50A 125-250V Troubleshooting Problems Series.

© janice142
 

50 Amp 125/250 Volt Power Plug Wiring How-To (4-wires)

This all started aboard a neighbor's large motor yacht. The boat is a beauty. She requires a 50amp dock power plug, which is split into two legs for the boat's circuits. A problem has been isolated to one of those 125 volt circuits. First though I had to understand how the power in that plug worked. These are my observations along with the testing procedure I utilized.
 

Please Note: I am NOT an expert. I can follow directions and know the first rule of power:

*DISCONNECT FROM THE POWER SOURCE. Also
MAKE CERTAIN no imbecile plugs the boat back in to "help".
 

*DISCONNECT totally. That specifically means turning off the breaker to the power source. When working in a boat I unplug the vessel, and then verify the inverter is turned off. Next, if the power is from a dock where a bozo (aka a "helpful" idiot) might walk by and plug the boat back in, I bring the end aboard the boat. This may sound like overkill, however please remember that electrocution is a Very Bad Thing.

On Amazon I was able to find a cool diagram which is definitely
helpful in identifying the differences between two types of 50A power plugs.

 

The previous chart did confirm that I was indeed dealing with a 125/250 Volt power line.
 

On the boat there is a receptacle for the 50 amp power cord. Please note the Ground in the lower quadrant, left side of the inlet.

The two blades with "L" shaped bends are positives. Each leg (blade)
carries 125 volts, totaling 250 volts on the 50 amp 125/250 volt power plug.
 

When wiring the plug, the ground goes onto the side. Each of the 125v wires connects to a bent prong. The final wire, a neutral, attaches to the last flat slot.
 

Here is how those wires look from the front side.

To test I pulled out my multimeter. That is when I ran into a problem. My multimeter prongs did not reach far enough into 50 amp plug to make a connection with the positive inside the plug. I had a solution however.

I scavenged a couple of leftover segments of 10AWG wire and cut two pieces. When doing wiring I almost always have one short length and the other is longer. This way the ends cannot possibly connect. As you can see, the white is nearly twice as long as the black wire. I shoved the prongs from my multimeter into the wire, then inserted in the 50 amp plug.
 

It would be wise to tape over the exposed metal where the multimeter prongs connect to my bridge wires.

During testing the exposed metal where the multimeter prongs connected to the bridge wires were covered in electric tape.
 

Now that we have power to the vessel, the troubleshooting continues.

As a quick peek at the future, here is the problem:

More on this mess shortly...
 

Tomorrow I shall show more about the problem on the 50 amp boat. We know where the power stops. That is the Problem, and hopefully one of you can help with a viable solution. See you tomorrow, and thanks for reading.
 

Troubleshooting a 50A Power Leg Problem.

This article concerns 50 amp 125/250 volt power. During the troubleshooting phase of this project first we ascertained that full power reached the boat via the power cord. That involved testing power at the breaker, power pole, and finally at the plug which connects to the vessel. I described the plug testing/wiring done in the 50 Amp 125/250 Volt Power Plug Wiring How-To (4-wires) article. We now have 125/250 volts to the boat.

One month ago all was well aboard the vessel. Her power systems were functioning perfectly. As all boat owners know however, while we are out on the aft deck relaxing with a cup of coffee or tea stuff inside is breaking.

Troubleshooting continued. There is a 50 amp 125/250 power cord that runs from the power post to the vessel. Hatteras has multiple power inlets on both port and starboard *amidships.

*amidships: the middle of the boat, outbound by the hull (versus dead center)
 

	← Inlets on port side   Starboard side inlets ↓
↑ click to enlarge ↑

Similar fittings are found on both port and starboard sides of this vessel.
50A 125/250V inlet	Under the round cover: Opened, male inlet for power (with the prongs)	power cord plugs into the boat
The female (has holes) plug attaches to the male (with prongs) and then is twisted to secure in place. This type is called a Twist Lock and is common on marine power cords. Marinco has been the most popular brand for decades.

Marinco Power Cord - 30 amps, 50'

For the curious, here are two power cords by Marinco. The 30A cord is significantly less costly  than the 50A (power cord. Both are 50' in length.   ← Affiliate Links →

Marinco Power Cord - 50 amps, 50'

These are the labeled port side inlets.

 

This picture ↑ appears innocent enough. Troubleshooting continued.
 

