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Index to this Page
Electrical regulations and standards
that apply to boat builders and recreational boats. Ignition wire,
conductors, over current protection, wire sizes, fuse sizes.
Definition - Regulations: When
referring to laws, that is, Federal Regulations or Statutes, I will
use the word Regulation and/or use a citation such as
CFR 183.501, (Code of Federal Regulations section
183.501 or USC 4301 (United States Code Subchapter 4301).
Definition - Standard: Industry
standards will be referred to by the name of the standard
organization such as ABYC, SAE, UL or NFPA. In most cases these
standards are voluntary and not law. However, beware! Almost all
of them are the accepted practice by the industry and used by builders, marine
surveyors, marine investigators, and attorneys as the de facto standard.
If you choose not to follow the standards you should be prepared to
defend why your practice is as good or better. See ABYC
https://newboatbuilders.com/pages/abyc.html See Also
Standards Societies.
Ignition Wire:.
See US Coast Guard Regulations
33 CFR Subpart I: Electrical Systems
https://newboatbuilders.com/pages/33CFR_electrical.html
Sec. 183.440 Secondary circuits of ignition systems.
(a) Each conductor in a secondary circuit of an ignition
system must meet SAE Standard J557.
Since this regulation was published the standard has
changed but the Coast Guard has not updated the Federal Regulation to match
the SAE standard. SAE standard J557 no longer exists. The current SAE
standard for marine ignition wiring is SAE J2031, which also covers road
vehicle ignition wiring.
(b) The connection of each ignition conductor to a spark
plug, coil, or distributor must have a tight fitting cap, boots, or nipple.
ABYC standard P-4 Marine Engines and Transmissions Says.
4.6.14.4 High tension ignition cable assemblies shall
conform to SAE J1191, High Tension Ignition Cable Assembly.
4.6.14.5 Ignition distributors shall conform to SAE J1294,Ignition
Distributors or UL 1120, Marine Engine Ignition Systems and
Components.
So all ignition wiring, wiring assemblies, distributors and
the boots, caps, and nipples should be made for marine use.
If you purchase engine packages from one of the marine
engine suppliers then the engine wiring will be pre-installed and meet all
of these standards. You are responsible for making sure wiring
leading to the engine complies with the regulations. However, if
you do your own marinizing or engine rebuilding then you must make sure the
wiring on the engine is up to the standard.
Protecting Conductors: 33 CFR 183.455
Wires need to be protected from shock, vibration, abrasion,
and flexing. In addition, they should be laid out so they do not make sharp
corners. They should be laid out neatly so there is easy access, and
easy replacement, and do not make contact with hot parts such as exhaust
manifolds, or hang in the bilges.
(a) Each conductor or group of conductors that passes
through a bulkhead, structural member, junction box, or other rigid surface
must be protected from abrasion.
Wires should be supported using clips or straps, at least
every 18 inches (45.5 cm), throughout their length. Where they pass
through bulkheads or other structure they must be protected from abrasion by
grommets or some other non-abrasive material.
(b) Each ungrounded terminal or stud that is continuously
energized must meet CFR Sec. 183.455 or must have a boot, nipple, cap, cover, or
shield that prevents accidental short-circuiting at the terminals or studs.
Positive terminals, such as the positive terminals on the
starter, solenoid, alternator and other electrical equipment must be covered
with a rubber boot, cap or nipple so that metal tools won’t accidentally
come in contact with them. Battery terminals were already discussed, but
just as a reminder they need to be covered as well. The amount of energy
released when a wrench or screwdriver accidentally comes in contact with one
of these terminals can be truly frightening, and start a fire or cause an
explosion if fumes are present.
Connections:.
ABYC Standard E-11: Solder must not be the sole means of connection between two
or more conductors or between a conductor and a connector.
