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The Masthead
received a query the other day asking about a really
important issue related to marine electrical system com-
ponent ratings for ignition protection. This is a common
question and it’s important because you don't want your
boat to end up looking like the one in the photo below.
The question goes like this:
Hi Ed,
I would like to know if any classes of products ac-
cepted as inherently ignition protected, not in need of
testing/a label. Specifically I am wondering about:
- Standard sealed inductive proximity sensors
- Brushless permanent magnet sealed motors (no air
blowing on windings)
- Sealed stepping motors
- Epoxy encapsulated electro-magnets/electrical
Basically electrical devices that generate NO sparks. Is
there any mention of this in the standards?
This question is a tricky one that is a little bit subject to the
interpretation of the USCG under the Code of Federal Regu-
lations (CFR), specifically under CFR Title 33, Section
183.410, Ignition Protection.
Basically, there are several statements made within the
above referenced regulation that suggest that all of the de-
vices/components you mention are indeed acceptable. I’ve
pulled the applicable text right from the official CFR, which
you can access on the Internet.
§ 183.410 Ignition protection.
(a) Each electrical component must not ignite a propane gas
and air mixture that is 4.25 to 5.25 percent propane gas by
volume surrounding the electrical component when it is op-
erated at each of its manufacturer rated voltages and cur-
rent loadings, unless it is isolated from gasoline fuel
sources, such as engines, and valves, connections, or other
fittings in vent lines, fill lines, distribution lines or on fuel
tanks, in accordance with paragraph (b) of this section.
(b) An electrical component is isolated from a gasoline fuel
source if: . . .
(1) Separate the electrical component from the gasoline fuel
source and extend both vertically and horizontally the dis-
tance 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 conduc-
tors, 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.
My interpretation of this centers on the statement found
next to (2) above. I believe that the components you are re-
ferring to will meet that requirement and therefore are prop-
erly separated.
Read Ed Sherman’s Blog,
Ed’s Boat Tips
, at:
June 2012 Page 23
What Constitutes Ignition Protection?
By Ed Sherman