Faulty 12 volt power point socket Fire put out with a jar of olives in Brine

[kryg]

I just experienced my first Electrical fire after 28 years owning my boat.

I wanted to share with you, today’s experience, so boat owners who have 12 volt female socket on board take care. About two years ago I installed what looked like a robust 12 volt duel all-weather power point socket. Mounted in my galley bulk head.

Background: These ones are the best most robust one I could find. Over a few years of continued use I experienced no issues of over heating.

As I had in the past I had bought a number of what I thought was quality 12 volt power sockets from a Marine store. I discovered that after some use they showed signs of heat deformed internals at the wire soldered to connectors on the internal plastic wire mounts, they where not up to the job of daily use in fact proved potential fire danger. So I changed them.

What happened? As normal I plug in a small 12 pump into the socket, with in a few seconds a short occurred inside the 12 volt power socket the plastic shorted and started to burn its housing where the Positive and Negative wires internally wired and sealed by the manufacture.

The fire was so quick to ignite, it stated to burn the boats bulkhead in seconds. Even though I had a fire extinguisher next to the fire, it was quicker to put it out with a large jar of olives in brine. (in the clean up I'm still finding olives in the odd places) Instantly I knew had a I put the fire extinguisher into operation it would have spread far larger area and quicker into the boats wood work as the boat is fitted out in light weight wood laminated balsa core to keep it light.

See photos of failed 12 volt unit. Now I have three others on board I will need to find ones that can't fail like this one has if anyone has a brand that is fire and short proof please let me know.

For the first time I experience how a fire in a few moments can destroy a boat because of faulty design or workmanship, After the internal short of the internal wire connecters the fire took hold by burning the surounding plastic housing at athat point then the bulkhead started to burn. Frankly lucky I was standing a few feet from the ignition to put it out so quickly. .
.

[smac999]

looks like it wasn't fused.... what size fuse did you have on the wire on the battery side?

[yachtsailing.gr]

Glad to see that you found a solution before it's too late. For what are you using these sockets? For usb chargers or something else? You can put on your next installation a fuse just after the 12v connection of the socket 1-2 amperes more than your devices need.

[rwidman]

Nothing is fire or short proof. Typical 12 volt outlets are a poor design left over from the cigarette lighter days. All it takes is a loose or corroded connection to overheat and possibly start a fire. By their design, these outlets are subject to loose connections and corroding of the positive contact.


BTW: Attempting to put out an electrical fire with water (or brine which is salt water) is not a good idea. Read up on the types of fire extinguishers and which to use on what type of fire. And it goes without saying (but I'll say it anyway) that the circuit should be properly protected with a fuse or circuit breaker.

[witzgall]

Fuse at the source would be my first suspect. I think these outlets are rated at a max of 8A at 12v, maybe less. So corrosion (it was in the galley) + high-amp usage (what were you plugging in??) + maybe less then stellar construction + no fuse at the unit?


On our last boat (wauquiez), we had some European two-pin connectors throughout the boat. I made up an adapter to plug in Cig lighter type items. Maybe that is a better way to go, with a Hella plug or something like it?


We have two of these cig lighter plugs on gossamer, I am going to inspect them both tonight, especially the one in the cockpit!


Thanks for sharing,
Chris

[a64pilot]

Guy's he was plugging in a pump, no idea of amperage, but here is the rub.
If you fuse these things to be able to work with higher amp loads like spotlights etc, then there is way more than enough current for a short to cause a fire, without popping the fuse.
I have five of these things on my boat and they have always made me a little nervous.
I'd think a twin wire, waterproof "plug" similar to what CPT uses to power my autopilot might just be a smarter plug than a Cigarette lighter.

Bottom of page, they don't make it of course, they buy and re-sell I'm sure, but it is an O-ring sealed, completely water proof connection when connected

Order Parts - CPT Autopilot Inc.

[GordMay]

For 12 Volt DC accessories, I use “Midget Twist-Lock Devices” (2 Pole, 2 Wire, Polarized, NEMA Code ML-1), such as the:
Hubbell #HBL7526C Flanged Receptacle (or Cooper #7468 etc.)
Standard Weather-Proof Coverplates are readily available available.
Mated with the:
Hubbell #HBL7545C Plug (male cord cap) (or Cooper #7467 etc.)
The series even has a female cord cap (to make an extension cord) #HBL7506C (or Cooper #7464N etc.)

