in this manual. Where this document differs from the Power Company s Six-State Electric Service Requirements manual regarding primary and secondary installations this document shall prevail. 1.3 Definitions Conduit Systems Closed Conduit System: A closed conduit system consists of conduit in a trench terminating in vaults. All 600-ampere systems require (and some non-typical 200- ampere systems may require) a closed conduit system. Open Conduit System: An open conduit system consists of conduit in a trench terminating in open pad boxes or flat-pads. Typically, most 200- ampere (amp) systems will be built as an open conduit system. Equipment Bases: Equipment bases include pad boxes, padvaults, flat pads, and secondary boxes. Equipment bases provide a platform for padmounted equipment. Underground System Conductors (See Figure 1.3.1): Modification of this document must be authorized by PacifiCorp engineering publications, (503)

10 Primary Conductors: Underground conductors between the Power Company s substation and the Power Company s distribution transformers. Depending on the area, these conductors are energized between 4,200 volts and 34,500 volts. Secondary Conductors: Underground conductors between the Power Company s distribution transformers and secondary boxes. Depending on the customer s application, these conductors are energized between 120 and 480 volts. Service Entrance Conductors: Underground conductors between the customer s service equipment terminals and the Power Company s source (a distribution transformer or a secondary box). For more information regarding service entrance conductors and conduit please refer to the Power Company s Electric Service Requirements at Figure Primary, Secondary, and Service Conductor Schematic Primary and Secondary Equipment Associated with Conduit Systems Distribution Transformer: A voltage device that converts power from a primary voltage to a secondary voltage. The secondary side of the transformer is used to serve individual customers either directly or via a secondary box. See figure Sectionalizing Cabinet (Ground Sleeve): A primary voltage device used as a junction for two or more primary cables. A ground sleeve cannot be used to serve a customer. Switchgear: A primary voltage device used as either a switch point or protection point for two or more primary cables. Switchgear cannot be used to serve a customer. Modification of this document must be authorized by PacifiCorp engineering publications, (503)

11 Secondary Box: A secondary voltage device used as a junction for two or more secondary or service cables. A secondary box can be used to serve a customer. See Figure Distribution Transformer Sectionalizing Cabinet Switchgear Secondary Box Figure Typical Primary and Secondary Equipment 1.4 Application Table 1.4 Conduit System Application Conductor Type Primary, 600 Ampere Primary, 200 Ampere Conduit System Closed Open 2 Underground Requirements Secondary 2.1 Customer Responsibilities Open The Power Company reserves the right to require a closed conduit system in non-typical 200 ampere applications. The customer shall meet the requirements described in this document to complete construction for underground installations. The customer is responsible for providing all trenches, backfill, compaction, conduit, and equipment bases. The Power Company may provide some of these services, such as providing and leveling box pads. The customer is responsible for these costs. Before installing any primary and/or secondary conduit system, the customer shall enter into a contract with the Power Company and obtain a job sketch from a Power Company representative. The customer is responsible for ensuring that all conduit system installations comply with Power Company requirements and the provided job sketch. Modification of this document must be authorized by PacifiCorp engineering publications, (503)

