Shore Power Cord Burn

[leighunt]

My husband and I own a 2015 28 Cutwater and have enjoyed cruising the FL Gulf Coast over the past year. This weekend when we were about to shut down and disconnect from shore power my husband noticed a burning electrical smell in the cockpit. We immediately shut down breakers and disconnected the Fusion cord from shore power. I have a photo but don't know how to attach in this forum yet. Two of the spaces on the plug are black and badly melted. Thankfully this didn't happen during the night or while away at dinner or we might have had a boat fire! When plugging up to shore power we are always careful to have all breakers off and marina breaker off as well before connecting and powering up breakers. We do run a heavy load while on shore power with AC, hot water heater, microwave and basically everything in the on position except the electric stove which we rarely use. On a couple of occasions power has tripped because a hair dryer was turned on while the AC was running. When that has happened we turn breakers off and trip the main breaker switch under the stove. I would like advice as to why you think this has happened and what we need to do to avoid this problem in the future. In addition to replacing the power cord, do we need a marine electrician to check the boat power connection and wires leading to it for possible damage? I look forward to hearing from you.
Leigh Hunt
Tampa, FL

 

[knotflying]

This is not uncommon. You need to make sure that your contacts are clean on the plug and the receptacle. I changed mine to a smart plug, which will trip when it reaches a certain temperature. I would definitely recommend switching it out. Here is a link to Defender for the plug and receptacle. It is a pretty easy project and well worth the safety.

http://www.defender.com/product.jsp?path=-1|328|2290035|2290039&id=3482949

 

[leighunt]

The Smart Plug is sounding like a good idea! You'd think they would install this as a safety feature from the factory. Thank you for your reply.

 

[NorthernFocus]

When you say "melted" do you mean the plastic or the metal stabs? If it's the plastic it may be simply from dirty contacts as Mike indicated. But if the metal stabs have melted spots on them, that is typically due to arcing. That occurs when the contacts make/break while there is a load on the system. You want to ensure that the plug/receptacle connection is tight to avoid this. Ensure that you twist the plug to lock it in and tighten the threaded collar to keep it tight. The collar is there to keep the plug from working loose. If the plug starts feeling "sloppy" when you plug it in it's a good idea to replace the plug and/or receptacle. A good connection is particularly important if the system runs heavily loaded as you indicated.

Plug problems like this are dangerous because they can occur without any increase in total amp draw on the system. So the boat and/or dock circuit breakers won't necessarily protect from this type of issue.

 

[leighunt]

The melting is all around two of the plastic female connectors on the plug. When we get back to boat we'll check to see if the metal prongs on boat look damaged. Starting over with installation of new Smart Plug system might make us feel a little safer.

 

[bradcarolR29S]

This spring I noticed some arcing damage on the shore power plug and receptacle. I promptly replaced both with a Smart Plug. It is far superior to the old twist types.

 

[Brian B]

This spring I noticed some arcing damage on the shore power plug and receptacle. I promptly replaced both with a Smart Plug. It is far superior to the old twist types.

I did the same this year also. Check pricing on Ebay, there was a dealer in FL who had excellent pricing.

 

[knotflying]

Also keep in mind that just because you have a smart plug it does not negate maintenance. It is always wise to make sure the contacts are clean. When you install the male end to the boat use either Corrosion Block or dielectric grease to keep the connections behind the liner as corrosion free as possible. I would do the same on the connections for the female end on the cord.

 

[doke01]

This is 'normal' if you don't make sure all of the AC on the boat is turned off prior to attaching/detaching the power cord to prevent arching. I had the same issue and did a ton of research on it. I had to replace the male side on the boat also. Make sure you look at it and replace, if needed. Once you get enough arching their is carbon build up, which increases resistance, and causes excessive heating. The insulation on the male side (you need to pull off the outlet to check) was also melted so badly bare copper wire was showing. The plastic was actually brittle and fell apart in my hands.

It is obviously a known issue by the outlet manufacturer since they sell just the male portion of the outlet, without the metal cover included.

 

[Spinner]

Glen Wagner (Journey) gave me good advice - first make sure that the prongs are free of corrosion,then fill up the slots with dialectic grease before you plug the shore power back into the boat. Since I keep the cord plugged in, this is a simple way to prevent corrosion and therefore overheating at the connection.

 

[Levitation]

This is what it looks like.
gallery2.php?g2_itemId=46209

 

[Scuffy]

The Smart Plug setup offers about 20% more contact area so they say. We find them to be a lot easier to plug in given the location of the receptacle. Plus the receptacle cover keeps the plug locked in. As mentioned before the thermal breaker cuts power if heat builds up for whatever reason. Shore power connections are one of the leading causes of boat fires. We changed out our standard receptacle for the Smart Plug setup. Then we also opted to use our existing power cord and changed out the plug on that to the Smart Plug type. That seemed to be cheaper than buying a whole new Smart Plug equipped power cord. We had done the same switch out on a previous boat. Never had an issue with it nor has the new owner. If anyone wants our standard factory supplied shore power receptacle which is in good shape as far as I can tell. If someone wants it just send me a pm. You will only pay for the shipping.