The situation is that inside the boat we have only a single leg of 125 volts
of power available, not the two that are live (hot/powered) inside that 50 Amp cord.

 

Troubleshooting continued. We peeked at the wires behind the inlets.

The forward inlet that we are utilizing has four wires on the back side.
 

Further aft, the second 50A 125/250 labeled power inlet has just three wires attached to the backside:

The missing wire attaches to one of the L-shaped prongs on the front.
 

After pulling the bundle of wires behind that inlet I could not find the missing black 8 gauge wire. It is not there. AND, that black is from an "L-shaped" prong. On 50 amp 125/250 volt cords the two L-shapes are both hot/powered. Each is 125 volts. So, the fact that there is no black wire running down to the panel MAY be an issue. Is it?
 

We have plugged into both the aft 125/250V inlet on the port side and the 125/250V inlet on the starboard side. Our panel voltage meter shows the same for all three 50A 125/250V inlets on this vessel. I am confused. Shouldn't all 125/250V inlets have four wires attached to the back. AND, plugging into all three outlets (two port, one starboard) result in the same bad news below, i.e. just one leg of 125 volt power arrives at the main panel.

THIS is the point where I should have looked at
the book describing the boat's wiring... But I didn't.

Instead of consulting the Power Connections paperwork for the vessel, I continued to troubleshoot the power situation. Fundamental errors were made.   #1) I believed the Marinco power inlet markings on the plug inlets and #2) I tried to understand why there were only three wires instead of the expected four.   Port Side aft 50A 125/250 inlet: Starboard Side 50A 125/250 inlet:

We tried all configurations of plugging in the Shore Power cord into every labeled 50A 125/250V inlet. Below, at the panel we still saw just one 125V leg with power. Argh!!!
 

Then I had the brilliant idea (Spoiler Alert: it wasn't!) to take apart the 50A 125/250V aft inlet on the port side. I wanted to switch the Red (hot) wire to that prong where the black belonged. I was so happy to have something that might work... except it would not. Here is why: The red wire runs down to the switch that functions perfectly. Merely switching the red to the black prong will change nothing. It will still end up at the exact same place/switch down below.
 

Part of problem solving is determining what is not
the problem. So far I am excelling at that component.
 

We clearly have multiple inlets for 50A 125/250V power. One appears to be wired
properly. Two are not. None provide power to the second leg of the electric panels below.

I finally figured out the problem is not the wiring. The Power Connections page is illuminating. (pun intended)

Tomorrow I will detail why there are 3-wire inlets labeled 50A 125/250V.
 

This is what the dock crew has been dealing with of late. As I wrote this article I did include our testing procedures. Though nothing was successful in solving the issue at hand, knowing what is not wrong is helpful. I do hope my failures will be enlightening to those of you who might face similar problems. I actually should have read the flipping book. A lot of time was wasted pondering when the answers were right where Sparky (the author) detailed them so many years ago.
 

Please be smarter than I was. And thanks for reading.
 

50A Power Cord Option to Save Money.

As mentioned in the previous article Troubleshooting a 50A Power Leg Problem, there are multiple ways to wire power into a boat. Most larger boats utilize 50A power. Today I will touch on one way to save money on wiring the inlets for power in your vessel. Aboard the yacht with the problem described in the Troubleshooting article, Sparky, the *ABYC certified wiring guy, installed multiple 50A 125/250V power cord inlets. This was both brilliant and dumb. Here is why.

*ABYC: American Boat and Yacht Council. The ABYC develop boat building and repair standards focusing on safety, equipment, installation, etc. ABYC also offers training and certification.
 

Aboard the vessel in question there are a total of five places to plug in a power cord.  Three are 50 amp power receptacles. Two are for 30 amp cords. The other inlets include a water fill station along with telephones (two) and a television connection point.
 

These are the port side inlets aboard the vessel:

Stainless Steel 30A 110V inlet

I was curious about those inlets. Therefore I checked on Amazon to see what power receptacles cost. On 31 August 2023, the 30 amp stainless steel inlet is nearly $90 however the 50A 125/250V inlet is a whopping $170, before tax!

Stainless Steel 50A 125/250V inlet

This boat usually utilizes a single 50A 125/250V power cord. Each leg described in the 50 Amp 125/250 Volt Power Plug Wiring How-To (4-wires) article feeds one 125V power distribution panel. She (the boat) also has one 30 amp power cord.
 