12 Any conduit system or any part of a conduit system installed before receiving a job sketch from the Power Company will be subject to Power Company rejection. 2.2 Conduit Installation Requirements The following list of requirements applies to all primary and secondary conduit installations. Sections 5 through 13 of this document clarify many of these requirements and provide photographs of typical installations Location The customer shall ensure that conduit is located away from (and never underneath) buildings, building foundations, or other structures. Conduits may run at an angle under retaining walls, but should not run parallel to the retaining wall Water Flow The customer is responsible for recognizing potential surface and subgrade water flows and coordinating with the Power Company to minimize potential runoff problems Dirt and Debris The customer shall keep the inside of the conduit free of dirt and debris during installation. Once the conduit is installed, it shall be temporarily sealed (plugged or capped) to prevent infiltration of water and dirt Pull Rope The customer shall provide a flat pull line or poly rope capable of withstanding 500 lbs. of tension, installed with six feet of extra line extending from each end of the conduit. The pull line shall be secured before the ends are sealed Conduit and Sweeps Material Tables and identify the appropriate types of conduit and sweeps to be used. Table specifies the sweep specifications. Table Below-Ground Conduit Applications Below-Ground Conduit and Sweep Applications Application 1 Type of Conduit Sweep Material Three Phase Primary Fiberglass or PVC Fiberglass Single Phase Primary 2 Fiberglass or PVC Fiberglass or PVC Secondary 2 Fiberglass or PVC PVC or Fiberglass 1 The Pow er Company reserves the right to require steel conduit in non-typical applications such as a railroad crossing. 2 Fiberglass can tolerate higher sidew all pressure than PVC. Longer conduit runs or conduit runs w ith multiple turns may require fiberglass sw eeps. The Pow er Company reserves the right to specify w hich sw eep is required. Table Above-Ground Conduit Applications Modification of this document must be authorized by PacifiCorp engineering publications, (503)

13 Above-Ground Conduit and Sweep Applications 1 Application 2 Type of Conduit. Sweep Material Three Phase Primary Fiberglass or PVC Fiberglass Single Phase Primary 3 Fiberglass or PVC Fiberglass or PVC Secondary 3 Fiberglass or PVC Fiberglass or PVC 1 Above-ground applications are installed by the Pow er Company 2 The Pow er Company reserves the right to require steel conduit in non-typical applications such as a bridge crossing. 3 Fiberglass can tolerate higher sidew all pressure than PVC. Longer conduit runs or conduit runs w ith multiple turns may require fiberglass sw eeps. The Pow er Company reserves the right to specify w hich sw eep is required. Conduit Diameter (in) Table Sweep Specifications Acceptable Elbow Sweeps 1 Secondary Conductor Conduit (in) Primary Conductor Conduit (in) In Trench Riser When PVC is Used 1 When Fiberglass is Used 1 2 Note n/a PVC Schedule n/a Long radii sw eep elbow sizes are based on cable sidew all pressure- bearing limitations. Depending on pulling calculations, the Pow er Company may require a larger radius sw eep or specify w hich material the sw eep should be made of. 2. It is not recommended to use 2 conduit for secondary. Minimum Fiberglass Wall Thickness (in) Modification of this document must be authorized by PacifiCorp engineering publications, (503)

14 Fiberglass conduit and sweeps must be black with three red stripes to identify electric conductors inside. For complete specifications on fiberglass conduit request a copy of material specification ZG033, or find this specification at Figure Fiberglass Conduit Figure Electrical Grade PVC Figure Fiberglass Sweeps Additional conduit and sweep requirements and comments: PVC shall be electrical grade 40 or better Fiberglass conduit shall meet or exceed the Power Company s material specification ZG033 Modification of this document must be authorized by PacifiCorp engineering publications, (503)

15 Each fiberglass sweep requires two factory-attached PVC, extra-deep, fabricated, expanded bell-ends as shown in Figure Fiberglass sweeps must be certified by a Nationally Recognized Testing Labratory (NRTL). High-Density Polyethylene (HDPE) conduit may be used upon approval of the Power Company. HDPE conduit can be installed by plowing and shortdirectional boring methods. Primary and secondary conductors can be pulled into this type of conduit. HDPE conduit shall meet the Power Company s specification ZG031 which can be found at Conduit and Sweeps - Installation 1. The customer shall provide and install conduit, including long-radius sweeps. 2. All PVC joints shall be glued and compressed to the depth of the coupling system. All fiberglass joints shall be glueless, using an interference and gasketed joint (see Figure ), and shall be compressed to the depth of the coupling system. Where straight ends and bell ends are joined, the straight end shall be beveled so as not to become an obstacle to mandrels or pulled cable. 3. Manufactured sweeps shall not be altered. However, field formed sweeps from straight conduit (PVC only) up to 15 degrees are allowed as long as the mandral can be pulled throught the conduit and the conduit is not damaged. Figure Fiberglass End Connections Figure Field Altered Sweep - Damaged PVC Modification of this document must be authorized by PacifiCorp engineering publications, (503)

