7_Attachment 21 - NSWCCD-23-TM-2009-58 RevB Boat Electrical Practices.pdf

Naval Surface Warfare Center Carderock Division Bethesda, MD 20084-5000

NSWCCD-23-TM-2009/58 Rev B October 2009

Ship Systems Integration and Design Department

Technical Memorandum

U.S NAVY BOAT ELECTRICAL PRACTICES

by

Kevin Burns

Combatant Craft Division (23)

DISTRIBUTION STATEMENT A: Approved for public release;

distribution is unlimited.

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N a v y B o a t E le c tr ic a l P ra c ti c e s

U.S. NAVY BOAT ELECTRICAL PRACTICES

NSWCCD-23-TM-2009/58 Rev B

Post-Release Revisions

Revision Reviewer/ Approver

Date Change Description

Page, Section

A MRRiley Sept. 20, 2010 Editorial revisions Various

A K Burns Oct. 17, 2010 Technical Various

B K. Burns Aug. 31, 2012 Technical Various

REPORT DOCUMENTATION PAGE

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1. REPORT DATE (DD-MM-YYYY)

15-10-2009

2. REPORT TYPE

Technical Memorandum

3. DATES COVERED (From - To)

Oct 09 to Nov 10

4. TITLE AND SUBTITLE

US Navy Boat Electrical Practices

5a. CONTRACT NUMBER

5b. GRANT NUMBER

5c. PROGRAM ELEMENT NUMBER

6. AUTHOR(S)

Kevin Burns

5d. PROJECT NUMBER

5e. TASK NUMBER

5f. WORK UNIT NUMBER

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) AND ADDRESS(ES)

NAVSEA Carderock

Surface Warfare Center Division

Combatant Craft Division

2600 Tarawa Court, Suite 303

Virginia Beach, Virginia 23459-3239

8. PERFORMING ORGANIZATION REPORT

NUMBER

9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES)

Attn: PEO SHIPS, PMS 325G

Commander

Naval Sea Systems Command

1333 Isaac Hull Avenue, SE Building 197

Washington Navy Yard, DC 20376

10. SPONSOR/MONITOR’S ACRONYM(S)

PMS325G

11. SPONSOR/MONITOR’S REPORT

12. DISTRIBUTION / AVAILABILITY STATEMENT

DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited.

13. SUPPLEMENTARY NOTES

14. ABSTRACT

Naval Surface Warfare Center, Carderock Division, Detachment Norfolk (NSWCCD DN) has developed a set of guidelines to ensure desirable design and installation attributes for

Electrical Systems installations on U.S. Navy Boats.

15. SUBJECT TERMS

Electrical systems, design, installation, testing

16. SECURITY CLASSIFICATION OF:

17. LIMITATION

OF ABSTRACT

18. NUMBER

OF PAGES

19a. NAME OF RESPONSIBLE PERSON

Scott Petersen

a. REPORT

Unclassified

b. ABSTRACT

Unclassified

c. THIS PAGE

Unclassified

See 12.

19b. TELEPHONE NUMBER

(include area code)

757-462-3107

Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39.18 iii

This page intentionally left blank iv

Contents

Page

Figures .................................................................................................................................................. v

Tables .................................................................................................................................................... v

Administrative Information

Acknowledgements

Summary

Introduction

Background

Objective

Scope

Electrical Design Standards

Electrical System Requirements

General Requirements

Specific Requirements

Design Guidance

Ungrounded Power Systems

DC Distribution System

Batteries

Twin Inboard Engines

Twin Outboard Engines

AC Electrical System

Bonding

Conductor Size

Material Selection

Marine Environment

Circuit Breakers

Cables

Switches v

Batteries

Ground Fault

Installation Practices

Testing

Labeling

Circuit Labels

Cable Labels

Conductor Labels

References

Distribution

Figures

Figure 1. Inboard Charging System

Figure 2. Outboard Charging System Two Battery Banks

Figure 3. Outboard Charging System Three Battery Banks

Figure 4. AC Generator Full Ungrounded System with Galvanic Isolator

Figure 5. AC Generator System with Isolation Transformer

Figure 6. Bonding and Lightning System

Figure 7. Battery Terminal Connectors

Figure 8. Example Circuit Label

Figure 9. Typical Cable Designations

Figure 10. Sample Conductor Label

Tables

Table 1. Electrical System Standard Documents

Administrative Information

This work was performed by the Combatant Craft Division (Code 23) of the Ship

Systems Integration and Design Department at the Naval Surface Warfare Center, Carderock

Division (NSWCCD). This effort was sponsored by the US Navy Small Boats Program Office, PMS 325G, in support of all small craft acquisitions.

