BEST PRACTICES

The Complexity of Plugging In Theory, standards, and best practices behind installing and maintaining shore-power .

Text and photographs by Steve D’Antonio

ot long ago, I sat with a client Many professionals in the industry 105 and 106). In either case, their great- Nhunched in the lazarette of his stumble on the question. est attribute is saving lives by reducing newly acquired boat. Looking over These units are indeed beneficial in the risk of shock, electrocution, and the humming shore-power trans- many ways, and those who decide electric shock drowning, or ESD (see former, he said, “I’ve heard these are whether to use, install, advocate for, or sidebar on page 112). When wired in useful, but I have no idea why. Can sell them should thoroughly under- isolation mode, a transformer is also a you explain it?” The boat’s builder, stand why. deterrent against galvanic corrosion, struggling to articulate a response, Shore-power transformers can be which results when nearby submerged, finally said, “Trust me, they are good wired in one of two configurations—for grounded metallic objects interact via to have.” isolation or for polarization (see pages the shore-cord-grounding conductor.

Above—Looking inside a new Hubbell auto-boosting shore-power transformer, note that the winding is potted in a sand/resin mix- ture, increasing its durability, moisture resistance, and weight.

100 Professional BoatBuilder Installation Left—Some transformers are located near an electrical panel to minimize While the operating principle of a cable runs, but they all must have plenty shore-power transformer is simple, of ventilation to remove the heat they there are peculiarities to be aware of to generate, and away from bunks, where ensure a safe, reliable, and effective the hum of operation would disturb installation. sleeping crew. In many ways a transformer behaves Below left—A true shore-power trans- much like a power source, a generator, former—the one at the head of the an inverter, or the utility company’s dock—is the source that shore power will transformer at the head of the dock. strive to return to. Sometimes its path runs dangerously through the water. The most important safety character- istic is the path takes after it leaves the transformer. Like all elec- They also generate and radiate con- tricity, it seeks a return to its origin siderable heat and need appropriate and not necessarily to ground. Elec- ventilation and air circulation. In addi- tricity “returns” to earth ground only tion, they produce a noticeable hum, when the power source is referenced which means you wouldn’t want one to earth ground. In the case of the under a berth or opposite a headboard. transformer at the head of the dock or If installed in accommodation spaces, in a marina parking lot, this is accom- under a helm or behind an electrical plished with a ground rod bonded panel, for instance, they should rest on to the transformer’s neutral output and flexible mounts. Some transformers are the green grounding conductor for the mounted amidships, near an electrical system (known as a grounded neu- panel and between bow and stern tral). The importance of this safety should never swim around vessels or inlets, to minimize wire runs. Ideally, feature cannot be overemphasized. docks energized with power originat- shore-power transformers should carry Shore-power electricity, once it passes ing ashore. a marine UL listing (while most indus- through the vessel’s transformer, will As well as protecting swimmers trial transformers are UL listed, few “return” only to that transformer, from electrocution, a transformer carry the “Marine” prefix), and adhere either through the white neutral con- eliminates the possibility of reverse to ABYC’s standards. ductor or the green safety-grounding polarity. That’s why boats with 120V conductor. (These two are typically onboard transformers are exempt bonded or connected either at the from ABYC’s reverse polarity indica- transformer output or at the electrical tor and double-pole branch circuit panel, but not both.) On transformer- breaker requirements. equipped vessels, it’s important that The benefits of transformers are there be only one connection location. tempered by their size, weight, and (For more on neutral-to-ground con- cost: The average 30-amp unit may nections, see the ProBoat online measure a little less than a cubic foot resource at https://www.proboat. (0.03m3) and weigh 60 lbs (27.2 kg), com/2011/10/demystifying-the-neu- while a 50-amp, 240V unit measures tral-to-ground-connection/.) Put sim- half again as large and more than 200 ply, if the grounding/bonding system lbs (90.7 kg). Transformers, especially is intact, electricity that originates at ABYC/UL-compliant boosting ver- an onboard transformer will not travel sions, can cost in excess of $5,000 through seawater to reach a utility (4,442€). company transformer at the head of the dock or elsewhere ashore. Instead, it will return to the vessel’s onboard Be aware that not all transformers are transformer, thereby protecting per- created equal. While they all have the sons in the water. Note that even if potential to be a fire hazard, the better operators know their boats are appro- options for onboard installation are UL priately grounded/bonded, they listed, and the best are UL Marine listed.

