Check those shore power connections!

[oscar]

Helped a buddy move his boat today for haul out. He couldn't unplug one of the 30A shore power cords from the boat end, it was stuck. Several tools and a half hour later I had it all apart. It had gotten hot and plastic had melted and fused things together.

The wiring showed significant corrosion. So, that creates resistance which in turn causes heat, as well a voltage drop and then the amps go up to meet the wattage demand and keep the two A/C's (in his case) running.

He got close to a fire there. And, this is where a LOT if not most of the boat fires start.

So check those plugs and make sure they are not overheating!

 

[Comodave]

That is exactly why we went to Smart Plugs on our shore power cords.

 

[Bacchus]

Oscar
Its been awhile since I checked the stats but its interesting that more electrical boat fires are due to DC than AC. It goes against what many, myseld included, would think. I dont know but might guess there are more folks messing with DC systems that don't really know marine electrical and ABYC guidelines. Likely they figure its only 12V what can go wrong?
Here's a recent Boat US summary... DC about 3X the # of AC
https://www.boatus.com/seaworthy/magazine/2015/october/boat-fires.asp
No argument that boat inlet it worthy of frequent checks and good practices. And if a cord end looks suspect change the boat inlet at the same time. Both go bad and one bad end can damage a new mating one.

 

[sdowney717]

I wonder how many drop their cord ends in the water, then try to dry it and simply plug it back in. If it falls in the water you must rinse it out with fresh, and shake it out. I have accidently dropped it at least twice in 20 years. I bought my boat 20 years ago and the cord was old then, but still in ok shape, it does not get hot when used.

My typical amp draw is under 10 amps when there, and if I run ac and something else, it can approach 20 amps, but I dont live at the boat, so that does not happen often. So most of the time the only draw is the AC charger and fridge, so about 2 - 3 amps max all the time

 

[psneeld]

DC caused fires probably lead the stats because looking at total numbers, the boats with AC systems are few and far between.....even many of the smaller AC equipped boats have simple systems and many in cooler climatse don't have power hogs like air conditioners and are pulled out of the water before needing heat.

 

[oscar]

That is exactly why we went to Smart Plugs on our shore power cords.

While they are without doubt an excellent product, if they connect to marginal boat wiring, as was the case on my friend's boat, they won't make any difference.

Don't know the stats of AC vs DC calamities, but I disagree with the statement that "Boats with AC systems are far and few between." Every boat in my marina has a yellow umbilical to the shore power pedestal and other marinas are similar.

People want, and have, A/C, often multiple, heat, microwave/convection ovens, water heaters, large battery chargers and increasingly cook with electricity.

 

[rslifkin]

Don't know the stats of AC vs DC calamities, but I disagree with the statement that "Boats with AC systems are far and few between." Every boat in my marina has a yellow umbilical to the shore power pedestal and other marinas are similar.

Don't forget to account for the multitude of boats that are trailered and either have no A/C power or never get plugged in.

 

[psneeld]

While they are without doubt an excellent product, if they connect to marginal boat wiring, as was the case on my friend's boat, they won't make any difference.

Don't know the stats of AC vs DC calamities, but I disagree with the statement that "Boats with AC systems are far and few between." Every boat in my marina has a yellow umbilical to the shore power pedestal and other marinas are similar.

People want, and have, A/C, often multiple, heat, microwave/convection ovens, water heaters, large battery chargers and increasingly cook with electricity.

So you think nationwide the majority of boats in the US are even in marinas?

 

[Steve1.0]

The wiring showed significant corrosion. So, that creates resistance which in turn causes heat, as well a voltage drop and then the amps go up to meet the wattage demand and keep the two A/C's (in his case) running.

Pitting on the connector blades also causes significant resistance. Pitting is caused by unplugging the cord without shutting of the breaker in the pedestal FIRST! The spark that jumps from the live outlet to the cord, on the dock and onboard, takes a small bit of metal each time it is unplugged. This makes the contact area pitted (less contact more resistance) thus heat.

