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Articles -


The Benefit of Serrated Flange Nuts

Ensuring a secure and correct connection Blue Sea Systems is now shipping product with serrated flange nuts which replace the more traditio...
August 07, 2014

Tin Plating Explained

Corroded connections are the main cause of high resistance connections that cause equipment to quit working or to work poorly. Frequently hi...
October 17, 2012

Fuse/Circuit Breaker Speed Explained

Speed Delay Opening speed, or delay, defines the relationship between the percentage by which the fuse or circuit breaker is operating over ...
October 17, 2012

Four Stage Battery Charging With Prefloat Explained

Bulk charges batteries to 75-80% of full charge. Absorption gradually completes remaining charge to full. PreFloat moves each battery indiv...
October 12, 2012

Independent Sourced Circuit ST Blade Fuse Block

The Independent Sourced Circuit ST Blade Fuse Block from Blue Sea Systems consolidates up to six independently-sourced branch circuits in on...
November 11, 2011

ELCI False Trips

The ABYC requirement for ELCI circuit breakers on all new boats with AC power has recently passed its first anniversary. Many units have bee...
October 13, 2011

ACR Operation

Legend ACR OPEN - Batteries are Isolated ACR COMBINED - Batteries are connected and both charging. ACR relay is open and batteries are ...
October 12, 2011

Blue Sea Systems Offers Solutions for Mounting ELCI Breakers to Comply With ABYC July 2010 Requirements

In response to a 2008 Coast Guard sponsored study entitled In-Water Shock Hazard Mitigation Strategy, ABYC standards now require boatbuilder...
February 17, 2011

285-Series Circuit Breaker Replaces Popular 185-Series Breaker at a Lower Price

The 285-Series Thermal Circuit Breaker is a direct drop-in replacement for the established 185-Series Thermal Circuit Breaker. The 285-Seri...
February 17, 2011

The Safety Fuse Blocks (AMI®/MIDI® and MEGA®/AMG®)

The Safety Fuse Blocks from Blue Sea Systems are ignition and ingress protected and provide in-line fusing for a single circuit.The Safety F...
November 11, 2010

The SafetyHub 150 Fuse Block

The SafetyHub 150 Fuse Block from Blue Sea Systems provides fusing for ten circuits, and is the marine market's first ten-circuit 1A–2...
September 24, 2010

Part 2: Select a Fuse and Fuse Holder For Your DC Product Installation

This is the second in a three part series of technical briefs on circuit protection. Part 1 showed how to choose the correct wire size for D...
August 31, 2010

Broad Range of Fuses and Fuse Blocks From Blue Sea Systems

Blue Sea Systems is expanding its circuit protection offering, adding a broad range of low amperage fuses to complement the existing line of...
August 31, 2010

SMS: Surface Mount System

Since July 2010, ABYC standards require all new boats with a shore power connection to include ELCI whole-boat protection to guard against e...
August 01, 2010

Part 1: Choosing the Correct Wire Size for a DC Circuit

Choosing the right wire size for your DC electrical project is important, since a wire that is too small can overheat and possibly start a f...
May 19, 2010

Do You Have The Ignition Protection You Need on Your Boat?

Keeping sparks and flammable vapors apart is vital on a boat, and many boaters fail to consider all the hazards. Careless gasoline storage, ...
March 25, 2010

The SafetyHub 100 Fuse Block

The SafetyHub 100 consolidates and ignition protects seven 1A–200A circuitsThe SafetyHub 100 was developed in response to OEM, install...
March 25, 2010

Mounting Options for ELCI/GFCI Circuit Breakers

Blue Sea Systems is pleased to offer ABYC–compliant single–pole 5mA branch GFCI and double–pole 30mA main ELCI circuit pro...
March 17, 2010

Two Below Deck Panels—Traditional Metal and 360 Panel System

Blue Sea Systems offers two choices for below deck electrical distribution panels—Traditional Metal and 360 Panel SystemBlue Sea Sys...
November 12, 2009

