50 amp shore power cord

Russ Calasant

Russ Calasant

Active Member
Dec 9, 2009
2,128
East Greenwich, RI
Boat Info
2001 480 DB
Engines
CAT 3196
I bought a used "working" shore power cord to leave on the dock. When I plug it in I'm getting 110v on the female end, shouldn't this be reading 250? How does that work? I have always had single or double 110v shore power. This boat is 250v, if I plug the boats cord directly there are no problems. If I plug the boat cable into this used cord I am only showing half or less voltage on the panel. Help!?
 
Not all 50amp cords are 220v. On my parents Carver, they're only 110v.

I just re-read your post. Is it a 4 prong plug? If so, it sounds like you're missing a leg of 110v.
 
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Some boats have an internal transformer stepping the 250V down to 110V...perhaps your boat can handle either 250V or 110V. Check and see.....some Sea Rays within the same model have the transformer, and some don't.

Don
 
Russ, take a look at the plug end. It should tell you if it is 125v or 250 v. I'm guessing you bought a 125v cord.
 
230 and 115 plugs/outlets will not interchange so it appears one or more conductors are broken inside the cable jacket. Have you checked all the conductors for continutity?
 
If you have a 50amp 250volt rated cord, the cord cap should have 4 prongs (2) hots, (1) neutral and (1) ground. If your cords have this NEMA configuration you may check the receptacle on the dock to see what the output voltage is. Maybe they lost a leg?
 
It is a 125/250v 50 amp cord. I know the boat and the dock are good. It is a three prong cord, just like the cable master cord on the boat. I measured 110v at the female end but have not yet done a continuity test. If the dock is 110, not 250, something in the boat has to be stepping up the voltage when I plug in directly, not using the extention. For some reason when I use the new/used cable I'm getting the 110 from the dock but it's not being converted to 250? I disassembled both ends of the cord set and cleaned the connections, no issues noted - white, green and black heavy gauge wire, plugs in good shape.
 
White green and black wires means 120 volts. If it were 250 volts and 3 prongs it should be green black and red but you never know if someone swapped the ends. Do you have a transformer on the boat? My friends 460 has a 50a 250v cord.
 
Russ,
If I follow you correctly, when you plug in the cord from the boat directly into the dock power, you have 250v, but if you use this cord as basically an "extension cord" between the boat cord and the dock power you only have 125v. Is that correct? If so, then you are missing a hot leg. You should be able to use a conductivity tester to see which one is not working. If your 250v cord plugs into the dock, I would have to believe the dock power receptacle is wired for 250v.
 
Interesting. The Hubbell ends have a red fourth hole for a wire but the cable itself only has 3 wires. The connectors on both ends do say 125/250 on them and look original. Is it possible they just used the 250 connectors on a 125 only cable? This sucks.

So the dock can be wired for 125 and 250 and depending on which cable you plug in it could deliver either?

I thought the prongs themselves were different. If they are both three prongs what does the fourth wire do? I thought I read that was a ground. I'm still confused.
 
cod said:
Russ,
If I follow you correctly, when you plug in the cord from the boat directly into the dock power, you have 250v, but if you use this cord as basically an "extension cord" between the boat cord and the dock power you only have 125v. Is that correct?

Exactly


If so, then you are missing a hot leg. You should be able to use a conductivity tester to see which one is not working. If your 250v cord plugs into the dock, I would have to believe the dock power receptacle is wired for 250v.
Click to expand...

it does work when plugged into the dock. I just wanted to leave it so I would not have to spool out all that cord while at the dock bow in. My slip is right on the Mystic River so stern out is the preferred way, I expect not the case in transient slips and will back in.
 
Russ,
Does this cord have molded ends? Or is it "home made"? It should be 4 wire cable used for this to work... If it's not 4 wire, you will never get 240V out of it properly.
 
Larry it's an older Hubbell cord set with the rubber end caps and I have slowly conceded to the fact that I'm going to have to buy another one if I want a "dock cord". That's why I bought used so I didn't have to spend so much for just a dock extension but my boat cord is just long enough if I drape it over the boat, PIA. My concern now is that unless a seller knows for sure you can't really tell if it's 250. My connectors state 125/250 so I thought it was the right one (seller also said it was), it's not, it only has 3 wires but unless I had taken it apart how would I have known? I see that Defender has one for $430, better than $700, maybe I will just break down and buy it.
 
390x said:
It can work with three wires. Two hots and a neutral.
Click to expand...

Theoretically you're right. But, the ground wire will be missing from the picture and the legs have to match to get 2 hots and negative side.

Russ, how about posting a pictures so we can clearly see what you got?

I never had a boat with 240v, but my understanding is that if you have a cable marked 125/250v this means that there should be another component involved to make it work. There's no magic, if this is a 3 leg cable, then it's 125v. If you have two of the cables they can/should be plugged in to a converter to produce single 250v output.
 
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It is so marked and I don't think there is another component. I'm not sure what you are talking about with two cables Alex but there is a cable on the boat in the cable master and the cable we are talking about that I was attempting to use as an extension. The male plug end from the boat has three prongs and looks just like the male plug on the "extension" cord that I'm plugging into the dock. The female end of the extension cord plugs into the male end of the boat cord as it should. When it is I am showing low voltage on the panel and reading 110 at the female extension plug, like it's missing a leg. It has 3 wires, not 4.
 
Russ Calasant said:
It is so marked and I don't think there is another component. I'm not sure what you are talking about with two cables Alex but there is a cable on the boat in the cable master and the cable we are talking about that I was attempting to use as an extension. The male plug end from the boat has three prongs and looks just like the male plug on the "extension" cord that I'm plugging into the dock. The female end of the extension cord plugs into the male end of the boat cord as it should. When it is I am showing low voltage on the panel and reading 110 at the female extension plug, like it's missing a leg. It has 3 wires, not 4.
Click to expand...

Ah, I see now. I thought that you wanted to have two sets of cables. One for home port and another as a travel set. But, if this is the one that's just an extension then obviously the situation is simple. If it's missing a leg, then there's your answer. However, going back to my comment about 2nd cable. If you have two of those 3 leg cables going in to a Y-converter 125/250v, then you can plug your original cable and have it extended. But, to keep things simple, I think you just need to get single 4 leg 250v cord.

Get the right cable and sell the 3-leg one on ebay or CL.
 
Yeah, I'm just concerned now that this one is marked 125/250 and is not, I don't want to make this mistake again. The 250 is still a 3 prong plug and looks the same, where is the 4th wire going?
 
The markings on the plug that say 125/250 50A is a configuration design, there are 250V 50A plugs as well and these have a different plug configuration (they will not mate together). your boat uses the 125/250V 50A configuration... That being said and the fact that you have only 3 wires, leaves you SOL! There was a guy by me I was talking to last week that was selling a 50' 125/250V 50A cable, he said it was 4 years old (all molded ends) and was asking $275... I can see if he still has it?
 
If the plug and receptacle end say 125/250 and they are molded ends, factory ends, you won't see 4 blades, the outer shell is the ground. read the cable itself, it should have marking's on it, part of it should say 6/4 marine cable, if so, it does have 4 wires, you may just have a bad end, easy to replace for about $100.00. Bob
 
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