SUMMER 2015 | MARINE TECHNICIANTODAY
13
An ignition suppression test is conducted inside a special explosion
chamber filled with an extremely flammable proportion of propane
and air. Propane is specified as it is a uniform product nationwide
for repeatability in testing and consistency in purity - unlike
gasoline produced by numerous refineries with constantly changing
formulations and additives.
Contrary to popular belief, a Coast Guard approved electrical
component is allowed to have a fire or an explosion inside of it, but
no thermal energy or flame may escape to ignite the surrounding
flammable environment. For example, a marine distributor is not
completely sealed and in the test chamber there is combustible
mixture inside the distributor cap as well as enveloping it. A
spark is induced internally allowing the mixture under the cap to
explode but the distributor must remain intact, plus it cannot ignite
the surrounding propane. To be awarded Coast Guard approval,
the item has to have the internal explosion test repeated fifty
times to prove its durability, remain operational, and not set fire
to the flammable environment in the test chamber. That is why
most marine distributors utilize screws to fasten the cap and not
spring-clip retainers as with some automotive versions. Starters,
alternators, and electric motors are tested the same way but while
operating at their maximum voltage and current ratings. They also
must withstand the fifty internal explosion episodes to successfully
earn the certification. Electrical parts may then be labeled as
Coast Guard accepted for marine use or that they meet an industry
standard such as SAE J1171 concerning ignition suppression in a
flammable environment.
Other electrical related items are subject to Federal Regulations. The
following excerpts apply to systems of 50 volts or less and are for
informational purposes only; not to be considered as the complete
regulation or legal requirement. Professional repair technicians
should know these, but the average boater may not be aware of their
importance or the legal ramifications involved.
• Batteries must be secured, not moving more than 1” in any direction
when subjected to a pull of 90 pounds or twice the battery’s weight.
• A battery cannot be directly above or below a fuel tank, fuel filter, or a
fitting in a fuel line. Dielectric shielding is required for a metallic fuel line
within 12” of a battery.
• To prevent accidental shorting of the ungrounded battery [positive]
terminal, an insulated boot or non-conductive protective cover is required.
• Stranded copper wiring is mandated on a boat, no solid wire allowed, and
insulation must conform to regulation §183.430.
• Wiring smaller than 16 AWG cannot be used separately, and 18
AWG or smaller be enclosed in a multi-conductor sheath.
• All wiring requires chafing protection when passing through a bulkhead,
junction box, etc. using grommets, sleeves, clamps, or caulking.
• Ungrounded [positive] wires require a fuse or a manually-reset circuit
breaker of not over 150% current capacity at the source of power. There
are exceptions for starting and ignition circuits and certain other situations.
The terminals and connections must be protected to prevent shorting.
• Spark plug wires must meet the requirements of SAE J557 or SAE J1191
and both ends of these conductors be protected by a tight fitting cap, boot
or nipple that meets SAE J1191 specifications.
• If more than one engine is on board, the cranking batteries’ ground
terminals must be connected by a cable sufficient to conduct the
amperage of the largest starter.
Never install automotive electrical components in a boat, it is not
only illegal but extremely dangerous. Property damage, injury, or
death resulting from unapproved parts or procedures could leave the
installer and the boat owner facing legal action or possibly criminal
charges. Talk to an attorney concerning the legalities involved.
There are other practices and procedures involving electricity
and safety in the boating industry. Organizations such as ABYC
(abycinc.org) and NMMA (nmma.org) have their own policies and
certification measures. Repair personnel should also be aware of,
and abide by industry standards and procedures for the protection
and the benefit of their customers.
It is for everyone’s safety - owners, passengers, and bystanders
alike - that Federal Regulations govern electrical systems used
in gasoline-powered boats. Insuring that the electrical devices,
workmanship, and fuel components in a boat are Coast Guard
approved and/or meet required protection standards gives one
peace of mind. By adhering to these governmental safety regulations,
both a boat repairer and a recreational boater are assured that their
onboard experiences will not turn into life-threatening situations.
Remember to always boat safe.
REFERENCE:
For the complete Code of Federal Regulations pertaining to electrical
systems and ignition protection on recreational boats, go t
or Google the term “ CFR Title 33 Part 183.
TODAY’S TECHNICIAN