The SafetyHub 250 Fuse Block with Remote Battery Switch

A consolidated electrical system for a single battery boat. The SafetyHub 250 Fuse Block with Remote Battery Switch is an ignition protected...
October 23, 2009

Ten Deadly Conditions to Check for in Your Boat's Electrical System - Part 2

In the September newsletter, 1 through 5 of the ten deadly conditions were presented (link to previous article). Deadly conditions 6 through...
October 19, 2009

MIDI®/AMI® Fuses

When evaluating available fuses for the SafetyHub family of products, Blue Sea Systems engineers discovered the compact and versatile MIDI&r...
September 28, 2009

Upgrading Battery Switching and Charge Management with the ADD A BATTERY Dual Circuit System

The ADD A BATTERY Dual Circuit System from Blue Sea Systems is a two-battery management system that simplifies switching and automates charg...
July 14, 2009

AC Ground Faults, the Boater, and ABYC—Understanding Equipment Leakage Circuit Interrupters (ELCIs) and Ground Fault Circuit Interrupters (GFCIs) to make your boat safer.

There are two potential failures in a boat′s electrical system that can put people on or around the boat at risk of lethal electric sh...
April 27, 2009

Monitor Bilge Functions With the VSM 422

The ability to monitor bilge pump cycles is critical for safe boat operation. Although a simple bilge monitor will alert the boater to some...
March 20, 2009

Automatic Charging Relay (ACR) Explained

For specific troubleshooting help with SI-Series PN 7610 and ML-Series PNs 7620, 7621, 7622, and 7623 ACRs, click on the following links: SI...
March 20, 2009

Questions to Consider When Choosing a Tank Monitor

There are many options available for monitoring tank levels, from single-function meters to advanced multiple-function monitors. The demand...
February 11, 2009

Selecting a Battery Type When Setting up the VSM 422

The VSM 422 uses battery type information to accurately compute State of Charge. To obtain the greatest precision when measuring State of C...
January 20, 2009

Battery State of Charge—What is it, and How is it Measured

Knowing Battery State of Charge is like knowing the amount of fuel in your fuel tank: it is relevant information for both peace of mind and...
January 20, 2009

Switching Solutions for Multiple Battery Banks

The Dual Circuit Plus™ Battery Switch is an ideal solution for switching multiple battery banks. One switch simultaneously switches tw...
April 18, 2008

24 Hour Circuit Solutions

With the growing demand for 24-hour circuits—such as for bilge pumps, alarms, clocks, and control circuits for remote battery switches...
April 18, 2008

ML-Series Heavy Duty ACR Supports High Amp Charging and Emergency Cross Connect

The ML-Series Automatic Charging Relay (ACR) is engineered for high current applications. When connected through a 4/0 cable, it is rated at...
March 16, 2008

Remote Battery Switch Improves ABYC Compliance in Battery Management

When installing a battery switch, ABYC guidelines call for consideration of these two factors: Minimize voltage drop between battery bank...
February 13, 2008

DC Push Button Reset-Only Circuit Breaker 360 Panels-An Economical Circuit Protection Solution

Push Button Reset-Only 360 panels are designed to provide an economical circuit protection solution for circuits that remain ON (24-hour) or...
January 18, 2008

Choosing the Ideal Remote Battery Switch

Five reasons to use a remote battery switch were presented in the October newsletter: increased safety, lower cost, reduced weight, lower vo...
January 18, 2008

Five Reasons to Use a Remote Battery Switch

Using a remote battery switch instead of a mechanical battery switch can result in increased safety and convenience, and significant reducti...
October 08, 2007

Preventing Hazardous Ground Faults on Boats

Standard circuit protection may not guard against two ground fault hazards in marine AC circuits: AC electric power leakage from boats into...
September 17, 2007

Circuit Wizard-Case Study

Using Blue Sea Systems Circuit Wizard to Size Main and Branch Circuits Blue Sea Systems' DC Circuit Wizard simplifies the calculations that...
August 20, 2007

