fried power cord

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J

John Dodge

We spent a wonderful weekend at a marina on Swan Creek, Md We arrived on Friday at noon and plugged in to the shore power and turned on the AC today, Monday I had trouble disconnecting the power cord (30 amp.) once I got it off I noticed it was burned pretty bad the recepticle was also damaged as well. I plan to replace both recepticle and power cord in the next 24 hrs. Any explanation for this? the circut breaker never showed a problem.
 
Jun 4, 2004
56
- - Sasafrass
Been there

Happened to me also. The cord was not tightly connected to the recepticle creating a hot spot. From an draw stand point you weren't pulling that much you were just pulling it thru a small spot on the plug and that spot over heated. Make sure in the future the plug is installed all the way and twisted and the support ring in screwed all the way on.
 
Jun 4, 2004
629
Sailboat - 48N x 89W
and

NEVER disconnect the cord from the receptacle "under load". Turn off all power before removing cord.
 
K

Karl

Karl

The problem was that either your power cord or your receptical we're corroded or perhaps both. Or you may not have screwed the power cord in tight enough. This caused arching and heat, thus destroying the cable and plug. Replacing both and you should be fine.
 
J

Jay

John

I have nothing to add about the power, but can I ask where you stayed in Swan Creek, how crowded was it over the 4th weekend, did you reserve ahead, etc.? Any problems getting past the shoal before Rock Hall, and what's your draft? I've been looking into places to cruise, so anything you can share would be welcome. Glad you had a nice weekend.
 
J

John Dodge

Swan Creek

We stayed at the Osprey Point Marina, Nice place. I think it was $2.00 per ft. Nice showers pool. Bicycles available to ride into town or walk about one mile. My draft is 4' 3'' We honored marker #3 with 12 foot of water. then it was into swan creek just followed the markers 9 -12 ft of water.
 
Jul 1, 1998
3,062
Hunter Legend 35 Poulsbo/Semiahmoo WA
Maybe your engine!

Well.... you know, the cause of the problem may have started with your engine. What happens with the shorepower connectors is that the set screws have to hold the wires really tight. A loosening of a set screw on the boat shorepower connection at some point will cause the connection to become poor to the point of increased resistance which will then result in heat. What causes the set screw to become loose? One culprit can be the engine (do you have a diesel?) The diesel causes the whole boat to shake including wires. The wire to the back of the shorepower connector might not have good support and it will sit there and vibrate - result: loss of pressure on the set screw. I'm not surprised the breaker didn't trip because the problem was more likely a lack of current vice too much. What do you think? Does this look like your situation? Also, if your engine is a diesel then other contacts can be at risk too so be on the lookout. For example, check the screws on the back of the electrical panel for tightness, especially the jumpers because they carry the bulk of the current for each row of breakers. Please let us know what you find out (i.e., feedback).
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
Just replaced a couple in our harbor.

Personally I do not think that starting the engine with the power cord connect, diesel vibration or any of these other theories hold a lot of water. I believe that it is electrical resistance is the culprit. There is little telling what is going on inside these plugs. Once you get enough resistance there is going to be additional heat and more corrosion. It may be prudent to just plan on replacing your shore power cord every 5-10 years. Whenever you see the least bit of discoloration. We just had this problem on two boats in our marina. It all started with using 120vac space heaters. The cords are pulling a lot of load with the space heaters, water heaters, chargers and other AC loads on these cords. We had breakers popping too. We changed out the cords and everything has settled down. I have personally started my engine with the power cord connected for 18 years. I am not saying that this is absolutely NOT the problem, but have never heard that it is not a wise thing to do or not.
 