 

[ghost]

Oscar
Its been awhile since I checked the stats but its interesting that more electrical boat fires are due to DC than AC. It goes against what many, myseld included, would think. I dont know but might guess there are more folks messing with DC systems that don't really know marine electrical and ABYC guidelines. Likely they figure its only 12V what can go wrong?
Here's a recent Boat US summary... DC about 3X the # of AC
https://www.boatus.com/seaworthy/magazine/2015/october/boat-fires.asp
No argument that boat inlet it worthy of frequent checks and good practices. And if a cord end looks suspect change the boat inlet at the same time. Both go bad and one bad end can damage a new mating one.

It’s been awhile since I’ve looked at the boatus data, but it suffered from being a summary. It did not allow interrogation of the denominator for those stats. Think of it this way, there are a,greater numbers of small boats than trawler style boats and even boats with shore power only a small percentage use it in the way the typical trawler does. So their statistic while true, is not as applicable to the typical marina with a bunch of floating boats around 30 to 60 feet in size. I’d like to see the numbers with an appropriate classification.

 

[oscar]

Don't forget to account for the multitude of boats that are trailered and either have no A/C power or never get plugged in.

Fair enough. But this point, and the others like it, are academic and not germane to the thread, ie the usual argument for argument's sake.

The point of this thread was for those that DO have shore power, which includes MOST of the people on this forum based on the avatars I see, to keep a very close eye on them as they are frequently the cause of fire on vessels so equipped.

 

[tozz]

[snip]
Don't know the stats of AC vs DC calamities, but I disagree with the statement that "Boats with AC systems are far and few between." Every boat in my marina has a yellow umbilical to the shore power pedestal and other marinas are similar.

This is a weather v. climate statement. AC shore power dominant for the boats observed in a marina but at least here in Washington, boats in a marina are the vast minority overall. We have an estimated 243,000 registered recreational boats (updated 2020 number) and over 90% of them are trailerable and 26 ft or less.

"The most representative boat in the Washington fleet is an 18′ fiberglass or plastic-hulled runabout powered by one or more gasoline outboard motors."

Some interesting stats collected over at the UW sea grant site:

https://wsg.washington.edu/community-outreach/outreach-detail-pages/washington-state-boat-fleet/


-tozz

 

[Redhook98]

I went to Smart Plugs after this almost burned up my boat. Upgraded interior main wiring as well. I am usually fastidious when it comes to my connections. My Portuguese Bridge door hit my cables and shook one loose. That won't happen again.

 

[firehoser75]

Redhook, you were lucky in dodging one there!! I am happy that you did.
Good advice on turning off the breakers before unplugging (disconnecting), and ensure that they are off when first plugging in as well. Connect or disconnect in the correct order as well, but not as important if all power is off.

I am surprised at how often I see people walking along the dock with a live cord end in their hands! Not only dangerous, but could, overtime lead to an overheat as discussed.

 

[oscar]

Good advice on turning off the breakers before unplugging (disconnecting), and ensure that they are off when first plugging in as well.

Unless, like in my case, you have separate selector switches. No need to also turn off the breaker. Nothing is connected until you move the selector from GEN to SHORE or vice versa. Every boat is different.

 

[firehoser75]

Sure enough Oscar, but the general principle still applies.

 

[psneeld]

Ever notice how many melted plugs are reported/seen/encountered....but how few boat fires from that situation ever occur?

 

[oscar]

Ever notice how many melted plugs are reported/seen/encountered....but how few boat fires from that situation ever occur?

And you have data for this?

https://www.boatus.com/magazine/2018/april/analyzing-electrical-fires-on-boats.asp

 

[firehoser75]

Probably very true PS, but not a chance I feel should be taken. The boat next to me at an overnight dock had a small fire caused by this. Lucky, they woke up and dealt with it! They heard the popping and crackling near their berth/bed.

 

[psneeld]

And you have data for this?

https://www.boatus.com/magazine/2018/april/analyzing-electrical-fires-on-boats.asp

Just like your comment on most boats use AC...laughable.

No, I dont have stats and neither do you on melted plug ends, just real life experience and common sense. Like most dangers in life, the ultimate outcome is rare...thus the term "close call".