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Inner Workings The specification tag for a transformer Through the principle of inductance, will tell you a lot, including primary and a transformer can achieve either polar- secondary voltage and whether it’s rated ization or isolation in the case of an to operate at 50 Hz, 60 Hz, or both. . In brief, shore The latter is particularly important for power travels from the dock’s wiring, vessels likely to cross oceans on their own bottoms or to be shipped overseas, through the shore-power cable(s) to where standard electrical service varies. the boat’s power inlet. (Note: One onboard transformer is required for each shore-power inlet that may be in One aspect of UL Marine compli- use.) Instead of going from there to the ance for shore-power transformers is vessel’s circuit breaker panel, the isola- the electrostatic shield between the tion transformer is inserted into the primary and secondary windings, circuit first. The incoming AC power which prevents arcing between the travels through the primary (or input) two. The shield (though not rated for winding of the transformer and back to lightning strikes) must be capable of shore. That’s as close as the actual dock- enduring surges of 4,000V for only side current ever gets to the boat’s elec- one minute to comply with ABYC trical system. Because electricity is elec- E-11. Unlike ordinary transformers, referenced to the shoreside ground; tromagnetically induced on the trans- the windings for marine-rated units however, that measure is required only former’s secondary (output, or boat- are typically potted in a mixture of when wiring in the isolation mode. side) winding from the nearby primary sand and resin, a process that improves No connections should be made to winding, no direct connection between shock resistance and prevents water the AC safety ground wire located the two is required. absorption. The shield is usually between the transformer and the inlet.

102 Professional BoatBuilder The inner workings and wire counts, and cost is not a factor, they windings of an unpotted trans- may make sense. Otherwise, the anvil- former are more likely to suffer like ruggedness of traditional trans- moisture issues over their life- formers would have greater appeal. time compared to a potted transformer. ABYC Transformer Guidelines hundreds of feet of heavy wire ABYC guidelines for transformer and iron cores, high-frequency installations are predictably detailed switching transformers use and specific, including sections on electronic circuitry, in much overcurrent protection. The relevant the same way inverters do, to sections are available as part of com- achieve isolation. They may plete ABYC standards or, for the pur- (depending on the specifica- poses of this article, on ProBoat’s web- tions), therefore, be smaller site at www.proboat.com. Follow them! and lighter than traditional A few details are worth more expan- transformers of equal capacity. sive consideration. For instance, if a The units I’ve seen rely on fan transformer is located within 10'/3m cooling, while most conven- (a measurement of the wire, not as the tional transformers do not. crow flies) or less from a shore inlet, No mention of transformer func- That means if the fan fails, the unit although a conventional circuit tion would be complete without may shut down, and the vessel may, as breaker is required, an ELCI (equip- noting there is a high-frequency a result, be without shore power. For ment leakage circuit interrupter) switching version. Instead of using applications where every pound device is not. While that satisfies the

