SmartPlug shore power system, has its time come?

Ben Ellison

Ben Ellison

Panbo editor, publisher & chief bottlewasher from 4/2005 until 8/2018, and now pleased to have Ben Stein as a very able publisher, webmaster, and editing colleague. Please don't regard him as an "expert"; he's getting quite old and thinks that "fadiddling fumble-putz" is a more accurate description.

43 Responses

  1. Ben Ellison Ben Ellison says:

    Incidentally, SmartPlug will purportedly soon have a line of 50 amp hardware. Also Bill at the Marine Installer’s Rant had quite the elaborate explanation about how loosening connectors — like a worn twist lock plug — create resistance and heat:

  2. Christopher says:

    Considering it took decades of house fires and deaths for the transition from floating, unpolarized two-prong to grounded, polarized three prong household connectors, I wonder how long it will take for this to gain traction. Much more persuasive and less commercially involved voices than ABYC and West Marine will be necessary.
    Perhaps getting the insurance companies to offer a discount or foot some portion of the transition cost could help. Then again they will quote stats that show well maintained and operated boats don’t have connector fires in numbers large enough to make the change an actuarily rational one.

  3. Ben,
    I agree the Smartplug is a no-brainer, and $200 is cheap insurance for something that is 10 times better than the design it replaces. What appalls me is how little regard folks seem to have for securing their connections using the existing style. The fact is that you can still get a reliable connection, IF you take the trouble to twist the connector tight, screw down the locking ring, and provide some type of strain relief for the cordset. Watching folks plug in their shiny new motor yacht like it was a lamp cord and walking blissfully away for the night makes me shake my head. The Smartplug is idiot-proof – something that is clearly needed in today’s boating environment.

  4. rxc says:

    Besides the temperature monitoring, does anyone have any idea why these plugs are better than the IEC 60309 connectors used in the EU? The IEC plugs are one of the few items that are much less expensive than the corresponding US items. I think I can buy a 32 amp connector here in France for around $7.00, compared to about $35 in the US. And they seem to work quite well in our wet climate.

  5. Ben Ellison Ben Ellison says:

    Obviously I think the temperature switch is a pretty big deal, as is the design’s large contact surface area, so hopefully a overheat situation doesn’t happen. But I don’t know anything about those EU connectors. This is one of the few references I can find to an IEC 60309 30 amp inlet, and it seems quite expensive:

  6. DougSea says:

    Hey Ben,
    A quick search for “Marine Shore Power Inlet UK” gave me this:
    They do look like an easier, more positive connection, but I’m sure they need the collar to lock.

  7. Peter says:

    Main concern of mine is the thermostat..something else to reliable is it and if it fails will it disable your shore power?
    For now I have not been inspired to change.
    I take apart my standard outlet every 2 years and re-torque the screws,make sure there is strain relief,and every so often give it a feel for temperature.(the back of my receptacle is easily accessible)As a live-aboard I am usually pulling 20 amps 24/7 over 10 years.The original S/S Marinco is still good.

  8. Matt Marsh says:

    “The fact is that you can still get a reliable connection, IF you take the trouble to….”
    And that’s exactly it. The old-style plugs are just fine if you use them properly. Trouble is, it’s possible to use them improperly- if they’re not locked, or not tight, or arcing a bit, they’ll still sort-of work for a while (until they melt/burn).
    I can’t figure out any way to use the SmartPlug improperly, short of dumping one end of the cable in the drink. You open the flap and shove it in. It either works perfectly or else it shuts itself off until you fix it.
    The only downsides I can see are that it’s darned pricey, and it’s another non-standard standard: see

  9. AaronH says:

    It’s brilliant. I have a clear bucket of burnt female cordset ends in my shop that always gets comments when people see it.
    However, although this is a great step forward, one problem this cannot solve is corrosion of the pins which also contributes to resistance and heat just like constant loosening from plug/unplug cycles and improperly secured cords. People still need to watch for it. I do think the tight locking mechanism will reduce the moisture getting into the connection.
    As for standards? If you carry a female (boatside) SmartPlug to male TwistLock 30a – you’re good to go (unless you lose/break your cord)! Although I’d love to see marina power posts change, because those get brunt pretty good as well.
    I’m not too worried about the thermostat, and see it as a crucial safety feature. I bet it’s similar to the thermostats built into recessed can lighting, and those are ubiquitous in the home nowadays and rarely, if ever, fail. They don’t have any moving parts, it’s just silicon on a chip.

