Attch 8_Electrical Systems and Const. Stds PNSY.pdf

Rev C 5/18

NAVFAC MID-ATLANTIC

Public Works Department Maine

PORTSMOUTH NAVAL SHIPYARD

ELECTRIC SYSTEMS DESIGN

CONSTRUCTION STANDARDS

May 2018

Table of Contents

Introduction

Medium Voltage

Considerations

Low Voltage

Considerations

Wiring

Wiring Devices

Raceways

Panel Boards

Switchboards

Lighting

Interior Lighting

Exterior Lighting

Utility Tunnels

Systems Furniture

Metering

Lightning Protection

IT/Telecom

Network Protectors (Surge Arrestors)

Contract Documentation

Contractor Requirements

Considerations

Introduction:

This electrical standard has been prepared to promote consistency in design and construction, and to establish preferred wiring methods and materials used in electrical installations. The intent is to not reproduce the content of the various codes and standards that apply to Navy electrical installations.

However, areas that have been identified as recurring issues in the design and construction of electrical systems have been included to avoid further confusion, and to eliminate the appearance of arbitrary decisions that can compound frustration to both the Navy and contractors in the execution of various contracts.

This document is not intended to contradict the requirements of the various UFCs, industry standards and codes governing the installation of efficient, cost effective, and safe electrical installations. With few exceptions, all the requirements indicated herein are in compliance with those various codes and standards. The electrical systems on the Portsmouth Naval Shipyard have evolved over many decades and under the supervision of many fine engineers, technicians and electricians from the past. To the greatest extent possible, this document attempts to respect the design rationale which resulted in the present state of the electrical distribution on the shipyard.

This is a living document which will be subject to periodic revisions. Changes are not meant to constrain, confuse, or trap contractors and engineers who perform the vital work on the shipyard electrical systems. This document is meant to level the playing field for all stake holders as well as respond to situations and changing conditions in the electrical industry. As with other such documents, engineers and contractors will not be held responsible for retroactive corrections due to new requirements and revisions to this standard as long as contract requirements are met for prior work.

Medium Voltage

Considerations:

o Nominal distribution voltage is 13.2 kV, resistance grounded, wye.

o Conductors shall be MV‐105, shielded, EPR insulation, 15kV class.

4/0 AWG for radials.

500 kcmil for loops.

Conductors and shields, Copper.

o Splices shall be 15kV class, hot shrink type suitable for wet location (Submerged).

o Terminations shall be 15kV class, 600 Amp, dead break type elbows for radials.

o Terminations shall be 15kV class, 600 Amp, dead break type elbows for loops.

o Surge arrestors shall be sized based on 15kV ungrounded distribution criteria.

o Standards & Specifications:

UFC 3‐550‐01

UFGS 33 71 02

IEEE C62.22

Low Voltage

Considerations:

o Low voltage distribution on PNSY is derived from a grounded, wye system from distribution Load Centers throughout the ship yard. Utilization voltage is 480 VAC.

The Load Centers are set up as double ended, separately derived systems with no ability to switch the neutral conductors. As such, PNSY does not allow pulling neutrals in feeders supplying facilities at PNSY.

480/277 systems are not allowed unless the neutral is locally derived at the load end of the facility feeder via isolation transformers.

Design calculations shall be provided for all new feeders used to supply existing and new facilities. No feeder will be approved for connection without the prior approval of the CI Electrical Branch and the UEM.

o Exterior Low Voltage Distribution Feeders Supplying PNSY Facilities:

UFC 3‐550‐01

UFGS 33 71 02

Conductors for the distribution of low voltage from load centers to various facilities are classified as feeders. Exterior distribution wiring type RHW‐2.

The shipyard has normalized on distribution in increments of 400 amperes.

Facility feeders shall be sized in 500kcmil increments.

Facility feeders with a demand load of less than 200 amperes may be served by

4/0 AWG conductors in lieu of 500kcmil. Coordinate with PWD ME Electrical

Engineering Branch.

All facility feeder runs shall have a properly sized grounding conductor originating at the load center and terminating at the load served.

Ducts shall be 5 inches nominal (typ.).

