If ONE end of my cable has to start on fire, I know which end I want it to be! ;^)
Scorched Plug
- Thread starter Sailgunner
- Start date
I had a similarly scorched plug where the pigtail plugged into my heavy cord going to the shore power on the dock. I changed out to the Smart plug and have been very happy with it. Always a good secure connection at the boat and less electrical resistance than the round plugs. The outlet hole pattern matched my existing round outlet so it was a snap to replace on the boat. Do it, you wont be sorry.
+1
I think that is most likely.
A less likely possibility is that there is a poor connection inside the molded section of the plug where the wire meets the prong.
I would plug that cord into a good pedestal & check for high temperature under load. If the cord end gets hot, then I would change the cord end or get a whole new cord promptly. If the cord end does not get hot, then I would call the marina where the problem happened & let them know that they probably need to put a new receptacle in that pedestal.
And this image shows why.
The SmartPlug also has a thermal disconnect. If the plug gets too hot, it disconnects the power supply. Earlier version had auto resetting thermal breakers, newer models don't.
The real problem occurs when folks don't insert the twist lock properly or fail to thread on the locking ring, if they have one at all.
I have seen more than a few basically brand new cord sets & inlets burned up despite zero corrosion, zero arcing and zero time in use because an owner over-loaded the cord set and failed to plug it in correctly.
All it takes is a mm or so of movement for the locking dimple to ride out of its hole and onto the blade surface. Once this happens you have virtually no surface area to transfer the needed current and the socket begins to heat up until it starts melting. If not caught soon enough the boat can burn or the marina.. The twist lock standard we use today would never pass current testing standards (it has been tested to the same protocols being required of the SmartPlug and fails, but it is "grandfathered"...
If the plug does not lock properly or gets tugged on..
Seems that a breaker switch wold be a mandatory requirement at the dock pedestal per electrical code for safety reasons. Are marinas that don't have breakers at the pedestal "grand fathered" to older codes?
A couple years ago I was getting a fault indication on my AC panel that resulted from a bad power input receptacle on the boat. Converted to a smart plug; one of the best improvements that I have ever done! No more fiddling with the plug getting it to engage and no more playing with the plastic ring trying to tighten without cross threading, or worse yet, trying to untighten the ring. The smart plug is a Substantial improvement in convenience and most importantly, in safety, as per mainsails excellent analysis.
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 23,141
No problem. I was thinking linear (cause effect). And it now resonates as a metaphorical experience.
I had been too long at home working. I’m now on the boat and my head is starting to clear.
We need to remember that a breaker can't stop a fire that is caused by high resistance. A high resistance caused fire can occur at well below a breakers trip rating. Marina's that make any upgrades are now required to install ground fault protection but this is opening up another huge can-o-worms...
The current NFPA 70 / NEC requirements Article 555 Marinas & Boatyards, which rolled out in 2011, requires a 100mA ground fault protection level for marina docks. In the upcoming 2017 NFPA 70 / NEC 555 this maximum level is reportedly going to drop from 100mA to 30mA. With soooooooooo many boats out there incorrectly wire, due to a "voluntary standard" the new shore requirements have been met with issues normally set aside for nightmares...
(Copy & paste from older post)
The Problem With the New Mandates:
#1 NFPA 70 / NEC requirements do not mandate protection at each dock pedestal, which would be the only prudent way to adopt or phase this into an entire industry where the safety standards are voluntary and arguably grossly ignored.
As I type this I am currently waiting for a customers phone to cool down so we can continue troubleshooting his shore system via video messaging. He is in the BVI and can't find a decent electrician to save his life. So far we've found on-board AC neutral bonded to AC Earth and his two 30A shore inlets have common neutral bonding. Somewhere in his travels he had a failed 8kW generator ripped out, by some hacks, who left a ghost transfer switch and ran the ghost wires to where ever they found an open terminal. It is a freaking mess, a mess I repeatedly tried to talk him into fixing before he headed off cruising. "seems to work" he'd say.... He began complaining of issues when his vessel began tripping up to code marina's and shutting entire docks down. The non-transients at these marinas were none too happy and the marinas finally told him not to plug in..