  10. Ron Rogers says:

    I have had one since the catastrophic marina fire here in January. I never have a question asa to whether my inlet plug is firmly attached and it never gets warm. Because the shoreside connection is the insecure conventional 30 amp connector; I use black wire ties to secure it.
    The construction is excellent with sturdy blades considerably larger than conventional ones. The boat is always in motion and this secure connection and the LED is most reassuring. Flawless performance for a year now.
    The fire here started at an inlet and destroyed 52 boats – mostly in a covered shed outboard of me. The VFD stopped the fire 3 slips from me and they fought it for 10 hours. You do not want to experience this.

  11. Roger B says:

    I asked SmartPlug if they were planning a EU /UK product – their reply
    Yes we plan on having our product available for the European market soon. We need to obtain a CE mark which is estimated to occur in the next few months. If you’d like to check back with us on a monthly basis, I can have a hard date delivered for you in the next month or two.
    Best regards,
    Aaron Bronson
    Earth: 25% land, 75% race course
    Tel: 206.285.2990
    Fax: 206.285.2981
    [email protected]

  12. Ben Ellison Ben Ellison says:

    Thanks all for valuable comments, but how about my time-lapse video? It’s a first attempt and I’m wondering if it was useful and/or entertaining?

  13. Aaron Bronson says:

    After reading through all these fine comments, I can see that there are still some product questions still lingering through some people’s minds. I’d be more than happy to answer any questions you may have about the SmartPlug. I can be reached by email at; [email protected] or by phone at; (206)285-2990

  14. Bill Bishop says:

    Thanks Ben, here is an photo of a Marinco plug that slagged down, and if it hadn’t been caught early, would have resulted in the boat catching fire. A temperature sensor is a good idea, including the locking levers:

  15. Don Joyce says:

    The time lapse video is effective in demonstrating the ease of swapping out the old connector for the SmartPlug.
    What would be interesting is to see whether the cord component is just as easy to install.

  16. Ben Ellison Ben Ellison says:

    Thanks, Don. Tim Flanagan did a nice write-up about installing a SmartPlug on an existing cordset, though unfortunately the photos aren’t showing now (because they were on the now defunct MadMariner site):

  17. Kevin R says:

    I installed the Smartplug on our boat last year and like it. As for the ease of install, that was one of the main drivers for me. It was easy, and the company has videos, see
    showing both boat-side and cord-side installation. Very easy job.
    No affiliation with Smartplug other than satisfied customer.

  18. HNick says:

    We’ve been waiting sooooo long (like 3 years, it seems) for the 50 amp/240 version.
    Seems to be always “…in 6 months…”.

  19. HenryD says:

    Ben or Aaron,
    The 50amp plug set has been mentioned for over a year now?
    I was told it was soon to be released in the fall of 2010. I burnt a twist-lock last Christmas and wanted to install a 50-amp plug set then. I replaced my cord last winter when the plug was burnt and I have the old cord ready to put SmartPlug end on.

  20. Russ says:

    Ben: The time lapse was nice and could be significantly enhanced by a time stamp so that we could tell if the time lapse covered two hours or twenty minutes.
    I’ve used the euro standard IEC 60309 plugs and found them very easy to use, wiring them up to my shore power cord in a few minutes. They’ve proided a secure connecton and survived tropical rains. They may not have all the thermo protection of the Smart Plug, but they are widely available, an accepted standard and very inexpensive.
    The SmartPlug company has been promising the 50a connectors for three years, always just six months away (below is an email I received from them in December 2009). You’ll note there are no caveats, it’s a flat assertion of fact. This tells me the company is at worst dishonest, and at best does not not have control of either its manufacturing or business.
    I’ve had near fires (fried connectors) on my last two boats and would really like to see the twist locks discarded as a historical relic. But all things considered, adopting the IEC 60309 plugs would achieve 80% of the benefits with a known solution available from multiple suppliers. Nobody is going to make an offical standard out of a product that is sole sourced from a company with dubious credibility.
    Dec 1, 2009 1:57pm: “Our 50amp connectors will be available this summer and will have the same footprint as the current configuration to make retro fitting easy. ”

  21. Mic says:

    This product is such a huge improvement over flimsy twist lock connectors. I’m glad to see all the endorsements. I believe in this product so much that I tell clients that I’ll install it for free. Of course The difference between retail and wholesale cost covers the 30 minutes it takes to install it. Happy and safe customers! -Mic

  22. Ben,
    Good job on the time-lapse install video…but it seems from the still photo at the top that you missed a screw… 🙂

  23. DJ says:

    “carefully designed to avoid heat-inducing resistance and it also contains a trip thermostat which cuts power at 200º F (just before wire insulation begins to soften)”
    If I am not mistaken, the thermostat is only cutting the N. Shouldn’t the L be protected too?
    Until it is I am going to hold off with the purchase.

