Pin and sleeve connectors for 30a shore power

[Jammer]

There have been substantial numbers of fires due to failure of twist-lock shore power connectors. Design wise, the connectors suffer from a small contact area, weak blades, and an ineffective primary locking mechanism.


Manufacturer "SmartPlug" offers a proprietary replacement that is relatively new to the market.


I would like to explore the idea that this is a solved problem. Industrial pin-and-sleeve connectors based on IEC 60309 have been in widespread use since about 1960. Larger versions are common for shore power service worldwide at 100 amps and above and for three phase service. The smaller 15/16a and 30/32a versions are in widespread use in Europe and the UK for dockside and RV (caravan) shore power connections, and for commercial, industrial, and food service equipment in wet areas.


For details, see: https://en.wikipedia.org/wiki/IEC_60309


Connectors and plugs are available at many price points; quality wise, you get what you pay for. But the contact area is much larger than that on twist locks, even on the less expensive devices, with better wiping action that tends to remove corrosion so it does not accumulate. The better ones are made with more use of high-temperature, fire-retardant resins.


I believe that the extensive installed base and field experience, including in marine environments, should provide greater confidence in these wiring devices than any newcomer to the market, no matter how well thought out on paper, should receive. They are also standards based and available from dozens of vendors worldwide rather than from a single source.



The 30 amp, 125v connector (pictured) is slightly larger than standard shore power connectors but will fit with minor modifications to the boat. I am thinking seriously about installing these on my boat during an upcoming power system upgrade.


Experiences? Thoughts?

[SailingHarmonie]

On most large yachts the boat side of the shore power cable is hardwired to the boat.

On my boat, the boat side of the shore power cable is hardwired to the electrical system inside the locker where the cable is stored, with a notch in the locker lid to feed out the cable while excluding weather. Has worked perfectly for 30 years.

I still have to replace those stupid twist lock plug on the shore side of the cable regularly, but not having a “fire starter” built into the side of my boat is just one less thing to worry about.

Completely eliminates the need for a supposedly waterproof fitting that has always been one of the real dangerous weak points in shore power systems.

[smac999]

the smart plug has been out at least 5 years. I'm not sure i'd call it new. lots of boats using them.

the "smart" part no longer exists. as they had to stop making it with the temp sensor. but the contacts are still better then a twist.

[Celestialsailor]

Well...I see it is not plated. I'm sure it is better than the twist locks but that brass is going to oxidize over time. BTW...You're a Mod now?

[s/v Jedi]

I like the IEC plugs. The US 110/240V 50A is okay as well, most of the problems are caused by the 120V 30A connectors and outlets.

The Smartplug is better than the IEC plugs. It has all the same advantages combined with bigger contact surfaces.

But of course I never saw a dock with those outlets. So for boats with a 120V 30A inlet I recommend to replace that with the compatible Smartplug, then use a shore power cable with several adapters for the shoreside. You can use the 120/240V 50A outlets which are good. I also used 240V on the blue 16A IEC outlets but of course you then need a transformer to make 120V out of that again.

[Jammer]

Originally Posted by Celestialsailor

Well...I see it is not plated. I'm sure it is better than the twist locks but that brass is going to oxidize over time.

You are correct that it is not plated. They have a "wiping" design, that is, the contacts slide against each other during connection and disconnection as a deliberate means of keeping them clean and polished. That, together with well-chosen alloy, should be good enough for typical use cases, particularly in combination with the watertight covers for both ends.


Plated contacts pose a number of tradeoffs. The most effective plating is gold as it is noncorrosive and an excellent conductor. It is cost effective low-current signal connections where the contact size is small, particularly for connectors that are cycled only once or a few times over their life which allows the plating to be extremely thin. With frequent use in high power applications it costs too much. Chrome and nickel are inexpensive but have higher resistance.

[Dockhead]

Originally Posted by s/v Jedi

I like the IEC plugs. The US 110/240V 50A is okay as well, most of the problems are caused by the 120V 30A connectors and outlets.

The Smartplug is better than the IEC plugs. It has all the same advantages combined with bigger contact surfaces.

But of course I never saw a dock with those outlets. So for boats with a 120V 30A inlet I recommend to replace that with the compatible Smartplug, then use a shore power cable with several adapters for the shoreside. You can use the 120/240V 50A outlets which are good. I also used 240V on the blue 16A IEC outlets but of course you then need a transformer to make 120V out of that again.

Agreed on all points!

The IEC connectors are incomparably better than the horrible Hubbell/Marinco twist connectors, which are totally unfit for purpose and should be illegal. The IEC connectors are cheap, reliable, easy to check, easy to install or replace. In this part of the world, that is what you normally get on the shore side (unless it's the odd Shucko socket), and I keep a bag of spare IEC connectors, both male and female, on board. I also have adapters to plug into two types of the red three phase ones for commercial or fishing ports (which I tend to use more often than leisure marinas).

We have these discussions regularly. I still say -- friends don't let friends use Hubbell connectors, at least not for the boat side connector. I can hardly believe they are still sold in this day and age.

Hard wiring the shore power cable is a great solution IF you can then store the cable in a reasonable way AND you have a good watertight way to get the cable into the boat.

Otherwise, I think the SmartPlug is the best solution, and it's the one which I implemented. The hardware is somewhat costly but it's much cheaper than replacing those dangerous Hubbell connectors every couple of years.

[Dockhead]

To the OP:


This is what you want:


https://smartplug.com/product/smartplug-inlet/





The IEC connectors are good, but they are not nearly as well waterproofed as these, and not nearly as robust.