16 2.2.7 Conduit Proofing All underground runs shall be proofed with a mandrel to remove obstructions, and to confirm at least 80 percent of the nominal conduit diameter. When requested by the Power Company, the customer shall perform a Power Company witnessed proofing of conduit systems. See Table 2.2.7, Required Mandrel Sizes for Conduit Proofing and Figure Table Required Mandrel Sizes for Conduit Proofing Conduit Nominal Diameter (in.) Mandrel Diameter (in.) Minimum Mandrel Length (in.) Maximum Mandrel Length (in.) Proof (%) Mandrel 2.5 Diameter 4 Mandrel 3.5 Diameter 6 Mandrel 5.5 Diameter Figure Typical Mandrels Change in Conduit Size No change in conduit size within a conduit run is allowed Conduit to Existing Equipment When the customer is installing conduit to existing (energized) equipment, the customer shall stop installation of the conduit two feet from the Power Company facility, unless otherwise requested by the Power Company. The Modification of this document must be authorized by PacifiCorp engineering publications, (503)

17 customer shall provide a sweep and extra conduit for use by Power Company employees Conduit to New Equipment Bases When the customer is installing conduit to new padvaults, flat pads, pad boxes, secondary boxes, or secondary pedestals, it shall be done according to Sections 8-13 of this document Conduit through Pavement When conduit extends vertically through a paved or concrete surface, a sleeve shall be placed around the conduit to prevent direct contact with the pavement. This helps prevent damage to conductors caused by ground movement Easements The customer must ensure all conduits are placed within the Public Utility Easement (PUE) or within the limits of the granted Right of Way for Rocky Mountain Power. 2.3 Trench and Backfill Requirements Call Before You Dig (811) State laws require the customer or excavator to call for underground utility locations. Excavation may not be started until locations have been marked or the utilities have informed the excavator there are no facilities in the area. Notify the local underground locating services (811) before you dig Trenching Requirements The customer shall provide all trenching. OSHA requires the trench be shored when the combination of trench plus the spoil exceeds five feet. To comply with OSHA rules when not shoring a trench, the customer shall keep the spoil at least two feet away from the open trench. The National Electrical Safety Code (NESC) states in section 321.A, The bottom of the trench should be undisturbed, tamped, or relatively smooth earth. Where the excavation is in rock, the conduit should be laid on a protective layer of clean tamped backfill. To the extent possible, trench bottoms shall be level and made of welltamped earth without sharp rises and drops in elevation. Rock spurs or ridges shall not project into the trench. If trenching is left open overnight, the customer is responsible for cleaning prior to conduit installation. Per NESC 321.A. the Power Company may require the conduit be laid on a protective layer of clean tamped backfill Backfill Requirements The National Electrical Safety Code states in section 321.B, All backfill should be free of materials that may damage the conduit system. RECOMMENDATION: Backfill within 150 mm (6 in) of the conduit should be free of solid material greater than 100 mm (4 in) in maximum dimension or with sharp edges likely to damage it. The balance of backfill should be free of solid material greater than 200 mm (8 in) in maximum dimension. Backfill material should be adequately compacted. Modification of this document must be authorized by PacifiCorp engineering publications, (503)

