shore power cord problems

[dhays]

Oh dear. Now, an electrical novice like myself has to choose between dielectric grease and conductive grease? It reminds me of my sailboat days, when I had to choose between a dozen different ideas of what was the "proper" way to establish the ground plane for my new single sideband radio.

A conductive grease will work fine, but I like to apply a lot of the grease to eliminate water intrusion. With a conductive grease you have be very careful, as tadhana said, to make sure that the grease is completely inside the plug slots or you can have a short.

A conductive grease increases the contact area for the plug. That is a good thing and it also prevents water intrusion. There are places where a conductive grease would be superior to a dielectric grease, such as bus bars or battery terminals. However, I wouldn't personally be comfortable using it in any place where there is both a positive and negative or ground connection in close proximity.

Marinco recommends dielectric grease for its plugs for what its worth.

I can find all kinds of ways to screw things up. For me, keeping just a can of dielectric grease on the boat and using it liberally is easy and simple.

 

[dhays]

Just use Boeshield or something like it and rest easy.

I'm curious when Boeshield became generally available and popular. I remember as a kid that my Dad would score some cans of it from his patients that worked for Boeing, I think before it became widely available back in the '70s I think.

Great stuff and I have a can of it in the same zip lock bag that has my can of dielectric grease.

 

[Capt.Bill11]

I'm curious when Boeshield became generally available and popular. I remember as a kid that my Dad would score some cans of it from his patients that worked for Boeing, I think before it became widely available back in the '70s I think.

Not sure when it became generally available.

But I've been buying and using it for decades now.

 

[Phil Fill]

I don't understand the theory behind this. If you have a 30 amp breaker next to the shore power outlet, and then another 30 amp breaker a few feet away on the main panel, it would seem kind of redundant to me. Why do the newer boats have both?

Older boats have breakers after the main panel power selector switch which does not protect the switch and or the power socket and cord. So new boats have breakers before and after. Our old power cord was 15+ years old, and was protect with the addition breaker. The plug ends where still in good shape but to be safe replaced the cord. The breaker at the dock power plug protects the dock end, and the reason very seldom that end is damaged. Its a requirement on all US sold boats. Redundancy is good.

Being the boat wiring is old we have breaker on all power out let's and high amp heaters. Figured when installing GFI required out let's might as well do them all. You can buy plug in GFI protectors at most hard ware stores.

 

[seattleboatguy]

Don't use either.

Why would you use one grease that could inhibit conductivity or one that can cause a short because is so conductve?

Just use Boeshield or something like it and rest easy.

You know, I think I have some of that stuff. I used to use it on the stanchions when I had my sailboat. I'll dig it out of my storage locker and give it a try.

 

[seattleboatguy]

Older boats have breakers after the main panel power selector switch which does not protect the switch and or the power socket and cord...

Good explanation. Thanks.

 

[River Rat]

Why don't the pedestals have the locking ring threads?

 

[koliver]

Check with your insurer. They may have a rebate program for an upgrade to Smart Plug at the boat/power inlet end. In my case the insurer sent me a cheque for $150 when I sent them a photo of my new installation.

 

[dhays]

Why don't the pedestals have the locking ring threads?

That is a great question! It really annoys me, particularly on transient docks, when the receptacle is so worn that the plug almost falls out.

 

[FF]

There is an ancient 120V 50A plug and socket style that would work.

My guess is the dock CB will pass more than 30A for long enough to melt the 30A.

Simplest would be a 240V 50A inlet fitting and plug on your 30A power hose.

With only one leg hooked up , carries 50A easily.

These would be robust enough and the dock CB would still protect the power hose and the boats CB would protect the boat.

 

[Capt.Bill11]

That is a great question! It really annoys me, particularly on transient docks, when the receptacle is so worn that the plug almost falls out.

You can at least keep a line attached to the dock end of the cord so you can tie it in place and take the strain off it.