This document (NSWCCD-23-TM-2009/58 Rev B August 2012) replaces the original document, which is obsolete and should be destroyed.

Acknowledgements

The author wishes to thank Mr. J.M. Coughlin, Program Manager at the US Navy Small

Boats Program Office (PEO Ships, PMS 325G), for sponsoring the original development of this guide, and Mr. Denis Bushey, PMS 325G for his overall management direction for revision A.

The experience and knowledge of the following individuals contributed greatly to this revised guide: Rodney Keith, Bill Stavenger, and Larry Michelon. Ms. Elena Murphy provided editorial and formatting for the final draft, and Mr. Michael Riley served as technical editor. The collective support of all these individuals is sincerely appreciated.

Summary

This document provides design guidance to assist boat builders, designers and engineers in the design, fabrication, installation, inspection, testing, and certification for safe and effective electrical systems on all Navy boats and craft. References for both Department of Defense and civilian design standards are provided, typical contract requirements are presented, best practices for system design, material selection, and installation practices are summarized, and lessons learned related to electrical systems are reviewed. Acceptance testing methods and boat builder information packages are discussed, and design certification processes established to mitigate the risk of unsafe conditions are presented. This guide provides a useful tool set, but it should not preclude the use of other good engineering practices or processes that can also deliver safe and effective capabilities. While not contractually binding, it presents a collection of Navy preferences and expectations that will be updated as new lessons are learned, and as new materials or techniques are developed. The following list is an outline of the electrical system design process presented in this guide.

Electrical Design Standards

Certification Responsibilities

Electrical System Requirements

Design Guidance o Ungrounded power systems o DC distribution systems o Batteries o AC Electrical Systems o Bonding o Conductor Size o Load Analysis

Material Selection o Marine environment o Circuit breakers o Cables o Switches o Batteries o Ground fault

Installation Practices

Testing

Documentation and Labeling

Introduction

Background

The capability provided by onboard electrical systems and the ability to safely operate them are critical to the mission success of Navy small boats. To achieve this end, requirements documents and procurement contracts specify required system capabilities, as well as the design features and verification tests required to ensure safe and effective systems are installed prior to delivery. System training packages and maintenance or repair information must also be delivered to military operators.

The overall success of a Navy boat acquisition program depends upon the timely exchange of key information and the knowledge of collaborating participants (both private industry and government). Acquisition program managers must ensure that boat requirements are clearly delineated. Boat builders must ensure they understand the requirements, apply applicable design standards and fabrication practices, and deliver products that meet the requirements. The government technical point of contact (TPOC) must ensure that proper design reviews and tests are performed to verify that the system design meets the requirements.

Objective

This document provides design guidance to assist boat builders, designers and engineers in the design, fabrication, installation, inspection, and testing of electrical systems for small boat.

References for both Department of Defense and civilian design standards are provided.

The layout of this guide includes technical information as well as “TIPS” that highlight lessons learned and cautions for avoiding common issues. Typical contract requirements are presented, best practices are summarized, and lessons learned related to electrical system designs are reviewed.

TIP: Successful acquisition and delivery of a new craft relies on collaborative teams of knowledgeable individuals. Ask the TPOC immediately if there are questions related to design requirements, applicable standards, or acceptance criteria.

In the context of this guide, “success” is defined as final delivery of a new craft to an operational squadron with all electrical systems verified as safe and effective for military use.

Scope

This guide is generally applicable to the design, fabrication, and certification of safe and effective electrical systems for US Navy small boats. It conveys typical government preferences and expectations as an educational tool for builders offering boats on the General Services

Administration (GSA) Federal Supply Schedule (FSS). The information contained herein is not contractually binding and does not supersede contract requirements.