18 The following list of requirements applies to all installations requiring backfill: 1. The customer shall provide trench backfill and site restoration. 2. All backfill shall be free of materials, such as construction waste, large rocks, or sharp rocks, that may damage the conduit system. Where natural backfill poses such a hazard the Power Company will require the backfill within six inches (6 ) of the conduit to be 4 minus or finer (capable of passing through a 4 seive) per NESC 321.B. 3. Backfill shall be adequately compacted. 4. Prior to backfilling over the conduit, the Power Company shall inspect the backfill material and conduit installation. The Power Company will not energize conductors until the customer completes the backfill to Power Company satisfaction. Extra caution should be taken when backfilling trenches. The customer is responsible for repairing crushed or damaged conduit, including any costs for crews to return to the job site Primary Conduit Trench The primary conduit trench is normally in the Public Utility Easement (PUE) or an established right-of-way (ROW). This trench may include both secondary and primary cable. When digging only a primary trench, the customer shall follow the dimensions shown in Figure Figure Primary Trench Secondary Trench When installing only secondary conduit in a trench, follow the dimensions and requirements in Figure Where the secondary conduit approaches a box pad, the trench will need to be deeper to allow the conduit and sweep to be installed under the box pad. Do not reduce the integrity of the box pad by putting holes in it. Modification of this document must be authorized by PacifiCorp engineering publications, (503)

19 Figure Secondary Trench Joint Use Trench Joint use trenching requirements may vary by area; consult the Power Company for requirements before installation. The customer may be allowed to place communication, signal, and other electrical supply conductors in the same trench as Power Company conductors, provided that the installation meets Power Company policy, and all concerned parties agree on the placement. The Power Company will not install electrical conductors in a common trench with water lines, sewer lines, or other drainage lines. For a joint use trench with gas lines, contact the Power Company for requirements. PacifiCorp prefers that other electric utilities be located in different trenches that have a minimum separation of 6 feet; however, the Power Company may allow a joint trench agreement with another electric utility. When installing secondary conduit in a joint use trench, follow the dimensions in Figure When installing primary conduit in a joint use trench, follow the dimensions in Figure Figure shows the secondary and joint use installed in a horizontal configuration. This is the preferred configuration. When easements are limited or crowded, the secondary conduit can be placed above the primary conduit. Please contact the Power Company for details. Modification of this document must be authorized by PacifiCorp engineering publications, (503)

20 Figure Joint Use Secondary Trench Figure Joint Use Primary Trench 3 Pad Boxes, Padvaults, Flat Pads, and Secondary Boxes Pad boxes, padvaults, flat pads, and secondary boxes are all equipment bases. 3.1 Padboxes (Box Pads) Padboxes, shown in Figure 3.1.1, support single-phase transformers and single- and three-phase sectionalizing cabinets. Padboxes are used in open conduit systems. The Power Company often provides padboxes, but the customer is responsible for the cost. Modification of this document must be authorized by PacifiCorp engineering publications, (503)

21 Figure Fiberglass Pad Box A padbox is a fiberglass base for padmounted equipment, with sufficient space inside for training cables. The customer may elect to use padvaults in lieu of padboxes. All new construction requires a 32 padbox. The padbox should be level and installed as shown in Figure Figure Pad Box Installation 3.2 Padvaults (Vaults) Padvaults, shown in Figure 3.2.1, are used to support: Switchgear in 600-ampere applications Three-phase transformers with four or more conduits on the secondary side of the transformer. Single and three phase equipment in other select non-typical 200-ampere applications. Modification of this document must be authorized by PacifiCorp engineering publications, (503)

22 A padvault is a two-part concrete box consisting of a pad and an open vault. Padvaults are used with closed conduit systems. Figure Typical Padvault Padvaults are designed to be set such that the top of the pad is about three inches above the final grade in non-pedestrian areas, as shown in Figure 3.2.2, and flush with the final grade in pedestrian areas. Padvaults should be level and supported by six inches of ¾-inch-minus gravel backfill, compacted to 90% of dry density, placed over undisturbed earth. Figure Typical Padvault Installation Modification of this document must be authorized by PacifiCorp engineering publications, (503)

23 3.3 Flat Pads Flat pads, shown in Figure 3.3.1, are used to support three-phase transformers that have three or less secondary or service conduits 1. The customer may elect to use padvaults in lieu of flat pads. Flat pads may be poured in place or purchased precast by the customer. In both cases, the customer shall follow good construction practices with 18 inches of soil removed, the remaining soil compacted, and the hole filled and compacted with ¾-inch-minus gravel prior to either pouring the pad or setting the pad. Pads shall be set so they are level with about three inches of the pad left above final grade. See Figure for flat pad specifications. Figure Three-Phase Transformer on a Flat Pad 1 Number of conduits is based on the preferred number of conduits identified in Power Company standard GS031. Modification of this document must be authorized by PacifiCorp engineering publications, (503)