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Overcurrent protection for trans- Polarization vs. Isolation formers can be tricky. Read and There are few but important distinc- fully understand the requirements tions between wiring a transformer for spelled out in E-11. Err on the side polarization or for isolation. of caution, and if in doubt, remem- The primary difference is in its ber that it’s safest to install a breaker, including an ELCI. means of grounding. The polarization transformer’s primary and secondary ground are connected, i.e., the vessel’s as close as possible to the shore onboard AC safety ground, bonding, inlet. and DC negative are common with the One ABYC standard I often see dock/shore AC safety ground (Figure violated is the need for a circuit 1). This affords the vessel a safe path for breaker for the secondary, or fault mitigation but no galvanic isola- letter of the ABYC “law,” bear in mind output, of a transformer if it’s pro- tion, the type required to prevent cor- that for overcurrent protection, every viding split-phase 120V/240V service. rosion induced from nearby vessels. foot (30.5cm) of wire between the This circuit breaker must be two pole, So, a polarization transformer must inlet and the transformer relies on the i.e., it opens both ungrounded or “hot” include another device known as a gal- dock-mounted circuit breaker, one conductors, and it must be placed vanic isolator to deter corrosion (see that may be deteriorated, inadver- within 7"/178mm (again, a measure- the sidebar on page 109). tently oversized, not ELCI-equipped, ment of actual wire length) of the Conversely, in the isolation wiring and whose condition is unknown. transformer. That distance may be configuration, potentially damaging Regardless of where the transformer is extended to 40" (1m), provided the galvanic current that normally would located, I recommend that my clients conductors are supplementally be allowed to come aboard, via the install a primary ELCI circuit breaker, sheathed or enclosed within a conduit. green grounding conductor in the

104 Professional BoatBuilder Figure 1. Polarization Transformer System with a Single-Phase 240V Input, 120/240V Output, and Shore-Grounded Secondary

Shore-power Encapsulated single-phase Transformer secondary cable Power inlet (electrically 1:1 isolation transformer overcurrent protection Branch circuit Shore connector insulated from boat) with metal case breaker (typical) connection Main shore-power disconnect circuit Shore-power breaker with ELCI cable (see E-11.11)

Black White Red Green 120VAC device

120VAC grounding-type receptacle

Optional galvanic isolater Shore side Boat side 3-pole, 4-wire Transformer case grounding-type ground connection plugs & receptacles To engine negative Ungrounded conductor Ungrounded conductor Grounding conductor Grounded neutral conductor terminal or its bus NOTES: 1. See E-11.17.5 240VAC 2. This diagram does not illustrate a complete system. device Black White Red Green abyc Example of a shore-power installation using a 240V primary transformer wired for polarization. Note the presence of a galvanic isolator. This is required, as transformers wired for polarization do not provide galvanic corrosion protection. All grounded and grounding connections remain the same as that of the isolation configuration, with two exceptions: a grounded shield is not required, and the shore and vessel ground are common. The secondary neutral and the case are still referenced to ground.

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Figure 2. Isolation Transformer System with Single-Phase 240V Input, 120/240V Output with Boat-Grounded Secondary, Transformer Shield Grounded on Shore, Transformer Metal Case Grounded on Boat

Shore-power Power inlet (electrically Encapsulated single-phase Transformer secondary Branch circuit cable insulated from boat) 1:1 isolation transformer overcurrent protection breaker (typical) connector with metal case Shore Main shore-power connection disconnect circuit Shore-power breaker with ELCI cable (see E-11.11)

Black White Red Green 120VAC device

120VAC grounding-type receptacle

Transformer

Boat side shield Shore side 3-pole, 4-wire Transformer case grounding-type ground connection plugs & receptacles To engine negative Ungrounded conductor Ungrounded conductor Grounding conductor Grounded neutral conductor terminal or its bus 240VAC NOTES: 1. See E-11.17.5 device 2. This diagram does not illustrate a complete system. Black White Red Green abyc Example of a shore-power installation using a 240V primary transformer wired for isolation. Note the presence of an ELCI primary circuit breaker. This should be installed as close to the shore inlet as possible. Note also the locations of the shield and case grounds, as well as the secondary neutral, which is also grounded to the case and to the vessel’s AC safety ground.