As a result of NFPA/NEC not requiring 100mA or 30mA ground fault protection at the pedestal level, for each boat, any vessel plugging into a dock pedestal that is protected by an upstream ground fault device can create nuisance trips for every boat on that same feed. This = BAD (safe, but bad)
Shore based ground fault devices that cover multiple pedestals (boats), can result in a nuisance trip that depowers all the boats on that string and create a lost power situation to all of those vessels, just as my customer has done, at no less than 3 or 4 marinas since leaving Maine. If he had listened to me, we could have fixed his AC issues before he left.
This NFPA / NEC roll out has already cost boaters significant $$ in destroyed battery banks etc.. Unfortunately the boaters who lost out may not have been the ones who created the problem. They were just the recipient of what I often refer to as Darryl & Darryl wiring, for those old enough to get the Newhart reference.. No offense to any Darryl's out there....
The NFPA / NEC ground fault requirements are only serving to expose the horrendous wiring that has gone on in the marine industry for far too long. Even if your boat is properly wired, to ABYC standards, you can still suffer the consequences of Darryl & Darryl hack jobbing their own boat because the NFPA/NEC requirement is not at the power pedestal/individual boat level but rater at the marina level.
For what it is worth I have very infrequently come across an owner who believed it was their boat creating the leakage or corrosion issues or the cause of ground fault issues.. In almost all cases it starts out as "someone else's problem" until the fault is found on-board...
#2 Far too many boats out there are not wired to meet or exceed the ABYC safety standards. The NFPA / NEC could really care less about this, it's not their issue. When you plug an incorrectly wired vessel into the new NFPA /NEC shore standards, requiring ground fault protection, it can now become everyone's issue not just the problem vessel.
Boats that are not wired to current ABYC standards, as a group, have very, very high ground fault percentages. For example the number of boats I measure with AC grounding (GREEN) and AC Neutral (WHITE) bonded on-board the vessel (A huge no-no) is in the range of 35-40% +/-. This is INSANE, but it is the reality of a voluntary standard that has gone largely ignored by boat owners, or DIY wiring done by local dock-xperts who think they know more than the standards organizations, and by far too many folks who simply hang a shingle and call themselves marine electricians..
Bottom Line? Improperly wired vessels, vessels not wired to ABYC standards, can cause nuisance tripping of shore ground fault interrupters. This will be rarer at 100mA or 30mA but would be a very common occurrence at 5mA due to accumulation leakage..
The sheer age of many vessels also means some of them have equipment that is so antiquated that it too creates an inadvertent neutral to grounding bond on-board the vessel..
#3 The Rx?
Marina Rx: Marina's who want happy customers should ideally install a 100mA or 30mA ground fault device at each pedestal, not 5mA, so one boat can not take out an entire dock or entire group of vessels. We must remember that a GFI, like a standard breaker, still won't trip due to high resistance but will trip on leakage. Installation of GFI at the pedestal level is in compliance with NFPA 70 / NEC and actually exceeds the minimum requirements. By installing a ground fault device at each pedestal we now prevent Darryl & Darryl's stellar wiring job from taking out your boat when they create a nuisance trip.
Marina's also need to comprehend and understand that leakage is additive. If we have ten boats each leaking 4 mA, which is not even enough for each boat to trip an individual 120V 5mA GFCI, those ten boats together can trip a single 30 mA ground fault device. D'oh......
Marina's should prohibit vessels that cause a nuisance trips, from plugging into their system, until the fault has been corrected. If a vessel is tripping a 100mA threshold device (and this is not due to additive leakage) this creates a very dangerous potential for electric shock drowning.
The issue & mess of nuisance tripping will only get worse when the NEC drops to 30mA in the next revision..
Marina's need to fully understand the new requirements and be trained on how to conduct spot audits and to check for individual vessel issues that would otherwise create problems for the rest of their customers. Or do it right and install a 30mA device at each pedestal, this way only the offending customer is left without power..
When a marina is re-wired or modified they now need to become in compliance with the current shore based standards. Shore standards extend to the dock pedestal receptacle only, and ABYC standards begin at the shore power cord.
This problem of nuisance tripping is already bad and is only going to get worse, much worse, as time goes on and more and more marinas become in compliance with the NFPA 70 / NEC requirements. Once the code drops to 30mA, to protect multiple pedestals, it will become even worse.
Boat Owner Rx: Wire your vessel to the current ABYC standards and you will no longer create dangerous situations, power loss or dead batteries for those around you who do have properly wired boats.