The design guidance presented in this document is a collection of lessons learned and best practices for consistent applications across various platforms to ensure that required capabilities can be achieved safely and effectively. This information provides a useful tool set, but it should not preclude the use of other good engineering practices or processes that can also deliver safe and effective electrical systems.

Electrical Design Standards

There are numerous Department of Defense activities and commercial organizations that publish standards for the design and installation of electrical systems suitable for the marine environment, including the U.S. Navy, U.S. Coast Guard Code of Federal Regulations (CFR), the American Boat and Yacht Council (ABYC), the National Electrical Manufacturers

Association (NEMA), the Institute of Electrical and Electronics Engineers (IEEE), and the

American Bureau of Shipping (ABS) for large craft. Table 1 provides a list of key documents cited in this guide and often referenced in solicitations for proposals or contract specifications.

ABYC offers a broad range of standards applicable to boat electrical systems, including

A-16 Electric Navigation Lights, A-20 Battery Charging Devices, A-25 Power Inverters, A-27

Alternating Current (AC) Generator Sets, A-28 Galvanic Isolators, E-2 Cathodic Protection, E-4

Lightning Protection, E-10 Storage Batteries, E-11 AC and DC Electrical Systems, H-22

Electric Bilge Pump Systems, P-24 Electric/Electronic Propulsion Control Systems, P-27

Electric/Electronic Steering Control Systems, TA-27 Batteries and Battery Chargers, and TE-4

Lightning Protection.

The numerous references cited above provide guidance based on proven commercial practices along with U.S. Navy lessons learned for design and installation of safe systems suitable for the marine environment. These standards are applied to achieve Navy goals related to operability, survivability, reliability, maintainability, and affordability over the life of the craft, including reduced maintenance requirements and simplified electrical system troubleshooting.

Electrical System Requirements

General Requirements

Craft solicitations and contract documents specify electrical system capability requirements based on the missions of the craft. Depending upon the craft being procured, the requirement statement may be as simple as “electrical system suitable for the marine environment”, or it may include a comprehensive list of capability and components, including

12 or 24 volt DC ungrounded distribution systems, multi-conductor cable, stainless steel cable banding, watertight electrical enclosures, battery switches, engine alternators, instrumentation packages, bilge pump, waterproof switches, cathodic and galvanic protection, lightning protection, 12 volt DC outlets, 120 volt AC grounded generator, 120 volt ground fault interrupt, waterproof breakers, and shore power receptacles, just to name a few. It is the boat builder’s responsibility to design systems and select components that satisfy ABYC, where silent then they should use standard maritime practices such as those listed in Table 1.

Builders are also typically required to provide technical data packages, including drawings, manuals, certifications, and information for acceptance, operation/training, maintenance, repair, modification, and supply support. The package should include all commercial equipment manuals and electrical and electronic drawings and schematics in accordance with IEEE-45 Section 1.4 and ASME Y14.100 series standards.

Table 1. Electrical System Standard Documents

Document Title

American Boat and Yacht Council Standard E-11

AC & DC Electrical Systems on Boats

IEEE Standards 45-2002 Recommended Practice for Electric Installations on Shipboard Circuit

Designations (Annex B)

Naval Ships Technical Manual S9086-KC- STM-101 Chapter 300

Electric Plant - General

USCG Title 33, CFR 183 Subpart I, Section 183

Electrical Systems

MIL-STD-1310G Standard Practice for Shipboard Bonding, Grounding, and Other techniques for

Electromagnetic Compatibility and Safety

DoD Standard 2003-1 Electric Plant Installation Standard Methods for Surface Ships and

Submarines (Cables)

NAVSEA Drawing 53711-300-5107858 Standard Electrical Installation Requirements and Nomenclature

NSWCCD Technical Memorandum

NSWCCD-23-TM-2009/59

U.S. Navy Boat Ungrounded Electrical System Verification Test

American Society of Mechanical Engineers Y14.38-1999

Abbreviations and Acronyms for Use on Drawings and Related Documents

Specific Requirements

Boat requirements documents may also include specific components (by vendor name) or require components to meet specific national commercial standards to ensure that specific mission capabilities are provided. The following list provides examples of specific components that may be specified in the requirements document:

