Out with the Old . . . In with the New ?

[ronbrown]

Has anyone installed the new Smart Plug that replaces the conventional shore power 30 amp plug on your boat? I purchased one (socket & plug) at the boat show">Annapolis Boat Show and was wondering if anyone out there is using it and how do they like it? Installation was fairly easy and I didn't burn the boat to the waterline. RB

[delmarrey]

It's not the boat end I worry about but the shore end that usually needs maintenance. So it's the marinas that need to update, or at least up keep.

[ronbrown]

Well I guess I'm guilty. I really did not mean to promote the plug but was wondering if anyone else has used this and what issues good or bad have they had. Any way I am new to this (posting and such) and will do better in the future.

[osirissail]

What exactly is the "Smart Plug?" Looking at their website, it only shows a different system of connecting the shore power cord to your boat's shore power receptacle. It also seems to use "straight" prongs versus the "twist lock" style prongs.
- - First off, burned out receptacles are due to salt air/moisture facilitating the "arcing" between your cord and the dock receptacle. Same with the boat side. This "arcing" is what makes the "black" burned look. This happens two ways - first the power is not turned off when the plugs are connected to the receptacle - which is very common. And then the age of the receptacle and frequent connects and disconnects and lots of wiggling has spread apart the blades inside the receptacle so that arcing is possible even when properly connected.
- - The twisting plug is designed to keep the plug/receptacle connected when something or somebody disturbs the power cord. On your boat end the ship's shore power connector, not only is it a twist lock but also it has a threaded ring on the "plug covering" to "screw" the whole assembly to the boat. If you don't do this then wiggling and arcing is a strong possibility.
- - I noticed on the website that the "Smart Plug" is only on the boat end of the shore power cord. The dock end is still the normal twist lock. This brings up the legal and insurance problems of changing an "approved" electrical connection to a "not-approved" system. Most assuredly your insurance would be invalid if your boat was damaged due to shore power malfunction.
- - Finally, you can go a long way to eliminating the arcing problem on both ends of the shore power cord if you use "dielectric silicon" compound. West Marine sells it -
ANCOR MARINE Ancor at West Marine
in tiny tubes and you can buy it in normal electrical supply houses in large tubes for less than West Marine's price. You smear the dielectric silicon on the plugs prongs and also squeeze it into the receptacle prong holes. Or put excess on the plug prongs and insert and remove the plug several times.
- - What the dielectric silicon does is to keep sea air from getting to the metal prongs and blades inside the plugs/receptacles so that any arcing is considerably reduced or eliminated.
- - Marinas, especially older ones, do not replace burned out old receptacles until enough boaters bitch and get on their case. They don't even want to buy replacement current style receptacles - I don't think they will buy more expensive "Smart Plug" systems even when/if they are "approved." Then there is the compatibility factor with older boats.
- - So the "Smart Plug" does not look like even a "good idea" but instead is a scam to relieve you of your money when all you need to do is to properly connect and protect the shore power plug/receptacle system you already have.

[GordMay]

Greetings and welcome aboard the CF, Ron.

I recall one of our (many) expert CF members extolling the SmartPlug’s virtues. They look, to me, like a decent product; but I don’t see marinas adopting them anytime soon. This means they’re only practical on the boat side.
➥ SmartPlug Systems - Shore Power Products and Accessories

[rebel heart]

I'd have a hard time spending that much money on something (shore power) that I don't like anyway. I'd rather put my effort towards making my own juice. You can cut out a lot of stray current problems, corrossion, and fire hazard.

But if it works for you and you dig shore power, go for it.

[CharlieJ]

Full Disclosure-I am a SmartPlug Dealer. Now some facts.

It's not the boat end I worry about but the shore end that usually needs maintenance.

As a working marine electrician, this has not been my experience. I replace 6 to 10 30 amp boat ends of cable assemblies a year. The reason is fairly interesting: The cable and receptacles depend on the twisting to ensure engagement of the land area on the blades and with the dimples engaging with the holes in the blades. Failure results when there is not adequate engagement and the dimples are contacting the blade resulting in a point contact which is a high resistance connection. This cause heat which causes the obvious problems without tripping any circuit breakers.

t also seems to use "straight" prongs versus the "twist lock" style prongs.

"Seems to use straight prongs..." Of course, that is the whole basis of the design. The straight, larger dimensioned prongs fully engage the female receptacles without depending on twisting/locking action. The locking of the male to the female is accomplished with two methods:
1. Two heavy, spring loaded tabs on the side of the cable end positively engage the female receptacle.
2. The receptacle cap is snapped down on the cable end and ears on the cap and plug engage detents on the opposite member.
As a result of these locking actions, there is no relative motion between the plug and the receptacle.

