Electrical
Systems
Manufacturer Requirements
FEDERAL LAW
183.410 - Ignition Protection
(c) Each bulkhead required by paragraph
(b)(1) of this section must:
(1) Separate the electrical component
from the gasoline fuel source and extend both vertically
and horizontally the distance of the open space between
the fuel source and the ignition source;
(2) Resist a water level that is 12 inches high or
one-third of the maximum height of the bulkhead, whichever
is less, without seepage of more than one-quarter
fluid ounce of fresh water per hour; and
(3) Have no opening located higher than
12 inches or one-third the maximum height of the bulkhead,
whichever is less, unless the opening is used for
the passage of conductors, piping, ventilation ducts,
mechanical equipment, and similar items, or doors,
hatches, and access panels, and the maximum annular
space around each item or door, hatch or access panel
must not be more than one-quarter inch.
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To effectively separate a gasoline fuel source
and an electrical component by a bulkhead, the regulation
has established certain criteria covering the following:
- the extent of the bulkhead both horizontally
and vertically.
- the water-resistant height of the bulkhead
and permitted rate of seepage.
- openings through the bulkhead below the
water-resistant height.
- openings through the bulkhead above the
water-resistant height.
Figures 9 and 10 depict a typical bulkhead installation
with a number of the regulated items noted.
Bulkhead Extent: A bulkhead
intended to isolate an electrical component from a gasoline
fuel source must effectively close off one space from another.
The bulkhead must be fitted closely to the sides, bottom and
top of the space or compartment. There should be no vent holes,
corners snipped off, limber holes or hand holds in this bulkhead.
It should reach the full width and the full height of the
space being closed off.
Water-Resistant Height: The
water-resistant height to be used for a particular bulkhead
is based on the maximum height of the bulkhead. The water-resistant
height is the lesser of 12 inches or one-third the maximum
height of the bulkhead. For example, if the total height from
the lowest point of the bulkhead to the uppermost point of
the bulkhead is 33 inches, then the water-resistant height
is 11 inches. If the total height is 42 inches, then the water-resistant
height is 12 inches (less than one-third of 42 inches). Any
openings for piping, wiring, ducting, controls, etc. must
have a sealed fitting used to prevent seepage around the item
going through the bulkhead. The total maximum seepage permitted
for the entire area of the bulkhead below the water-resistant
height is one-quarter ounce (approximately one-half tablespoon)
of fresh water per hour.
Openings Below the Water-Resistant Height:
Bulkheads used for isolation may have openings for: wiring,
piping, ducts, controls, doors, hatches, access panels, drains,
and other such purposes, but each opening located below the
water-resistant height of the bulkhead must be sealed or have
a fitting to minimize seepage. Doors and hatches or portions
thereof must also be fitted or sealed to minimize seepage.
The maximum seepage permitted for all openings and edges of
the bulkhead may not exceed a total of one-quarter ounce (approximately
one-half tablespoon) of fresh water per hour.
Openings Above the Water-Resistant Height:
Openings above the water-resistant height are permitted for:
wiring, piping, ducts, controls, doors, hatches, access panels,
drains, and other such purposes, but each opening must not
have more than a one-quarter inch wide space around whatever
passes through the bulkhead, such as piping, wiring, ducts,
controls, etc. Hatches, doors, access panels, etc. must be
fitted so there is no more than one-quarter inch clearance
around them when they are closed, except if they extend below
the water-resistant height (see above), where they must be
sealed.
Openings for wiring, piping, etc. in the bulkheads
surrounding the engine and exhaust
components may also allow carbon monoxide to enter the accommodation
spaces of the boat. Extra attention is recommended to seal
those openings to reduce the passage of carbon monoxide gas.
SPECIAL NOTE:
The U.S. Coast Guard has developed the following compliance
policy concerning drain holes in isolation bulkheads:
“Any hole installed for drainage
in an isolation bulkhead must be fitted with a plug or sealing
device that is intended to be in place when the boat is
being used. The plug or sealing device must be attached
to the drain fitting or the bulkhead near the drain hole
so it will not be lost. It must be understood that when
this drain hole is open, the isolation integrity of the
bulkhead has been breached causing a potentially hazardous
condition. It is the responsibility of the boat manufacturer
to make this intent known to the consumer via means such
as labeling, information in a boat owners manual, etc.”
FIGURE
9 - Isolation Bulkhead Requirements
FIGURE
10 - Bulkheads
NOTES TO FIGURE 10:
(1) Seepage of not more than one-quarter fluid ounce per hour
permitted below the water-resistant height. This includes
bulkhead fastenings and around any openings.
(2) Openings above the water-resistant
height may not have more than 1/4 inch annular space around
the opening.
TO COMPLY WITH THE LAW
Is each bulkhead used for isolation -
(1) between the gasoline fuel source and
the electrical component?
(2) extended to a full width and height?
(3) water-resistant, except for permitted
seepage, to the lesser height of 12 inches or one-third
the maximum height of the bulkhead?
Is the annular space around hatches, doors,
access panels, etc. or items passing through the bulkhead
and located above the water-resistant height of the
bulkhead not more than 1/4 inch? |
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