shore cable sockets burned, what should I do?

[becrux]

I read every single post and NOT ONE mentioned the necessity of a drip loop at the boat end. Especially if the cord runs across the coach roof and then down to the connector, it MUST drop below the level of the connector and then come up again to plug in. Otherwise there is a straight line path for water from the coach roof to run into the plug. This can happen very easily with a slightly worn connector, or if the screw on attachment is only slightly loose.
It is not even necessary that the AC system on the boat be energized - only the pedestal. If water (doesn't have to be salt water) causes a short between the hot and the ground or neutral, your boat could be toast.

To be fair, thinwater said to keep the connection out of the weather.
I think a drip loop is still a necessity.

Originally Posted by thinwater

It's too late now, but prevention is simple:

• Keep them clean. No salt, not dirt, no corrosion.
• Keep them greased (which solved the corrosion problem). Green Grease (Advance Auto has it) is one of the best anti-corrosion products for this application.
• Keep them out of the weather if possible. Cover them. Under a hard top or dodger is best, out in the open is poor construction.

Yes, they can handle 30 amps without heating, with a safety factor, if properly maintained. UL tested them. I've run that much heating and cooling. That they cannot is based on many experiences with poorly maintained plugs.

Really, ALL external connectors need to be cleaned and greased at least 2x per season. You will be glad you did.

[EngNate]

I'll submit my 2c, I have a lot of experience with these, including repair of a boat that had a fire because of one (about $35K total damage, 6K to electrical system).

The ends the OP pictured needed to be replaced, and were showing it, years ago. Burned connections are always the result of power being drawn through high resistance - any indication of heating near the contacts indicates the time for replacement is now. You cannot see what's going on inside the female connector. Besides corrosion, the terminal fingers get spread apart so they no longer grip the male ends. When there is any resistance, heat is generated in proportion to amps squared, and rises rapidly as load increases, much more rapidly than the voltage drop, which is usually what brings people to realize there is a problem. 30 amps through 1/10th ohm resistance will cause a voltage loss of just 3 volts, and the power dissipation (heat) at the point of resistance will be 90 watts! You can solder wires with just 25 or 30 watts.

On the boat I mention, the wire inside from the inlet got hot enough more than a foot away where it was attached to ignite the fiberglass, which just barely smoldered along upward until it found some wood fuel. The cord was unplugged and the boat went out fishing with 6 aboard, and several hours later as they were coming back and almost to the slip fire was discovered. They happened to be right in front of the harbor patrol station - and the fuel dock on the other side - response was quick! But they had just earlier been several miles up the coast and would have indeed been in peril.

Shore cords have to be the most neglected thing in the boating world overall. Somebody should take the bright idea to make dead-front caps for the female ends, what a difference that would make as so many of them are just unplugged and dropped on the dock when the boat goes out. For stored 30A cords Marinco has a collar that fastens and seals a male/female connection.

Get silicone dielectric grease for electrical connections, don't use regular grease - it does not spread thin like silicone, and it will dry and buildup residue. Spray silicone lube is good. Note that nothing you spray or wipe on is going to do any cleaning of the terminals.

Connectors spread the high resistance disease, it's the V.D. of the dock. A bad plug or socket will cause arcing and heating and transfer contaminants to a good one. So, examine your dockside receptacle and if it shows any sign of heating, ask the marina to replace it if/when you replace your cord or dock end.

It is a mystery to me why, but the Neutral - the grounded current carrying conductor, always corrodes first and worst in the same conditions, you will always find the white wire terminal the one that's burned. In DC systems it is the same with the negative side of the circuit.

[Tellie]

Originally Posted by becrux

I read every single post and NOT ONE mentioned the necessity of a drip loop at the boat end. Especially if the cord runs across the coach roof and then down to the connector, it MUST drop below the level of the connector and then come up again to plug in. Otherwise there is a straight line path for water from the coach roof to run into the plug. This can happen very easily with a slightly worn connector, or if the screw on attachment is only slightly loose.
It is not even necessary that the AC system on the boat be energized - only the pedestal. If water (doesn't have to be salt water) causes a short between the hot and the ground or neutral, your boat could be toast.

To be fair, thinwater said to keep the connection out of the weather.
I think a drip loop is still a necessity.

Ahh, a drip loop. Absolutely a great idea.

[valhalla360]

Originally Posted by Brewgyver

Hmmm, by that standard, the vast majority of aALL sailboats are poorly constructed?