First off, burned out receptacles are due to salt air/moisture facilitating the "arcing" between your cord and the dock receptacle.

This may be a secondary or tertiary cause. In my experience, the main cause is point contact causing high resistance.

And then the age of the receptacle and frequent connects and disconnects and lots of wiggling has spread apart the blades inside the receptacle so that arcing is possible even when properly connected.

You are absolutely right concerning the aging and relative motion being culprits in this whole scenario. However, arcing, in my experience, is not a big player.

The twisting plug is designed to keep the plug/receptacle connected when something or somebody disturbs the power cord. On your boat end the ship's shore power connector, not only is it a twist lock but also it has a threaded ring on the "plug covering" to "screw" the whole assembly to the boat. If you don't do this then wiggling and arcing is a strong possibility.

Again, almost absolutely correct! The locking ring is critical to keeping the relative motion of the assembly under control. Unfortunately, there are a very large number of vessels on the waterfront that are missing the locking rings. And you know my views on arcing as a failure mode....

I noticed on the website that the "Smart Plug" is only on the boat end of the shore power cord. The dock end is still the normal twist lock.

SmartPlug is available for both ends of the shore power cord. However, most of the failures that I see are on the boat end...and that is the part that burns. The availability of the improved system allows the boat owner to control what he can control.

This brings up the legal and insurance problems of changing an "approved" electrical connection to a "not-approved" system. Most assuredly your insurance would be invalid if your boat was damaged due to shore power malfunction.

You are absolutely wrong on this point. The SmartPlug meets the requirements of the ABYC Standards and is, thus, "approved".

So the "Smart Plug" does not look like even a "good idea" but instead is a scam to relieve you of your money when all you need to do is to properly connect and protect the shore power plug/receptacle system you already have.

This is pretty inflammatory and unprofessional. There were several years of on-shore engineering, prototyping and tooling to develop what I certainly believe is a superior product. To deride it as a "scam" is pretty darn poor and something I would not expect from somebody who has posted so often.

Finally, and to reiterate, the failure mode is not from arcing but from loss of contact surface area between the male and female components that can degrade to the point of a point contact.

Hope this clarifies the issues.
Charlie

[GordMay]

I agree that the SmartPlug may be an improved shore power connector, and also agree with most of Charlie’s specific comments.
However and notwithstanding Charlie’s undoubted experience, I believe arcing to be either a proximate cause, or contributing factor (which came first, the arc or the hi resistance connection - chicken & egg), of most twist-lock connector failures.
I also question wjhether “most of the failures ... are on the boat end ...”
In my experience, many, if not most, failures are on the shore side.
I agree with Charlie that: “The locking ring is critical to keeping the relative motion of the assembly under control.”; but would note that the absence of these locking rings might equate to the absence of the “ Two heavy, spring loaded tabs on the side” of the Smart Plug.

I might also assume that Charlie became a dealer after becoming convinced of the SmartPlug's superiority.

[osirissail]