IEEE-45 multi-connector cable

NEMA 4X electrical enclosures

XXXX(vendor name) batteries or equal

ZZZZ pumps with WWWW pump switch

Or, vendor specific LED lights, 12 VDC outlets, breakers, work lights

TIP: When vendor components are specified, the phrase “or equal” may be included. This implies the vendor’s product meets some specific design or testing standard that may also be met by other products with equivalent capability. In the event of uncertainty, ask the TPOC to clarify the intended specific capability.

There may also be specific requirements to provide calculations based on ABYC methods to demonstrate system design capability. For example, calculations may be required to demonstrate a 2 hour battery reserve capacity with two charging sources for separate battery banks.

Design Guidance

The following sections provide preferences and expectations for electrical system designs on Navy small boats and craft.

Ungrounded Power Systems

Ungrounded power systems are required on all U.S. Navy boats. An ungrounded power system is defined in Reference (1) Section 300-3.2.5 as a power system where there are no permanent, low resistance electrical connections between the power system and the structure of the craft.

TIP: Note that even though the system may be isolated, no system is truly ungrounded (Reference (1) Section 300-2.2.2.1). There will always be some inherent resistances or capacitances to ground in the electrical systems equipment or cabling.

In an ungrounded system, if a ground fault momentarily or permanently occurs to any one leg of a system, the grounded leg does not normally trip the circuit protection, allowing only a small amount of current leakage to flow to the hull. Critical equipment in an ungrounded system will continue to operate until steps can be taken to remove the fault. The rationale for using only ungrounded power systems includes the following.

(1) Familiarity – U.S. Navy electricians are trained on the benefits of ungrounded power systems as presented in Reference (1). Reference (1) provides an explanation of the electrical power system used on naval boats and in particular, explains with text and picture illustrations, why electrical power systems on U.S. Navy ships are normally the ungrounded type. This design rationale also applies to U.S. Navy boats.

(2) Reliability – If a ground momentarily or permanently occurs on any one leg of a system, the system can still operate and current through the ground does not normally trip the circuit breaker.

(3) Prevention of Galvanic Corrosion – Ungrounded systems do not have an intentional low resistance connection to the hull that will prevent galvanic corrosion and current flow. Galvanic corrosion is caused by current flowing through the hull material, through welded joints and dissimilar metals (Reference (1) Section 300-3.2.5). Galvanic corrosion can be further defined as when the hull metal acts as an anode and corrodes.

The hull in this case is the least noble and most active metal, giving up material to a metal (cathode) that is nobler and least active.

(4) Safety - The ungrounded system provides a high level of protection for personnel and supports the continued operation of equipment. Since the perfect ungrounded system does not exist, personnel should never intentionally come in contact with any conductor or work on the system while energized as the possibility of shock, though minimized, still exists.

TIP: Reference (2) provides a field test procedure for ensuring that an electrical system is ungrounded.

A grounded system is designed with an intentional physical return connection to the hull.

There are a limited number of grounded electrical systems that find application on ships and small craft. These systems are normally isolated from the main system through the use of transformers and power supplies (Ref (1) Section 300-3-2-7).

TIP: If a power system is permanently grounded at one point to the hull, any unintentional or accidental ground occurring in an individual load, because of a power leg connection coming in contact with the hull, will immediately cause a large ground fault current to flow. The fault can result, as a minimum, in causing a fuse or circuit breaker to trip, possibly securing vital craft systems or cause severe detrimental results such as destruction/melting of wires and cabling, loss of equipment, fire or electrical shock.

DC Distribution System

The craft DC electrical system should utilize a two wire insulated return, ungrounded distribution system (24 Vdc for inboard engines) with double-pole circuit breaker protection. For outboard engines the system will be 12 Vdc and only the engines will be grounded. If specified in the contract, the DC electrical system should utilize a ground fault monitor with visual and audible alarms (see Material Selection section for additional information).

