Several years ago I became aware of the American Boat & Yacht Council’s (ABYC’s) requirement for drip protection in Chapter A-31, “Battery Chargers and Inverters.” Section 188.8.131.52.1 states that chargers and inverter/chargers shall be installed “in a ventilated, dry, accessible location,” while 184.108.40.206 dictates that “physical protection from falling objects or drippage shall be provided unless such provision is integral to the unit” (italics mine). And, 220.127.116.11.4 adds still more, saying that a charger and/or inverter “be mounted at least 24” (0.6m) above normal accumulation of bilge water, or protected so it is not subject to bilge splash.” I must confess, before reading this I simply assumed that manufacturers of marine battery chargers and inverters built in protection from that virtually inevitable onboard phenomenon, dripping water. That is decidedly not so: all one has to do is look at the gaps and holes in the tops and sides of many of these components.
Other than these obvious water-ingress avenues, how is one to know if a particular piece of gear is protected from dripping water, or if an external deflector is required? (Note that A-31 also calls for chargers to meet UL 1236, which includes drip-resistance requirements; therefore, a charger that complies with UL 1236 should, in theory, be protected from dripping water. If your eyes tell you otherwise, then you should be suspicious.) Enter the IP Code, or International Protection Marking System, often (logically) referred to as “Ingress Protection.” While it’s not referenced specifically in ABYC A-31, the standard, published by the International Electrotechnical Commission (IEC), provides those who select and use this gear with an indication of resistance to access through the chassis, as well as resistance to water. The two-number IP code system is in widespread use and covers everything from simple junction boxes to cell phones. You’ve almost certainly seen—and probably ignored, as I initially did—these numbers when perusing installation manuals and online specifications.
Here’s how it works: The first numeral (0-6) essentially specifies the size of the largest object that could fit through openings or gaps in the component’s enclosure, starting at no protection against ingress, i.e., an open, unenclosed device (0), to openings that would allow the back of a hand (1), fingers (2), tools and wires (3), insects (4), and ultimately, dust-tight (6).
The second numeral (0-9) is where it gets interesting. Starting again with no protection against harmful ingress of water (0), then moving up to resistance to vertically dripping water (1), dripping water when the device is tilted up to 15° (2), spraying water (3), and the highest rating, being able to resist a powerful jet of high-temperature water (9K). See the tables below for specific details, including the duration of these tests.
While this isn’t part of the ABYC Standard, the IP code system can serve as a guideline for installers who are attempting to comply with A-31. If no IP code is present, then you’ll have to follow your judgment and the manufacturer’s written descriptions. If clear openings are present in the top or upward-facing surfaces—and, in some cases, sides (a hole in the side of an enclosure could potentially admit water, while a louver may shed it)—then clearly the component, out of the box, is not compliant. Given my druthers where IP ratings for chargers and inverters are concerned, I’d like them to meet IP 22 or 32.
Table 1: Solid Particle Protection
|Level||Protection against object sized||Effective against|
|0||—||No protection against contact and ingress of objects.|
|1||>50mm||Any large surface of the body, such as the back of a hand, but no protection against deliberate contact with a body part.|
|2||>12.5mm||Fingers or similar objects|
|3||>2.5mm||Tools, thick wires, etc.|
|4||>1mm||Most wires, slender screws, ants, etc.|
|5||Dust protected||Ingress of dust is not entirely prevented, but it must not enter in sufficient quantity to interfere with the satisfactory operation of the equipment.|
|6||Dust-tight||No ingress of dust; complete protection against contact (dust-tight). A vacuum must be applied. Test duration of up to 8 hours based on airflow.|
Table 2: Liquid Ingress Protection
|Level||Protection against||Effective against||Details|
|1||Dripping water||Dripping water (vertically falling drops) shall have no harmful effect.||Test duration: 10 minutes
Water equivalent to 1mm (0.04”) rainfall per minute
|2||Dripping water when tilted up to 15°||Vertically dripping water shall have no harmful effect when the enclosure is tilted at an angle up to 15° from its normal position.||Test duration: 10 minutes
Water equivalent to 3mm (0.12”) rainfall per minute
|3||Spraying water||Water falling as a spray at any angle up to 60° from the vertical shall have no harmful effect.||Test duration: 5 minutes
Water volume: 0.7 liters (0.18 gal) per minute
Pressure: 50–150 kPa