ST (Screw Terminal) Blade Fuse Block - Features and Applications

Blue Sea Systems' ST Blade Fuse Block continues to be a best seller for good reasons. The features that it offers, and its low price per ci...
August 20, 2007

Selecting the Appropriate Fuse Rating When Installing the 120A SI ACR

When installing Blue Sea Systems 120A SI ACR, PN 7610, use this chart to select the appropriate wire size and fuse rating. ...
August 17, 2007

Simplified Circuit Protection Selection

In the April issue of Circuit Solutions™ newsletter, Blue Sea Systems’ DC Circuit Wizard was introduced. The DC Circuit Wizard simplifie...
June 26, 2007

Sizing a Shunt to a DC Ammeter

DC ammeters require shunts for their operation. Some meters have built-in shunts, some meters have external shunts. External shunts are plac...
June 26, 2007

Strategies for Monitoring DC Current

There are various reasons to monitor DC current in boats. The most common are to check charger output, whether battery banks are receiving a...
June 26, 2007

Refitting with a WeatherDeck™ Circuit Breaker Panel

This is the second Application Brief describing the refit of the electrical system on a Harborcraft runabout. The first Application Brief de...
May 15, 2007

Introduction to Blue Sea Systems' New Online DC Circuit Wizard

Blue Sea Systems’ DC Circuit Wizard simplifies the calculations necessary to choose appropriate DC circuit protection and wire size. The D...
April 16, 2007

Adding a Secondary Battery, Battery Switch, and Automatic Charging Relay (ACR)

This is the first application brief in a series that describes the refit of the electrical system on a Harborcraft runabout. The boat is use...
March 15, 2007

Preventing Cycling in Battery Combiners, Voltage Sensitive Relays, and Automatic Charging Relays

The primary functions of battery combiners, which include voltage sensitive relays and automatic charging relays (ACR), are: Combine battery...
March 15, 2007

Fusing the Negative Circuit of ACRs and Other Electric Relays

Problem. Electric switches such as automatic charging relays (ACRs), battery combiners, load shedding devices, and zero-drop isolators a...
March 15, 2007

Solving ACR/Multi-Program Multi-Output Charger Interference

There may be interference between the output of multi-program multi-output chargers and normal ACR performance. For a discussion of these in...
February 16, 2007

Applications of ACR and Multi-Program Multi-Output Chargers

This is the third technical brief related to applications of automatic charging relays (ACR) and battery chargers. Automatic charging relays...
February 16, 2007

SI ACR Performance during Charger Float Mode

The primary function of an automatic charging relay (ACR) is to combine battery banks so that they can share the output of a single charger....
January 19, 2007

360 Panel Circuit Breaker Module Offers Broadest Amperage Range Selection

Click to read an overview of the 360 Panel System. The new 360 Panel System makes it possible for boaters to install circuit breakers rangin...
January 19, 2007

The 120 Amp SI ACR Handles ”Noisy” Charger Output

The primary function of an automatic charging relay (ACR) is to combine battery banks so that they can share the output of a single charger....
January 19, 2007

Windlass and Bow Thruster Relay Contact Chatter

Problem The relay contacts in windlasses and bow thrusters may chatter when they are switched ON and when they are switched OFF. This contac...
December 18, 2006

The Versatility of the 360 Panel System

Blue Sea Systems has developed a new line of panels based on a unique open architecture design. The 360 Panel System provides complete flexi...
December 18, 2006

Start Lockout for Two Engines

See Application Brief: Overcoming Dropout of House Electronics during Engine Starting for a brief explanation of Automatic Charging Relays (...
November 13, 2006

Overcoming Dropout of House Electronics during Engine Starting

Automatic Charging Relays (ACRs) combine and isolate batteries (or battery banks) in response to changes in voltage. When a charge from a c...
November 13, 2006