Two Easy Tests for 120V 30A Service (these two tests barely scratch the surface but its a start):
1- Use a high resolution AC clamp meter set to measure A or mA. Extech, Yokogowa and Fluke all make excellent AC leakage clamp testers. Ideally every marina should own one. Power up your on-board AC devices (hopefully all of them) & place the clamp around your shore power cord. The reading should be 0.0A. Any reading above this is indicating an amperage imbalance between the hot and neutral AC conductors and indicating that this missing current is leaking elsewhere eg: into the water..
2- One of the easiest tests or starting points is to physically unplug your vessel from the pedestal and be sure your inverter is decoupled from DC so it does not auto-invert. Make sure any manual transfer switches are set to SHORE. Now test for continuity between AC WHITE/Neutral and AC GREEN/Earth/Grounding pins at the shore end of the cord or at your on-board grounding bus and neutral bus.. There should be no continuity.
If you find issues you are unsure of I would suggest bringing in a professional....
So here's the latest. I'm plugged into the pedestal with my splitter using my 30A and a tight Marunco cap on the other end. We leave for the day and another boat comes in across from us. When we return our freezer isn't running and I switch the breaker off and on. It begins to run again and we discover the box temperature about 36 degrees. Some chicken was thawing so we're going to use it soon.
I happen to inspect the pedestal and I find the other boat has also plugged in to our splitter. Quick discussion with the other owner about not plugging into some one else's line, especially when hot and the boat name written in several places on the splitter. He said the marina gave him the go ahead since they said it was their splitter. I don't think they did since the dock master was very cautious when we plugged in to have all breakers off. Morning rant coming.
All U Get
I happen to inspect the pedestal and I find the other boat has also plugged in to our splitter. Quick discussion with the other owner about not plugging into some one else's line, especially when hot and the boat name written in several places on the splitter. He said the marina gave him the go ahead since they said it was their splitter. I don't think they did since the dock master was very cautious when we plugged in to have all breakers off. Morning rant coming.
All U Get
Slightly off topic, but sort of relevant. If the chicken only went to 36*, it is perfectly fine to re-freeze it. The issue with refreezing meat that has has thawed or partially thawed is that ice crystals form in the meat and breaks down the cell structure. Each time the meat is thawed and frozen, more cells are broken down and the meat becomes mush. None of this applies if the temperature of the meat goes above 40* for any length of time, because then the bacteria get going and the meat could spoil.
More on topic, it just isn't neighborly to unplug someone's shore power without permission or the other party's knowledge.
Wow, "discourteous" doesn't quite cover that action on your neighbor's part. What marina were you at?
We switched to a smartplug two years age and it's a huge improvement. There was no visual defect in my existing cord but I liked the extra safety and design features of the smartplug. Easy to change. When I took off the in-hull receptacle, two inches of the hot (black) lead were charred and the conductor was fused - Ouch! could have started a fire at any time - and I regularly inspected and cleaned my power connectors.
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I was wondering where you were. I just did three days at St.Michaels and thought maybe you'd be there for the Oyster Festival. Returned to Back Creek and saw a boat anchored that looks like it could have been yours.
I have a question: Is the photo of the plug in "as found" condition, or did you clean off the blade? The reason I ask, is that for the case to turn black, normally the blade will also turn black and show corrosion or melt. Since the blade still looks pretty good, I suspect the problem may be inside the plug itself - potentially a loose screw terminal.
Plugs themselves don't normally catch fire, as they must be flame proof material. However, power connections can damage equipment inside your boat, especially anything with a motor in it. Things like AC compressors or refrigerators don't like low voltage. I'd be much more worried about the items inside the boat being damaged or potential fire hazard than the actual plug itself catching fire.
Plugs themselves don't normally catch fire, as they must be flame proof material. However, power connections can damage equipment inside your boat, especially anything with a motor in it. Things like AC compressors or refrigerators don't like low voltage. I'd be much more worried about the items inside the boat being damaged or potential fire hazard than the actual plug itself catching fire.
I think he "borrowed" them from Maine Sail.
https://marinehowto.com/shore-power-cords-smartplug-vs-1938/
Thanks to Google I borrowed it from some RV site (http://www.rvrepairstream.com/smartplug.html), who seems borrowed one or more of them from Maine.