What? I can't use solder? Yes you can, BUT, it must not be
the only connection. You must also have some sort of mechanical connector,
such as crimp type connectors, that hold the two wires together. When you
solder the wire it becomes essentially a solid single conductor wire. It
forms a hard spot in the wire that concentrates the stress at that point and
becomes prone to breaking. So use a connector as well as soldering. Some
marine wiring experts even advocate not using solder at all. But this is a
matter of opinion. Some think the acids in the solder cause corrosion,
others disagree. So if you do solder, use an acid free solder and make sure
it is good solid solder not a "cold solder"
The same applies to connectors inside of junction boxes and
electrical panels.
DO NOT USE WIRE NUTS! They do not supply a
good mechanical connection and they are prone to vibrating off. They also
allow moisture to collect inside the wire nut, causing accelerated corrosion
of the wire. The corrosion raises the resistance of the wire creating heat,
and causing a large voltage drop at this point, which means you will not be
getting full voltage down stream, at the appliance. Low voltage at the
motor, light, or other appliance you are running causes the item to overheat
and burn out.
This is another item that was in the Federal Regulations,
but was taken out in the deregulation process. However, it is still good
practice not to use wire nuts. There are some manufacturers of wire nuts who
claim their product can be used on boats. Don't do it. They have the
same problems as regular wire nuts.
ABYC Standard 11.16.3.6. is very specific:
Twist on connectors, i.e., wire nuts, shall not be used.
Exception. Sometimes wire nuts are used inside
of appliances such as refrigerators and washers and dryers. These do not
have to be removed.
OVER CURRENT PROTECTION:.
33 CFR 183. 455 Each ungrounded current carrying conductor must be protected
by a fuse or by a manually reset trip-free circuit breaker.
This means that the hot wire, that is the positive wire in
DC systems, must be protected. The negative wire does not have to be
protected.
There is often confusion here. The circuit breaker or fuse is not there to
protect the motor or appliance. CIRCUIT PROTECTION IS THERE TO PROTECT THE
WIRE. Too much current in the wiring causes it to get hot, melt the
insulation and start a fire.
If there are still any positive ground systems out there in
the world, everything is then reversed from what I am saying here.
Manually reset trip-free circuit breaker: What in the world is a manually reset, trip-free circuit
breaker? Obviously it is a circuit breaker, but what does the rest mean.
Well, it means it can't automatically reset itself. You have to
manually reset it. Trip free means you can't hold it in the on
position while there is still a fault. If the circuit is going to trip
the breaker, it must trip whether you are holding it place or not.
Look for the UL MARINE listing on the package.
DO NOT USE circuit breakers intended for
house wiring! They are not designed for marine use and are not ignition
protected.
DO protect all circuits.
The only exception is the starter motor circuit.
Location of Overcurrent Protection 33 CFR
183.455
The fuse or circuit breaker must be within seven inches
(17.8 cm) of the source of power.
Exceptions:
Exception 1. If it is physically
impractical to put the fuse or circuit breaker within seven inches of the
source of the power it can be up to 40 inches (101.6 cm) away, if the wire
is contained for it's entire length between the source of power and the
circuit breaker, in a sheath or an enclosure.
This has been interpreted many ways. The obvious is a
conduit. But who uses conduit on a boat? Conduit might be used on really big boats. Putting
a sheath such as wire loom or heat shrink wire covering over the wire works.
Some even say that wrapping it in electrical tape is ok. I think that this
is really a shoddy way to do it and not very professional. There are
many different wire sheaths available, some that are fire resistant.
Also if the wire is in an enclosure such as a panel box or electrical box
then it is ok. The whole idea here is to protect the wire in such a way that
if it overheats it doesn't set the boat on fire. Here are some links
so you can see what I'm talking about.
The following links are not an endorsement of these products. The are just presented as examples of products available.
CableOrganizer.com
http://cableorganizer.com/wire-loom/
Oxide.com
http://xoxide.com/wireloom.html
Heat Shrink Tubing
http://cableorganizer.com/heat-shrink/
Exception 2. Each ungrounded output
conductor from a storage battery must have a manually reset, trip free
circuit breaker or fuse, unless the conductor is in the main power feed from
the battery to the cranking motor. The fuse or circuit breaker must be
within 72 inches (182.9 cm) of the battery, unless it has a battery
disconnect switch.
