Smart Plug Shore Power Inlet Install

[CaspersCruiser]

My 2012 Ranger Tug R27 is the first boat I’ve owned that has had shore power. When removing the shore power cord, a few times this season I noticed that the plug was somewhat warm (but not hot) to the touch. Since I didn’t have a frame of reference of what was “normal”, I did some reading and research.

I found that shore power connections are a fairly significant source of boat fires. The typical twist lock style shore power connection has some problems ranging from insecure or inadequate connection to weather tightness. Some respected folks recommended a new style shore power connection called the Smart Plug (http://www.smartplug.com) that addresses these issues.

Installing a Smart Plug shore power system is supposed to be easy and the company has some good installation videos on their website. The screw pattern holding the inlet to the boat is the same for both style inlets so no drilling is required.

Today, I installed a Smart Plug shore power inlet on my tug. The inlet installation video shows the installer removing four screws and easily pulling out the existing inlet assembly with about a foot of slack in the wiring coming from inside the boat.

I was not so lucky. There was ZERO slack after I removed the four screws. Gaining access from inside the battery compartment, I traced the wiring to the shore power inlet and there appeared to be some slack available. What was preventing the slack from being pulled through the inlet hole was a 16 gauge wire hooked to the galvanic isolator by a ring terminal. I removed the nut securing the ring terminal and was able to pull about eight inches of the shore power wiring out the inlet hole.

I was anxious to see the condition of the existing shore power inlet because during my research, including right here on Tug Nuts, I had seen photos of scorched or melted components on shore power inlets. On my shore power inlet, there was absolutely no evidence of thermal stress on the plastic parts or wiring. The ends of the wires were clean, bright and shiny with no hint of corrosion.

I could have reinstalled the existing shore power inlet, but I do like the features of the Smart Plug so I went ahead with the installation. There are no special tools required and the wiring is very straight forward- just follow the colors, e.g., green wire in the green hole. If you can change a wall outlet in your home, you have the skills to install a Smart Plug inlet.

If you put a Smart Plug inlet in your boat, you will also have to change the boat end of your shore power cord. Smart Plug assemblies are sold in kits that provide the inlet and shore power cord end. Shore power cord ends are also sold separately so that additional shore power cords can be converted to Smart Plug configuration. And pre-configured Smart Plug shore power cords can be purchased.

A downside I see to making this conversion is that you must now have a shore power cord with the Smart Plug end on it to have shore power. You won’t be able to borrow a regular shore power cord and use it. Also, there is certain amount of risk of unintended consequences any time you mess with wiring, but there is really no way to check the condition of your shore power inlet wiring without fairly major intrusion. For me, it was worth it for my peace of mind.

 

[Brian B]

I installed one over a year ago and l did have some discoloration and excess heat going on. I really like how it plugs in and locks itself, no more trying to line up the contacts and twisting the plug in. Yes don't forget to take the cord with you when traveling.

 

[knotflying]

An expensive alternative would be to make a small cord with one end smart and the other end dumb, but then you kind of defeat the purpose of the smart plug. At least you can borrow someone's cord though. 😀

 

[Brian B]

Just had a bright :idea: , carry the old boat side plug with you. If you ever run into that situation it would be a fast and easy swap.

 

[CaspersCruiser]

An expensive alternative would be to make a small cord with one end smart and the other end dumb, but then you kind of defeat the purpose of the smart plug. At least you can borrow someone's cord though. 😀

I was thinking of just such an arrangement to be used on a temporary basis, if needed. It could also be loaned to “smart” friends in need.

 

[CaspersCruiser]

Just had a bright :idea: , carry the old boat side plug with you. If you ever run into that situation it would be a fast and easy swap.

I considered that as well. I think a short “patch cord” is the easiest solution.

 

[NorthernFocus]

An expensive alternative would be to make a small cord with one end smart and the other end dumb, but then you kind of defeat the purpose of the smart plug...

Not really defeating the purpose. At least you move the higher risk plug off the boat.

 

[Spinner]

I did this also. You can buy a kit to replace the standard end on your shore power cord with a smart plug end.

My set-up is now Smart Plug outlet on boat, one shore power cord with a smart plug, one standard shore power cord for times when I need more distance, and one additional smart plug replacement end (in case my smart plug cord gets damaged).

 

[HRowland]

I also did the Smart Plug conversion over 4 years ago.

One warning about the cord retrofit connector, watch for corrosion of the stranded copper wire. After a few years of use the 3 dogs that clamp the cable inside the connector shell failed. This allowed the cable to move around a bit and broke the rubber seal. The conductors became corroded. Kudos to Smart Plug and the 7 year warranty, they quickly sent a repair kit at no charge to fix the failed cord end connector. However, when I tried to cut the cord wire back some to get clean copper I had issues. I first tried a few inches, but the conductors were still very corroded and stiff. I kept trimming back 6 inches at a time, and could not get to clean copper. After loosing a few feet I realized this cord would not be useful as a 50' shore power cord any more so I cut it back to about 30 feet to make a shorter cord. I purchased a new Smart Plug shore power cordset which has molded cord ends which will be much more reliable. Smart Plug also uses tinned conductors, something not done by the other major shore power cord manufacturers, they are just regular stranded copper. The Smart Plug cord is also much more flexible.