Batteries

Twin Inboard Engines

In the case of twin inboard engine installations, the system design should include two battery banks with one bank dedicated to house power and one for engine starting. The design should maintain engine alternator isolation between engines by installing a two-alternator, two-battery bank isolator (or two separate isolators) between the alternators and the battery banks.

Each battery bank should have a dedicated battery switch vice the use of a dual circuit battery switch. Figure 1 shows a sample inboard wiring diagram that should be modified to suit the application. The design should provide for paralleling of battery banks via a dedicated paralleling

“battery” switch or momentary paralleling relay to aid in starting an engine if the starting batteries are drained/dead.

Twin Outboard Engines

In the case of twin outboard engine installations, the design should maintain engine alternator isolation under normal operation when engines are running by installing a dedicated battery bank per engine. The design should also provide for temporary paralleling of batteries to aid in starting an engine if its dedicated starting battery is drained/dead, and provide for emergency paralleling of batteries (for the duration of the mission) in the event of an engine alternator failure. Each battery bank should have a dedicated battery switch vice the use of a dual circuit battery switch. Figure 2 and Figure 3 show examples of outboard engine wiring configurations that should be modified to suit the application.

All electrical loads should be shared by both engine-charging systems, while maintaining engine alternator isolation. This should be accomplished with the installation of an isolator(s).

Batteries for the engine starting bank shall be sized based on the engine OEM Cold

Cranking Amps (CCA) requirement. Batteries for the craft service/house battery bank shall be sized using the ABYC E-11 calculation with 2 hrs of reserved capacity for most small non-complex craft. For larger more complex Electrical Load Analysis (ELA) shall be accomplished.

This ELA is similar to the AC Electrical System analysis described in the next section.

In addition, a load analysis of the power system is required to verify that the engine alternator capacity (at all speeds, including idle) will carry the anticipated functional load for the boat, with excess capacity for charging batteries. Alternator pulley selection should maximize load capacity while ensuring the maximum rated RPM of the alternator is not exceeded at maximum engine RPM. For boats equipped with converters or inverters, a load analysis is required to verify that converter/inverter capacity will carry the anticipated functional load.

It is desirable for all power sources to be sized with additional capacity for future growth

(typically 20% minimum)

AC Electrical System

For smaller craft, if an AC electrical system is specified in the contract, it should be a 2-pole, 3-wire, 120 VAC in accordance with ABYC, with the exception that the AC ground wire will not be connected to the DC negative bus. Typical electrical loads associated with this system are receptacles, battery charger, engine pre-heaters, and lights. Power can be provided by either a

120 VAC single phase generator, inverter (fed off the craft batteries), or a combination of the two. If shore power is provided, then a mechanical interlock shall be provided to prevent paralleling of shore power and on board power source(s). Figure 4 and Figure 5 show sample system configurations that should be modified to suit the application.

For larger more complex craft, higher voltage (208, 220 or 440 VAC) systems shall be considered. Where the contract is silent, system voltage selection is achieved by evaluation of voltage requirements for auxiliary electrical equipment on the craft. For example, HVAC systems, air compressors, hydraulic power units and space heaters can operate from 120, 220, or

440 VAC depending on the size of the equipment. Voltage selection should maximize system efficiency and avoid multiple voltage transformations that add cost and weight to the design.

Some basic guidelines for this determination are provided below:

240/120 VAC Single Phase System: this is a 3-wire system with 2 hot leads and 1 neutral lead (ungrounded). 240 VAC is measured between phases (hot leads) and 120 VAC is measured between either phase and the neutral lead. A general rule of thumb for using this system is when a motor or motors require a higher voltage but is still single phase.

208/120 VAC Three Phase System: this is a 4-wire system with 3 hot leads and 1 neutral lead (ungrounded). 208 VAC is measured between phases (hot leads) and 120 VAC is measured between one phase and the neutral lead. A general rule of thumb for using this system is when a craft has many motors with the largest being under 20 hp. This system is also ideal for craft with weight requirements since both primary and secondary voltages are present without the need for a step-down transformer.