24 Figure Flat Pad Installation Specifications Modification of this document must be authorized by PacifiCorp engineering publications, (503)

25 3.4 Secondary Boxes Secondary boxes, shown below, are used as the base for secondary pedestals which provide service to multiple customers (typically homes). Secondary boxes should be installed on compacted soil, and the equipment base should be about three inches above final grade. Equipment Base Figure Secondary Box with Pedestal Figure Installed Secondary Box with Pedestal Modification of this document must be authorized by PacifiCorp engineering publications, (503)

26 4 Clearances, Firewalls, and Enclosed Spaces 4.1 Working Clearances The Power Company needs working clearances to maintain equipment once it is installed. The customer shall comply with the distances shown in Figure 4.1. Where access is required on one side of the equipment such as transformers and sectionalizing cabinets Where access is required on two sides of the equipment such as switchgear Non-access side Access side Distances are from the hinge on the access door. Distances are from the hinges on the access doors. 4.2 National Code Clearances Working Clearances Figure 4.1 Working Clearances to Pad-mounted Equipment Notes on Figure 4.1: Depending on the base the customer may not know exactly where the equipment will sit on the equipment base. As a rule of thumb assume the clearances will be from the edge of the equipment base. If these rule of thumb clearances cannot be achieved, contact the Power Company. No vegetation other than grass shall be present in the clear workspace. Trip hazards such as gutters, spigots, etc., shall not exist within the clear workspace. Curbs may be acceptable in the clear workspace; contact the Power Company during site scoping. National codes require minimum clearances to oil-filled equipment. Transformers contain a mineral oil. Although all padmounted equipment does not contain oil, the clearances shown in Figure 4.2 and Table 4.2 are required for all padmounted equipment. Modification of this document must be authorized by PacifiCorp engineering publications, (503)

27 Figure 4.2 Clearances between Oil Filled Equipment (Transformers) and Structures Table 4.2 Clearances between Oil Filled Equipment (Transformers) and Structures Clearance From Clearance in Front of (ft) Clearance to Side of (ft) Vertical Clearance from (ft) Fire escape n/a Doorway n/a Window that can be opened n/a Window that cannot be opened Air vent intake Air vent exhaust Combustible surface 8 n/a n/a Non-combustible surface 3 n/a n/a Fire Hydrant (non metallic equipment) 4 4 n/a Fire Hydrant (metallic equipment) 6 6 n/a Notes on Figure 4.2 and Table 4.2: Distances are from the equipment. If the building has a combustible overhang, the distance is measured from the outside edge of the overhang. Outside walkways or stairs attached to the building are considered part of the building. Minimum clearances must also be maintained from walkways used for exiting to a place of safety. Distances less than those specified in Table 4.2 (but not less than the required working space) may be allowed if approved by the appropriate code enforcement authority. This may require alternate means of fire protection per NEC Section and NESC Section 152(A)(2), including fire barriers, fire-rated walls, sprinkler systems, oil-containment means, or other measures. Use of alternate means of fire protection must be approved by the local code enforcement authority. The final grade at the location of the transformer shall provide oil drainage away from the building. Otherwise, an oil containment means is required. Modification of this document must be authorized by PacifiCorp engineering publications, (503)

