SAFE-BOAT SMART-BOAT: Electrical systems – Vent, ground, protect to prevent onboard fires

by Fred Mattera –

Faulty or compromised electrical systems are a primary source of engine room fires.  These fires are often exceedingly hot, allowing you little or no time to manually extinguish them.  So, let’s talk about some steps you can take to be sure your boat’s electrical systems are properly installed, used, and maintained.

Electricity is a must, but, for many of us, it’s a mystery, too.  A fisherman once said to me that the extent of his knowledge about electricity was simple – plug the unit in and turn the unit on.

Since a lot of fishermen can relate to this, I’ll first offer two pieces of universally accepted wisdom:  First, hire only qualified personnel to carry out electrical installation and maintenance services; and, second, until proven otherwise, always treat an electrical circuit as though it is live.


A qualified Coast Guard-approved marine drill instructor, Fred Mattera of Point Judith, RI is the owner/president of North East Safety Training Co. (NESTCo), which conducts fishing vessel drills and inspections and basic safety training workshops.
A commercial fisherman for 40 years, Mattera is a member of the Commercial Fishing Safety Advisory Committee to the Coast Guard, and, since 1998, has been president of the Point Club, a fishing vessel mutual insurance group. He also has served on the board of directors for Sunderland Marine Mutual Insurance Co., the principal underwriter for the Point Club and more than 2,000 US fishing vessels, since 1998.

That said, let’s move on to some basic things to keep in mind.

To the extent you can, locate electrical equipment so that it is both accessible and protected from dust, oil, fuel vapors, and any source of water or moisture.

Make sure electrical equipment is designed, constructed, and installed to prevent accidental contact with energized parts.  Installation should be secure enough to accommodate the roll, pitch, and vibration of your vessel underway.

All electrical equipment should bear the label of a nationally recognized testing laboratory, such as UL, to ensure that it is designed to be explosion proof, ignition protected, and fundamentally safe.

Most importantly, electrical equipment that will be exposed to spray or moisture should be waterproof or watertight.

Faults in the electrical system can lead not only to fire but also to the failure of vital onboard systems such as alarms and pumps and corrosion in the hull.

When maintaining or modifying any electrical system on your boat, it’s vital to keep saltwater away from the bare metal of the circuitry, junction boxes, switches, and fittings.

The introduction of saltwater to unprotected metal causes rapid and serious corrosion, which can lead to a broken circuit that can arc and start a fire.  Corrosion in a circuit also can build up to the point where there is so much resistance that the circuit ceases to operate.

So, remember, keep junction boxes, fittings, and switches away from windows or vents where water may enter.  And think about where you put your wet stuff.  I have gone into engine rooms and seen foul weather gear and gloves laid out on starter motors and electrical fittings to dry.  This is a bad habit.  Keep wet clothing and gear away from electrical connections.


Tight spaces

Be sure to remove all flammable liquids such as oil, paint, and solvents from vessel lockers, tanks, and compartments that house electrical equipment.  If lighting is essential in such spaces, it must be explosion-proof.

Spaces or compartments that house internal-combustion engines must be adequately ventilated to prevent the buildup of fumes that can be ignited by defective electrical equipment.

Metal enclosures for electrical equipment should be grounded.  Portable electrical equipment should be double-insulated or have exposed metal parts grounded.

All portable electrical equipment should be regularly inspected and protected from the elements.


Power sources

Vessel construction standards require that every vessel have at least two sources of electric power for vital loads – a main source and a backup source.  The captain and designated crew must understand how to switch from main to backup power to support systems necessary for the safety of the vessel.

These safety-related systems include bilge pumps, engine and machinery ventilation, lighting, steering, communications, alarms, hydraulics, auto-control equipment, navigation lights, and navigation equipment.

For vessels larger than 39′ and not relying on electrical power for propulsion and steering, the focus needs to be on having enough juice for emergency lighting and battery-powered navigation and communication systems.  So, these boats need a battery backup power source, usually in the pilothouse.

A battery backup power source should have its own charger and isolation switch so you can be sure the batteries are fully charged.  It must be capable of providing six hours of power to safety-related systems to allow for the operation or evacuation of the vessel if necessary.

Emergency lighting, ranging from flashlights to an alternate power source such as 12V and/or 34V lights, is mandatory on all vessels and must be in working order.

Over the years, I have suggested investing $40-$50 to buy 110V battery-backup lights that immediately illuminate when your 110V system shuts down.  Many vessels have installed these units in appropriate areas such as the pilothouse, galley hallway, engine room companionway, and by the generator crossover panel.

Trust me.  It beats searching in the dark for a flashlight only to find out the batteries are dead.


Electrical panels

Electrical panels must be located in as dry a space as possible.  Make sure they are protected from dripping water through use of a drip shield or other means.  All insulating material in and around the panel should be moisture resistant and fire retardant.

There should be adequate space around panels to permit operation and maintenance.  A panel should have no exposed live parts and panel wiring should be flame retardant.  Be sure to place nonconducting deck materials, mats, or grating around panels.

The metal case of the panel should be grounded, and it’s important to label all circuits to clearly identify the equipment that’s hooked up.  Be sure that all equipment is adequately sized for the expected loads.

Each power source should be protected against overcurrent by a fuse, circuit breaker, or overcurrent relay.  The proper rating or setting of the protective devices for each circuit should be permanently marked.

That’s enough for now.  We’ll follow up next time with a review of batteries, cables, miscellaneous equipment, and maintenance along with a few more safety tips.

Fred Mattera