You are right, the "SmartPlug" is UL and UL Marina by the IMMNNA Labs. The website makes no obvious mention of this until you download their brochure. They should put that certification information in a prominent part of the website.
- - However, there is difference in our definitions about arcing. Your "point contact" when the plug and receptacle are not properly full locked results, as you say, in too much current through too little contact surface - which considering that I have and can hear the "sizzling" inside the receptacle causes me to describe the process as arcing. This process in the presence of sodium chloride laden moisture accelerates the vaporization of the blades. The end result is the same, burnt away blades inside the receptacle and blackened holes as shown in the webpage example.
- - My use of the word "scam" is not appropriate given that the units are UL and UL marine certified.
- - What's with the "twice the price" of the standard 30 amp boat side connector/receptacle? I would thing "SmartPlug" would want to be competitive?
- - But "Smartplug" is relying on exterior locking tabs instead of interior locking via the twist lock system. Just like the problem you cited of the attachment rings missing from the boatside connector, what, or better yet, how long will those exterior spring tabs function in the marine environment?
- - What metal are the spring tabs made of? Are they using an actual spring or are they using "flex" to perform the "locking" mechanism? Can't they fail just as easily as the "lost" threaded ring? And if they stop functioning what is to keep the plug/receptacle together? Yes, the cover is supposed to provide an additional locking function, but can the cover only, suffice? As we all know any plastic cover/holder exposed to the Sun's UV will dry, crack and split rendering the external locking function unusable.
- - Also there does not appear to be any "weather-proofing" of the plug/receptacle when in use. If the unit was round then maybe an O-ring system could keep spray and rain from getting to the blades. The standard ship's plug has a rubber seal system, at least on my boat, to keep rain and spray out. Others have the locking ring.
- - I would submit that most of the failures are at the dock box and not at the boat end. I and many other cruisers take great care of our equipment and electrical systems. The folks who do not care or take care are the marina owners with burnt out receptacles, receptacles with no weather cover, and fried circuit breakers. And if you look inside the dock boxes you will - as an electrician - recoil with horror at the rat's nest of improperly sized and twisted and taped together wire junctions and wires not even connected to the ground terminal in the older marinas. I have personally seen a boat plug a 30 amp connector to a dock box receptacle, turn on his air conditioner and the dock box bursts into flames. That is real life in the 3rd world and in out of the way small and old marinas everywhere.
- - So the "SmartPlug" may be a better and more expensive "mousetrap" but it will be a very long time before it replaces the old fashioned thumb catching mousetrap which works just fine - if used properly.
- - Nothing personal, just whenever a new, better "thing" arrives there are always some unforeseen aspects that take awhile to surface and get worked on to make an even better product.

[CharlieJ]

I might also assume that Charlie became a dealer after becoming convinced of the SmartPlug's superiority.

Gord-You are correct...I would not represent them otherwise.

- - However, there is difference in our definitions about arcing. Your "point contact" when the plug and receptacle are not properly full locked results, as you say, in too much current through too little contact surface - which considering that I have and can hear the "sizzling" inside the receptacle causes me to describe the process as arcing. This process in the presence of sodium chloride laden moisture accelerates the vaporization of the blades. The end result is the same, burnt away blades inside the receptacle and blackened holes as shown in the webpage example.

The arcing is an effect, not the cause unless the female leafs have lost so much of their spring force that there is a gap.

- - What's with the "twice the price" of the standard 30 amp boat side connector/receptacle? I would thing "SmartPlug" would want to be competitive?

I do not where you got your facts but...the West Marine website shows a stainless boat inlet (147421) for $100; a locking boot (2041689) for $24 and the female cable end (1873926) for $40 for a grand total of $164. The West Marine website shows the SmartPlug conversion kit (boat inlet and cable end; 11697034) for $200. More expensive but not twice as much as you allege.

- - But "Smartplug" is relying on exterior locking tabs instead of interior locking via the twist lock system. Just like the problem you cited of the attachment rings missing from the boatside connector, what, or better yet, how long will those exterior spring tabs function in the marine environment?

The exterior locks are spring loaded with real springs, are 2 3/4 inches long, 3/4 inch wide and about 1/8 inch thick. They are stainless steel and substantial. The ends engage slots in the boat inlet.

- - What metal are the spring tabs made of? Are they using an actual spring or are they using "flex" to perform the "locking" mechanism? Can't they fail just as easily as the "lost" threaded ring?

See the description of the locks above. No they cannot fail in the same mode as the lost locking ring as the lost, plastic ring is generally "lost" when the cable end is dropped on a deck or dock and it breaks.

And if they stop functioning what is to keep the plug/receptacle together? Yes, the cover is supposed to provide an additional locking function, but can the cover only, suffice?

The cover DOES provide TWO additional locks as described in my earlier post. If one were to pry the locks off of the cable end, the cover would, with its two locking slots/tabs, keep the assembly together.

As we all know any plastic cover/holder exposed to the Sun's UV will dry, crack and split rendering the external locking function unusable.

Hard to make this jump as the cover has a stainless tab and a stainless slot to mate with the tab on the cable end and a slot on the cable end. When in service, these portions of the cable end are shielded from UV by the stainless steel cover.

- - Also there does not appear to be any "weather-proofing" of the plug/receptacle when in use. If the unit was round then maybe an O-ring system could keep spray and rain from getting to the blades. The standard ship's plug has a rubber seal system, at least on my boat, to keep rain and spray out. Others have the locking ring.

There is a lip seal inside the hooded section of the cable end that engages with the seating surface of the boat inlet providing a weather proof seal. There is also a lip seal on the inside of the cover to keep the boat inlet dry when the cable is not installed.

- - So the "SmartPlug" may be a better and more expensive "mousetrap" but it will be a very long time before it replaces the old fashioned thumb catching mousetrap which works just fine - if used properly.