106 Professional BoatBuilder shore-power cable, is thwarted, marked difference between the isola- and are not prevented or reduced by because there is no longer any direct tion transformer and the galvanic iso- the isolation transformer, galvanic connection to shore-side ground or lator. Where the galvanic isolator isolator, or any other device except a current-carrying conductors (Figure blocks DC voltage (nearly all galvanic proper bonding system and general 2). The transformer’s secondary is, in corrosion is DC in nature) from com- ABYC-compliant wiring procedures. effect, the source of power, and thus ing aboard up to a given threshold of With the installation of the isolation the ground reference. about 1.4V, the isolation transformer transformer, all onboard bonding, DC Either approach to wiring, if carried severs this connection altogether, with grounds, and AC safety grounds out in accordance with ABYC stan- no limitation. It’s the most thorough remain unchanged. Also, because the dards, offers the required level of electrical separation that can be transformer’s enclosure cannot be safety, with a few caveats. achieved under these circumstances. connected to both primary and sec- It is impossible to determine by The onboard AC green safety ondary grounds (doing so would elimi- casual visual inspection whether a grounding conductor originates at nate its isolation and corrosion effec- transformer is wired in polarization or the secondary winding of the isolation tiveness), absolute attention to detail is isolation mode. The identical, fully transformer. As a result, primary and a must when installing AC wiring ABYC-compliant transformer may be secondary ground—i.e., the shore- through the transformer’s metallic wired either way following manufac- side ground and the boat’s ground— case—usually mild or stainless steel, turer guidelines during installation. have nothing in common. That for ABYC compliance. Accidentally Only by carefully inspecting the actual eliminates the potential for “foreign” connecting primary and secondary wiring connections and/or by using a (originating off the boat) galvanic- grounds could result in the case becom- multimeter can the mode be deter- and stray-current corrosion. Stray- and ing energized without tripping a cir- mined for certain. galvanic-current corrosion that origi- cuit breaker. Because the case cannot The distinction between polariza- nate aboard a transformer-equipped be referenced to both shore and boat tion and isolation also represents a vessel remain potentially destructive ground, it’s typically referenced to

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Left—One of the most common transformer installation faults involves inadequate chafe protection and strain relief where wires pass through the metal housing. Right—This approach, using nonmetallic compression fittings, is ideal. the vessel, thereby presenting an housing. In my experience, chafe protection—with few exceptions (see electrocution hazard. Correctly con- protection alone is wholly inadequate below), a circuit breaker that embod- figured, proprietary, and preferably for transformer-enclosure wire pass- ies ground-fault protection and is nonmetallic strain-relief fittings must through locations. commonly referred to as an ELCI. This be used to eliminate the possibility In accordance with ABYC recom- amalgamation of a circuit breaker and of chafe or contact between an ener- mendations, primary input cabling a GFCI-like receptacle offers ground- gized conductor and the unit’s metal must be equipped with overcurrent fault and overcurrent protection to the

108 Professional BoatBuilder Galvanic Isolators

or boats fitted with polarization transformers (which Fafford no galvanic isolation), or for those that have no transformer at all, a galvanic isolator must be installed to deter corrosion caused by adjacent vessels, steel pilings, bulkheads, etc. Among the most common corrosion-related misunder- standings is the role shore-power plays in this phenome- non. With rare exceptions, 120VAC and 240VAC shore power does not cause corrosion or rapid consumption of zinc anodes or underwater metals. Corrosion is primarily Select a galvanic isolator that meets the current ABYC stan- a DC phenomenon. The shore-power cord and the green dard for a fail-safe design, which continues to provide a safe safety ground wire it contains, however, often are an path to ground for fault current even if it fails. accessory in the process. The moment a non-isolation transformer or a boat with- out a galvanic isolator is connected to a dock pedestal via the marina and their underwater metals. Such an arrange- a shore cord, and before the dock or vessel circuit breakers ment can wreak havoc with anode consumption rates and are turned on, a connection has been established between corrosion of underwater metals. If, for instance, the owner the boat—including all of its grounded underwater metals, of the vessel in slip number one hasn’t replaced his or her zinc anodes, seacocks, shaft, strut, etc.—and the dock’s AC anodes in a year, but the owner of the vessel in slip number safety ground, and thence, in theory, to every other boat in three has regularly inspected and replaced the anodes, they