The above distances are measured along the wire. In other
words we are talking about wire length, not the straight line distance from
the power source to the fuse or circuit breaker. Also note, this is
only
in the output conductor (wire) from the battery to the cranking motor
(starter). The obvious solution here is to install a battery switch as close
to the battery as possible and that is what most boats have. Just make sure
you use a good quality UL listed switch. There are a lot of cheap,
poor quality fakes on the market. Buy a good brand name. Why? Because
a lot of current flows through this switch, and when the switch is thrown
sometimes arcing occurs. You want a switch that can stand up to this.
I have seen cheap ones that melted or caught fire.
Sizing Circuit Breakers
or Fuses: 33 CFR 183.455
Circuits of less than 50 volts: (DC Circuits)
A circuit breaker or fuse should not be rated for more than
150% of the amperage that the circuit is rated for. Suppose you have a
30 amp circuit. Then the circuit breaker or fuse should be no more than 45
amp. This is so it will blow, but not blow for the occasional spike in
current that occurs when you first turn on a piece of equipment. You
don't want it rated higher than this because then the wire may burn before
the breaker trips.
Circuit breakers in low voltage DC circuits should break
only the positive wire. If you break both wires you break your
connection to ground.
Circuits of 50 volts or more: (AC circuits
or high DC voltage circuits)
The circuit breaker or fuse should be sized at the same
amperage as the circuit. If you have a 30 amp circuit then the breaker or
fuse should be 30 amps. If you can't get the exact size then it
should not exceed 150%. But it is best to rate
it at the amperage rating for the circuit.
Circuit Breakers in AC circuits should be double
pole, that is, break both the black and white conductors at the same time.
In AC this important because if you do not break both the hot and neutral you
may still have a hot circuit. This is dangerous to a person working on the
system.
For all circuits the voltage rating of the fuse should be
the same as the circuit voltage. It the circuit is 12 volts then the
breaker or fuse should be 12 volts. If it's 110 volts then it should be
rated for 110 volts. Do not mix breakers. Yes, you can use a 120 volt
breaker on a 12 v circuit, but definitely don't use a 12 volt breaker
on a 110 volt circuit. But you should use a breaker or fuse sized for the
correct voltage.
Special Applications:
There are some special circumstances that permit a variance
from the above.
If it is the power feed from the battery to the starter it
does not have to be fused. However, make sure the wire is sized
correctly because this circuit carries a lot of current when you try to
start the engine. Also try to locate the battery so that this wire is
as short as possible. Don't get fanatic about it, but the shorter it is then
the less resistance the wire has and the more power you get to the starter.
If
the alternator or generator is not self-limiting then there must be a fuse
or circuit breaker on the output. The breaker or fuse cannot be rated
for more than 120% of the maximum current output at 60 degrees C. Today
most engines have alternators (AC) rather than generators (DC) and most
alternators have a built in regulator that makes them self-limiting, but
there are still some around that aren't.
This is generally not something the boatbuilder or owner has to worry about
because most buy an engine package from one of the engine manufacturers and
all this is done by them. But you should be aware of it. If the
alternator or generator is self-limiting then this requirement doesn't
apply. Ask the people you buy the package from if the alternator is
self-limiting, that is, does it have a built in regulator.
WIRE SIZES: 33 CFR 183.425 For wire sizes see the
table listed below.