220 VAC Three Phase System: this is a 3-wire system with 3 hot leads and no neutral lead. A step down transformer is needed to provide the secondary voltage (120 VAC). The general rule of thumb for using this system is when a craft has many motors with the largest being under 20 hp.

440 VAC Three Phase System: this is a 3-wire system with 3 hot leads and no neutral lead. Step down transformers are needed to provide the secondary voltages (120 VAC and 240

VAC). The general rule of thumb for using this system is when a craft has several motors of 15 hp or any motors over 20 hp.

Generator sizing shall be based primarily on the Electrical Load Analysis (ELA) along with other considerations such as voltage dip, minimum loading and future growth considerations.

The ELA shall consist of a table with all electric power consuming devices listed with their electrical load characteristics (voltage, full load amperage, motor starting current, motor

HP, kilowatts, KVA, phase). Load summaries shall be provided for the following basic operating categories (other categories may be created to suit the craft mission packages as defined by NSWCCD or the user): Shore, Cruising, Functional (intended major mission) and

Emergency. ELA shall be accomplished for both winter and summer load conditions to analyze the load extremes associated with onboard heating and air conditioning systems. Each electric power consuming device shall have a load factor assigned to it for each category, correlating to the percentage of expected usage in that operating scenario. For example, a 0.7 load factor indicates that a device will be operating at 70% of maximum load during a specific operating scenario. Typical electrical device load factors can be found in the NAVSEA Design Data Sheet

(DDS) 310-1. This document can only be used as a guide since all applications are different. In particular, for smaller boats and craft, load factors for most electrical devices approach 1.0 for many operating scenarios.

Generator voltage dip shall be limited to +/- 20% of rated voltage for start up of the largest motor load. Builder shall provide motor data to generator OEM for voltage dip calculations.

Minimum loading of generator shall be 30% of the generator rated load for most manufacturers. Consult the generator OEM for minimum loading specification. Running a generator set for extended periods under light load can lead to engine damage and higher maintenance costs. This condition is commonly referred to as “slobbering”.

Generator shall be sized with a 20% future growth margin or as close as possible to 20% while not allowing the generator to run in a lightly loaded condition as described above.

If an ungrounded AC electrical system is specified in the contract, a ground fault monitor with visual and audible alarms should be included.

Shore power isolation transformers are recommended for all boats but especially on steel and aluminum boats. Isolation transformers eliminate any possible ground path to shore and galvanically isolate the boat from the shore thus reducing electrolytic corrosion. The shore ground lead shall connect to the primary shield lead inside the isolation transformer (see Figure

5). The transformer case shall connect to boat ground (see Figure 5) and be isolated from the primary shield and secondary neutral lead.

Bonding

A common grounding bus should be supplied for equipment grounding, bonding and lightning protection (optional) in accordance with ABYC and Figure 6. The common grounding bus should not be connected to the DC negative bus or the AC neutral bus. The DC negative bus and the AC neutral bus are full current carrying circuits, so they should be isolated from the common grounding bus which is a non-current carrying circuit.

COTS (Commercial Off The Shelf) equipment (i.e. radios, laptop docking stations, etc) with metallic enclosures that have a chassis/safety ground that is connected to the DC negative power input line should be isolated from the main craft DC power system by the use of an isolated type DC-DC converter.

TIP: If the ground is not necessary for proper operation of the equipment then the ground can be physically isolated from the hull in lieu of installing a converter.

Conductor Size

Conductor size should be designed to achieve 3% maximum voltage drop between the voltage source and the load. Few exceptions will apply (e.g., the voltage drop may be a larger percentage for starting circuits or windlasses).

Figure 1. Inboard Charging System

Figure 2. Outboard Charging System Two Battery Banks

Figure 3. Outboard Charging System Three Battery Banks

Figure 4. AC Generator Full Ungrounded System with Galvanic Isolator

Figure 5. AC Generator System with Isolation Transformer

Figure 6. Bonding and Lightning System

Material Selection

Marine Environment

All electrical system components should be selected based on the ability to minimize corrosion, to maximize longevity, and to have sufficient ruggedness to withstand the rigors of

Navy use. For example, all hardware and fasteners should be UNS S31600 corrosion resistant steel, and nuts should be the self-locking type. The following additional examples of preferred materials are based on navy lessons learned and satisfactory performance.