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The most effective galvanic isolators are fitted with a . Galvanic Isolators

to all the other boats?” The short answer is an emphatic Single diodes Blocks ±0.6VDC No. That connection must exist to carry fault current back block 0.6VDC to its source, typically a transformer at the head of the dock. It’s worth repeating: The green safety ground connec- tion between the vessel and the dock and on to the trans- former must not only remain in place, it must be sound and free of corrosion and excess resistance. Without it, Blocks ±1.2VDC Double diodes and there’s no reliable, safe, low-resistance path for fault current block 1.2VDC to take back to its source, which in turn will, hopefully, trip capacitor a circuit breaker. passes AC passes 120VAC There is, however, an alternative: a galvanic isolator. This device is inserted in line with the green safety ground as it enters a vessel, typically between the shore-power inlet and the electrical panel. (Much like an isolation transformer, it’s critically important that no connections be made to the AC will protect both vessels, or several vessels, for a time, until safety ground between the galvanic isolator and the shore they are depleted, which can happen rapidly. inlet, as doing so will negate its effectiveness.) The isolator’s Many boat owners, and some professionals, have asked, role is simple: allow low-level AC fault current to pass “Can’t I just do away with the green wire and its connection unimpeded, while blocking, to a point, DC voltage up to

110 Professional BoatBuilder transformer’s primary cir- about 1.4V. With this approach, cuit installation—albeit small AC faults are safely conveyed with a significantly higher back to their source, while destruc- 30-mA trip threshold when tive galvanic DC current is blocked. compared to that of a com- With a galvanic isolator in place, mon 5-mA GFCI recepta- anodes now protect only the under- cle. This device also serves water metals of their own vessel and to prevent electrocution not those of other vessels, and “hot and ESD in the event of marinas” are of little concern. a ground fault between Be sure the galvanic isolator you the transformer and the choose is designed to be fail-safe, shore inlet, where no pro- which means if it fails, it continues tection is provided by the to provide a safe path to ground for transformer. fault current, and is compliant with Because the transformer the latest (July 2008) revision of behaves much like a power ELCIs, also known as residual current devices, add ABYC Standard A-28. It’s important source, units wired for split- a measure of safety to a transformer installation, to recognize that if a fail-safe gal- phase 120V/240V three- particularly for the wiring between the shore inlet vanic isolator fails safe, as adver- wire service must include and the transformer itself, which is afforded no protection by the transformer. tised, the device no longer provides overcurrent protection for corrosion protection, so test these the secondary, or output, devices at least annually. wiring as well, and it must be installed Polarization transformers, on the —Steve D’Antonio within 40" (1m) of the transformer, other hand, maintain the shore-side the closer the better. ground connection. While these

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Electrocution and Electric Shock Drowning

nlike conventional electric shock, which causes the boat and the nearby dock where the boy was swimming. Uvictim’s heart to stop or to go into ventricular fibril- Because this was fresh water, the current made its way in lation as a result of exposure to a sufficiently high level a narrowly focused field back to its source ashore, and of electric current, electric shock drowning (ESD) simply the boy entered its path. paralyzes the muscles so the victim can’t swim. As a result of the saline content of the human body, it In one well-known fatality from 1999, a nine-year-old is a much better conductor than fresh water—a com- boy was electrocuted as he swam adjacent to a marina paratively poor conductor—and offers the leaking cur- dock in fresh water. He was wearing a life jacket, and his rent a lower-resistance path. face never touched the water. His mother jumped in to Had the vessel with the electrical fault been properly save him and as she did so, her limbs and extremities went bonded, it’s likely this fatality would never have occurred, numb in an early stage of ESD. Had she been unable to as the fault current would have passed safely ashore over swim away from the electric current field, she may have the green safety grounding wire, where it would most drowned. She was able to pull her son to the dock, where likely have tripped the dockside circuit breaker. Simi- others helped pull them from the water, but it was too late. larly, if the vessel had been equipped with a shore-power The ensuing investigation determined that this trag- transformer, leaking current would have returned to it edy occurred because of an electrical fault in a nearby rather than through the water, which also would have unbounded/ungrounded boat. An improperly overcur- saved the boy. If no other lesson is learned, let it be this: rent-protected DC wire had melted into an AC wire and, Never swim in a marina or adjacent to docks where shore in turn, allowed AC-shore-power current to leak into the power is present. DC system and from there into the water around the —S.D’A.

