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Old 08-15-2016, 07:04 AM   #41
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Ohms law dictates, double the volts then half the amps for the same load and visa versa. Whack a mole.

Amps is where the heat comes from. 50 Amps at 240 is like 100 amps at 110, right? so I think you are on to something here FF, at an affordable price. Just go to home depot and pick up a dryer plug, male and female.

Now for the fly in the ointment. How will this play for the surveyor and insurance company? Electrically you are solid.
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Old 08-15-2016, 07:14 AM   #42
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Ohms law dictates, double the volts then half the amps for the same load and visa versa. Whack a mole.

Amps is where the heat comes from. 50 Amps at 240 is like 100 amps at 110, right? so I think you are on to something here FF, at an affordable price. Just go to home depot and pick up a dryer plug, male and female.

Now for the fly in the ointment. How will this play for the surveyor and insurance company? Electrically you are solid.
Actually the 50A 125/250 circuits are just 2 legs of 110 Volts each.

If your boats electrical panels aren't set up for it, it may not be easy or cheap to take advantage of the additional power available.

All I think FF is talking about is using the heavier duty common plug versus a Smart Plug.
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Old 08-15-2016, 07:17 AM   #43
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I just mangled the male end of my power cord. Again. This time even one of the metal connectors was missing. Every now and then I untie the mooring lines and back out w/o thinking about the power cord. Too many years of running smaller boats w/o power cords I guess.
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Old 08-15-2016, 08:21 AM   #44
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Actually the 50A 125/250 circuits are just 2 legs of 110 Volts each.

If your boats electrical panels aren't set up for it, it may not be easy or cheap to take advantage of the additional power available.

All I think FF is talking about is using the heavier duty common plug versus a Smart Plug.
Yes, I agree. The 50A/240V twistlock plugs and receptacles are very robust. The only place a Smart Plug makes any sense is when replacing a 30A plug set. But to me, going non-standard is a huge down-side. The North American standard plugs are available pretty much anywhere if you need to replace one, you can get a replacement power cord pretty much anywhere, and you can use any combination of different length cords, including those borrowed from friends. With any non-standard plug set on your boat, you are now limited to one cord, one length, carried by you. You just created a single point of failure.

Going to a 50A/240V inlet on your side of the boat, even if you only use one leg of the 120/240 circuit, and even if you use adapters to get back to a standard 30A cord, you have accomplished all the same things as a Smart Plug, but done so using standard parts.

Oh, and getting back to the original question.... I've generally found that it's only a small amount more to just replace a whole 30A cord vs replacing the end plug. It depends a bit on the cord length, but $70-$90 for a whole cord set and probably half that for one cord end. And the factory made cord sets usually have molded plugs so better water intrusion protection. 50A cords are a whole different story where the cord set costs $500-$700, and a plug end costs $90.
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Old 08-15-2016, 09:01 AM   #45
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." Just go to home depot and pick up a dryer plug, male and female."

That works just fine INSIDE for changing the boat from shore power to noisemaker power to inverter power.

INSIDE is the key.

A 240V 50A MARINE plug and socket is water proof if you do it properly.Hubbel is always my only choice.

The 30A power cord will not over load the 50A 240V marine unit , esp if you split the load and wire both pins to operate together.

The 50A pins and socket should be pretty cool with 15A as a max load..

The use of dryer items inside the boat should not bother your insurance guy , as it is an excellent simple system to use.
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Old 08-15-2016, 09:21 AM   #46
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Gimme some guidance here. I have 30 amp service. Looking on line at "smart plugs" it appeared the plug pattern was different than my standard, locking Marinco cord and female on boat side. Also the replacement plugs are EXPENSIVE. On sale I find 30 amp cords +- $70. What am I missing?

See my earlier post re insurance co rebates. Made my conversion cheaper than buying one new end by Marinco.

I now have one cord with a smart plug female end to the boat that has the smart male end. That cord has a standard Marinco plug on the other end, that I will replace when it starts to show deterioration from sparky dock fittings. I have spare cords for longer runs, that are only fitted with standard Marinco ends.

I always make sure the boat breaker is off when connecting or disconnecting, at the dock. Likewise I always disconnect at the dock before I disconnect at the boat, and vice versa for reconnecting. This will save my smart ends from sparks and limit the dock end damage.