True, no one wants melted plugs or worse fire....but TF has to be one of the most fearmongering sources of info I frequent...granted I don't frequent many as my life revolves around boating both personally and professionally. So I keep to my lane most of the time.....comment on things close to my experience.

 

[Beaverlake]

Our marina’s old pedestals had no provision for attaching the “ring” to help insure a solid connection. I used a bungee cord carefully wrapping the cable and plug to the pedestal to keep everything aligned and solidly connected. Don’t know how that solid connection was impaired (male plug connectors were corrosion free and I use Boeshield liberally for corrosion protection), but it was. Fortunately a neighboring live aboard and the dock master were sharing a beer when the flames broke out. They saved the day - and the pedestal, but it was a reminder to make sure both ends of the cord are solidly connected to good wiring. Amazingly, the pedestal repair was only $70.

 

[ghost]

Not being a data expert hasn’t prevented some from trotting out the accurate but misleading boat us data quite often. Don’t know if it’s fear mongering or not, but in my area (your area of expertise?), there is a high percentage of marinas that have had boat fires in the winter and they rarely seem to burn just the culprit boat. I only wish I had accurate numbers on both the known and minor incidents and causes together with accurate counts of the population of wintering boats in the water, dimensional by length, type, age, ac power type, meter usage, etc. The boat US data would be a good start if they published enough attributes to be useful, but I’ve never seen it. What data I do have says that in my area, it’s a valid concern and cord sets have been accused frequently in the investigation. Subjective, yes. If somebody has the right cut of data, they have not shared it. Probably competitive advantage to keep that confidential.

I think you are right that there are a lot more cord failures than fires. That can be argued either way. What is the acceptable failure rate for cord failures that generate charred remains?

I’m in covered moorage and we won’t have burnout panels for quite a few years. It’s a target rich environment with the wooden marina construction from the 70’s. Witnessed quite a few boat fires locally and with a 40 year old boat in good condition, don’t think insurance would really make me whole. It might cover the value, but not the condition and upgrades. I guess if you want to call it fear mongering, fine. Maybe that’s even true in other geographic locations where unmonitored boats running heaters are less common.

Lots of locals here who hardly ever use their boats with dodgy cords, running heaters, etc... Of the major marinas in my town of Anacortes and nearby LaConner. I can’t think of one that has not had a fire in recent memory. Maybe Fidalgo hasn’t, and my own marina has been almost ten years I’d think which is super as long as it doesn’t indicate we are overdue. We spend very conscious time monitoring cord sets on our docks. Time will tell I guess. My friend is a firefighter and a live aboard in town and we have talked annually about the issue. Maybe we are fear mongering paranoid, but it’s not because the fires caused by cord sets are rare.

Yeah, it is definitely one of my bigger long term worries. As someone who works with data professionally, I’d love to see the real risk rate in useful measurements, but Empirically I deeply suspect that a view of data that convinces me this is no big issue is not going to materialize.

 

[rslifkin]

With covered docks, in my mind, there should be sprinklers placed to provide a water curtain between boats. That would buy a lot of time in a fire before it spreads to a bunch of neighboring boats, unless of course the overhead goes up too easily (even with sprinklers).

 

[Fletcher500]

Rslifkin, a typical closed head sprinkler system of light to moderate design (roughly .20 gpm/sq. ft end head density to around .30) will not provide a suitable water curtain to prevent spread between adjacent boats that are essentially oil in solid form. High density water based systems (>.60 gym/sq.) are used in aircraft hangers of similar combustible loading to a boat house. These are often open head (deluge), foam (often AFFF), and they are supplied by a fire pump that is turned by a Diesel engine or electric motor boosting the public pressure up to make it all happen. Sprinklers over the typical boat house can provide some cooling and delay fire spread during the incipient growth stage and likely help with egress times for people to get out, but once things get going you need a heavy industrial system as I have described above to provide any degree of actual fire protection from a property protection standpoint.