The maker claims the SmartPlug has 32x more contact area than the Hubbell type. I believe it.

[Celestialsailor]

Originally Posted by Jammer

You are correct that it is not plated. They have a "wiping" design, that is, the contacts slide against each other during connection and disconnection as a deliberate means of keeping them clean and polished. That, together with well-chosen alloy, should be good enough for typical use cases, particularly in combination with the watertight covers for both ends.


Plated contacts pose a number of tradeoffs. The most effective plating is gold as it is noncorrosive and an excellent conductor. It is cost effective low-current signal connections where the contact size is small, particularly for connectors that are cycled only once or a few times over their life which allows the plating to be extremely thin. With frequent use in high power applications it costs too much. Chrome and nickel are inexpensive but have higher resistance.

Knowing the marine industry as I do, they are probably very pricey, like every other marine product. Having years of experience in manufacturing, I can almost guarantee this cord would be 5 times more expensive than a commercial cord in an Industrial setting. A few thousands of plating is not going to raise the price more than a fraction of a dollar. In all honesty, it's just another product made overseas who's bottom line is planned obsolescence in the case of an unplated one.
I do see some other ones on the market that are plated, so some of your statements do not apply.

[s/v Jedi]

Originally Posted by Celestialsailor

Knowing the marine industry as I do, they are probably very pricey, like every other marine product. Having years of experience in manufacturing, I can almost guarantee this cord would be 5 times more expensive than a commercial cord in an Industrial setting. A few thousands of plating is not going to raise the price more than a fraction of a dollar. In all honesty, it's just another product made overseas who's bottom line is planned obsolescence in the case of an unplated one.
I do see some other ones on the market that are plated, so some of your statements do not apply.

Wrong.
https://smartplug.com/smartplug-prou...de-in-the-usa/

[Celestialsailor]

Originally Posted by s/v Jedi

Wrong.
https://smartplug.com/smartplug-prou...de-in-the-usa/

Thank you for pointing that out in your not so subtle way. Still, the unplated one originally shown, I believe that may be problematic down the road. I will say the twist-locks are definitely problematic. Mostly do to the hap-hazard way people use them. Not only do the cord ends wear out but the dock receptacle does as well.

[s/v Jedi]

Originally Posted by Celestialsailor

Thank you for pointing that out in your not so subtle way. Still, the unplated one originally shown, I believe that may be problematic down the road. I will say the twist-locks are definitely problematic. Mostly do to the hap-hazard way people use them. Not only do the cord ends wear out but the dock receptacle does as well.

There’s lots of confusion in the thread… probably my fault too. I assumed you were talking about the SmartPlug being from China or similar and way expensive etc. It’s an American product also heavily used for RV’s etc.

But that picture of unplated contacts isn’t Smartplug but the European style plugs. Those work well but not better than Smartplug. They use Smartplug in Europe as well, I saw it just months ago in the Netherlands.
(https://www.bateaubootservice.nl/acc...or-16a-of-32a/)

[Celestialsailor]

I will agree that a solution should be found for the twist locks.

[thinwater]

The NEC says shore power connectors must meet UL 498M.

* Is this still correct?
* Do Smart Plug or pin connectors meet this?


My understanding is that ABYC and NEC only recognize the twist lock type, so that is what we are going to see on pedestals for the foreseeable future.


Is the problem the twist lock, or that they are 20-30 years old and poorly maintained? I'm also guessing ABYC and NEC are waiting to see about the failure history of Smart Plugs over 20-30 years. The population is still rather small and they are new.

[wholybee]

Originally Posted by thinwater

The NEC says shore power connectors must meet UL 498M.

* Is this still correct?
* Do Smart Plug or pin connectors meet this?


My understanding is that ABYC and NEC only recognize the twist lock type, so that is what we are going to see on pedestals for the foreseeable future.


Is the problem the twist lock, or that they are 20-30 years old and poorly maintained? I'm also guessing ABYC and NEC are waiting to see about the failure history of Smart Plugs over 20-30 years. The population is still rather small and they are new.

The issues with the twist lock are varied. The smartplug has more contact area. But the twist lock it doesn't need to have so little. The blades on a twist lock are plenty big, it's the design inside the receptacle that limits contact area. It could easily be improved with a redesign of just the socket. The concept of a twist lock is sound, and the blade profile doesn't need to change.

That said, the 30A twist lock is good for 30A continuous when new and installed correctly. But it doesn't hold up well to constant plugging in and unplugging, and the smaller contact area is reduced to almost nothing if you don't fully twist it, or if it becomes untwisted. Many people don't know the trick to twist the cable backwards (counterclockwise) so that as the cable tries to untwist it is locking itself in place.

Also, while we hear how dangerous they are, I would like to know how many failures were due to very old cables (20 year old cables are common) or user installed replacement plugs on a cable, that probably were not installed correctly to the old wire.

No doubt, the smartplug is better. But I think the failure rate of a newer, properly installed and maintained twist lock is actually rather low. Just my gut without any real data. I have personally seen a handful of boats burn at the dock, and all were no surprise, in terrible shape, with the owner doing their own shoddy work. I don't blame the twist lock as the reason for any of those fires, even if the receptacle is where it started. And smartplug isn't perfect either. There was an unfortunate sailor on here that lost his boat to a freshly (about 1 year iirc) installed smartplug.

One interesting anecdote. The Marin County fireboat at my marina uses a smartplug.