112 Professional BoatBuilder transformers ensure correct onboard In either case, the installation must Take the Boost polarity in the event of a dockside meet current ABYC guidelines and Standard shore-power transformers fault, as well as reducing the likelihood manufacturer-recommended installa- offer what’s known as a 1:1 power ratio, of electrocution and ESD, they will do tion schematics, which offer several i.e., identical input and output. Option- little if anything to prevent corrosion, options. ally, transformers may be designed because the connection between shore-side and vessel ground remains intact. Advocates for polarization transform- ers point out that the units are safer than isolation transformers: Because their metal enclosures are connected to shore and to the vessel’s grounding system, an unresolved ground fault to the case is nearly impossible. When used with a galvanic isolator, they too provide a measure of shore-induced corrosion protection (up to 1.4V of blocking volt- age versus the infinite blocking ability of the isolation transformer). Most shore-power transformers can be installed in either the isolation or For vessels equipped with polarization transformers, an associated non-ABYC-compliant polarization mode, depending entirely galvanic isolator does not meet fail-safe requirements and should be replaced with an upon the ground-connection method. up-to-date model.

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Manual transformer to select the correct winding “tap” to primary selection for achieve the needed boost, if any. shore inlet voltage is an option, but the onus is on On manual boosting transformers, the user to make the the user typically moves a rotary correct selection. switch to select the known input volt- age. Both work well; however, the manual version is fraught with the potential for sending damaging over- voltage into the vessel’s electrical sys- tem if, for instance, the user forgets to switch from 208V to 240V input when refrigeration and air- moving to a dock that provides 240V. conditioning compres- While electrically savvy do-it-your- sors. Thus, a standard- selfers are free to take the manual ized voltage of 208V (or approach, my advice is to avoid offer- less) on many docks, par- ing or agreeing to install this option. ticularly in older marinas, It’s simply too risky. could be boosted to 220V Common 240V, 50-amp (often or more. expressed as 12 kVA or 15 kVA, or for either manual or automatic boost- Most off-the-shelf boosting trans- kilovolt-amperes) transformers are ing capability. With this design, low formers are automatic. The user sim- typically wired for a 240V input or dockside voltage can be boosted to ply plugs the vessel in, and the trans- primary alone, from which they pro- a degree, reducing the detrimental former’s circuitry senses the available vide “split phase,” i.e., 120V/240V from effects, particularly for motors, and power and controls internal switches the secondary. For 1:1 nonboosting

114 Professional BoatBuilder transformers, this can present a prob- With more and more docks being equipped with lem. If the primary voltage is 208V pedestal RCDs, soft-start (and often less when voltage drop devices are becoming a occurs on long docks, or in summer, necessity for transformer when every vessel’s HVAC is run- installations. This one can ning), the split-phase output voltage be added to any installation. will be no more than 208V/104V, which is below the voltage specified by most equipment manufacturers— for motors, and air-conditioning and refrigeration compressors. By con- trast, a non-transformer-equipped, dockside split-phase circuit will yield More Options 208V/120V. In some cases, a 1:1 For transformers with a transformer may in fact yield low primary input of 240VAC, voltage, and potentially lead to equip- a useful option is to also ment malfunctions and failures. include a 120V primary Lower operating voltage for motor input. With this configu- and compressor circuits yields higher ration, the transformer current, more heat, tripped circuit can be used when only a 120V, 30-amp of 120V and 240V gear, even when no breakers, and potential damage to or 50-amp shore- is 240V power is available on the dock. armatures. My advice to electricians, available, albeit at a diminished capac- For transformers that have this yards, and builders is to install only ity of 3.6 kW or 6 kW. The beauty of 120V primary, the installer must boosting transformers. this arrangement is the judicious use include some external switchgear—a