Table of Allowable Amperage of Conductors
https://newboatbuilders.com/pages/elect2.html
What do we mean by wire size? It means the actual
physical size of the wire in mils, usually stated as wire gauge. Simply, how
thick or thin is the wire? The concern here is resistance and
voltage drop. Resistance and voltage drop are caused by two
things, the size of the wire and the length of the wire. The thinner the
wire the more resistance it has and the longer the wire the more resistance
it has. So, there is not much you can do about the length of the
wire except move things closer but that is often not an option. So
then you have to size the wire so that it has the least resistance and least
voltage drop. Here is link to Wikipedia
that explains American Wire Gauge.
http://en.wikipedia.org/wiki/American_wire_gauge
Why? All electrical and electronic equipment is
designed to work at a specified voltage. If the voltage is too high it can
burn out the equipment. If the voltage is too low it can also burn out
the equipment. We are concerned with too low. If a wire has too much
resistance the voltage will drop from the high of say 12 volts to maybe 11
or 10 volts at the other end. For example, starters require a constant
voltage and high current. If the voltage drops, they slow down, and get
really hot. So we need to make the wire the right size to give the starter
the right voltage. This also causes the wire to heat up and if it gets
too hot, melt the insulation and set things on fire.
Wire comes in various sizes from really big at 000 gauge (ga)
(sometimes shown as 3/0) to really small at 22 gauge and even smaller sizes.
The smaller the size the bigger the number of the gauge. On a boat, the
smallest you can use is 16 gauge. Except, you may use 18 gauge in
sheathed wire bundles. This would make you think, the bigger the
better. That's not the case. The best way is to determine the wire size you
need and then go one size bigger (smaller gauge). For example battery cables
are typically 4 gauge but can be as large as 0 gauge. It depends on the
battery capacity.
How To Calculate
Wire Size . https://newboatbuilders.com/pages/elect3.html
Wiring Color: Color Codes:
https://newboatbuilders.com/pages/elect5.html
Basic Wiring Diagram
For Full Size or Print image Click Here or the image. This is a basic wiring diagram and only meant to be used
as a training aid. Read the instructions on the image.
Planning your DC Electrical System:
https://newboatbuilders.com/pages/electrical_planning.html
See sample US Coast Guard Wiring diagrams:
https://newboatbuilders.com/docs/USCG-WiringDiagram-Inboard-IO_Runabout.pdf
https://newboatbuilders.com/docs/USCG-WiringDiagram-Cruiser-LowV-DC.pdf
https://newboatbuilders.com/docs/USCG-WiringDiagram-Cruiser-AC-DC.pdf
https://newboatbuilders.com/docs/USCG-WiringDiagram-Aux.Sailboat.pdf
https://newboatbuilders.com/docs/InstrumentWiring.pdf
https://newboatbuilders.com/docs/Diagram4Harness.pdf
Basically that's it. These are the
requirements. But remember that this is the minimum you must do.
If you really want to do electrical systems right it is best to follow:
ABYC
standard E-11, DC and AC Electrical Systems For Boats. https://www.abycinc.org
Also
on Ike's List you
will find references to electrical sites on the internet, and references for
books on electrical systems for boats.
https://newboatbuilders.com/pages/links_electrical.html
References: Some excellent web sites for boat electrical questions:
Marine Electrical Checklist
http://www.islandnet.com/robb/marine.html
Getting Grounded By Ed Sherman
Professional BoatBuilder, April 2003 Order ProBoat#82
April-May 2003
https://pbbackissues.advanced-pub.com/
Electrical On Board
http://www.sailnet.com/forums/gear-maintenance-articles/19661-electrical-power-board.html
Frequently Asked Questions on electrical systems: Peter Kennedy;
https://shop.pkys.com/Technical-Pages_ep_41.html
33 CFR Subpart I: Electrical Systems
https://newboatbuilders.com/pages/33CFR_electrical.html
TP 1332: CONSTRUCTION STANDARDS FOR SMALL VESSELS Section 8 Electrical
Systems Canada Standards for small craft.
http://www.tc.gc.ca/eng/marinesafety/tp-tp1332-menu-521.htm
ISO
Standard 10133: Small craft — Electrical systems — Extra-low-voltage d.c.
installations International Standard For small craft
ISO
Standard 13297: Small craft — Electrical systems — Alternating current
installations International Standard For small craft
http://www.iso.org/iso/catalogue_detail.htm?csnumber=46477
46 CFR Subchapter T Part 183 Electrical Installations: Passenger Vessels
under 100 Gross Tons.
https://www.ecfr.gov/current/title-46/part-183
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