28 4.3 Firewalls The customer shall conform to all local building codes and/or ordinances affecting the equipment location. Combustible/non-combustible construction types are defined by respective state building codes. At locations where the space separation is inadequate to provide fire protection, a firewall may be constructed. The firewall shall be constructed such that the heat and flame from a dynamic event are deflected away from the storage tank. The firewall shall be approved by local authorities. Contact the Power Company for information on firewalls. Also see ESR White Paper 5 Firewalls at Figure 4.3 Typical Firewall 4.4 Power Company Equipment in Enclosed Spaces The Power Company requires 24-hour access to equipment in gated and enclosed spaces. If a single- or three-phase transformer, padmounted piece of equipment, or pedestal is to be placed in a gated or enclosed space, the Power Company shall be granted proper access prior to installation. For more information, see ESR White Paper 5 Gated and Enclosed Spaces at 5 Installation Guidelines Trenches and Backfill The customer is responsible for providing all trenches, backfill, and compaction. The customer shall meet the requirements described in this procedure to complete construction for underground installation. The customer is responsible for ensuring that all conduit system installations comply with Power Company requirements. During development/construction, the customer is responsible for ensuring that all subsequent contractors in the vincinity of Power Company facilities exercise care to maintain the integrity of the conduit system (conduit and equipment bases). If the Power Modification of this document must be authorized by PacifiCorp engineering publications, (503)

29 Company is required to return to the site to repair the conduit system, the customer will be held liable. 5.1 Trenching Call Before You Dig 811 For trenching requirements see section 2.3, Trench and Backfill Requirements. The trench bottom should be level and well tamped. Figure Typical Primary Conductor Trench The trench should be level and well tamped. Modification of this document must be authorized by PacifiCorp engineering publications, (503)

30 5.2 Backfill Figure Typical Conductor Trench For trenching requirements see section 2.3, Trench and Backfill Requirements Acceptable backfill. No large or sharp rocks. No construction waste. The power company inspector will determine if native soil can be used as acceptable backfill around the conduit. Figure Acceptable Backfill Not acceptable backfill. Large or sharp rocks and construction waste may damage conduit. Acceptable screened backfill around the conduit should pass through a 4 sieve. Figure Unacceptable Backfill Modification of this document must be authorized by PacifiCorp engineering publications, (503)

31 6 Installation Guidelines Conduit, Conduit Proofing, and Conduit Sealing The customer is responsible for providing all conduit and sweeps. The customer shall meet the requirements described in this procedure to complete construction for underground installation. The customer is responsible for ensuring that all conduit system installations comply with Power Company requirements. During development/construction, the customer is responsible for ensuring that all subsequent contractors in the vincinity of Power Company facilities exercise care to maintain the integrity of the conduit system (conduit and equipment bases). If the Power Company is required to return to the site to repair the conduit system, the customer will be held liable. 6.1 Installing PVC Conduit For conduit installation requirements, see section 2.2.6, Conduit and Sweeps - Installation Inside Outside To glue PVC conduit together apply the glue to both the outside male and the inside female ends of the conduit. If installing the pull rope a conduit section at a time use caution to ensure the rope does not dry in any residual glue that may exist inside the conduit. Figure Applying Glue to Conduit Modification of this document must be authorized by PacifiCorp engineering publications, (503)

32 Push conduits together until they are seated. 6.2 Installing Conduit to Energized Equipment Figure Seating the Conduit For conduit to energized equipment requirements, see section 2.2.9, Conduit to Existing Equipment A conduit left two feet from existing energized equipment. This is required for safety reasons. Not shown in this picture is the sweep and additional conduit left to complete the installation into the energized equipment. In this case the conduit is sealed wit duct tape with the pull rope taped to the inside wall of the conduit Figure 6.2 Installing Conduit to Existing (Energized) Equipment Modification of this document must be authorized by PacifiCorp engineering publications, (503)

33 6.3 Installing Conduit through Pavement For conduit through pavement or concrete requirements, see section , Conduit through Pavement. Figure 6.3 Installing Conduit through Concrete 6.4 Pull Line, Proofing, and Sealing the Conduit For conduit sealing and pull line requirements, see sections 2.2.3, Dirt and Debris and 2.2.4, Pull Rope. For conduit proofing requirements, see section 2.2.7, Conduit Proofing. Conduit plug A pull line capable of withstanding 500 lbs. of tension, installed with six feet of extra line extending from each end of the conduit. The pull line shall be secured before the ends are plugged. Figure Conduit Plug and Pull Line Modification of this document must be authorized by PacifiCorp engineering publications, (503)