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Some transformers are rotary switch, slide-lock circuit break- available with a remote ers, or automatic shore-power relays— readout and controls, which to prevent inadvertently supplying can be mounted for more 120V and 240V simultaneously to the convenient monitoring transformer. and operation. For vessels that use a transformer with a 240V primary and a perma- nently installed shore-power cord-reel system, yet another benefit is available: Standard shore cords used without transformers in split-phase applica- tions have four wires—two hot legs, one neutral leg, and a safety ground. However, because 240V shore-power transformers require no neutral at the primary, this wire can be safely elimi- nated, making the cord smaller, lighter, and less expensive. However, for a standalone non-cord-reel shore- power cord, this three-wire approach could be disastrous: If this cord were inadvertently used to supply power to a vessel without a transformer, the result would be the equivalent of a “dropped neutral”—a dangerous sce- nario potentially leading to excessively high voltage, damaged equipment, and fire. A limited number of transformer manufacturers produce units appro- priate for either recreational or com- mercial vessels. While there are many industrial manufacturers of terrestrial transformers, none that I know of offers automatic boosting, and few produce units compliant with current UL Marine and/or ABYC standards. I recommend sticking with marine- industry-specific manufacturers, because they offer considerably better support. Yet another option involves a soft- start device. With the advent of dock- side residual-current devices (RCDs), it’s not unheard of for a transformer- equipped vessel to trip the RCD if the power is engaged at just the wrong moment in the AC waveform. A soft- start device, available from some man- ufacturers as a built-in option or as an add-on, will typically solve this problem. Many marine-specific transformer manufacturers also offer remote con- trols. They can be as simple as a series

116 Professional BoatBuilder of visible lights in the cabin, so no one I also recommend photographing builders and owners and others in the has to crawl down to where the trans- correct installations upon completion— industry as Steve D’Antonio Marine former is installed. Alternatively, especially wiring and cord grips—to Consulting. An ABYC-certified Master remote control and monitoring can establish a record in case a failure Technician, he sits on that organization’s also be handled by a smartphone or results from third-party modifications. Hull and Piping and Engine and Power­ tablet via Bluetooth connection. For train Project Technical Committees, new builds and refits alike, remote and is also Professional BoatBuilder’s control/monitoring makes good About the Author: A former full-service technical editor. sense. yard manager, Steve works with boat- Finally, make sure your installations comply with transformer manufac- turer instructions and ABYC stan- dards. When you complete an isola- tion transformer installation, test its isolation function with a multimeter and/or inductive leakage meter. Isola- tion-transformer-equipped vessels should exhibit no leakage current when measured at a shore cord. If leakage is present, a bonding or ground connection might have been made between the transformer and shore inlet—a scenario that demands immediate investigation, as it would negate the transformer’s isolation properties.

Resources

(Not all transformer and galvanic isolator manufacturers offer ABYC-compliant and/or boosting models.) Transformers ANG: atlasmarinesystems.com Charles: charlesindustries.com Hubbell: hubbell.com/wiring device-kellems/en Olsun: olsun.com Ward’s Marine Electric: wardsmarine.com Nauti Tech (boosting trans- formers and rebuild kits): nauti-tech.com Galvanic Isolators DEI: dairyland.com Newmar: newmarpower.com Professional Mariner: promari ner.com

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