Another power plug mishap.....

[psneeld]

I have seen plenty of burnt shore power plugs at the pedestal end.


I believe that using a better plug than the standard 30A twist lock is a huge help...just switching plugs doesn't really change much except usually a better connection...if you don't change the shoreside plug or wire of CBs...just changing a plug doesn't induce more dangers. The real advantage is the total upgrade to a 50A 125/250V capable boat.

 

[tadhana]

Connecting stranded wire directly under a screw is not recommended. Crimp a ring terminal to the stranded wire then place that under the screw.

The hull inlet fittings from Marinco, Hubble, and Smart plug ALL use a screw compression connection. This type of connection is standard. These connections are acceptable for use on boats provided the screw does not bear directly on the stranded conductor. Generally this is achieved by having the screw bear on a plate, or in the case of Smart Plugs the screw has a rotating end cap fitting so that as the connection is torqued, the cap does not spin as you torque the screw.

 

[tadhana]

Of all the burnt power connections I have seen is always on the boat and not on the dock end which jives with my opinion that most problems are due to operator error. (Failure to fully twist the plug and locking the plug in place with the locking ring) we can see the wear on our dock lines due to the movement of the boat, but don’t check our electrical cords.

Actually the dock end of the cord is much more likely to burn first. At the boat end the cord can be locked in with the locking ring so the connection is watertight, and there is no movement in the connection as the boat moves in the slip. At the dock end end of the cord, the receptacle is not provided with a threaded ring to lock into. (We are full time cruisers and are in +/- 30 marina slips per year. On the entire east coast I have only come across 3 marinas with power post receptacles to which we can lock the dock end of the cord into the power post.) Since they cannot be locked in they are open to the weather and there is a lot of salt in the air along the coast. so corrosion builds. When boats leave a slip the receptacle cover is often left open and the receptacle is exposed to salt air. More corrosion builds on the connections inside the receptacle. since the cord cannot be locked in, the electrical connection moves as the boat movers. The cord come s loose and there will be arcing inside the connection. Arc burns add resistance=heat.

Anytime you come to a marina look at the power post receptacle before you plug in. If there is evidence of burns or damage, do not plug into that receptacle. It has already been damaged. If you pull a heavy load through that receptacle you are likely to burn your own cord.

 

[FF]

The simple precaution of chopping off a foot or so of cable and remounting the plug after each time its dropped/dunked in sea water would be a big help.

 

[tadhana]

Statistically speaking, most boat fires are the result of shore power faults. One observation from the photo, the back of those inlets are supposed to be covered/insulated, you should do that on the replacement, even if it's a Smart Plug, their inlets lack full insulation without an enclosure. If you can see a energized screw, it should be covered.

Steve as designed the hull inlet connectors produced today from Hubble, Marinco and Smart plug do not have any exposed electrical connections where someone might accidentally contact it and get a shock. I suppose you could stick your fingers into the recessed set screws if you tried though.

What I see in that picture though is that the boat wiring is not supported and the weight of the hull cable wiring is hanging on the wire connections of the hull inlet. The wire should be secured and supported independently of the hull inlet.

 

[cbouch]

Does anyone use Boeshield T9 as a water repellent- anti corrosion spray on their shore power cables? Any suggestions on what might be a superior product? Thanks Cliff

 

[tadhana]

I use CRC 656. I also use it when I plug into a transient slip ( about 30-40 times per year) The trouble is that if you plug your cord into a corroded receptacle the resistance in the connection creates heat which can damage your cord.

The attached pictures are from June in Hampton VA. It is a brand new Smart Plug cord set. It was a warm day 95 degrees, and we were drawing 24 amps consistently. The power post got up to 120 degrees, so I pulled the cord out an checked the pin temperature. 190 degrees! And some minor discoloration of the plastic in my new cord.

So it appears from this that the internal temperature of a cord running 25 degrees above ambient is about 70 degrees .

 

[Cortez]

If the setup is not foolproof...then what IS the acceptable continuous rating...as corrosion, looseness,etc could do the same at many different amp draws...why not limit them to 15A as safe?

Thirty amps means 30 amps to me. That is conservative and prudent for 10 wire. Your breaker will protect the wire from anything over.

I agree that the problem is loose connection or corrosion.