When I told a Smart Plug rep at a Boat Show about the corrosion, he smiled and asked how much cable I had to cut off! He claimed that they are the only shore power cord manufacturer that uses marine grade tinned wire.

For the Nordic Tug 37 that we just bought I have ordered two Smart Plug conversion kits, however I chose the kits that include a stainless steel boat side inlet and a complete 50' shore power cord. The boat came with only one shore power cord (it uses two) and the cord is very weathered and stiff so I did not want to retrofit it. I took advantage of a recent email discount deal at Fisheries Supply and got a great price on the two conversion kits, less than $450 shipped to RI.

Howard

 

[baz]

Regardless of what shore power cable you have, it's good practice to not coil the unused cable length as this can cause unwanted heat build-up.

I know most people will want to coil the unused cable for making it tidy and there are cable holders that secure the complete cable and keep the unused portion inside.

I've had extensive chats with the Smart Plug folks here in Seattle where the product is designed and this was a piece of advice given me.

My most alarming witness of a shore power cable and/or the dock's power pedestal fire hazard was a few years back. I was leaning over gawking at the boats in our Marina's Guest moorage when all of a sudden a power pedestal in use by one of the big boats shot up into air with a plume of smoke and fire - much like what you would witness in a James Bond movie. Fire engines were on site in a jiffy and broke into the unattended big boat to detect any further issues. The Marina never did explain/announce what the root cause was but rumor had it that the big boat was the culprit. The Marina had to spend big bucks to re-wire the complete Guest moorage electrical power.

 

[NorthernFocus]

Regardless of what shore power cable you have, it's good practice to not coil the unused cable length as this can cause unwanted heat buildup...

...I've had extensive chats with the Smart Plug folks here in Seattle where the product is designed and this was a piece of advice given me..

Interesting. Did they explain the physics behind that advice?

 

[baz]

Dan: I don't recall. However, you can experiment with a smaller case by coiling a small household power cable and drawing current through it for a while and noting whether it's warming up.

 

[stwendl]

The warning about coiling shore power cords, due to magnetic fields, might warm them a bit. But I can’t imagine that it would be cause of concern. You frequently find coiled shore power retrieval systems on larger yachts and I can’t imagine they roll out the entire length if not needed. Coils may be a trip hazard and may pull out connectors when someone gets entangled

 

[Osprey]

The physics is quite simple. The power cord has some (small, but measurable) resistance. The power dissipated is calculated using the equation current squared X resistance. So if drawing say 30 A with say 0.5 ohm resistance the power works out at 450 watts. With the cord coiled the heat energy tends to be contained so the cord gets hot.

 

[NorthernFocus]

The physics is quite simple. The power cord has some (small, but measurable) resistance. The power dissipated is calculated using the equation current squared X resistance. So if drawing say 30 A with say 0.5 ohm resistance the power works out at 450 watts. With the cord coiled the heat energy tends to be contained so the cord gets hot.

Theoretically correct but not practically relevant for the given application. Which is why I asked. Sounds like the folks who made the recommendation used to work as either a fire inspector or insurance risk specialist. Both of whom commonly require removal of self-coiling spools in work shops. And rightly so. In those applications it is very common to have 90 percent of relatively long conductors coiled tightly on a small spool. In such a case heat build up is definitely a valid concern. A few feet of cable coiled loosely on a dock/deck is another story.

 

[baz]

If coiling the shore power line is of any concern to people then running a 50-foot shore line cable around the boat one time before routing it to the shore power pedestal should avoid coiling being a necessity. 🙂 Some slack in the cable is necessary as the boat can swing about some and the slack in the cable can accommodate that.

One of the aspects of shore power cables laid out along a dock always bothers me as placing a foot on the cable it acts as if you're standing on a moving roller ball object and this can lead to one losing balance, and being at the edge of a dock is a safety hazard. If the dock has planking I try to lay the cable in the plank gaps as best I can to minimize this issue. At my dock I have placed/secured Marinco plastic cable clips to secure the cable at every 3 feet from where it leaves the boat up to close to the shore power pedestal. The edge of my dock is wooden so screwing down these clips was easy. If it were concrete this technique would be more difficult to arrange.

 

[Osprey]

Right Dan, a few feet coiled on the deck is not going to be a problem. Now think about the use of a "Cordpro XL plastic enclosure designed to contain 50 feet of 30 A power cord. If you check their web site you will see an image of such an enclosure sitting on a boat deck next to the boat's power receptacle. Depending on the distance between the dock's power pedestal and the boat's receptacle, a considerable length of power cord could be enclosed (coiled) in the Cordpro XL case. There could be an over temperature problem here.

 

[NorthernFocus]

Right Dan, a few feet coiled on the deck is not going to be a problem. Now think about the use of a "Cordpro XL plastic enclosure designed to contain 50 feet of 30 A power cord. If you check their web site you will see an image of such an enclosure sitting on a boat deck next to the boat's power receptacle. Depending on the distance between the dock's power pedestal and the boat's receptacle, a considerable length of power cord could be enclosed (coiled) in the Cordpro XL case. There could be an over temperature problem here.

Indeed there could. I guess I'm old school. It never occurred to me that anyone on a class vessel like an RT would do such a thing. But if determined to go Walmart not likely to read the instructions either which says to downrate the cable rating by half if used while in the enclosure.

So I guess I'm on board. Simpler to just say no. Don't do it...