  24. George says:

    I, too, have been waiting for the 50 amp.
    I am amazed at how lightly boaters take this issue. I was recently going to sublet a slip for three months when we (actually my sharp-eyed wife) noticed that the 30 amp female plug in the dock box was melted and slightly burned. The person handling the lease shrugged it off, saying that the previous boat had experienced no problems!
    We left the slip immediately — somebody lost out on $1000+/month moorage fees because they didn’t keep an eye on their electrical outlets. When you are berthing a fairly new 53′ boat it doesn’t pay to take chances especially if you are ever planning on sleeping aboard. Two large boats in Everett burned yesterday at the dock.
    (They did replace the plug the next day and called us back, but by then we had made other arrangements.)

  25. Evan says:

    I replaced my vessel side plug with a SmartPlug over two years ago after inspecting my old plug and finding scorch marks on it. I wish I could do the same with the shore side, but since the marina’s power boxes, which were all replaced in the last 5 years, do not even have the threads for the standard twist on collar, I am sure I am out of luck.
    It has been a number of years since I have taken a European cord apart, but I dont seem to recall the plugs to be significantly better than the US ones, although you were able to buy them cheaply at the local hardware store. However, my European friends were always at great pains to tell me how much safer their whole electrical wiring system was, unfortunately I do not remember why any more.

  26. Roger says:

    Does anyone know what exactly happens when you drop one into the water for a few seconds? This happens occasionally and I’m wondering whether the connector will get ruined etc?

  27. Dan Corcoran (b393capt) says:

    On my existing boat side connector, I have a light to tell me the dock end of the cord is live.
    I don’t see such a feature in the brochures for the SmartPlug.
    Did I miss something? Any chance that feature is on the road map?

  28. Ben Ellison Ben Ellison says:

    Dan, you mean another power light besides the blue LED mentioned in the opening paragraph and seen in the photo?

  29. Dan Corcoran (b393capt) says:

    Yes that’s it, that blue power light right there. So it shouldn’t be a surprise I flunked my eye exam 2 hours after I wrote that comment this afternoon. Need new glasses.
    The product has moved up from novelty to possible upgrade on Breeze Pleeze, after seeing it on Gizmo. It’s still real money (I have 2 x 30Amp), might like to see a little corrosion first before I replace mine. Could take awhile, I treat the original plug and connectors with Corrosion-X twice a year.
    Packaging the combination plug plus replacement cable end (for existing cable) is a good move Aaron. It drives home the fact that we can adopt this technology without changing the dock end of the power connection.

  30. I have one on my boat and am much more comfortable with it than I was with the old twist-lock… it’s well-made and unambiguous. One minor burp on installation, though… the body diameter was slightly larger than that of the original Marinco, which had been installed with very tight tolerance. I had to do a fair bit of grinding to get it to fit (steel boat).
    Other than that, which slowed installation and scattered iron filings, I love the SmartPlug and would certainly buy it again.

  31. Jim in Saint Helens says:

    I am sold on the SmartPlug. I have just two comments:
    1. Be sure to get the cord set, not just the plug to modify an existing shore power cord. I found that mounting the SmartPlug on an existing Marinco 30-ampere shore power cord to be very difficult indeed. Buying the complete cord set is well worth it.
    2. While the built-in thermostat is a fine feature, it breaks only the “hot” (black) lead in the shore power inlet, and will re-connect that conductor when the inlet cools down. You still need an ELCI (Equipment Leakage Circuit Interrupter) near the SmartPlug shore power inlet to provide a trip-free breaking of both the “hot” and “neutral” (white) conductors to disconnect the boat from the shore power cord in case of a fault somewhere on the boat that causes current to flow through the “safety ground” (green) conductor. (See ABYC E-11 standard: section E-11.11.1; section E-11.17.1 and Diagrams 1,2, and 3; section E-11.17.2 and Diagram 4; section E-11.17.3 and Diagram 5; section E-11.17.4 and Diagram 6; etc.)

