Shore power short

[Bmarler]

Interestingly, when the harbor replaced the outlet, they told me exactly the same thing happened to another boat just a few boats down, at almost exactly the same time. Makes me think there was some kind of power surge or brownout or something.

power surge or brownout don't cause that sort of issue. it's just a coincidence that it happened when yours did. when you run electric heaters off shore power for extended periods you'll burn those plugs up. it's just the way it is. i've been living aboard for close to 30 years now, and i know, if you run on the edge of your 30 amps all winter you'll have trouble. all the trouble spots have been mentioned. wire and buss bar on the pedestal, receptacle, breaker, your cable, the wiring behind your shore inlet. the plugs are rated for thirty amps, but if you load them to that they'll fail. we're stuck with them though, it's what every marina has.

 

[Caballero II]

I agree that the L5-30 connectors just aren't robust enough for shore power use. The NEMA SS-1 and SS-2 connectors used for 50 amp are much better. They have more contact area, but they also have an outer sleeve that keeps things seated tighter and makes for better contact. The L5-30 relies entirely on the pins, so they move more, the contacts wear and get loose, and they fail.

For 30A, the IEC or smart plug connectors are much better. For 50A, I'm less convinced that the smart plug connectors offer much improvement.

I agree, and in fact I first tried to trade out my 30 amp receptacle on the boat for a 50 amp version, but the boat wiring could not except the 50 amp plug for some reason. So I went with the very expedient Smart Plug.

As for the more industrial plug and receptacle mentioned above, I know nothing about them other than the fact nobody I work with mentioned them as an option. The link on the article excerpt did not take me to a picture of them, so I don't really know what they are.

 

[Marco Flamingo]

As was mentioned, the shore power needs to be off every time before removing or plugging in the boat connection. You can hope that everything onboard is off and just get little unnoticeable sparks, but turning off at the shore power first is the only way to make sure that you don't get carbon and pitting building up over time.

I consider the old-style 30A connector perfectly adequate for <20A if care is taken by turning off shore power before connecting/disconnecting. If I ever thought I might go over 20A, especially when not onboard, I'd opt for a Smart Plug.

 

[Comodave]

If I still had L5-30 plugs and I intended on keeping them I would do thermal checks periodically to confirm they are not overheating.

I went with Smart Plugs on our last boat and it was one of the first things I changed on our new Formula. Formula actually had a system that prevented the problem by wiring the 50’ shore power cords directly to the breaker in the stern. It removed the L5-30 plug on the boat but created another problem in that you had to feed all 50’ of both cables in through a small hole in a locker on the transom. It basically took 2 people to do it so I had to change that. I installed 2 SmartPlug inlets and now it is simple and safe.

 

[Cartouche]

When I came to the boat today, the shore power was out. I eventually figured out that the breaker on the power supply on the dock had tripped. I unplugged the shore power cord, plugged it back in, and reset the breaker, and there was a big scary flash that fried my shore power cord and the area around the plug. Pictures attached.

I disconnected shore power and fired up the generator, and it charged normally and supplied AC through the inverter without any apparent problem. No breakers tripped on the boat at any point.

My question is whether the problem is a short or some other problem on the boat, or a problem with the power supply on the dock. I’m an ignoramus when it comes to electrical issues. Does anyone have any ideas?

Change your boat side to smart plug - Marinco connections when aged short and do exactly what you show, (they did on our boat) Hopefully you have 2 outlets connected for a boat your size, and if you are running the whole boat on (1) 30amp breaker this on a Marinco is also a cause. a https://www.marineoutfitters.ca/ind...0107|11997&product=67408611&code=614458746047

 

[sbu22]

But even if you still have the L5-30 connector on the dock and the Smart Plug on the boat you have moved the likelihood of a fire from the boat end to the dock end. I would much rather have a fire on the dock than on the boat.

Exactly! I wrestled with the two L5-30s on my boat for a decade or so. New cables, new connectors boat and cable side, religeous about using and replenishing di-electric grease - all to have baked & fried spots on the connectors after a while. Gave up, bit the bullet on Smart Plugs on the boat side. Makes me sleep better.

 

[bowball]

I replaced this 50 amp socket as it looked close to failure.