And I submit that the existing system does not work properly.

- - I would submit that most of the failures are at the dock box and not at the boat end. I and many other cruisers take great care of our equipment and electrical systems. The folks who do not care or take care are the marina owners with burnt out receptacles, receptacles with no weather cover, and fried circuit breakers.

My experience has been different as evidenced by the number of cable ends that I regularly replace.

And if you look inside the dock boxes you will - as an electrician - recoil with horror at the rat's nest of improperly sized and twisted and taped together wire junctions and wires not even connected to the ground terminal in the older marinas.

I know, I know.

That is real life in the 3rd world and in out of the way small and old marinas everywhere.

"...real life..." Got the T shirt.



By the way, the standard 30 amp twist lock shore power fitting is rated for 23 amps continuous duty. A little known fact.

Hope this helps clear the air.

[osirissail]

And all of the above great information should be included in the SmartPlug website or literature as the available descriptions are woefully short on good technical information such as you have graciously supplied.

[ronbrown]

One of the Smart Plug's virtues has not been discussed and that is the built in circuit breaker that thermally (at 200 degrees) trips before the arcing or resistance causes the fire and then resets itself (at 130 degrees). Most of my experience has been burning at the boat plug vs the power tree. I have never had this happen to my boat (arcing or burning) but the positive 4-way locking would eliminate this condition. Also my wife & daughter can easily use the plug (day or night) with out being shone how. I was always worried whether they fastened it correctly. I think the virtues (safety & simplicity) far outweigh the cost.

[Intentional Drifter]

I am not an electrician so I can't knowledgeably debate the electrical properties of the Smart Plug. I saw one of the reviews and since their office is only a few blocks from Shilshole, I decided to stop in. I was very impressed, both with the people and the product. They seem to be a serious bunch and are able to logically review, in great detail, the qualities of the system discussed above.

One of the things that hasn't been mentioned above is that the current "standard" 30 amp plug configuration was originally designed in 1930's and wasn't done with marine applications necessarily in mind. It has since been dominated by two companies - Hubbell and Marinco. Now, I am definitely not inferring any malfeasance or other improper behavior toward either of them. I imagine that both of them have acted according to what they thought was best, but they are also both major players and have a financial interest in keeping the current standard, since they make their products according to it. So, I find the argument that since the Smart Plug does not conform to the competitors' standard, then it must not be according to Hoyle, to be a problem. Smart Plug would say that they surpass the standard.

Frankly, after seeing (and holding) their product and talking with them, I agree. I bought one and installed it. The system is very easy to install (took about 30 minutes, total) and goes according to their directions.

I have no doubt, whatsoever, that after living aboard and cruising for a couple of years, dealing with the "standard" many, many times, that the Smart Plug is definitely superior. The attachments are far more watertight. The plugs have much more contact area. The plug is far easier to properly insert. The connections are much tighter.

I like it, a lot. And, no, I have no financial, family, or social relationship with the company of any kind. Just a happy customer.

By the way, there is a very nice write up in "Seaworthy" (the BoatUS magazine dedicated to safety, and a very nice one, too) on shore power issues. They did a sidebar on the SmartPlug in that, which is one of the items that caught my attention.

See: http://www.boatus.com/seaworthy/magazine/SeaJul10.pdf

ID

[ValiantV]

I see this is an older post, but was curious if there were any new opinions or updates in the last 10 years.

As someone who has worked on automotive electrical systems professionally, and home AC systems as a D-I-Yer for decades, I have seen, experienced and repaired FAR too many melted electrical connections that all failed due to the heating associated with high-resistance connections. All the result of various causes from poor initial design or construction, to age and abuse, or water/corrosion. Getting a large enough, CLEAN, metal-to-metal connection always solves the problem.

That said, the dodgy shore power connections at both ends of the cable give me nightmares, and the "SmartPlug" looks like a great way to fix at least ONE of those points of failure.

I've been reading reviews on Amazon and have found a handful of negative ones that seem to center on something being brittle and breaking easily - though I can't tell if they're talking about the plug or receptical. One reviewer claims he talked to the factory (2014 I believe) and that a fix was in the works.

Bottom line: what's the latest on the SmartPlug out here in the real-world?

BTW, as far as the other end of the cord goes, I plan to replace the pedestal receptical with a new, name-brand, specification-grade one so at least the past 20 year's wear, age, and abuse by ham-handed boaters won't be an issue.