There are two HOT LEGS ↓ in the 50A 125/250V power cord. Each carries 125 volts. This was
detailed in the 50 Amp 125/250 Volt Power Plug Wiring How-To (4-wires) article.

 

As I can presently see on the Power Connections page, just because the inlet says on the face 50A 125/250V does NOT mean four wires are attached. Thus, two of the three labeled 125/250V power inlets are actually feeding just three wires below. Basically that means that instead of both 125 HOT slots having a wire running to the power panel below, only one hot is connected. Therefore those inlets are providing 30 amps to the electric panels.
 

On the starboard side the Power Connections paperwork clearly states:

 

In retrospect Sparky, the ABYC installer could have installed 30 amp inlets, thus saving a boatload of money. 30 amp receptacles cost $90 each, whereas the 50A 125/250V receptacle currently retails for $170, plus tax.
 

Below are pictured the starboard side power receptacles. Though one cord plugs into the 50A 125/250V power inlet, it is not wired inside the boat for both of those 125 volt legs. The two receptacles regardless of the fancy stainless cover individually provide 30 amps apiece. Each feeds one of the 125 volt power distribution panels.

The port side ↓ does have an actual 50A 125/250V power receptacle. In addition there is a 50A 125/250V pretender, wired to provide one leg of 30 amps below. Also one 30 amp/125 volt power inlet is installed on the port side.

Marinco Power Cord - 30 amps, 50'

For the curious, here are two power cords by Marinco used aboard the boat. The 30A cord, currently at $100 is significantly less costly  than the 50A power cord which retails for $365. Both are 50' in length.   ← Affiliate Links →

Marinco Power Cord - 50 amps, 50'

The brilliant part of the whole set-up was utilizing the 50A 125/250V cord as a 30 amp provider, in addition to a true 30 amp cord. The not-so-great part of that set-up is that the 50A cord was so costly. As the boat requires two lines of 125 volt power, having two 30 amp power cords would have been a better option in my opinion.
 

Of course most of us can spot places where we could have/would have/should have made changes. For instance, recently I had the wire from my power receptacle to the AC panel replaced with the same 10AWG wire as previously utilized. Now, a month later, I wish I had saved up to buy 3 strand 8AWG for that 12' length. On the other hand, I did have extra 10 gauge, so...!
 

If you have a vessel requiring 50A 125/250V power, may I be so bold as to suggest you rethink that? Consider simply using two 30A cords  to provide for your power requirements.
 

For me, the weight of a 50' 50 amp power cord is well
beyond my strength. Quite frankly, even my 30 amp cord is heavy.
 

That said, the wiring confusion is not the cause of the problem the yacht owner is experiencing. I chose to post this because figuring out why the second 125 volt power panel does not work interested me.  One panel functions well. The other does not. And that is the problem. Specifically this one power selection switch is most likely in need of replacement. Maybe.

So that is the story hereabouts. Seaweed and I did well during Hurricane Idalia. I was fortunate.

The final part of this series will be posted shortly. I really could use your guidance and advice on the problem switch. Stay tuned, and thank you for reading.
 

8awg Selector Switch Needed.

In the beginning, aka the 50 Amp 125/250 Volt Power Plug Wiring How-To (4-wires) article, the dockside fellows and I were attempting to track down why one leg of a yacht's power was not functioning. The critical side is of course the one that is not working. The switch powering the air-conditioners functions perfectly. The one supplying power to the battery chargers for both 12-volt and 32-volt battery banks, along with the refrigerator, staterooms, and main salon has zero voltage. Isolating what part needed replacement is the next step in the troubleshooting process.
 

We definitely have 125/250 volts into the vessel. From the side deck inlets power is fed to two switches. These switches are your basic On-Off-On, labeled 1-Off-2. They are large enough to accept a lot of 8 awg wires.

Selector #1 indicates shore power. Center is Off. #2 is for power incoming from the onboard diesel Onan generator.

 

This is the back of the switch:

 

Both the Port (on left) and Starboard (on right) power distribution switches are shown here:

The switch on the left powers the top air conditioning panel. The one on the right feeds power to the bottom house panel.
 

On power issues the standard process is to start at the source. Wherever the power stops is the problem.
 

This is the complete power panel for the vessel:

Each of the breakers are labeled. The top section is powering the four air conditioners and circulation (cooling) pump aboard this yacht.
 

The first set of meters is for the air-conditioning breakers. The meter on the
right shows 125 volts incoming. Thus we know the 1-off-2 switch on the left functions.