Grounding and Circuit Protection for Inverters and Battery Chargers

Battery chargers, inverters, and inverter/chargers form an electrical bridge between a boat's AC and DC systems. When installing these devic...
October 19, 2006

Ten Deadly Conditions to Check for in Your Boat's Electrical System - Part 1

Blue Sea Systems’ engineering department has identified 10 conditions that, when present in your boat’s electrical system, can cause ser...
September 15, 2006

Blue Sea Systems’ Mini Clamp Multimeter with True RMS

Compact and feature-rich AC/DC multimeter simplifies diagnosis of marine electrical problems and features True RMS for accurate measurement ...
August 19, 2006

Automatic Charging Relay - An Alternative to Multiple Output Charging Systems

What do you do when the number of battery banks on your boat is greater than the number of charging outputs from your system′s battery...
June 23, 2006

Using Blue Sea Systems' Battery Switch AFD Terminals to Indicate Switch Position

Alternator Field Disconnect (AFD) is a feature of some battery switches—for example, Blue Sea Systems’ e-Series ON/OFF (PN 9004), HD-Ser...
June 23, 2006

Flat Actuator Circuit Breaker Designs Provide Protection From Accidental Switching

Toggle actuated and raised rocker circuit breakers can be accidentally switched. While this could be only a nuisance in some situations, it ...
June 23, 2006

Blue Sea Systems' CL-Series BatteryLink™ ACR

When combined with the Dual Circuit™Battery Switch, the CL-Series BatteryLink™ ACR fully automates the charging of two batteries. B...
June 23, 2006

Pilot House Navigation Battery Isolation Using the CL-Series BatteryLink™ ACR

The Coast Guard has found that vessels may lose communications if there is flooding of the engine room. With the engine room flooded, chargi...
May 23, 2006

Choosing Circuit Protection

Blue Sea Systems' engineers identify new factors to consider when selecting high amperage circuit protection. Circuit protection devices are...
May 23, 2006

Charge Current Limiting for a Remote Battery Using the CL-Series BatteryLink™ ACR

Powering a bow thruster or windlass from the main battery banks requires running large wires through the entire length of the boat since cab...
May 23, 2006

Load Shedding Using the CL-Series BatteryLink™ ACR

Non-essential loads, such as entertainment equipment and refrigeration, can draw large amounts of power from a boat's battery banks. This ca...
May 23, 2006

Supplying Power to Large Loads

The 600 Ampere busbar from Blue Sea Systems, PN 2104, also is useful for supplying high current to large loads.When you supply high current ...
April 17, 2006

600 Ampere Busbar Negative Tie Point

The 600 Ampere busbar from Blue Sea Systems, PN 2104, is useful as a negative tie point. It has a continuous amperage rating of 600A DC. In ...
April 17, 2006

Improvements to Blue Sea Systems' 150A Busbars

Busbars perform a very simple but important function in a boat’s electrical system:To distribute power from a large positive conductor...
March 22, 2006

Common Switching Applications

The wiring diagrams presented below are for several common switching applications that you may want to wire through your WeatherDeck™ ...
February 15, 2006

WeatherDeck™ Water Resistant Circuit Breaker Panels

WeatherDeck™ Water Resistant Circuit Breaker Panels are versatile enough to meet the needs of most boaters. They are available in four...
February 15, 2006

DC Main Power Distribution

Blue Sea Systems’ Battery Management Panels can be used to provide a complete stand-alone DC main power distribution system. The panels al...
December 23, 2005

DC Circuit Protection

Electrical shorts are the number one cause of fires on boats. In fact, more than half of boat fires are electrical in origin. More than half...
December 23, 2005

Blue Sea Systems' Dual Circuit Battery Switch

The Dual Circuit™ Battery Switch simplifies multi-bank battery switching with a single ON/OFF switch. It eliminates the confusion surr...
November 11, 2005

Navigation Light Switching for Vessels Under 20 Meters

The possible switch configurations for navigation lights vary greatly depending on the vessel size, type, and purpose. This article addresse...
January 25, 2005