Splices shall be 600V class, hot shrink type suitable for wet location

(Submerged).

o Ground Resistance Testing: Due to the logistics of driving test rods, potential subterranean obstacles, congested, and over utilized real estate, use of the Fall‐of‐

Potential method for measuring earth ground resistance is impractical. Contractors and designers shall consult with the PWD ME Electrical Engineering Branch to coordinate alternate test methods.

o Feeder Calculations: Significant additions or loads added to existing infrastructure shall be preceded by a load study of the affected source—(service entrance, sub‐panel, etc.)—prior to commencement of design and construction. The method used shall comply with NFPA 70, Art 220. (See Appendix A: Determining Existing Loads.)

The designer of record shall be responsible for determining the suitability of any proposed electrical source for any new loads served under any given project.

30 amps or greater @ 480, 30 amps or greater @ 208 for service and feeder calculations.

The designer of record shall provide short circuit calculations for any equipment and current interrupting device added to any facility or electrical system.

Coordinate calculation method with PWD ME Electrical Engineering Branch.

Electrical connections derived from double ended sources may be calculated based on infinite bus at the line end of a feeder or service.

Minimum KAIC rating shall be 10kA.

o Multi‐wire branch circuits should be avoided.

In the event that multi‐wire branch circuits are necessary (i.e., systems furniture) all ungrounded conductors shall be switched simultaneously by the branch circuit disconnecting means.

Multi‐wire branch circuits shall originate from a single panel or switch.

Each ungrounded conductor shall originate from adjacent poles from the power source.

Standards and Specifications:

NFPA 70, Art. 210.4

Wiring:

o Insulation shall be THHN/THWN. Type TW is acceptable for grounds.

o Conductors shall be copper.

o Conductors sized #12 AWG or larger shall be stranded.

o Conductors sized #14 AWG or smaller shall be solid.

Exception: Stranded wire as allowed in UFGS 26 20 00 o Twist on connectors (wire nuts) shall be suitable for both stranded and solid wire terminations. Coordinate with manufacturer’s tables and recommendations.

o Type “NM” cables are prohibited for new work.

Existing type “NM” embedded in walls & feeding existing wiring devices and utilization equipment shall be allowed. (Existing utilization equipment relocated to new branch circuits shall be considered as new equipment.)

o Standards & Specifications:

UFC 3‐520‐01

UFGS 26 20 00

Wiring Devices:

o Wiring devices shall be “Spec” or “Commercial” grade as a minimum.

o General purpose toggle switches shall be 120/277 volt rated.

o Plastic wall plates shall be shatter proof.

o Ground fault receptacles shall be side wired or screw clamp back wired type. Provide receptacles with through wire protection via the ground fault circuit.

o Cage clamp terminations on wiring devices are prohibited.

o Wiring devices shall be screw clamp back wire type when terminating with stranded wire. Side wire termination of stranded wire is prohibited.

Exception: side wiring of stranded wire is acceptable if terminated with crimp‐ on connectors.

o Standards & Specifications:

UFC 3‐520‐01

UFGS 26 20 00

Raceways:

o EMT connections and couplings shall be made up using steel compression fittings.

Die‐cast compression fittings are prohibited.

Set screw fittings are prohibited.

o IMC is prohibited.

Exception: IMC shall be allowed if the installation methods are the same as those used for EMT. Use listed steel compression fittings. Threaded connections and couplings of IMC are prohibited. Coordinate with PWD ME

Electrical Engineering Branch.

o PVC Rigid Non‐Metallic Conduit shall be limited to underground, duct banks in concrete, under floor slabs, and similar applications. Limited use of PVC is approved in corrosive applications on a case by case basis.

o Outlet Boxes shall be solidly grounded.

Do not rely on wiring device yokes to provide equipment ground.

o Standards & Specifications:

UFC 3‐520‐01

UFGS 26 20 00

Panel Boards:

o Panel boards shall be commercial grade with bolt‐on circuit breakers. Snap‐in circuit breakers are prohibited.

o New 480 volt panel boards shall be coordinated with PWD ME Electrical Engineering

Branch to ensure compatibility with available fault currents.

o The use of tubs with pre‐punched knockouts is discouraged.

Applying field punched knockouts to panel board tubs with pre‐punched knockouts is prohibited.

o Adding new circuits to existing panel boards that have been in service in excess of 30 years shall be coordinated with the PWD ME Electrical Engineering Branch.

Under no circumstances will new work be allowed on Federal Pacific panel boards and switchboards without prior coordination with and authorization from the PWD ME Electrical Engineering Branch.

o Series rated circuit breakers are prohibited.