 

[rslifkin]

Rslifkin, a typical closed head sprinkler system of light to moderate design (roughly .20 gpm/sq. ft end head density to around .30) will not provide a suitable water curtain to prevent spread between adjacent boats that are essentially oil in solid form. High density water based systems (>.60 gym/sq.) are used in aircraft hangers of similar combustible loading to a boat house. These are often open head (deluge), foam (often AFFF), and they are supplied by a fire pump that is turned by a Diesel engine or electric motor boosting the public pressure up to make it all happen. Sprinklers over the typical boat house can provide some cooling and delay fire spread during the incipient growth stage and likely help with egress times for people to get out, but once things get going you need a heavy industrial system as I have described above to provide any degree of actual fire protection from a property protection standpoint.

It would take a good bit of water, but it could be kept more manageable if the system were zoned. No need to dump water 5 boats away from the burning one.

I also wouldn't expect sprinklers to prevent spread, but keeping the surrounding boats cooler and delaying damage can buy an extra few minutes for the fire department to show up.

 

[psneeld]

I will bet again the fires start within the boat from poor wiring or overloaded multi outlets or extension cords...not from a melting shore power cords.

Not saying it never happens, but not as often as many think. Look at all the melted plugs with no fire or one that burns up a pedestal and nothing more.

Until I see stats, I am skeptical its this huge issue....one to be aware of but vigilance probably goes a long way to charred prongs and no fire.

Or if still dealing with crappy NEMA 30A plugs, sure I guess Smart Plugs are a good idea if not upgrading to standard 125V/250V 50A service.

 

[Fletcher500]

Rslifin, you are making comments about a subject that you are not familiar with.

 

[Xsbank]

My opinion is that almost all boats involved in power cord failures or fires are overloading their systems. Lots of owners feel that if they have 30 amps available its OK to run the toaster, the charger, the fridge, the microwave and a cabin heater or two, the water tank and cell phone chargers, maybe some lights. Fresh water pump? All are considered to be able to be running on the boat, just not all at once. However, for 30 amps you only have about 3000 watts to play with and every watt that is taken from the system above that will cause overloading; the power will find the weakest, most vulnerable circuit and burn it or blow it. Breakers are designed with a buffer and some are designed to be very slow to blow and ALL of them are designed to primarily protect from shorts. Most all breakers are less effective with an overloading situation. Remember those old power company ads that showed an extension cord plugged into another extension cord with all the sockets filled and the video showing it bursting into flames? House burns down, breaker intact.

If your cord is in good shape and you have checked your connections, there should be zero (none) heat in the cord or you are overloaded. Your cord is acting like a heater because there is too much current in the circuit and you are courting disaster. Make a list of everything you expect to have running on the boat, check its wattage (eg one toaster, 1500) and decide what very few systems you can leave powered while plugged in. Even a cell phone charger takes power.

A Smart Plug may make a better connection but it is called "smart" because it was designed with a thermostat that cuts power if the cord gets too hot. Early Smart Plug failures were because of that doodad. But guess what happens if you have a great connection at the dock and you still overload? The fire will start in your electrical box or under the bed or the wheelhouse and it is just as bad. It finds the weak link. If nothing else, the old dock cords provide a very crude breaker themselves, you will be very lucky if you overload your dock cord and it fails from overloading and it just burns itself out instead of surviving so that the weak spot in the boat starts the fire.

 

[Skeeter]

I had nothing but problems with these type of connectors, forever replacing them.
I switched to Bulgin bulkhead connectors on the house and on the end of my shore power cords and they are great.
Screw ring for tight connection and integral seals make them water tight

https://www.bulgin.com/products/pub/media/import/attachments/Circular_Power_Connectors.pdf

Reasonably priced too!!!!!

Cheers

 

[Comodave]

No, the wires in the boat are not the weak link if the boat is wired properly. The L5-30 plugs are the weak link. The contact area is just too small and if you run much over 25 amps they tend to overheat and get worse as time goes by. The wiring in the boat has permanent connections so they don’t overheat if the wire is sized properly and has overcurrent protection. If the boat isn’t wired properly then all bets are off but that isn’t typically the case.