Although these devices are intended for AC use (UL rated for 15A 125VAC - polarized), they are an excellent alternative to the conventional DC outlets.
They are rugged, corrosion resistant, easily installed, attractive, and best of all “Twist-Lock”.

Not normally available at Marine stores, these NEMA type "ML-1" Midget devices are available at any good Electrical (or Industrial) Distribution Supply house.

Unfortunately, they are expensive.
➥ http://www.stayonline.com/detail.aspx?id=8797

[a64pilot]

My issue with that is I am sure the wife or kids would plug their curling iron into the 12 VDC plug, or worse, plug my handheld VHF charger or spotlight into 120 VAC

My use constant of 12 VDC is for our CPAP machines, it is much more efficient to run them off of 12VDC direct than it is to run the inverter all night and convert DC to AC to DC, I just installed two Cigarette lighter receptacles in the cabin to power them, maybe I ought to just wire direct and skip the plugs? Issue is we are asleep when these things are in use.

[btrayfors]

My boat was built in Hong Kong by Cheoy Lee in the 1980's. It came with both AC and DC sockets located throughout the boat.

The 120VAC sockets are the standard 2-prong plus ground used throughout the U.S. They look like this one:


The 12VDC sockets are very robust and unique on a small boat, I think. They are standard 250V 15A plugs & sockets like this one:


These use flat blades which are oriented 90-degrees differently than the 120VAC plugs. They cannot be confused with one another. Additionally, these plugs are very robust, and are generally available at reasonable prices at Home Depot or Lowes or any electrical supply house, e.g.,
Shop Hubbell 15-Amp 250-Volt Black/White 3-Wire Grounding at Lowes.com

I have made up several small pigtails with various connectors at one end which allow me to plug in 12VDC equipment as needed: pumps, lights, fans, etc. Works well for me; no problems in 26 years.

BTW, all my sockets are clearly labled "12VDC".

Bill

[a64pilot]

Flat plugs would help, labeling it wouldn't.

Yesterday I noticed oil on the garage floor where the wife's car is parked, kid had just changed oil.
So I called her and asked what the oil pressure was as I was worried. She had no idea, I've tried for years to get her to read the manual, it isn't happening.

Hope you can understand why I have to have it so the plugs cannot be inserted wrong.

[btrayfors]

Originally Posted by a64pilot

.....

Hope you can understand why I have to have it so the plugs cannot be inserted wrong.

I do. And, with the system I mentioned, the plugs cannot be inserted wrong.

The labeling is just so those unfamiliar with the boat can find a 12VDC socket.

Bill

[GordMay]

Originally Posted by a64pilot

My issue with that is I am sure the wife or kids would plug their curling iron into the 12 VDC plug, or worse...

The Midget Twist-Lock Devices, I recommended, are a unique Midget, Twistlock, Polarized design like this:

[Frankly]

After noticing that the CL style connectors can get hot powering their rated 10A, I fused all mine at 5 amps (got a bunch around the boat including the USB chargers). That takes care of most of the loads that I typically plug in. For the spot light Marinco makes a similar styled connector for trolling motors that is rated at 40 amps. Kind of a PITA to plug/ unplug but O ring sealed and up to the job. A serious connector and not really that much more expensive.


http://www.defender.com/product3.jsp...946&id=1450028

[Terra Nova]

NEVER use AC plugs/receptacles for DC. Extremely dangerous.

OP--what brand are the failed DC receptacles?

[exMaggieDrum]

Loose connections can cause a great deal of heat. A loose connection is not a short so may or may not cause a fuse to blow. I would think it would take a fair amount of current to cause damage like this though.

Loose connectors are one of the main causes of fires on boats, but usually on bigger wires, like alternator connections. It does not take a huge spike in current to start a fire, as only a steady current can do the damage.

I would inspect the fuse holder and the fuse on this install to see if the fuse had shorted and was therefore routing current around it or the fuse was too big for the application.

I would also inspect the plugs in use at the time. AND, whenever a male or female plug gets hot the corresponding female or male socket should be inspected as it make be damaged by the heat and/or causing the problem in the first place. Shore power cords/receptacles are a known and serious hazard in this regard. A hot shore power plug that has to be replaced should also cause you to carefully inspect the other side and replace if there is any suspicion at all of damage to it.

You were very fortunate you were onboard at the time and noticed the problem and were able to put it out. Liquids should not be used for electrical fires though. Glad it worked for you though.