Lessons Learned - June 2018

Shore Power

A short time back several of us had just returned to the marina late in the afternoon after a day outing and were getting our boats secured and set for shore side operation. The intent was port and cigar hour would start as soon as we were all secured and hooked back to shore power. Just as I was settling in to my favorite dock chair and deciding between a Montecristo #2 Torpedo or a Davidoff Year of the Dog Gran Churchill a fellow yachtsman, I will call him Jim to protect his identity, called me over to his boat. As I approached there was that distinctive odor of burning electrical insulation.

I have written many times about the lack of due regard some folks have with 120V shore power. Not a day goes by that I do not see a boat whose owner has demonstrated a cavalier attitude with connecting shore power to his or her boat. With power cords hanging in the water, obvious loose connections, not using the proper sealing collars and locking rings and exposed wires due to wear or strain we see examples on every dock just about every day with predictable results.

Jim, however, is not one of those. His power cords are well supported at both ends, are connected together with the proper sealing collars and locking rings and the power cords are fairly modern and did not exhibit any sign of wear or excess strain, until that day. So what could possibly be the problem? Since the sun was setting and we had already delayed port and cigar hour and with the shore power disconnected, breakers shut off, and the boat safe, we decide to deal with the problem the next morning.

The next morning after checking the power cord dock connections and confirming good power at the cable end, we disassembled the shore power receptacle on the vessel to inspect the wiring. What we found was a shock, pun intended. The power connections at the back of the receptacle had burned beyond the strain relief and back several inches. The issue apparently was the screw connections on the hot wire becoming loose and developing a high resistance which caused the connection to heat and create more resistance. This would not have been discovered without disassembly of the inlet connections and checking the tightness of the screw connections. This is a preventative maintenance item that should be completed at regular intervals to prevent just these types of catastrophic failures. Having determined the cause, the proper fix, a quick visit to West Marine, new parts installed and the shore power was back in operation in short order.

Fast forward a few weeks. I was working with our mechanic on one of our client’s boats in Sausalito when we both, almost simultaneously, commented that we smelled something burning. While he kept on wrenching on the port engine I climbed out of the engine room and once on deck what I saw startled me. There was the 240V/50A shore power connection positioned where it always is, but now had the added feature of flames shooting out the side! I quickly made my way to the shore power breakers on the dock and found that they had been tripped, although apparently not quickly enough to prevent a near meltdown of the power connectors and a charred spot on the teak deck.

After a thorough inspection of the shore power cords and connectors it was easy to see that the neutral (white wire) had overheated and started the chain reaction resulting in a meltdown of both ends of the shore power connection. Of course the next question is why did this occur at that fortuitous moment when I happened to be on the boat? That particular day we were on the boat attending to some mechanical work on the port engine and while the mechanic was busy in the engine room I was checking the various vessel systems such as heat/AC, hot water, and lighting. The heavier than usual load on the shore power system exacerbated a compromised connection and started the chain reaction.

The fix is relatively simple, although a bit costly. Obtain new male and female 240V/50A power connectors, new waterproof boots, and new sealing collars and locking rings. Assemble and test.

Once I started disassembly of the old connectors it was apparent that something like this had occurred in the past. The vessel’s Cablemaster system has a white power cord but the male connector and boot was yellow. A sure sign it had been replaced at some point in the past. While preparing the cords for assembly, I had to cut back nearly three feet on the power cords to find clean wires. Salt water at some point had entered the connections and over a long period of time corroded the wires enough to create a high resistance connection.

The danger of poor AC electrical boat wiring or compromised connections is not only the danger of fire, but also the potential for putting AC currents in the water eating up your and your neighbor boats’ sacrificial anodes and the potential to electrocute someone in the water.

 

What Is New In
Shore Power?

On July 21, 2010, the ABYC (American Boat Yacht Council) standard E11.11.1 took effect which recommends an ELCI (Equipment Leakage Circuit Protector) be installed in addition to the main shore power disconnect breakers. Think of this system as a whole boat GFCI (Ground Fault Circuit Interrupter) that we see in the vessel’s galley and heads or in your home kitchens and bathrooms. The ubiquitous GFCI is a protective device that will open a circuit when a leakage current of 4-6 ma is detected as required by the UL943, Ground Fault Circuit Interrupters, requirement. Both the GFCI and the ELCI operate on the same principle of measuring any imbalance of current between the hot and neutral lines and tripping the circuit in a prescribed amount of time when an imbalance of a specified limit is detected. While a GFCI will trip with a leakage current exceeding six milliamp, an ELCI is less sensitive and will trip when the leakage current exceeds thirty milliamps. Why is this important? ESD and the potential for fire.