Battery Isolators and Automatic Charging Relays

Battery Isolators, Automatic Charging Relays (also called ACRs , combiners, or voltage sensitive relays) are all intended to keep a load (or...
October 18, 2004

DC Main Overcurrent Protection Requirements

ABYC standard E11.12.1.1.1 states that each ungrounded conductor connected to a battery charger, alternator, or other charging source, shall...
December 30, 2003

ST (Screw Terminal) Blade Fuse Block

The ST (Screw Terminal) Blade Fuse Block was designed with screw terminals to comply with ABYC Recommended Practices and built with tin plat...
December 30, 2003

Parallel DC Main Distribution System

It can be a big advantage to have two banks of batteries on board to make sure the engine starting battery isn't drained by use for house po...
August 21, 2003

Green Wire (Controversy)

The green wire referred to in this "controversy" is the safety ground wire that connects the DC negative ground block to the AC safety groun...
August 21, 2003

Wiring Inverter Load Group (sub Panels)

The Theory:Modern inverters that convert DC battery power to AC power are able to supply many of the loads commonly found on boats and RV's....
December 27, 2002

Organizing the Tangle of Wires on My Boat's Battery Terminal

Project Description As a boat's electrical system grows, more and more large cables seem to find their way onto the battery terminals. This ...
August 14, 2002

Differences in USA and European AC Panels

In the USA the two commonly supplied shore-power voltages are 120 Volts (60Hz) AC and 240 Volts (60Hz) AC. The standard in Europe is 230 Vol...
July 31, 2002

Switching Inputs to Digital Meters Part II

Using a single 8200 Series AC Digital Meter to monitor multiple AC voltages and currents Switching Inputs on AC MetersAC Digital Meters (Mod...
June 24, 2002

Switching Inputs to Digital Meters Part I

Using a Single 8200 Series Digital Meter to Monitor Multiple Voltages and Currents OverviewThis application note will be presented in two pa...
May 15, 2002

Electrical Conductivity of Materials

The differences in electrical conductivity of various materials used in marine electrical products are often not well understood. Making ass...
May 15, 2002

Inverter High Load Isolation

Installation of an inverter on board offers the convenient use of AC devices while away from the dock. However, using an inverter to power h...
May 15, 2002

120/240 Volt Panels

Blue Sea Systems offers five 120/240 volt panels in the Standard power distribution panel line. One is a 240V AC main circuit breaker only....
April 01, 2002

Current Flow in 120/240 Volt AC Systems

AC Current flow in 120/240 V AC single phase three or four wire systems is frequently misunderstood. This technical brief goes through a ste...
April 01, 2002

The Case for Cut-Off Switches

Commonly, shipboard devices like windlasses and inverters are installed with fuse protection in their DC supply lines as is appropriate. Wha...
March 07, 2002

m-Series Battery Switch

The mini battery switch that outperforms switches twice its size.Blue Sea Systems' new m-Series Battery Switch, available in four practical ...
February 11, 2002

DC Digital Meter

Typical (Traditional) Two Battery System with Wiring for Digital Meter The typical marine system with two batteries and a battery switch, wh...
February 11, 2002

Reverse Polarity Indicators

The Technical Brief AC Reverse Polarity describes why and in what cases Reverse Polarity Indicators are required by ABYC in shipboard AC sys...
February 01, 2002

AC Source Management with Source Selector Panels

Frequently a boatowner will decide to install an AC appliance with amperage demands that added to existing AC loads would overload the boats...
January 15, 2002

AC Reverse Polarity

The power companies have developed a standard for 120-volt single-phase power distribution in which one of the two conductors is designated ...
January 02, 2002

AC Reverse Polarity False Indicators

In the Technical brief on Reverse Polarity the flowing diagram of a Reverse Polarity sensing circuit is shown. Diagram 1It is possible for...
January 02, 2002
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