 

[timb7734]

Actually had a fire in the shore power connection a few years ago, but did not save the pictures. I was leaving the boat headed for dinner out when I smelled smoke, and found smoke billowing out of a cockpit locker where the shore power connection was. Long story short, disconnected there and reconnected to bow alternate plug, and went to replace the male boat end plug because of melted and scorched connections. Found that over time, the downward pressure of the weight of the plug, combined with the twisting leverage from connecting, these forces had put a hot and a ground in proximity to short out. Dock breaker did not trip, boat breaker did not trip either. Surprise!! When I procured a replacement Marinco plug it was redesigned to eliminate that from happening on the new product. I then replaced the alternate plug on the bow as well. The boat was originally built in 2008, do not know when the design was changed, but replaced that boat with a 2019 model and the new boat had the newer design.

 

[sunchaser]

Statistically speaking, most boat fires are the result of shore power faults. One observation from the photo, the back of those inlets are supposed to be covered/insulated, you should do that on the replacement, even if it's a Smart Plug, their inlets lack full insulation without an enclosure. If you can see a energized screw, it should be covered.

For some time I've recommended smoke alarms be installed above shore inlets, again statistically speaking it's high risk.

More on shore power overheating here https://stevedmarineconsulting.com/october-2011-newsletter/

(In Taiwan)

Thanks for the input Steve. As oft mentioned in this thread, the wiring setup behind this or any vessel connection bears close scrutiny, beyond just adding a smart plug arrangement.

 

[syjos]

Does anyone use Boeshield T9 as a water repellent- anti corrosion spray on their shore power cables? Any suggestions on what might be a superior product? Thanks Cliff

Boeshield is a lubricant that leaves a residue which might reduce contact and increase resistance.

Dielectric grease will reduce corrosion but it is not conductive.

MG Chemicals 846 Carbon Conductive Grease is a carbon-filled, electrically conductive grease. It lubricates, reduces contact resistance, repels moisture and inhibits corrosion.

 

[Mike3888]

WOW want to thank ALL for your input and guidance!
I will be checking my pedestal and boat connections and the temps.
I am a little worried about the splitter going from the 50 amp pedestal to the 2 30 amp legs. One leg came loss the other day noticed I did not have hot water and no indication on the right side of the electrical panel. Went out and saw the splitter (one leg) had come loose. We are good about shutting most everything off when we leave but a little worried about the splitter coming loose while we are away..I will also use some CRC 656; which is??? on the connectors..Thanks MUCH!

 

[caltexflanc]

I like Corrosion X HD for "potting" high current connections. You make the connection first THEN protect it with the coating of your choice.

 

[tadhana]

WOW want to thank ALL for your input and guidance!
I will be checking my pedestal and boat connections and the temps.
I am a little worried about the splitter going from the 50 amp pedestal to the 2 30 amp legs. One leg came loss the other day noticed I did not have hot water and no indication on the right side of the electrical panel. Went out and saw the splitter (one leg) had come loose. We are good about shutting most everything off when we leave but a little worried about the splitter coming loose while we are away..I will also use some CRC 656; which is??? on the connectors..Thanks MUCH!

Mike, It sounds like you are not using the connecting collar and locking rings? If you don't use the collar water can get in and lead to corrosion, and the electrical connection is loose so you will get some arc burns which increase resistance too.

 

[FoxtrotCharlie]

The simple precaution of chopping off a foot or so of cable and remounting the plug after each time its dropped/dunked in sea water would be a big help.

Exactly what I did when we bought our boat - was shocked at the loose condition of the connections - put new male and female ends on the cord at that time also. We sleep much better now 50 amp.

 

[Mike3888]

that is EXACTLY what is looks like. Can I buy the connecting collar and locking rings?
Thanks much!

 

[Mike3888]

where can I

 

[FoxtrotCharlie]

Bought our's at West Marine store.

 

[tadhana]

that is EXACTLY what is looks like. Can I buy the connecting collar and locking rings?
Thanks much!

Mike, I'm sure you can get them through Amazon of most marine stores. https://www.amazon.com/Amp-Up-Weath...jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==


and

https://www.amazon.com/Amp-Up-Threa...d_r=D6KVBWT8JGMNHBNGRCGR&psc=1&qid=1583264082

 

[tadhana]

In my second picture you will also see a 30A sealing cap. Sometimes we plug into a 50 Amp post but only want to pay for 30. I keep the unused plug capped to protect it from wind, rain, salt spray and dogs. https://www.westmarine.com/marinco

 

[Steve DAntonio]

Connecting stranded wire directly under a screw is not recommended. Crimp a ring terminal to the stranded wire then place that under the screw.