34 Pull line (500lb test) Mandrel being pulled through a conduit riser. Figure Conduit Proofing Plugging the ends of the conduit. Figure Plugging the Conduit Modification of this document must be authorized by PacifiCorp engineering publications, (503)

35 6.5 Joint Use Separation For joint use separation requirements see section 2.3.6, Joint Use Trench. Primary Conduit Secondary Conduits Primary and secondary conduit in the same trench. Note the difference in elevation between the primary and secondary conduits. Conduits should be at least 12 apart. Figure Primary and Secondary Conduits in Trench 12 Joint use conduit and cables should be at least 12 from primary and secondary conduits Figure Joint Use Separation Modification of this document must be authorized by PacifiCorp engineering publications, (503)

36 Note the spoil set back from the edge of the trench. Joint use conduit and cables should be at least 12 from primary and secondary conduits. Figure Joint Use Separation Modification of this document must be authorized by PacifiCorp engineering publications, (503)

37 6.6 Transition from Overhead to Underground When transitioning from overhead conductors to underground conductors, the Power Company will identify the appropriate location where the conduit riser shall be, relative to the pole. The nearest edge of the conduit sweep should be eight inches from the pole. If a riser already exists on the pole, the new riser shall be attached such that the new riser is parallel to the existing riser. 8 The sweep is to be 8 from the pole. The Power Company will decide the location of riser on the pole and mark it so the customer knows where to install the riser base. Figure Riser 8 from Pole 8 Sometimes a bracket is installed to assist the customer with placement of the riser sweep and support the sweep until the riser is built. The company will remove the bottom bracket after the riser is constructed. Figure Riser 8 from Pole Modification of this document must be authorized by PacifiCorp engineering publications, (503)

38 Sweep too close to the pole. 7 Equipment Bases General Information Figure Riser Too Close to Pole 7.1 Site Selection The site shall be inspected prior to selecting the equipment base or determining the installation details. The job sketch and associated documents should clearly identify each equipment base and location. The Power Company is responsible to design the job and determine the location of the equipment; however, input from the customer is valuable. Customer input will be reviewed and, if possible, incorporated into the design prior to the final design. The following items should be included in the inspection and accounted for in the job design: Soil class. Soil stability shall be determined and recommendations made on shoring or sloping requirements. Water table. Precautions should be taken to prevent any flooding affecting customer-owned equipment in adjacent structures or properties. Frost considerations: Consideration shall be given to local ground and frost conditions such that the installation remains structurally sound. Final grade. If the final grade has not yet been established, measures shall be made to allow for anticipated grade changes. Where radical changes in grade are anticipated, installation should be delayed until near-final grade has been achieved. Modification of this document must be authorized by PacifiCorp engineering publications, (503)

39 Site accessibility. The site location for any pad box or vault should be within 15 feet of gravel or paved surfaces. Future access requirements for operation and maintenance of equipment shall be considered when determining equipment location. 7.2 Site Preparation Excavations should be no deeper than necessary to install conduit and set the equipment base. Disturbed soil beneath any type of equipment base shall be compacted in six-inch lifts, and leveled to within a 2% slope prior to setting or pouring at the site. The customer shall supply: a six inch deep base of 3/4-inch-minus gravel compacted to 90% of dry density under padvaults, when required by the Power Company a six-inch base of 3/4-inch-minus gravel compacted to 90% of dry density under padboxes and secondary boxes, and an 18-inch deep base of compacted 3/4-inch-minus gravel compacted to 90% of dry density under flat pads. In marshy areas, where an adequate foundation cannot be created through normal methods, pilings may be required. 7.3 Height above Final Grade Equipment bases should be set such that approximately 3 will be above the final grade in non-pedestrian areas, and set flush with the final grade in pedestrian areas. 7.4 In Residential Subdivisions Padboxes and secondary boxes in subdivisions should typically be set 24 behind the sidewalk and near the property line. 24 to Sidewalk Edge Figure 7.4 Positioning of a Pad Box Modification of this document must be authorized by PacifiCorp engineering publications, (503)