At my YC Moorage, we have a display board with several badly burned cord ends, both male and female. So far nobody has burned a Smart end to add to the display. Hope it stays that way.
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Old 08-15-2016, 10:21 AM   #47
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[QUOTE=FF;469877]Smart plugs are far too expensive and will never take over

The cheapest concept is to install a 50A240V plug and inlet on the boat and keep the std 30A 120v power cord and dock end.

When you overload/or corrode, the dock CB should blow or at least the fire will be at the dock , not at your power inlet.

If you are going for the cheapest solution, the cheapest and most reliable solution is to have a permanent bolted connection inside the boat.

If you have corrosion and resistance in the connection, the circuit breaker will not trip. You can have a fire while drawing 20 amps through a corroded 30 amp plug connection. The breaker trips on current overload and not heat in the inlet.
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Old 08-15-2016, 10:54 AM   #48
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Bacchus is 100% on the right track. You don't need to just change the discolored connector, you need to resolve the problem that caused it, which was too many amps going thru one or all of the terminals or connections at one of the plugs. High amperage draw is caused by corrosion, broken wire strands or loose connections. ............
High amperage draw is not caused by corrosion, broken wire strands or loose connections. High amperage draw is caused by using too much current. And, the amount of current is the same for the hot and neutral conductors and connections. The ground connection should see no current unless there's a fault.

Corrosion, broken wire strands or loose connections will cause excess heat and possibly arcing which will destroy some of the metal the connections are made of.

Quite often, corrosion or signs of arcing on your shore power cord's male end are caused by worn out connections on the dock pedestal.
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Old 08-15-2016, 10:58 AM   #49
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See my earlier post re insurance co rebates. Made my conversion cheaper than buying one new end by Marinco.

I now have one cord with a smart plug female end to the boat that has the smart male end. That cord has a standard Marinco plug on the other end, that I will replace when it starts to show deterioration from sparky dock fittings. I have spare cords for longer runs, that are only fitted with standard Marinco ends.

I always make sure the boat breaker is off when connecting or disconnecting, at the dock. Likewise I always disconnect at the dock before I disconnect at the boat, and vice versa for reconnecting. This will save my smart ends from sparks and limit the dock end damage.

At my YC Moorage, we have a display board with several badly burned cord ends, both male and female. So far nobody has burned a Smart end to add to the display. Hope it stays that way.

On my sailboat when I made the switch I bought a Smart Plug cord (standard 30 amp male and for the dock and a Smart a Plug female end for the boat) then I changed out the female end of my existing cord for Smart Plug female. I always like having two power cords, one to leave on the dock and the other in the boat that goes with me. This is not only for convenience, but I consider it a safety factor as well. The dock pedestal at my old slip had a very worn 30amp female plug. It didn't have locking ring threads and didn't fit tight. I ended up using some small stuff to tie the cord tightly the pedestal so there was no movement and used dialectic grease on the connection. Plugging and unplugging a 30amp cord causes wear over time. That can lead to a poor connection and that can lead heat. I want a solid connection that remains untouched other than for inspection a couple times a year.

I did like the led at the female end of the smart plug. There are some docks where it can be hard to tell if the breaker is on at the pedestal. If you plug into the pedestal and the led lights up, then you know it is live. If you can't find where to turn it off, then you can unplug it and then plug into the boat first, turn off your boats breaker,then plug into the dock carefully.
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Old 08-15-2016, 11:05 AM   #50
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[QUOTE=tadhana;469940]
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If you have corrosion and resistance in the connection, the circuit breaker will not trip. You can have a fire while drawing 20 amps through a corroded 30 amp plug connection. The breaker trips on current overload and not heat in the inlet.
This is true. A 30 amp breaker will not trip at 31 amps, it takes a significant fault current above 30 amps to trip it.

I put my hand on the plug body to check the temperature and wiggle it to make sure the clamping ring is still tight. Sorta like checking trailer hub bearings for heat when you stop to fill up for gas on the freeway, quick look at the tires, etc.

Regarding amps: I got one of these and it has turned out to be one of the most used tools on the boat, it measures AC and DC amps up to 100 amps, and is so sensitive to 2 or 3 decimal places, making it useful for tracing down small currents too. Compact and fits into the small spaces on the electrical board...

Uni-T UT210E True RMS AC/DC Current Mini Clamp Meters w/ Capacitance Tester

Cut and paste that into Amazon or your favorite site.
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Old 08-15-2016, 11:23 AM   #51
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It is a very easy job. The terminal screw heads are color coded so it's hard to get it wrong. .
Most of my career involved electricity and repairing things that were often screwed up by the owner or used. They can and do get it wrong.
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Old 08-15-2016, 11:25 AM   #52
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How do you see power at a glance?
Touch it and you see stars.