Not only is it not recommended it's prohibited as far as ABYC standards are concerned. Screws cannot bear directly on wires. A plate between the end of the screw and the wire makes it indirect bearing, which is OK.

 

[Steve DAntonio]

I do not understand why people think that, switching to the so called smart plugs or to 50A plugs should solve their issues or prevent the above damage.
- Do not waist your money on these plugs because the dock side will still be the same 30A.
You can save your boat however, a fire on the dock is pretty much the same. Also, you are still at risk inside your power panel or somewhere else that is not visible on the boat.
- Please, do not replace your 30A connectors and shore power cables to 50A. You need to know that all your wiring inside your boat is still designed for 30A system.
- the best item to add to your boat and to protect it is a current meter for every 30A (or a single gauge with a switch). Boats are designed for 80% continuous draw however, system do get old and the current draw will most likely to go up. Proper maintenance of your systems and proper power management (80% rule) is recommended.
Monitor you current draw to protect your boat.

Indeed, the dock side plug remains the legacy style, with all its faults, however, to dismiss SmartPlug's improvements as not valuable or a waste of money is simply incorrect.

The consequences of an overheated pedestal connection are far less than those of an overheated boat inlet. I encounter melted and burned dockside outlets on a regular basis. It's the boat side where the fire is likely to start, so replacing the legacy 30 or 50 amp plug with one that offers clear improvements is indeed worth the effort and cost. Perhaps the most significant difference is the passive locking mechanism, you can't plug a Smart Plug into the boat inlet without it locking automatically. Failure to properly engage the shore cord into the boat's inlet is a major cause of overheating, Smart Plug all but eliminates that possibility.

 

[Comodave]

I completely agree that the Smart Plug is way better. If it prevents a fire on the boat that is awesome. If the end on the dock melts and catches fire at least it isn’t on the boat. I would much rather have a fire on the dock than on the boat.

 

[Steve DAntonio]

Statistically speaking, most boat fires are the result of shore power faults. One observation from the photo, the back of those inlets are supposed to be covered/insulated, you should do that on the replacement, even if it's a Smart Plug, their inlets lack full insulation without an enclosure. If you can see a energized screw, it should be covered.

Steve as designed the hull inlet connectors produced today from Hubble, Marinco and Smart plug do not have any exposed electrical connections where someone might accidentally contact it and get a shock. I suppose you could stick your fingers into the recessed set screws if you tried though.

What I see in that picture though is that the boat wiring is not supported and the weight of the hull cable wiring is hanging on the wire connections of the hull inlet. The wire should be secured and supported independently of the hull inlet.

My standard for AC connections is if I can see it, or touch it, even with the tip of my finger, I consider it un-insulated. Part of my concern is water dripping on the connection, if it's exposed that becomes a possibility. I believe you are correct, late model Marinco and Hubbell inlet backs are fully enclosed.
This photo, of a Smart Plug back, taken on a recent inspection, illustrates the point regarding exposure. I believe these should be enclosed/covered.

As far as wire support goes, you are correct, that too is an issue. As far as ABYC standards are concerned, if you can pull on a wire and that force is transmitted to the connection at an enclosure (a common issue on battery chargers, inverters, transformers), it's not compliant, strain relief should be present. The same holds true for a shore inlet terminals. The wires themselves should be supported a minimum of every 18".

ABYC E-11.14.4.1.2 All conductors shall be supported and/or clamped to relieve strain on connections.
11.14.4.1.3 All AC cables from the shore power inlet to the main shore power breaker shall be in conduit or supported according to E-11.14.4.1.9.2 or E-11.14.4.1.9.3.