Electric Shock Drowning refers to in-water injuries or fatalities resulting from an electrical shock. ESD generally occurs when low levels of AC current is present in the water and passes through a person’s body. When an electrical fault condition on a boat or dock occurs and a voltage source comes into contact with the water, an electric field is developed that radiates out from the source. As a swimmer approaches the electric field current begins to flow through the swimmers body. Since the human body has a much lower resistance than fresh water and acts as a better conductor, current begins to flow through the person and not the water. Currents as low as 10ma can cause paralysis of the muscular and skeletal systems while immersed in either fresh or salt water. When paralyzed, the victim is unable to swim or move to safety and will ultimately drown. Unfortunately it is a person’s natural instinct to swim towards the boat or dock, but, just the opposite is best and the victim should swim away from the source of current. ESD can be deceptive since the victim may not be exposed to the stray voltage field when first entering the water and then believing that the water is safe for swimming, will unintentionally enter the voltage field. I know what you are thinking and the answer is yes, any boat can be retrofitted with the addition of an ELCI.

While the ABYC standards are recommended best practices for yacht manufacturers, most but not all, follow most, but not all, of their recommendations. To address these shore power safety issues the NEC (National Electrical Code) in 2014 changed article 555.3 which now requires marinas to install GFP (Ground Fault Protection) in the marinas shore power system. You may have already visited one of the bay and delta marinas that have installed shore power equipment meeting the new standard which, just like the GFCI or ELCI, measures the imbalance of current and trips the circuit. In this case the power is cutoff if the imbalance exceeds 100 milliamps.

 

Coming To A Marina Near You

Based on research conducted by the Fire Protection Research Association, the NEC in 2017 changed article 555.3 again. The new rule requires that all over current protective devices (circuit breakers for example) in marinas, boatyards, and at commercial and non-commercial docking facilities provide ground fault protection not exceeding 30ma. This is the same protection level as an ELCI that the ABYC recommends new boats have. This marina rule will protect older boats that do not have onboard ELCI but will not protect the vast number of older boats that are berthed in older marinas. And, it is important to remember that a person in the water will be incapacitated with a current of 10ma and the new marina rule calls for no more than 30ma of leakage current. Perhaps this new requirement is not stringent enough. Keep in mind that compliance with codes and safety standards will help to protect an individual that inadvertently enters the water around a dock or boat equipped with electric power, it is not meant to be the green light for in water activities around a boat or dock.

Many yachtsman with older boats, boats that have non marine rated equipment installed, or new boats with faulty electrical wiring have been discovering issues with their boats when connecting to a renovated marina. Finding the exact cause of problems can be difficult however the more likely culprits are household appliances on the boat, improper inverter wiring, corroded electrical connections, and faulty power cords. Ground faults onboard our vessels that are connected to marina power with cut, breaks or poor connections can be a serious shock and fire hazard.

According to one marine insurance company, most AC electrical fires start somewhere between the shore power pedestal and the vessel inlet connection. Use only marine grade power cords and connectors and use the locking rings and collars to make the connections watertight and mechanically secure. Do not ignore the other high risk area; the back of the shore power receptacle. It is recommended that these connections be inspected at intervals not exceeding 10 years. If your boat is older than 2008, when did you last inspect the back of the shore power connections?

 

Lessons Learned?

Do not take AC power around your boat or dock lightly. Until seeing the back of the inlet connection on Jim’s boat I had not considered these connections should be inspected regularly. If there is any sign of a worn connection anywhere in the shore power system, inspect closely and replace any component that is suspect. If your boat is having power issues at one of the new marinas with Ground Fault Protection, have a marine electrician inspect your boat’s AC system. Do not blame the marina if you are having problems. Another solution would be to install an isolation transformer on board your vessel. As the name implies the isolation transformer “isolates” your vessel from the shore power and any ground currents that appear on board will not be carried back to the shore and trip the GFP device. These transformers have other advantages as well as they can compensate for low marina voltage, correct reverse polarity problems and provide galvanic protection. Getting angry with a renovated marina that has installed modern shore power equipment designed to protect you and your guests will not solve the problem.

Last word is an apology to Jim. Port and Cigars are on me next time. That is it for this month. Have a good story to tell send an email to patcar son@yachtsmanmagazine.com. I love a good story. H


© 2010 Yachtsman, All Rights Reserved.   |   Home   |   Contact Us                     Bookmark and Share