Circuit Breakers

For Direct Current (DC) systems, double pole, waterproof circuit breakers (or non-waterproof circuit breakers installed in waterproof enclosure) should be used for circuit over-current protection unless otherwise specified. Main feeder circuit breaker should be a UL489 type circuit breaker (Airpax 209 type or equal) installed in a suitable enclosure. Breakers downstream of the main feeder circuit breaker should be UL1077 type circuit breakers (Airpax waterproof IUGN type or equal) for circuits up to 50 amps or UL489 type circuit breakers

(Airpax 209 type or equal) for circuits up to 100 amps installed in a suitable enclosure. For breakers greater than 100 amps, single-pole waterproof breakers (Cooper-Bussman series 25X or equal) can be used.

For Alternating Current (AC) systems, double or triple pole UL489 circuit breakers should be used for circuit over-current protection installed in a suitable enclosure unless otherwise specified. Breakers up to 100 amps should be Airpax 209 type or equal. Shore power circuit breakers should be Equipment Leakage Circuit Interrupter (ELCI) capable in accordance with ABYC E-11.

As a minimum, breakers shall be molded case breakers meeting UL 489, suitable for 40 degree C ambient operation with exception of breakers installed in the engine room which should be rated for 50 degree C ambient operation.

Note: UL489 type circuit breakers are rated for use as branch protection while UL1077 type circuit breakers are rated for use as supplemental protection. The important difference between these two types of circuit breakers is the ability of the device to keep working after a short circuit. UL489 breakers can survive a short circuit and can continue to be used after the fault has been corrected. A UL1077 breaker will trip after a short circuit but may not survive and be used again (requiring replacement). Based on past experience with Airpax IUGN type circuit breakers on US Navy boats and craft, it is acceptable to use these breakers for branch protection as long as a UL489 breaker is used upstream of the UL1077 breakers. The Airpax

IUGN breakers are sealed breakers and have been found to be able to survive the harsh environment found on US Navy boats and craft. The Airpax IUGN breakers have been used on numerous boats and craft in the past and have a low failure rate.

The number of spare circuits should be no less than 20 percent of the number of active circuits used (with a minimum 2 spares per system voltage or as specified by contract.)

Fuses should not be used. Original equipment manufacturer (OEM) in-line fuses provided with equipment should be removed, and an equivalent sized breaker should be installed. The exceptions to removal of fuses are for fuses integral to engine harnesses or integral to a device, such as a power supply with built-in fuse protection. Fuses integral to OEM equipment or engine harnesses should not be removed. For OEM supplied switchboards and motor starters, UL1077 circuit breakers vice fuses are desired for supplemental protection internal to equipment where available from OEM.

Cables

Unless low smoke MIL-spec cable is specified in the contract, as a minimum, all boat builder provided electrical systems shall utilize commercial low smoke zero halogen (LSZH) marine multi-conductor cable (compliant with IEEE-1580 and accepted by USCG & ABS) with tinned copper conductors per ASTM B-33 flexible stranding (Tricab "BV Series" or equal).

Single conductor UL1426 wire (Ancor or equal) may be used in enclosures and for jumper wires.

IEEE-45 or Ancor Battery Cable may be used for battery/starting circuits.

Switches

Switches should be toggle type (metal bat handle) and environmentally sealed (Eaton

8500 series switches or equal). One exception to the toggle switch preference includes the rotary battery disconnect switch.

TIP: Boats with inboard engines and keyless start switches should have switches that provide a mechanically maintained “run” position to prevent accidental switching and unintended engine shutdown.

Batteries

Batteries should be absorbed glass mat (AGM) or Gel type, deep cycle (Optima Blue Top or equal.

The size, quantity or total amp hour of the batteries should correspond to the required cold cranking amperage (CCA) of the engines and/or the reserve capacity required for the house service loads, as specified in the contract.

Ground Fault

If ground fault monitoring is specified in the contract, then the ground fault monitoring system should be Model A-ISOMETER IR425 manufactured by The Bender Company or equal.