 

[Bacchus]

Here is some interesting reading for you on this subject...
Rod is a very bright guy.
Bruce

Shore Power Cords - SmartPlug vs. 1938 Photo Gallery by Compass Marine How To at pbase.com

And he does a great job of documentation and presentation.
Best write up of plug deficiencies that I've seen

 

[tadhana]

These melted hull inlets are not melting due to high amperage, they are melting due to high resistance.The circuit breakers cannot react to this resistance problem. The electrical connections themselves get corroded or burned through use and abuse. This damage to the metal electrical tabs and socket connections makes for resistance. This resistance leads to increased heat, even though the socket burns the current flowing is less than 30 amps so the breaker will not trip. . Your can melt a 30 amp inlet at less than 15 amp current flow.

 

[dhays]

You can at least keep a line attached to the dock end of the cord so you can tie it in place and take the strain off it.

Yeah, I always did that with the 30amp plugs. My current 50/120 plug is nice and tight.

 

[Capt.Bill11]

These melted hull inlets are not melting due to high amperage, they are melting due to high resistance.The circuit breakers cannot react to this resistance problem. The electrical connections themselves get corroded or burned through use and abuse. This damage to the metal electrical tabs and socket connections makes for resistance. This resistance leads to increased heat, even though the socket burns the current flowing is less than 30 amps so the breaker will not trip. . Your can melt a 30 amp inlet at less than 15 amp current flow.

This is true to a point. But if the load goes high and the contacts are going bad you get the same result.

 

[Capt.Bill11]

Yeah, I always did that with the 30amp plugs. My current 50/120 plug is nice and tight.

Nice and tight is a good thing.

And yes, I know there's a joke there.

 

[Xsbank]

With 30 amps, 2 loads such as a toaster and a water heater or battery charger will put the cord at its limit. Add lighting, stereo or a galley fan and the load is exceeded. If you plug your digital meter into a power outlet and you get less than 110 volts (ideally nothing lower than with no load) you are exceeding the cord's capacity and it will overheat and melt.

The contact you want is metal-to-metal, using dielectric grease will not impede that and will keep all moisture out of the connection. Using Conducting grease with a power cable is asking for an electrocution, damn dangerous!

 

[tinped]

Coming from the marine commercial end as an electrician,we used coppershield on all exposed metal contact points.Comes with brush in can,easy to apply.Coat the male pins very lightly,not the female side.Dielectric grease is Not meant for movable parts,rather to insulate a permanent splice.You are being mislead about using dielectric grease.

 

[tadhana]

Using Conducting grease with a power cable is asking for an electrocution, damn dangerous![/QUOTE]

Ok I am always ready to learn. Can someone help me understand why using conductive paste sparingly on the contacts is dangerous and asking for an electrocution?

Thank you.

 

[rwidman]

How often do you apply this grease?

Whenever I think about it. That's the truth. Probably every month or so but more often if you are moving your boat and connecting and disconnecting the cord.

 

[tinped]

Again,if someone uses the product properly,there is no increased risk.Coppershield is a very thick paste,that does not thin or run,the key is a very thin layer.Used it extensively on the SI ferries for ten years almost daily on thousands of motor contacts,and never saw it run.Was approved for that use by the uscg.The idea behind the conductive paste was to fill in the non mated surfaces to increase the amount of conductor area.No contact point system,regardless of what any one tells you is perfect,even brand new.We used to put carbon paper between all contact points,to locate the high spots,then redress the points with emery paper.

 

[rwidman]

Have found that this problem is caused by using to many heavy amp devices,a/c and water heater on one circuit. Would replace both ends and try to regulate your loads so you don't draw too many amps. The ground wire cannot take the load of two heavy devices. Since watching my loads I have had no problems since.

Unless there's a fault, no current flows in the ground wire.

 

[rwidman]

Newer boats have a breaker right after next to the boats shore power out let between the out let and the main panel selector switch to protect the cord and out let. Older boats do not have the breaker. We updated our electrical with a smart plug for addition safety.

