The contractors I’d trust would be the ones who put their equipment away under cover when not in use.
My biggest two concerns would be storing a cord where it’s potentially exposed to the elements for significant lengths of time, and verifying that there’s not just a GFCI breaker but a 15 Amp breaker somewhere in the path to whatever equipment’s being plugged in. There’s lots of stuff that can overheat if allowed to draw twice the current it was designed for.
In fact, even the Marinco 30 amp shorepower cord and boatside power inlet will also overheat if corrosion messes up the contacts. I had to replace both after a near-fire on a five-year-old boat some years ago.
If I was doing a new system, I’d definitely go with SmartPlug.
With any 110V electrical power cords around a boat, regardless of amps or connection method, I’d definitely urge regularly dosing the contacts with corrosion-blockers.
Procedures are great for making sure you don’t forget something important. But I think I would drop number 1 from the disconnect procedure and number 7 from the reconnect.
Why? Circuit breakers wear out. I know that almost nobody thinks about it, but it’s true. I have one in my panel right now that is rated at 15A. It should trip with a surge of 15A or 12A sustained. But it actually trips at about 7A sustained. (It’s the starboard AC circuit which only serves the head, so I just don’t use it, but I really need to replace it.) I’ve also replaced a worn out household circuit breaker. It does happen.
The primary purpose of a circuit breaker is safety. While you can use circuit breakers as switches it does shorten their life. So why shorten the life of the most important breaker on the boat when there’s no need to do so? Once the dock breaker is off, there is no current supplied to the boat and so nothing for the boat’s main breaker to protect.
Turning off shore power at the dock breaker is a very good first step as it completely removes the AC threat right up front. Likewise, it should be the last step when reconnecting and after you’re sure everything is in order.
I do use the boat’s main breaker when working on the onboard AC circuits. I hate that ZzzzzzT! feeling you can get if you don’t.
When I bought my 22 I was planning on adding a shore power system, then I read an article in Latitude 38 that pointed out the downsides. If those systems aren’t maintained scrupulously they can turn dangerous. My boat is only 22 feet, and AC is not necessary here. Got a nice 30 amp extension cord with the head pictured, those yellow velcro straps with the screw hole to mount it along the dock edge, and I drop it through the anchor scupper. It’s fine. The only hassle is taking it off the boat when I go sailing. It takes about as long as untying the spring line.
You might be able to find the article on line in Lectronic Latitude’s archives, very comprehensive, with pictures for people like me.
I have exchanged some emails with Marinco tech support. While the male end of the pigtail is a 30 amp rated connector, the conductors in the cabling are only 12 gauge which is inadequate to pass 30 amps continuously without overheating. In addition, the triple female connector is only rated at 15 amps - not per socket, but apparently for the whole subassembly. So they only rate this pigtail at 15 amps. And there is no 15 amp circuit breaker or fuse, only the GFCI.
It is legal. (Consider an example: you can plug a 16 gauge extension cord - which is really only good for about 8 amps continuous load - into a 20 amp circuit and it is your responsibility not to overload the cord.) But it is not very practical. You sure don’t get much for the high cost of the cord and the pigtail. And I think putting a triple socket on it was a really bad idea on their part. A shop vac and a sander would exceed the rating of the cable, but not blow the 30 amp breaker. A heater should probably not be run with anything else. Attention will always need to be paid to the current draw by anything that gets plugged into it. I think this gives more credence to Bob’s concerns about things potentially going wrong after time passes and attention shifts to other things. If you do it, you’ll always have to pay attention to how much load you are putting through the 15 amp rated components.
There must be a lot of boats without AC circuits in them. What do those owners do when they need power? The last two marinas I was at in Oregon actually had 20 amp outlets and people just used regular extension cords when working on their boats. And you always need to make sure your equipment does not exceed the cord’s capacity.
More good info Brian. If I understand correctly we should wear out our main panel breaker by using it so it will only handle a seven amp load before tripping, thereby saving the pig tail from over heating. Of course that does reduce the number of items we can run. The 1500 watt heater may be out. Seriously though, the pig tail is pretty limited, but do you happen to know if the main cable is fully up to handling 30 amps?
I was at the boat, yesterday, and looked at my cable. It has 10 gauge conductors and so is fine for 30 amps. I’d be very surprised if they made them any other way. (But then I was surprised that they cheesed out on the pigtail, too…)
I think the bigger issue with the Marinco power cables is that they use untinned copper conductors. Later yesterday afternoon I talked to a guy whose cable overheated and he had to strip back a few feet before he could find uncorroded copper to attach his new connector onto. I think Bob Neches might have mentioned some similar issue that he had, too? This might be the biggest reason I think the Smart Plug is better.
Do you use a setup like this on your boat, Mark? Not being critical, just curious. I find it hard to believe that there is no safe way to use AC power on the many thousands of boats which were not built with permanent installations in the first place.
As for the pigtail we’ve been talking about, since it is deceivingly inadequate for the three 120V plugs it offers, I think it would be better to use one of their plain pigtails with a single 120V plug and supplement that with a GFCI adapter such as this: https://www.homedepot.com/p/Yellow-Jacket-1-Outlet-GFCI-Extension-Cord-Adapter-2762/204667709 I use one just like that (only yellow) with my tile saw and it does pop occasionally when a lot of silty water starts flying around. So I know it works. Just be sure to never leave these extension cord setups unattended.
And if using just a single plug pigtail, use a SmartPlug cable and pigtail (they do make them) instead of Marinco to get the tinned conductors. And then the expensive cable will already be on hand if an integral AC system is installed in the future.
La Reina did not have shore power when got her. I have since added it. I had a professional marine electrical company do the install. I have a Smart Plug on the boat side but the cable is a standard Marinco 30 amp 50’ cable. The cable is nearing end of life. When it gets there I will splurge on the full Smart Plug cable.
At our marina the shoreside pedestals use standard GFCI breakers. I hope they are rated for outdoor. I have to use a Marinco pigtail adapter to go from the cable to the pedestal socket. The sad part is the sockets were recently installed as part of the electrical system upgrade.
Of course that does reduce the number of items we can run. The 1500 watt heater may be out. Seriously though, the pig tail is pretty limited, but do you happen to know if the main cable is fully up to handling 30 amps?