|4||Splashing water||Water splashing against the enclosure from any direction shall have no harmful effect.||Test duration: 5 minutes
Water volume: 10 liters (2.6 gal) per minute
Pressure: 50–150 kPa
|5||Water jets||Water projected by a nozzle (6.3mm) against enclosure from any direction shall have no harmful effects.||Test duration: at least 3 minutes
Water volume: 12.5 liters (3.3 gal) per minute
Pressure: 30 kPa at distance of 3m (9.8’)
|6||Powerful water jets||Water projected in powerful jets (12.5mm nozzle) against the enclosure from any direction shall have no harmful effects.||Test duration: at least 3 minutes
Water volume: 100 liters (26 gal) per minute
Pressure: 100 kPa at distance of 3m
|6K||Powerful water jets with increased pressure||Water projected in powerful jets (6.3mm nozzle) against the enclosure from any direction, under elevated pressure, shall have no harmful effects.||Test duration: at least 3 minutes
Water volume: 75 liters (20 gal) per minute
Pressure: 1,000 kPa at distance of 3m
|7||Immersion, up to 1m depth||Ingress of water in harmful quantity shall not be possible when the enclosure is immersed in water under defined conditions of pressure and time (up to 1m of submersion).||Test duration: 30 minutes
Tested with the lowest point of the enclosure 1,000mm (39”) below the surface of the water, or the highest point 150mm (6”) below the surface, whichever is deeper.
|8||Immersion, 1m or more depth||The equipment is suitable for continuous immersion in water under conditions which shall be specified by the manufacturer. However, with certain types of equipment, it can mean that water can enter but only in such a manner that it produces no harmful effects. The test depth and/or duration is expected to be greater than the requirements for IPx7.||Test duration: continuous immersion in water
Depth specified by manufacturer, generally up to 3m
|9K||Powerful high-temperature water jets||Protected against close-range high-pressure, high-temperature spray downs.
Smaller specimens rotate slowly on a turntable; larger specimens are tested freehand for a longer time. Smaller specimens are tested from 4 specific angles.
There are specific requirements for the nozzle used for the testing.
|Test duration: 30 seconds in each of 4 angles (2 minutes total)
Water volume: 14–16 liters (3.7–4.2 gal) per minute
If you find that a component lacks an IP rating or is otherwise not compliant with ABYC A-31, all is not lost. You can install a relatively simple “rain shield” over the component. Sometimes these are available from manufacturers as accessories. If made in-house, this will be no more than a section of a metallic or acrylic sheet (the latter is flammable and could pose a fire hazard in the event the charger or inverter overheats or catches fire; many inverter and charger manufacturers call for installation on noncombustible surfaces, and all manufacturer-supplied hoods I’ve encountered are metallic). It should be ideally up to an angle of 15° (the angle is my recommendation; it’s not specifically mentioned in the ABYC Standard). And it should prevent water from running behind the gear, so the mounting flange may require bedding.
When it comes to protection from bilgewater, obviously these units should be mounted well above (18”/0.5m or more) the level of water that would trigger a bilge pump. On a couple occasions I’ve seen chargers, inverter/chargers, and power converters being “showered” by leaking stuffing boxes while under way. Mounting these components in the path of a leaking packing gland is simply unwise and should be avoided.
While I’ve called out chargers and inverter/chargers, primarily because they are specifically mentioned in ABYC A-31, my recommendations apply elsewhere as well. For instance, ABYC E-18.104.22.168.1 states: “Junction boxes, cabinets, and other enclosures in which electrical connections are made shall be weatherproof, or installed in a protected location [hopefully, most boatbuilders and installers rely on the latter, unless the location is exposed to weather or bilgewater], to minimize the entrance or accumulation of moisture or water within the boxes, cabinets, or enclosures.” The definition of “weatherproof” according to E-11 is “constructed or protected so that exposure to the weather will not interfere with successful operation under the test conditions specified in NEMA 250, Type 3 or IEC 60529 Type IP 54.” Here, the IP rating is noted, which removes doubt and the need for interpretation.
Careful consideration should always be given to installation locations and drip protection for chargers and inverter/chargers, as well as for all electrical gear including transformers, converters, and junction boxes.
About the Author: For many years a full-service yard manager, Steve now works with boat builders and owners and others in the industry as Steve D’Antonio Marine Consulting. He is an ABYC-certified Master Technician, and sits on that organization’s Hull and Piping Project Technical Committee. He’s also the technical editor of Professional BoatBuilder.