In high fault current installations it may be impractical to select circuit breakers with equivalent or greater withstand ratings. In such cases, installation of a properly sized current limiting fuse ahead of the downstream breaker may be considered. Coordinate with PWD ME Electrical Engineering Branch.

o Standards & Specifications:

UFC 3‐520‐01

UFGS 26 20 00

o Labelling:

The contractor shall be required to provide a new, typed panel schedule for any panel board in which new circuits are added. The new typed panel schedule shall include all existing branch circuit designations as well as new branch circuit designations.

All panel boards shall have a new Arc Flash Warning label affixed to the exterior of the cover or door if an existing label does not currently exist. Coordinate the

Arc Flash label with PWD ME Electrical Engineering Branch.

Switch Boards o Low voltage switchboards used for general distribution to shipyard facilities shall be unitized, enclosed switchgear.

Typical arrangement shall be of double ended feed utilizing a main‐tie‐main configuration.

Fault bracing shall be sized to withstand the full available short circuit capacity of the system assuming both mains and the tie breaker are closed in.

The transformers feeding each end of the switchgear shall be grounded wye configured as separately derived systems.

The main‐tie‐main circuit breakers shall be capable of simultaneously switching the neutral bus if neutral branch feeders are desired. Coordinate the need for neutral switching with the PWD ME Electrical Branch.

Long time, short time, and instantaneous breaker settings shall be adjusted to provide selective coordination.

Maximum breaker settings shall not be set greater than that required to protect the feeder individual conductors.

Breaker settings shall be ideally adjusted to limit arc flash to less than 2 calories/cm2 within the arc flash boundary . (PPE Category 2 or less.)

Breaker settings shall be maintained in a log.

The designer of record shall be responsible to provide breaker settings via electronic analysis of the system.

o Low voltage switchboards used for distribution of industrial electrical services to shipyard facilities (dry docks, berths) shall be unitized, enclosed switchgear.

This class of switchgear shall meet the criteria previously stated for general purpose, service distribution as previously indicated. See additional criteria below.

The fault bracing shall be sized to consider 50% motor contribution.

o Labelling:

All panel boards shall have a new Arc Flash Warning label affixed to the exterior of the cover or door if an existing label does not currently exist. Coordinate the

Arc Flash label with PWD ME Electrical Engineering Branch.

Lighting

Source:

o In general, all lighting shall be LED type. Use of fluorescent, HID, incandescent shall require coordination and approval of PWD ME Engineering.

Interior Lighting o Standards & Specifications:

UFC 3‐530‐01

UFGS 26 51 00

Exterior Lighting o Standards & Specifications:

UFC 3‐530‐01

UFGS 26 56 00

o Per UFC 3‐530‐01: Solar lighting is prohibited for roadway, walkway and parking lot lighting.

Utility Tunnels o Wet location listed, exposed.

o IP66 or greater.

o 60C rated.

o Materials compatibility:

resistant to seawater, resistant to pH of 11.3 (calcium hydroxide.).

System Furniture

System Furniture generally constitutes a multi‐wire branch circuit, and wiring and distribution shall be configured as such. The UFC specifies 5‐wire, and 8‐wire branch circuit configurations.

5‐wire should be used for general distribution of standard work station layouts. (3 circuits per cluster.)

8‐wire should be used for standard workstation with a printer or copier module on the 4th circuit. (4 circuits per cluster.)

There shall be no more than 4 work stations per circuit. (Equivalent to 3 duplex outlets per workstation max.)

Standards and Specifications:

o UFC 3‐520‐01

Metering

Revenue metering is required on all facilities. The system used throughout the Shipyard is AMI which is an enterprise wide network which combines monitoring of various energy commodities including electrical consumption.

Electrical meters shall be Weston Nexus 1272.

The meters shall be networked with the AMI system.

o In the absence of AMI, provide network connectivity from the Weston Nexus 1272 to a designated telecom backboard.

Standards and Specifications:

o UFGS 26 27 14.00 20

Lightning Protection

Lightning protection is required for all facilities. Provide lightning protection on all new and existing facilities. (The need for lightning protection on new facilities shall be governed by thresholds in construction per the applicable UFC.)

Standards and Specifications:

o UFC 3‐575‐01 o UFGS 26 41 00

IT/Telecom

Network Protectors o Surge protection of incoming and outgoing shall be UL 497 Primary Protector for

Communication Circuits type: 3B1E or 4B1E. 4B1E provides an additional level of protection without requiring replacement in the event of a fault.