11.14.4.1.9 Conductors shall be supported throughout their length or shall be secured at least every 18 inches (455 mm) by one of the following methods:
11.14.4.1.9.1 By means of nonmetallic clamps sized to hold the conductors firmly in place. Nonmetallic straps or clamps shall not be used over engine(s), moving shafts, other machinery, or passageways, if failure would result in a hazardous condition. The material shall be resistant to oil, gasoline, and water and shall not break or crack within a temperature range of -40°F (-40°C) to 185°F (85°C);
11.14.4.1.9.2 By means of metal straps or clamps with smooth, rounded edges to hold the conductors firmly in place without damage to the conductors or insulation. That section of the conductor or cable directly under the strap or clamp shall be protected by means of loom, tape, or other suitable wrapping to prevent injury to the conductor;
11.14.4.1.9.3 By means of metal clamps lined with an insulating material resistant to the effects of oil, gasoline, and water.

 

[Steve DAntonio]

Boeshield is a lubricant that leaves a residue which might reduce contact and increase resistance.

Dielectric grease will reduce corrosion but it is not conductive.

MG Chemicals 846 Carbon Conductive Grease is a carbon-filled, electrically conductive grease. It lubricates, reduces contact resistance, repels moisture and inhibits corrosion.

The problem with grease, conductive or dielectric, on shore plugs is it attracts dust and dirt and becomes messy after a while. I've found a light spray or wipe down with 6-56 every so often achieves the goal. Ultimately, you should be looking carefully at male and female cord ends every time you use them, if you see any signs of pitting, arcing or overheating, don't ignore it.

Dielectric grease is designed to be used on electrical connections, and while it is an insulator, which seems counter intuitive, it's designed to be displaced by the connection, while surrounding it and thereby eliminating air and moisture. Conductive grease does the same thing except it improves conductivity. However, they are not interchangeable, you could not, for instance, use a conductive grease on a multi pin booted plug type connector, common on engine and genset wiring harnesses for example, because it could make contact from one pin to another, while a dielectric grease will not have this issue.

 

[CharlieJ]

Just a note shore power pedestals and SmartPlugs:
SmartPlug is working with the major pedestal manufacturers to market a direct replacement module for the "standard" twist lock connectors in shore power pedestals. They are well into the certification process and should be in the marketplace soon.

 

[tadhana]

On the shore end of the power cord I cannot see any value in having a Smart Plug pin configuration. It will be very expensive for marinas to convert to the new power post receptacles and it will require every boat to adapt as well. Unfortunately, I think it will be decades before we really see many marinas with this receptacle configuration. If you have a smart plug pin configuration at the dock end of your cable, you will have to use an adapter at every marina dock visit. This adapter will have the standard twist lock connection for the standard power post connections. The known issue of burned power post outlets will continue and the chance of a fire on the dock will not be diminished, because you are using the same old twist lock connection.

If your home marina converts to the SP pin configuration outlets, then you can have a cord with the SP pins. But you will have to have an adapter for all the other marina you visit so you can connect to the twist lock power pedestal outlets. See paragraph above.

I don't think I'd buy a cable with the Smart Plug pin configuration at the shore end right now though. I spent my entire career in the marine industry, including 20 years owning or operating boatyards and marinas. I have changed out a lot of burned fittings. If I had to guess it is a bout 20:1 pedestal replacement vs hull inlet.

There is one relatively simple and relatively less expensive solution to the issues with the power post 30-amp twist lock receptacles. There are outlet covers available which include a threaded connection. They are rarely seen. We have seen them at several marinas including; Burton Island State Park VT, and at the new power pedestals in Beaufort SC, and the power pedestals at the Mega Dock, City Marina in Charleston. If all power pedestals had them then we could always lock our power cord in at the pedestal just as we do at the hull inlet. That would make a huge safety improvement at far less cost to the marinas.
A few builders have switched to Smart Plugs. I convinced Helmsman who built our boat to switch and for the past 3 years all of their boats have had Smart Plugs, standard.

 

[CharlieJ]

@tadhana #117:
I concur but it makes sense to start the conversion. Continuing to use 1938 technology that was never really intended for marine use when there is a better alternative is questionable logic. But...it is going to take quite awhile for the transition.

 

[Porgy]

I never thought we could convert from eight track to CDs. Or serial to USB. Who’d of thought it possible.

I for one, look forward to Smart Plugs at both ends but there’s no question it would take time.

 

[cardude01]

My boat uses 2-30amp cords, and on one of them the plug looks a little sketchy.

Should I retrofit my cords and boat to smartplugs or just buy a new regular 30a cord? My boat is not that old (2008) so hate to replace the plugs on the boat if not really needed.

If I run both AC units I have to use both 30a cords, but if not one seems to be fine.