  32. Anonymous says:

    the UK shorepower is 250V so amp draw is half and cord sets have smaller guage wire than USA

  33. Kees says:

    Well nearly — single cycle power in the UK and EU is 230 V, 50 HZ AC. This is an EU standard. UK used to be 240 V, continent was 220 V so they met in the middle.
    Only breaking the ‘live’ or hot wire is a very bad idea, the neutral conductor will carry some voltage in practice, depending on the local imbalance in the system and wiring setup. In Europe consumers aren’t even taught the difference: they are told that both wires are dangerous, and that there is a 230 V potential between them. This reflects in household plugs, which can go in both ways (even the grounded variants in most european countries.)
    I guess the way the IEC blue and red connectors and sockets might be ‘better’ than the yellow US ones is that they have a longer ground prong, making sure that ground is connected before Live and Neutral. I don’t know how this is done in the US standard style connectors.

  34. Ben Ellison Ben Ellison says:

    SmartPlug now has 50 amp inlets and connectors according to this press release:

  35. Pat Cowan says:

    In Vancouver, BC, some of the insurance brokers will give the boat owner a credit or discount for installing this system. Often the credit covers the cost of the unit, in either one or two years, and the discount applies for as long as the unit is installed.

  36. HenryD says:

    Thank you for the posting. I have been waiting for the 50a plug. I hope to buy two for my boat at the Miami boat show in a few weeks.

  37. The fifty amp version is not yet “available in stores”. I spoke to the rep at the Seattle Boat Show and apparently they are waiting on some parts to assemble the initial units. (I did have a demo in my hand though). The expectation is that these will actually ship in two to three weeks. I ordered a set from Fisheries.

  38. Reawakening an older thread..:) I put a 30a SmartPlug on ATSA back in ’13 or ’14, and it was easy to do (also fixed a minor leak at the boatside connector). After 3-4 years in the sun, however, the rubber cable seal/strain relief on the plug part is definitely failing, and I doubt it’s keeping out rainwater any more. The rest of the assembly looks just fine.
    So I’m trying to figure out how to obtain a new one (or two) but it doesn’t seem like they sell parts & pieces. I’ve sent queries via their “Contact” form on their web page, but no reply (yet).
    Has anyone else experienced this problem, and were you able to find a replacement? If I had known it was going to fail this quickly, I’d have put some sacrificial tape over it!)

  39. Hartley, I haven’t seen this personally, but I agree it doesn’t seem right. I would definitely follow up with a phone call on Monday morning. Their contact in Seattle is 206.285.2990. They’ve been pretty responsive in my experience, and I wouldn’t be hesitant to push for a replacement if this is a design issue.
    It’s opening day of boating season here, so you might not get very far with an email response until Monday!

  40. Thanks, Grant – I think I will give them a call on Monday while it’s on my mind – I sent them a query on this back in February, but then we got busy heading to the Bahamas, and followup slipped my mind 🙂 We didn’t plug in much over there, so now that we’re plugged in again, it is sitting there looking at me.
    I also note that looking at the current installation instructions, it seems they may have a new seal – while mine is smooth black rubber, the new one appears to have molded serrations similar to the molded plug – perhaps they’ve updated.

  41. Roger that – I’d say that’s a pretty good indication that the original seal design was suspect. I think, as an “early adopter”, you ought to be recognized with a new plug!
    Good luck,

  42. Success! – I never did remember to call them, but I got an email from Terry Gilliland, and he is sending me a “kit” under warrantee. The kit includes the cable seal (and it appears to be a different material and different design), new cable retaining clamp and a new plug seal. I don’t think I need the plug seal (yet), but the other two parts look like a good thing.
    I should have them in a couple weeks when we get up to my B-i-L in Connecticut.

  43. Geebus – has it been most of a year already? The new parts went in effortlessly, and the new seal looks great – we’ll keep an eye on it, as it will be out in the sun just like the last one.
    I also bought another spare plug, and used it to convert a short extension cord so I could (easily) use a Yamaha 2 KW portable generator for all of last summer – the diesel 12V generator is running again, thanks to the good folks at Deltaville, VA so it won’t see as much use next year (I hope!)

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