Two separate monitors should be included, one for each of the AC and DC systems for craft with ungrounded AC and DC electrical systems.

TIP: For unique design configurations or non-standard material selections, confer with the TPOC prior to system procurement or installation on the craft.

Installation Practices

All electrical systems should be installed in accordance with the manufacturer’s recommendations and applicable ABYC recommended practices. Reference (3) provides additional recommended standard electrical installation practices for U. S. Navy boats and craft.

Each conductor should be installed using ring terminal lugs except where a component is configured for a different type of connection. All terminal lugs should be tinned copper (Ancor marine grade or equal).

Battery cables should be fitted with terminal lugs. Starting/charging connections should be secured to large (automotive) battery posts (see Figure 7 for recommended crimp battery terminal connectors) with CRES nuts and split lock washers. Nylon lock nuts are not to be used for battery connections. Other connections (e.g. voltage sensing circuit) to battery screw-terminal posts are permitted.

Battery stowage/securing methods should provide support and prevent movement in any direction (plastic battery boxes should not be used).

Preferences related to installing cable and conductor labels are presented in the

“Labeling” section of this guide.

Figure 7. Battery Terminal Connectors

Testing

In addition to normal electrical system operational tests, the builder should perform a verification test to demonstrate that the electrical power system is ungrounded. Reference (2) provides the preferred test procedure. This test should be performed prior to the builder scheduled Pre-Delivery Inspections and Trials (PDIT) for the first craft.

TIP: Successful completion and demonstration of the ungrounded electrical verification test documented in Reference (2) prior to PDIT significantly increases the likelihood of avoiding costly delays due to system discrepancies during PDIT.

Labeling

Circuit Labels

All power circuits should be labeled with information provided on the electrical drawing(s). For example breaker size, equipment served, an alphanumeric designation, voltage

(12 Vdc=12P, 24 Vdc=24P, 120 Vac=120P) should be included. Figure 8 shows an example label.

RADAR

12P-A 10 AMP

Figure 8. Example Circuit Label

Cable Labels

Cables should be clearly labeled using aluminum cable tags or shrink tubing with mechanically applied lettering and shall reflect cable designations provided on the electrical drawing(s). Corrosion resistant metal (any aluminum alloy is acceptable) cable tags should be in accordance with Detail “5-C” of Reference (3), and installed on cables in accordance with note

E-1 of Reference (3). Cables should be identified by a short noun or abbreviated name

(abbreviations IAW AMSE Y14.38 where applicable) corresponding to the equipment serviced.

Cable designations should also include the power circuit designation or an IEEE- Std 45-1998

ANNEX B designation prefix where applicable (example: radar antenna cable, “R-RN1”, as shown in Figure 9). Cable designations should be the same as those used on electrical drawings supplied with the boat.

Conductor Labels

The following is additional guidance for labeling conductors to be used with note E-16 of

Reference (3).

All conductors should be labeled at termination points (exception: color coded OEM supplied wire harnesses) and should reflect information provided on the electrical drawing(s).

See Figure 10 for examples. Individual conductors should be labeled with white sleeving, or by other permanent means, with mechanically applied markings (i.e. type writer, machine printer, etc). Each conductor should be identified using the power circuit or IEEE designation prefixes (if applicable), followed by the polarity, lead color and/or lead number of the conductor. The markings should be neat and legible. A short noun or abbreviated name corresponding to the equipment serviced may also be included with the information shown in Figure 10 or on the reverse side of the sleeving.

Figure 9. Typical Cable Designations

12P-A(POS) RADAR

Front Back

R-RN1, YEL RADAR

Figure 10. Sample Conductor Label

References

1. Naval Ships Technical Manual S9086-KC-STM-010 Chapter 300, Electric Plant – General

2. Stavenger, William, “U.S. Navy Boat Ungrounded Electrical System Verification Test”, Naval

Surface Warfare Center Carderock, Combatant Craft Division Technical Memorandum

NSWCCD-23-TM-2009/59, October 2009

3. NAVSEA Drawing 53711-300-5107858, Standard Electrical Installation Requirements and

Nomenclature, Revision A, July 2006

Distribution

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