Not necessarily. Yours might. Most do not. There must be a breaker within ten feet (measured along the length of the wire) of the inlet. If the main panel breaker is within ten feet of the inlet, no additional breaker is required.

 

[rwidman]

Dielectric grease is an insulator, non-conductive... Yes, it will keep air out of the joint but won't pass electricity. Better choice would be a conductive grease.

Nope, a conductive grease would increase the chance of arcing and could lead to a direct short. Read my explanation of how dielectric grease works on electrical connections in my original response. Dielectric grease is the standard protection for situations like this.

 

[tinped]

Can we please put this dielectric grease issue to bed.The following is from Wikipedia.Pay particular attention to the last paragraph,and then refer to my original post concerning mating surfaces of contact points.



ric grease[edit]

Dielectric grease is electrically insulating and does not break down when high voltage is applied. It is often applied to electrical connectors, particularly those containing rubber gaskets, as a means of lubricating and sealing rubber portions of the connector without arcing.
A common use of dielectric grease is in high-voltage connections associated with gasoline engine spark plugs. The grease is applied to the rubber boot of the plug wire. This helps the rubber boot slide onto the ceramic insulator of the plug. The grease also acts to seal the rubber boot, while at the same time preventing the rubber from becoming stuck to the ceramic. Generally, spark plugs are located in areas of high temperature and the grease is formulated to withstand the temperature range expected. It can be applied to the actual contact as well, because the contact pressure is sufficient to penetrate the grease film. Doing so on such high pressure contact surfaces between different metals has the advantage of sealing the contact area against electrolytes that might cause rapid deterioration from galvanic corrosion.
Another common use of dielectric grease is on the rubber mating surfaces or gaskets of multi-pin electrical connectors used in automotive and marine engines. The grease again acts as a lubricant and a sealant on the nonconductive mating surfaces of the connector. It is not recommended to be applied to the actual electrical conductive contacts of the connector because it could interfere with the electrical signals passing through the connector in cases where the contact pressure is very low. Products designed as electronic connector lubricants, on the other hand, should be applied to such connector contacts and can dramatically extend their useful life. Polyphenyl Ether, rather than silicone grease, is the active ingredient in some such connector lubricants.
Silicone grease should not be applied to (or next to) any switch contact that might experience arcing, as silicone can convert to silicon-carbide under arcing conditions, and accumulation of the silicon-carbide can cause the contacts to prematurely fail. (British Telecom had this problem in the 1970s when silicone Symel® sleeving was used in telephone exchanges. Vapor from the sleeving migrated to relay contacts and the resultant silicon-carbide caused intermittent connection.)

 

[dhays]

Wikipedia not withstanding, Marinco specifically mentions using it on their shore power plugs as a way to help prevent oxidation on the plugs. Since they actually manufacture the plugs, I assume they probably have good reasons for recommending it.

I do appreciate the additional information you have provided. It gives me more to consider.

 

[tinped]

yes,they do recommend it,but nowhere do they advise applying it directly to the electrical contacts.It is designed to seal out moisture(usually rubber gaskets)to help prevent corrosion.And by the way,loved your input on the sunglasses.

 

[seattleboatguy]

Coming from the marine commercial end as an electrician,we used coppershield on all exposed metal contact points.Comes with brush in can,easy to apply.Coat the male pins very lightly,not the female side.Dielectric grease is Not meant for movable parts,rather to insulate a permanent splice.You are being mislead about using dielectric grease.

Where do you buy this stuff? I didn't see it at West Marine, Defender, or Home Depot.

 

[tinped]

Any electrical supply will carry it.Just remember,the male part of the plug only,and as thin of a layer as possible.Also,wear gloves,this stuff is really hard to remove,and will not come out of clothes.

 

[tinped]

It is widely used in the commercial/industrial field,that is why you are unlikely to find in a recreational boating store.