 

This is the Air Conditioning distribution panel. It is powered by the 1-off-2 switch on the left (port) side.

The amperes meter at the top shows zero power being used. That is because all of the air conditioners are turned off at present.
 

Travis ↓ is at the lower helm located in the main
salon of the yacht. There is an air-conditioner on that level.
 

The ac unit for the main salon runs off that top ac distribution panel via the main switch on the left.

 

We do have an anomaly: the bottom section of the ac distribution panel is not receiving power. Was this due to a broken connection between the shore inlet plug and the switch? To test that the onboard Onan generator was started. The results were unchanged.

When checking the power panel the same results occurred:

 

This second distribution panel is honestly the most critical of the two. The House breakers are for important things like the galley, all three staterooms, a 12 volt battery charger, the 32 volt battery charger, plus lights and more. Frankly, this one powers the "house" whereas the other makes it cool and comfortable aboard.

The 32-volt battery charger on that lower distribution panel is vital for charging the 32-volt battery banks.

The owner does not have a portable 32v charger, so having the house distribution panel functional is important.

I wrote about replacing those 32-volt batteries in the St. Pete's Electro Battery article.
 

The AIR CONDITIONING BREAKERS SWITCH ↓ is shown on the left. To the right is the ↓ HOUSE BREAKERS SWITCH.

Aboard this larger vessel are four air conditioners which provide zone cooling. Thus the need for a separate power panel for those AC units. The House is basically everything else running on standard *125 volt power, including the refrigerator/freezer, water heater, staterooms and heads, etc.

*125 volts: Though in this article we are using the term 125v, actually I use this interchangeably with 110v and 120v. This is your standard house power. Indeed 125 volts does reach the vessel. Aboard Seaweed I see 118v or so. Everything electric works fine.
 

The back of the distribution panel is a mass of wires:

 

Notes are also on the bulkhead regarding power cables:


 

There are a lot of wires aboard a larger yacht. It is complex.

Electrical gurus may be interested in these pictures. Click (or double click) to get the full sized versions.
The fourth picture and the one below each have two circle gizmo thingies on wires. I do not understand them, though I am curious. If you know could you please enlighten me? Either comment or send an email please to me at janice@janice142.com Thanks!

The top AIR CONDITIONING BREAKER PANEL ↓ has 125 volts of power, thus the switch on the top left works.
Because the bottom HOUSE BREAKER PANEL ↓ has zero incoming power I believe the switch on the top right is broken.

 

This is the back side of the selector switches shown above.

As a reminder, this is the back side... thus the problem switch is on the LEFT,
versus the right. There are a boat-load of 8awg wires feeding into those switches.

The proper way to verify that the bad switch is indeed not functioning would be to remove the wires from both switches and swap them. Quite frankly, that looks incredibly intimidating to me. All testing has proven power gets to both switches (verified via multimeter) however nothing passes though to the House Distribution panel from that second switch.
 

So, the decision was made. Replace this switch:

 

Here is the problem: The switch was manufactured in Austria. It was purchased some 20-odd years ago. The numbers do not match to anything I have seen online. That said, I am not great at searching. Can you help with a source to purchase a replacement?!?
 

The numbers written on the back of that switch are:
C63 63 amp.
50hp 600 V 3ph
A 211
 

What say the experts? Is there a work-around we have not considered? All of us here on the docks would appreciate your ideas. If you know where to buy a replacement, that would be ideal. I am hoping one of my online friends can help. Thanks!
 

That's it from the water. I thank you for reading.
 

title

?
And, ?
 

COMMENTS:
<iframe src="https://janice142.com/comments.php?kkey=A-title" width='100%' height='300%'></iframe>

© 2023

Categories: Boat Talk, Boats, Books, Characters, Gear, In the Bilges,

Anchorages, Becoming Clutter-Free, Boat Talk, Boats, Books, Channel Markers of Life, Characters, Comfort, DVDs, Entertainment, Fishing, Galley, Gear, Humor, In the Bilges, Locations, Memory Lane, Money, Organizing, Pets, Recipes, Recommendations, Relationships, Security, Simplify, Sojourners Saloon, Unmentionables, Vignettes, Wild Things, The Writer's Block, YouTube Channel,

fix this ~ Previous Post ...    ... Next Post ~ coming soon

First Mate's Gallery now open ~ Crew photos welcome via Email.

I am also an Amazon Affiliate.