I'm guessing that the boat end has a pilot light but some "standard" cords do as well. Of course, to be safe and follow the directions, one would never turn on the dock breaker before plugging in the boat end so any though of using the light to find the socket on the boat would be a very bad idea.
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Old 08-15-2016, 11:37 AM   #53
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Smart plugs are far too expensive and will never take over
I'd like to ask those who posted that they prefer Smart Plugs: Why?

I'm not trying to start an argument. And I'll accept the possibility that I'm just being cynical about it. But frankly, I don't see a huge benefit to ME. I see lots of benefit for the company which wants to replace every dock and vessel power inlet and outlet in the world.

And yes, I've seen overheated connections, and even caused one once. I know it can and does happen. I'm not convinced it can't happen with a Smart Plug.

To me a truly "smart" plug would (1) work with existing dock outlets and boat inlets, (2) be easy to connect without stripping threads or coming unlocked, and (3) reduce the possibility of overheating.

If I could phase in the implementation, I'd certainly pay extra for these qualities. But I'm not scrapping every component I already own, and I'll be very upset if I pay for a slip at a marina that requires me to buy something new before I can plug in. I have too many adapters already!
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Old 08-15-2016, 11:54 AM   #54
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I'd like to ask those who posted that they prefer Smart Plugs: Why?
Significantly larger contact engagement surface.
Better locking system
Easier to connect

While I really like the system, I probably won't be changing my 50 amp connectors over to them. 50 amp 240 twist lock marine plugs are far better than their 30 amp cousin.

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Old 08-15-2016, 11:54 AM   #55
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I'd like to ask those who posted that they prefer Smart Plugs: Why?
These are the reasons I did it. Again, they were reasons important to me and not everyone would find them sufficient reasons to change.

1. Increased safety.
2. More solid connection (very tight and secure)
3. More convenient and faster to plug in, even in the dark.

It isn't cheap, but then I have a lot of things on my boat that are a lot more expensive that are there to add safety and/or convenience.
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Old 08-15-2016, 11:55 AM   #56
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Significantly larger contact engagement surface.
Better locking system
Easier to connect

While I really like the system, I probably won't be changing my 50 amp connectors over to them. 50 marine plugs are far better than their 30 amp cousin,
Great minds.....

I haven't yet changed out my 50amp/120v plugs on my current boat for the same reason.
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Old 08-15-2016, 03:08 PM   #57
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I'd like to ask those who posted that they prefer Smart Plugs: Why?

I'm not convinced it can't happen with a Smart Plug.

If I could phase in the implementation, I'd certainly pay extra for these qualities. But I'm not scrapping every component I already own, and I'll be very upset if I pay for a slip at a marina that requires me to buy something new before I can plug in. I have too many adapters already!
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Have you looked at the Compass Marine comparison?
Best 3rd party review I've seen.
I believe the benefits... haven't switched yet but will when I need a new inlet.
You can "phase in" w/o scrapping everything! Smart plug is for boat end not marina pedistal and you can get plugs to retrofit ypur cords.
It sounds like your mind is made up and that's ok. I've had & seen too many bad cord boat ends that I would rather mnimize the chance of a meltdown or fire on my boat. ..
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Old 08-15-2016, 03:16 PM   #58
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For 30 Amp ends.....

Let's be fair to the whole discussion....
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Old 08-15-2016, 03:41 PM   #59
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Every now and then I untie the mooring lines and back out w/o thinking about the power cord.

It's called the yellow spring-line for a reason
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Old 08-15-2016, 11:21 PM   #60
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Our primary power inlets are 50A, and I see zero benefit to change them. As others have pointed out, they already have all the positive attributes of a Smart Plug, cost less, and most important, are a standard.

But we also have a 30A inlet that converts on-board to 240V so we can run at reduced power off 30A/120V is that's all that's available. But I also don't see a compelling reason to change that to a Smart Plug. I get the benefits of a Smart Plug and don't dispute them, but don' think the down-side is worth it. First, the boat-side connection is the one that I can control and prevent from becoming damaged by hot plugging, not twisting to lock, overloading, etc. Of the two ends of cord, to me, it's not the problem end. And if it does become a problem, I'll just replace it. The problem-end is at the dock, and more importantly the dock receptacle. And like it or not, I have to live with that, Smart Plug or not.
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