Agreed, most manufacturers use the cheapest option available.

[valhalla360]

Originally Posted by billcrowley

…or, do what I did: added 180 watts of solar panels and an appropriate controller to my boat (1980 Newport 30) when I got it 6 years ago, and have never used the shore power cord - in fact, it is at home. This system has adequately operated my electrical needs flawlessly for all that time; storage is in two Group 24 deep cycle lead-acid batteries. I have a 1,000 watt inverter installed for my occasional 120 volt AC needs (mainly power tools and a small heater), and have never used the 40-year-old AC system on the boat.

If 180w of solar is sufficient for your needs, you are highly unlikely to ever burn up a 30amp cord in the first place.

[rwidman]

1) Making a drip loop when connecting the cable to the boat is a very good idea. A drip loop s simply a downward loop in the cable before the connector so any water that runs down the cable falls off the loop and doesn't continue to the plug.

2) Something that I haven't seen mentioned is strain relief. I secure my shorepower cord to a railing with a Velcro strap to take any weight off the connection and to protect against any strain from the cord moving.

3) Someone mentioned "Green Grease" for protecting the contacts from corrosion. I have never heard of "Green Grease", but if you are going to use any product on the contacts, it is vitally important that it does not conduct electricity. This would be "dielectric grease", ("dielectric" means, non conductive). If you smear a conductive grease on the plug or socket, you will have current flow between the pins and that is not what you want.

When you apply dielectric grease to a plug and socket connection, the act of plugging the plugging the pins into the sockets wipes the grease from the actual contact surfaces while leaving it everywhere else and protecting the contact surfaces from air and corrosion.

[steveinusa]

Electrical connections like to have as much surface contact area as possible. I'd replace both of the connecting pieces that are mating together as it appears one or both of them aren't seating very well together.

[pesarsten]

Since it appears that you have 2 damaged shore power cords, it may be a great opportunity to make an investment in safety.

Cut the damaged female ( boat side ) ends off of the cords. purchase the SmartPlug plug and socket . install the new female smartplug on one cord, and the new new Smartplug recepticle in your boat. Then replace the other damaged cord end with a new 30 amp twist lock recepticle.
safer plugs and sockets on the boat side and a handy shore power extension cord for those times when your cord wont reach.

[goboatingnow]

Having just replaced two marinco shore power plugs due to arcing in the live contact ( these are 230Vac rated ) I’ve come to the conclusion that these twist lock style shore power units are quite frankly “ junk “. For a euro boat they remain common but a cursory examination of a few shore leads finds many have evident of arcing

In my opinion they are not fit for purpose IEC60309 shore power interconnects are far more durable , with significantly more contact area and never seen to suffer this issue.

[boatpoker]

Our two 30amp cords are hard wired, thats six fewer conections to worry about.

They lead to a locker in the pilot house where we pull them in from the inside.

[noelex 77]

Originally Posted by boatpoker

Our two 30amp cords are hard wired, thats six fewer conections to worry about.

They lead to a locker in the pilot hose where we pull them in from the inside.

I am surprised this solution is not used more often.

Originally Posted by goboatingnow

In my opinion they are not fit for purpose IEC60309 shore power interconnects are far more durable , with significantly more contact area and never seen to suffer this issue.

The IEC60309 are technically excellent and also very inexpensive.

These two above ideas can be combined.

A socket that is hard wired but connected to cable can be easily periodically replaced before any corrosion can occur. The low cost and ready availability of IEC60309 sockets combined with the easy wiring of socket to a cable makes this practical.

[Lake-Effect]

I wonder how many shorepower connectors get arc'ed and damaged because people connect or disconnect them without first ensuring that their boat's AC master breaker is off.

[boatpoker]

Originally Posted by Lake-Effect

I wonder how many shorepower connectors get arc'ed and damaged because people connect or disconnect them without first ensuring that their boat's AC master breaker is off.

We see that often. It also sends chargers and inverters into fits as the connections are wiggled loose.

[goboatingnow]

Originally Posted by Lake-Effect

I wonder how many shorepower connectors get arc'ed and damaged because people connect or disconnect them without first ensuring that their boat's AC master breaker is off.

Proper connectors don’t care. The Marinco connector has a poor mating area and in my opinion is a disaster , the arcing I’ve seen took place over a period of months and burned out the live contact

[MarkSF]

The second time my connector burned out at the boat side, I got the Smart Plug. Never looked back. The design is so much better in every possible way.