40 7.5 Leveling All equipment bases should be level, with no more than a 2% grade from edge to edge. Level the equipment base in both directions Figure 7.5 Leveling the Equipment Base 7.6 Equipment Base Location Barrier Post Protection In locations where equipment damage due to vehicular traffic may occur, protective barrier posts shall be installed by the customer. Six-inch steel barrier posts shall be painted or galvanized, and may be filled with concrete. Six-inch concrete barrier posts shall be painted. The posts shall have a domed top, and shall be free of burrs and sharp edges. Each barrier post shall meet the following requirements: Each barrier post shall be set in a concrete foundation at least 12 inches in diameter and 24 inches in depth, below grade, as shown in Figure In areas where construction equipment traffic poses a temporary threat to equipment, barrier posts shall be provided by the customer, and shall remain in place until the threat has been eliminated. Enough barrier posts shall be installed to adequately protect the pad mounted equipment from vehicular traffic. If the distance between two posts, or between a post and a non-traffic area, is greater than six feet, an intermediate post shall be installed as shown in Figure Barrier posts shall be placed so as not to obstruct the opening of the equipment doors, nor to impede the operation of the equipment. If this is not possible, removable posts shall be used in the obstructive location(s). Modification of this document must be authorized by PacifiCorp engineering publications, (503)

41 Figure Barrier Post Details Figure Barrier Post Layout and Clearances Modification of this document must be authorized by PacifiCorp engineering publications, (503)

42 7.7 Joint Use Bonding Wire To meet NESC joint use bonding requirements a 10 length of #6 copper wire is required in pad boxes and flat pads. The bonding wire is used to bond joint use facilities to the Power Company ground. The customer is responsible to install the bonding wire when installing box pads or flat pads. Place the copper bonding wire in the right front corner of the pad box or flat pad. Feed underneath the bottom and coil each end as shown. 10 length of #6 AWG copper wire. Figure Joint Use Bonding Wire in a Pad Box Modification of this document must be authorized by PacifiCorp engineering publications, (503)

43 8 Three Phase Sectionalizing Cabinet Equipment Base - Customer Responsibility The drawings and pictures in this section represent typical installations. If you have any questions about any drawing or picture, please contact the Power Company. Figure 8 shows a properly installed three phase sectionalizing cabinet. Figure 8 Three Phase Sectionalizing Cabinet 8.1 Pad Box Dimensions Three Phase Sectionalizing Cabinet Pad box dimensions Top View Front View Figure 8.1 Three Phase Sectionalizing Cabinet Pad Box Dimensions Modification of this document must be authorized by PacifiCorp engineering publications, (503)

44 8.2 Excavation Three Phase Sectionalizing Cabinet The customer will excavate a 7 x 10 hole to the appropriate depth. Notes: Legend Excavate the pad box hole to at least 29 below final grade plus the size of the largest conduit (3 6 ). Open Excavation Not drawn to scale 7' Trench Conduit 10 Figure 8.2 Excavation Dimensions - Three Phase Sectionalizing Cabinet 8.3 Customer Installs Pad Box The customer will install the pad box and conduits as shown in Figures to Note that the number of conduits may vary depending on the infrastructure design. Modification of this document must be authorized by PacifiCorp engineering publications, (503)

45 Notes: For each conduit run: One 45 elbow permanently attached Elbow should terminate 6-10 inside the pad box as shown. Equipment base leveled to 29" below final grade Equipment base must be supported by compacted ¾ minus backfill Legend Open Excavation Backfill Conduit Pad Box Top of Pad Box Not drawn to scale Elbow The customer is responsible to install the bonding wire. Reference section Figure Top View - Three Phase Sectionalizing Cabinet Pad Box 3 Final Grade Elbow 3 6 Figure Side View - Three Phase Sectionalizing Cabinet Pad Box Modification of this document must be authorized by PacifiCorp engineering publications, (503)