Plug gets warm + salty air, oxidation starts, resistance goes up, plug gets hotter, process accelerates until plug and receptacle fried. When you replace with new units spray everything with "Corrosion Block", then let it cure for a day or two before first use. This is the most useful product I have on our 430! Use on any exposed metal (have a bronze sea strainer that looks brand new after 4 years). See: http://www.learchem.com/C.B.Page.htm
Shore power plug keeps burning out...
- Thread starter Levin
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Levin,
I had the same problem during the first few years that I owned my 420. Had to replace sockets and cords.
After the second socket replacement I started coating my plugs with white lithium grease (same concept as "robertclasalle"'s post... it keeps moisture out of the socket).
I have not had a problem since I began doing this (and reapplying about twice a year).
Try it ... what do you have to lose?? :dance:
I had the same problem during the first few years that I owned my 420. Had to replace sockets and cords.
After the second socket replacement I started coating my plugs with white lithium grease (same concept as "robertclasalle"'s post... it keeps moisture out of the socket).
I have not had a problem since I began doing this (and reapplying about twice a year).
Try it ... what do you have to lose?? :dance:
Boeshield T-9
is a heck of a lot better than WD-40, which I've "banned" from our boat. Use the better stuff. The concept of spraying the connections is a good one, but then also check the other stuff mentioned in this thread.
is a heck of a lot better than WD-40, which I've "banned" from our boat. Use the better stuff. The concept of spraying the connections is a good one, but then also check the other stuff mentioned in this thread.
This is my last word on the subject. The connections are poorly designed and very expensive. One poster talked about fryer plug used in restuarants. High load in a bad environment. I below coating the contacts with lithium greasse or any other coating not made to keep of corrosion while still be conductive is adding to the problem.
It is very diffulcult to keep a water proof seal when the inside of these recepticales are open. Meaning where the boats AC wires are connected. The key is to watch your load. Make a good seal , given the poorly design device we are stuck using. Agian, as to any math calculations to figure out what load is good, that only works in theory, not in the real world where your China made heater is rated at 1500 watts maybe using more. Put an extension cord on that, length of shore power cord, etc.
Be careful and do not stuff equipment near the recepticle so when it burns, it will short it self out before it starts a fire.
And the circuit breaker seldom trip! I know everyone feels safe having them on the boat and the power tower, but again wires act like a toaster, heating up, glowing then burn.
It is very diffulcult to keep a water proof seal when the inside of these recepticales are open. Meaning where the boats AC wires are connected. The key is to watch your load. Make a good seal , given the poorly design device we are stuck using. Agian, as to any math calculations to figure out what load is good, that only works in theory, not in the real world where your China made heater is rated at 1500 watts maybe using more. Put an extension cord on that, length of shore power cord, etc.
Be careful and do not stuff equipment near the recepticle so when it burns, it will short it self out before it starts a fire.
And the circuit breaker seldom trip! I know everyone feels safe having them on the boat and the power tower, but again wires act like a toaster, heating up, glowing then burn.
another burned out plug
This has been a great thread for me to catch. I had a similar problem traveling down the east coast this Nov. I was at one marina and everything was ok two days later at a diff marina I could get no power from three diff dock posts, finally figured it might be a problem at my end. My shore power cord connects inside my seat locker, I never touch it, just coil up cord and put it in locker. It had been a cold trip and I had been using two electric heaters some times and it would trip a panel breaker if I had them on the same circut. When I disconnected the cord in the locker I almost died, both the male and female metal connectors were vaporized and had a 1/2 hole in the cord and receptacle, very scarry. After looking at it for a while we decided it was probably a loose connection which caused the problem. According to everything I have read here this seems right. I was going to replace both the receptacle and plug end, then I got thinking that I never disconnect the end in the locker, why do I need it, I cut the end off the cord and ran it through the conduit and hooked it directly to the panel. So far so good, I wonder what you all think of my fix?
This has been a great thread for me to catch. I had a similar problem traveling down the east coast this Nov. I was at one marina and everything was ok two days later at a diff marina I could get no power from three diff dock posts, finally figured it might be a problem at my end. My shore power cord connects inside my seat locker, I never touch it, just coil up cord and put it in locker. It had been a cold trip and I had been using two electric heaters some times and it would trip a panel breaker if I had them on the same circut. When I disconnected the cord in the locker I almost died, both the male and female metal connectors were vaporized and had a 1/2 hole in the cord and receptacle, very scarry. After looking at it for a while we decided it was probably a loose connection which caused the problem. According to everything I have read here this seems right. I was going to replace both the receptacle and plug end, then I got thinking that I never disconnect the end in the locker, why do I need it, I cut the end off the cord and ran it through the conduit and hooked it directly to the panel. So far so good, I wonder what you all think of my fix?