Standards and Specifications:

o UFC 3‐580‐01 o UFGS 26 20 00 o UFGS 27 10 00

Contract Documentation

Comprehensive grounding diagrams shall be included along with the various one line & riser diagrams associated with electrical plans and specs in accordance with UFC 3‐501‐01, Para 3‐

3.18.

o Standards & Specifications:

UFC 3‐501‐01

Contractor Requirements

Considerations:

o Operation of circuit breakers, switches and other energy regulating components of the utility systems on the shipyard shall be coordinated through the Back Shift Rep via a formal outage request. Under normal circumstances, all switching shall be the responsibility of the PWD ME utility operators.

Operation of electrical devices under the contractor’s control may be operated by qualified contractor personnel. The contractor shall establish the line of demarcation between contractor control and PWD ME utility control prior to the start of each project.

o Standards and Specifications:

USACE EM 385‐1‐1

APPENDIX A: DETERMINING EXISTING LOADS

In order to ensure that sufficient capacity is available on any feeder or service that any person, project, code, or entity wants to add additional load onto, the following policy shall apply. This will include any load center, switchboard, panelboard, or other device that is used to distribute electrical power.

Background:

NFPA 70, Art 220.87 Determining Existing Loads. The calculation of a feeder or service load for existing installations shall be permitted to use actual maximum demand to determine the existing load under all of the following conditions:

1) The maximum demand data is available for a 1‐year period.

2) The maximum demand at 125 percent plus the new load does not exceed the ampacity of the feeder or rating of the service.

3) The feeder has overcurrent protection in accordance with 240.4, and the service has overload protection in accordance with 230.90.

In the absence of maximum demand data as indicated in sub‐paragraph 1), the following exception shall apply.

Exception: If the maximum demand data for a 1‐year period is not available, the calculated load shall be permitted to be based on the maximum demand (the highest average kilowatts reached and maintained for a 15‐minute interval) continuously recorded over a minimum 30‐day period using a recording ammeter or power meter connected to the highest loaded phase of the feeder or service, based on the initial loading at the start of the recording. The recording shall reflect the maximum demand of the feeder or service by being taken when the building or space is occupied and shall include by measurement or calculation the larger of the heating or cooling equipment load, and other loads that may be periodic in nature due to seasonal, operational or similar conditions.

For the purpose of this policy, demand shall be defined as follows:

The electric load at the receiving terminals averaged over a 15‐minute interval.

Qualifications:

All PWD ME, CI electrical engineers and electrical engineering technicians shall fully understand and be able to apply this policy and its procedures.

All PWD ME, CI electrical engineers and electrical engineering technicians shall demonstrate a comprehensive knowledge of all the instruments used in the collection of data, and diagnostic software associated with the processing of instrument data.

Procedure:

Installing and removing the test equipment required to conduct the demand study is an invasive process that may require at least 2 outages in many cases. Outages are an inconvenience to the tenants served by the equipment that will be disturbed throughout the test. The engineer should make every attempt to collect the data without the need for conducting outages. For instance, at remote sites like Prospect

Harbor, billing information can be sought that will cover the preferred 1‐year period indicated above.

It will be the engineer’s or AE’s responsibility to collect required data or conduct the 30‐day study prior to execution of contract activity or project execution. All equipment that will likely not be included in the feeder measurement , but is part of the overall load shall also be the responsibility of the engineer or AE conducting the study.

Procedures are as follows:

1) Submit a work plan indicating the feeder to be studied. The work plan will include the following:

a. Dates for the start and finish of the data collection period.

b. Instrument or device used to collect data. Include sufficient data to indicate the settings used to collect the data.

c. Means necessary to ensure the security of the instrumentation and safety of unqualified persons. (Ensure that unqualified persons do not have exposure to or contact with hazardous voltages.)

d. Qualifications of the individual that will administer the testing and reporting.

2) Submit outage requests through the proper procedures for the installation and removal of instruments or devices.

3) Submit a report of the study findings to include the following:

a. Tabulated and time stamped date in numerical and graphical formats.

b. Summary data of the maximum demand determined during the test period.

c. Calculated estimate of demand elements that were not measured during the test period but will none the less have an impact on the feeder demand. (Examples: HVAC equipment, process equipment, etc.)