J

Jay

Swan Creek

Sounds like a nice place. I only asked about the shoals + draft because I read some postings elsewhere where people were discussing difficulty with the depth entering the Rock Hall harbour area. Thanks for the info, John. Regards, Jay
 
Jun 4, 2004
844
Hunter 28.5 Tolchester, MD
Swan Creek

Responding to the Swan Creek questions: I wouldn't suggest crossing the bar unless you have 'local knowledge' and under 4' draft. Green Can #3 at the south end of the bar is sometimes difficult to see so it's a good idea to have it logged in on your GPS. Saturday & Sunday there was a constant stream of boats to Rock Hall as well as all the way in to Swan Creek. The channel runs almost due North passing the sea wall of Gratitude Marina and at that point there are several red marks up to and around the bend in the channel into the creek itself, Continue to honor ALL the marks and don't cut the corner to turn North too soon. Depths hold consistently to about 5-7 feet fairly far back - just remember to figure the low tide. July 3rd, Swan Creek was probably the third largest 'city' on the Eastern Shore. Fortunately, while we were there everyone was holding in the same direction to both wind and tide. I can't say what happened later in the evening as we needed to leave for home, but there were an awful lot of boats and more comming in all the while.
 
Jul 1, 1998
3,062
Hunter Legend 35 Poulsbo/Semiahmoo WA
Starting w/ engine elaboration

As a little elaboration with regard to "starting with the engine", by that I meant that the diesel engine may have initiated the problem, that is, the loosening of a set screw. I did not mean that by starting the engine with the shore power cord connected would be a problem. The diesel engine causes constant vibrations which over time can cause metal fatigue. The same mechanical vibrations will cause a length of wire to vibrate and what I was trying to point out was that a foot or two of unanchored three conductor cable going into the back of the shorepower connector will also vibrate which can result in the loosening of the connection. The conductors are stranded copper wire and the copper is a soft metal which will deform easily. One solution told to me by a respected marine electrician to mitigate the wire vibration is to apply silicone sealant to the conductors where they enter the back of the receptacle. This makes sense as the silicone will help to dampen the vibration as well as inhibit corrosion.
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
John, It was a holy mess.

John: When we replaced the receptical it was burnt quite badly. The plastic cover on the back of the unit was melted and the cord (female) end was blackened. The wires were still intact (except the ones that had burnt). Anyway, it is prudent to check these out once in a while. If you are having any AC electrical problems (blowing breakers, low voltage), the cord and recepticals are a good place to start.
 
Jul 12, 2004
285
Catalina 320 chestertown
Swan Creek

Jay, Swan Creek is a great place to stay, either in a marina or anchor out. Over the 4th it is always very crowded. If you are interested in places to sail, pick up a Chesapeake Crusing Guide. It is a great book. If you want to exchange some places to anchor out, contact me off-line at ilove2sail@intercom.net I am very familar with Pasadena, Annapolis, Chester River, and several places on the Eastern Shore all the way to Solomons Island and part of the Patomic. Paul
 
T

Tim Welsh

wires on the back side of inlet receptacle

I ruined a new 30amp lighted shorepower cord because the wires connecting the inlet receptacle on my boat were bad corroded and caused a hot spot. I replaced the receptacle and cord and have not had another problem since. Had to strip the wire back until I could find no more corrosion. Tim Welsh H34 AKA Cabo Wabo
 
Jul 1, 1998
3,062
Hunter Legend 35 Poulsbo/Semiahmoo WA
Just Had Loose Wires on Running Lights

Steve - totally agree about checking screws on terminals once in a while. In fact, a few days ago I had a Coast Guard safety inspection on my boat and learned that the bow running lights didn't work. Neither of them. That really surprised me because just a couple days earlier we were out late and I had the running lights on and they worked just fine so that left me puzzeled. Turned out the set screw that held the white wires on the stb'd light was loose! The conductor goes from the panel to the stb'd light and then to the port light so neither of 'em worked. In the past I've found "loose" screws on the backside of the panel mostly just needing a quarter turn or so to make them good and tight but once had a jumper wire come loose enough that the radar, gps, and autopilot started having problems all at once - in pea soup fog! And in an area with lots of traffic and rocks. Not your fun experience. Someday when the wife is on shore shopping it would be a good idea to go around the boat with a screwdriver and check those terminal screws for tightness. Maybe even paint a dab of locktight on the side of the screw head as a check to see if it ever moved? Picture attached is Oro Bay between Tacoma and Olympia with "sleeping" Mt. Rainer in the background. This is where I discovered my loose running light screw over this fourth of July weekend.
 
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