Re: another burned out plug
Jharding, All you have done is is turned the extension cord into an appliance cord. Your boat being an appliance, very little different from an electric stove as far as power requirements are concerned. Seems like a good idea. Make sure you check the terminals once in a while.
Jharding, All you have done is is turned the extension cord into an appliance cord. Your boat being an appliance, very little different from an electric stove as far as power requirements are concerned. Seems like a good idea. Make sure you check the terminals once in a while.
Captain Km
In general two things can cause this 1. Corosion or bad connection. If the plug on your boat is bent or corroded heat will be generated causing the problem, Possible the way you lay your cord not allowing a stress free connection. or 2. You are drawing too much current. If your cable is 30 amp and you constantly use 30 amps or more. ie microwave TV water heater fridge AC and your breaker is incorrectly wired or defective you will draw too much causing heating and the problem you see. Both of the above problems need attention to stay safe from fire.
In general two things can cause this 1. Corosion or bad connection. If the plug on your boat is bent or corroded heat will be generated causing the problem, Possible the way you lay your cord not allowing a stress free connection. or 2. You are drawing too much current. If your cable is 30 amp and you constantly use 30 amps or more. ie microwave TV water heater fridge AC and your breaker is incorrectly wired or defective you will draw too much causing heating and the problem you see. Both of the above problems need attention to stay safe from fire.
Plugs
We have the shore power plug inside the anchor locker which keep it out of the rain. I also coat the contacts with dielectric compound which keep the mositure out but keep the resistant low. I also don't use power to the rated limit. Don't ever use grease. It only increase resistance as less contact area able to pass current. When it heats up, it flows between the good contacts further reducing area to pass current.
We have the shore power plug inside the anchor locker which keep it out of the rain. I also coat the contacts with dielectric compound which keep the mositure out but keep the resistant low. I also don't use power to the rated limit. Don't ever use grease. It only increase resistance as less contact area able to pass current. When it heats up, it flows between the good contacts further reducing area to pass current.
Hello again everyone...
Ok, after reading through all the posts I think I now have an answer. It looks like it is a combination of factors leading my plugs to burn out. One of them in the inferior design of "twist lock" plugs themselves for keeping moisture out of the socket. Secondly is the fact that I am a live-aboard and probably pull more power than average boat owners do on a daily basis, leading my plugs to heat up more. This in turn causes the plug to start to oxidize and corrode and then leads it to heat up even more... and as the cycle continues the problem continues to get exponentially worse.
So it sounds like the cure is to make sure it never corrodes in the first place by keeping all water out. Lots of suggestions have been made for this over the course of this thread: WD-40, Corrosion Block, Dielectric, lithium grease, etc. However some people have pointed out that using this stuff will only lead to higher levels of resistance at the plug, thus more heat... so is this a really wise choice? Isn't less resistance what I'm after so the plug doesn't heat up as much and burn?
It seems like I have my answer save for the people who point out that using any of the above products in combination with the new plug I will be installing soon will lead to more heat... thus sending back through this whole process again.
Anyway thanks so much to everyone for your input...
Take care,
-Levin
Ok, after reading through all the posts I think I now have an answer. It looks like it is a combination of factors leading my plugs to burn out. One of them in the inferior design of "twist lock" plugs themselves for keeping moisture out of the socket. Secondly is the fact that I am a live-aboard and probably pull more power than average boat owners do on a daily basis, leading my plugs to heat up more. This in turn causes the plug to start to oxidize and corrode and then leads it to heat up even more... and as the cycle continues the problem continues to get exponentially worse.
So it sounds like the cure is to make sure it never corrodes in the first place by keeping all water out. Lots of suggestions have been made for this over the course of this thread: WD-40, Corrosion Block, Dielectric, lithium grease, etc. However some people have pointed out that using this stuff will only lead to higher levels of resistance at the plug, thus more heat... so is this a really wise choice? Isn't less resistance what I'm after so the plug doesn't heat up as much and burn?
It seems like I have my answer save for the people who point out that using any of the above products in combination with the new plug I will be installing soon will lead to more heat... thus sending back through this whole process again.
Anyway thanks so much to everyone for your input...
Take care,
-Levin
The two types of water
Fresh rain water and moisture from the water around the dock.
The fresh rain water is easy just make a shelter for the outlet. Options are numerous to include a saran wrapping the outlet once you connect.
The moisture from the dock water can be kept out with greases and ointments but avoid their use on the terminals. a lot depends on what the outlet on the dock looks like. If it is inferior then you have your work cut out for you.
You have to check the dock side outlet though. If that is burned and pitted then it will continue to heat and take your equipment out.
Fresh rain water and moisture from the water around the dock.
The fresh rain water is easy just make a shelter for the outlet. Options are numerous to include a saran wrapping the outlet once you connect.
The moisture from the dock water can be kept out with greases and ointments but avoid their use on the terminals. a lot depends on what the outlet on the dock looks like. If it is inferior then you have your work cut out for you.
You have to check the dock side outlet though. If that is burned and pitted then it will continue to heat and take your equipment out.
Next time that you have to replace your male or female connector on your shore power cord go to a electrical supply house and purchase a small tube of "Penetrox". This will most likely solve your problem for a long time. Penetrox keeps the corrosion out and is designed to aid in conductivity especially between dis-similar metals. Capt. Andy
I am with Newly Anonymous - The contacts must be clean to conduct electricity. To keep them from corroding, stop by at any auto store and ask them for a 2 oz tube of dielectric compund. I use this inside my spark plug caps or highvoltage wires to keep moisure out and keep contacts clean in my car and my outboard. It will extend the life of your plug. It looks like vaseline, squeeze some in each of the 3 prongs. Good luck
There may likely be more than one problem. I am not an engineer but do electrical work on boats. You probably have an "undersized" service for your vessel's equiptment. I think that I would start with the wires on the boat. You said that you replaced the shore cord so I would assume that that is not the problem if you replaced the cord and not just the ends. If the wires on the boat leading to the shore receptacle are compromised (green, black or in any way corroded) this will lead to your problem. The reason that your cord burns and doesn't trip the breaker has to do with the increased resistance in the wire. When the resistance increases the amperage will not increase but continue to heat the wire until some other problem occurs and either trips the breaker or burns. It is common in shorecords to burn up a corroded wire and never trip the breaker. This is only my opinion based on some instances that I have seen.
A Last thing to check for overheating shore power plugs
Any high current through a bad connection will produce unwanted heat. This heat can soften the spring of the socket connector which produces the tight, low resistance of a good connection. I have observed roasted plugs in my marina, and a slight char on the socket. This indicates the marina's socket has also begun to fail. If you are maintaining a low corrosion power cord and the problem continues, the culprit would seem to be the marina's socket. In my marina, a persistent polite request eventually resulted in a new and cooler socket. Hope this helps
Any high current through a bad connection will produce unwanted heat. This heat can soften the spring of the socket connector which produces the tight, low resistance of a good connection. I have observed roasted plugs in my marina, and a slight char on the socket. This indicates the marina's socket has also begun to fail. If you are maintaining a low corrosion power cord and the problem continues, the culprit would seem to be the marina's socket. In my marina, a persistent polite request eventually resulted in a new and cooler socket. Hope this helps
This is basic stuff, but I have seen people forget: I assume you DO connect the boat end of the power cord first? And that the shoreside breaker is turned off? Otherwise, you might get an arc of electricity between the cord and the outlet when they get close, and that can wear off the contact surfaces.
okay, this from a lifetime rver, who has average experience on sailboats and has just lived aboard once, back in the early 80's for a few months. we have 3 different motorhomes (with 30 amp service), all of which we've had various plumbing, electrical, you-name-it problems with throughout the years and have learned to fix ourselves, since most rv places just overcharge you for a problem, basically just shotgunning the potential solutions, and figuring you'll be back eventually (or not) to have them go through it all again. tweaking, tweaking, tweaking and billing accordingly... anyway, what we've found in our electrical issues over time is pretty much what is described above by just about everyone. one thing i did NOT see, but might have missed is really quite simple. without making another change, and with the same plugs, connectors and extensions you already have, would it be possible to MOVE your boat to another slip, just to check to see if the same problem exists over there??? we actually have run an rv park for a couple of months at a time for a friend of ours, and we had a near-identical problem to yours. we just kept burning the expensive umbilicals and fittings up. finally, we had a cancellation at a newer site, about halfway across the park, moved over to it for about 2-3 weeks, and you guessed it, the problem was GONE. we hired an electrician to come out and fix the pole/box where the original problem kept popping up - cost us several hundred bux in expensive, heavy gauge rv cords over two summers there, and similar end-fitting burnouts were happening to us sporadically in (older) rv parks in central texas and oklahoma. don't know what he found, but in just over an hour, and with whatever he replaced, the problem's never happened again to us or anyone else at that site. he did say that 'we were running low voltage to norm, with some major spikes' or something like that. i've kept one of the $60, brand-new, but burned up cable plugs in my electrical compartment just to remind me to watch where we park. we also got a $300 voltage regulator dongle-thingy on sale for $150 or so, and we use it at every park we go to. ALL of our electrical problems are GONE! likely for good... to us it's a miracle in those old parks. i'm sure it'll save an a/c unit or two for us over the years. just file this under the 'just a thought' column as it's just about worth that or less.
jack b
in midland, tx usa
jack b
in midland, tx usa
wIRE cORROSION
You may want to check your wire from the boat receptacle to the panel, or elsewhere on the boat. Moisture will travel inside the wire and corrode it and you won't see it. I have conducted 3 foot immersiion testing of electrical equipment and seen units fail for moisture ingress at the potted end of the wire for water travelling inside the wire. Remember these are stranded wires and almost impossible to seal. I've seen wire on boats that are black inside and the actual wire diameter is about 1/10th of the original as corrosion eats it up. Also has your boat ever been hit by lightning? I've read where lightning will vaporize the metal inside the insulator cover and you don't even know it other than the wire is an open connection.
You may want to check your wire from the boat receptacle to the panel, or elsewhere on the boat. Moisture will travel inside the wire and corrode it and you won't see it. I have conducted 3 foot immersiion testing of electrical equipment and seen units fail for moisture ingress at the potted end of the wire for water travelling inside the wire. Remember these are stranded wires and almost impossible to seal. I've seen wire on boats that are black inside and the actual wire diameter is about 1/10th of the original as corrosion eats it up. Also has your boat ever been hit by lightning? I've read where lightning will vaporize the metal inside the insulator cover and you don't even know it other than the wire is an open connection.
Captain John
Sorry that I don't an answer because I seem to have the same problem. I have two 30 amp connections, the original, and another added for the airconditioner. My boat was purchased new six years ago and I have replaced cable connectors and bulkhead connectors in both circuits. The first one to burnout was the AC circuit. I concluded, at the time, that it failed because of loose screws in the bulkhead connector wire terminations. When the other circuit failed, the screws were the first thing I checked. The screws were tight.
I had not been diligent about secureing the shore power connector nuts and maybe wiggling of the connectors as the boat rocks, loosens the friction tention of the mating contacts, maybe allowing some arcing within the mated connectors. I now screw the connector nuts down tight which should eleminate that possibility. According to your comments, you tighten the connector nut securely, each time, so maybe I'm still at a lose.
I'll be interested in the solution if you get one. Please keep in touch.
Captain John
johnlynn@cfl.rr.com
Levin
Sorry that I don't an answer because I seem to have the same problem. I have two 30 amp connections, the original, and another added for the airconditioner. My boat was purchased new six years ago and I have replaced cable connectors and bulkhead connectors in both circuits. The first one to burnout was the AC circuit. I concluded, at the time, that it failed because of loose screws in the bulkhead connector wire terminations. When the other circuit failed, the screws were the first thing I checked. The screws were tight.
I had not been diligent about secureing the shore power connector nuts and maybe wiggling of the connectors as the boat rocks, loosens the friction tention of the mating contacts, maybe allowing some arcing within the mated connectors. I now screw the connector nuts down tight which should eleminate that possibility. According to your comments, you tighten the connector nut securely, each time, so maybe I'm still at a lose.
I'll be interested in the solution if you get one. Please keep in touch.
Captain John
johnlynn@cfl.rr.com
I've seen this phenomena before on my boat and others. The charring is caused by heat. Heat is caused by some resistance in the connection. So if you are running 20 amps through your AC cord and the contact has a resistance of only 0.05 ohms the connector will dissipate W=I^2*R or 20 watts. Twenty watts in a small space is a lot of heat. And we are only talking about 50 Milli-ohms of contact resistance.
Notice in this example we are no where near the capacity of the cable which is rated at thirty. If the cable is not properly seated it will have more contact resistance and also I believe as the socket wears out there will be more resistance.
On your boat the AC connector uses a set screw to tighten the wire to the contact. If this gets loose do to vibration for any reason contact resistance increases and so does the heat. If there is charring hear best to replace both the wire (and if you have enough extra just cut some off) and the connector. I use a drop of pink (the wimpy kind) locktite to ensure the crew stays set. And my all means sock down the screw with as much force as possible. The set screw uses a slot drive. Make sure the screw driver is the exact right size and use leverage to ensure it is as tight as possible. This should eliminate your problem.
Be aware if you have a bad enough connection a 3 amp load, a factor of 10 lower than the 30 amp rating will cook your connector.
Tight connections=minimum heat
Notice in this example we are no where near the capacity of the cable which is rated at thirty. If the cable is not properly seated it will have more contact resistance and also I believe as the socket wears out there will be more resistance.
On your boat the AC connector uses a set screw to tighten the wire to the contact. If this gets loose do to vibration for any reason contact resistance increases and so does the heat. If there is charring hear best to replace both the wire (and if you have enough extra just cut some off) and the connector. I use a drop of pink (the wimpy kind) locktite to ensure the crew stays set. And my all means sock down the screw with as much force as possible. The set screw uses a slot drive. Make sure the screw driver is the exact right size and use leverage to ensure it is as tight as possible. This should eliminate your problem.
Be aware if you have a bad enough connection a 3 amp load, a factor of 10 lower than the 30 amp rating will cook your connector.
Tight connections=minimum heat
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