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Old 19-07-2008, 05:18   #1
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Hi All,

So here we are victorious in our "first to finish", with a solid 5 boat lead mood, when all of a sudden a call from bellow of smoke?

We had no sooner crossed between the committee boat and the mark, and fired up the iron genny,when one of the crew says in a rather nonchalant manner "hey there is some smoke down here?" Well the skipper and I immediately kill the engine and pop the genny back out while calling for a shut down of the battery selector switch. Within seconds the smell of an electrical fire is filling the cockpit and the cabin looks like a Cheech & Chong movie only it doesn't smell quite as good..

I grab the helm and the owner goes bellow and begins digging into things. About 20 minuted later he pops his head up with a 24" long piece of bare 14 ga SOLID copper wire. I chuckle and say "see solid wire has no place on a boat!!".. Unfortunately I had no idea how wrong I was! That 14ga SOLID copper wire had been 14ga tinned multi stranded wire with a jacket just minutes before!!

Never in my 35 years of sailing have I seen a two foot long piece of multi-stranded wire turned into a piece of unjacketed solid copper so fast!!

Now I know the "alarmist crowd" may come out in full force on this thread but let me assure you this boat (it's the "red boat" for those in the know) is kept in pristine mechanical and physical condition This is not a boat that is left much to chance on ANYTHING and the owner spares no expenses keeping her up!!

So here's the safety reminder!!!!!!


So here's what we found. The ground lead for the metal cigarette lighter and female quick connect that looks like this picture
came disconnected!

When it did it began swinging into the stud for the house bank on the back of the battery selector switch! OUCH!!!!
Who said there is NO vibration on boats? I'm sure the "no vibration on boats" crowd will be commenting at some point.. Remember this wire went straight to the ground buss and was rubbing the battery selector switch terminal post a direct ground short of the worst type!

Eventually it hit hard enough, possibly aided by the vibration caused from starting the engine, to literally weld itself to the stud and then turn the wire to a solid conductor! I'm not kidding when I say that I could not decipher this wire from a piece of Romex used in house wiring. There was no physical sign of any stranding left anywhere and no sign of any tinning either. this wire got so hot there was not even any residue left from the melted jacket just BARE copper..!

Luckily this was only a 14ga wire and it actually blew like a fuse after it thankfully got hot enough. A fuse at the battery post such as a ANL type like the one bellow
would have stopped this ground short in about a nano second!!:

Unfortunately, this fuse block is one of those items the owner had been "GOING to add" but as boats go it kept getting further and further down the "to do list" as other chores and projects piled up... We all are guilty of this type of mistake!! "Oh I'll get the flares on the NEXT trip to West Marine..."

So what have I learned?:

#1 Be very, very, very careful using "quick connect" terminals on boats! If you MUST use them use the fully insulated style and NOT the un-insulated ones!!! EVEN ON GROUND WIRES!!! ABYC says the ONLY connectors for use on boats is ring or "captive spades" so quick connects don't typically comply with the ABYC suggestions which are a general, good guideline. Fully insulated quick connect crimps look like this:

#2 You should make every effort protect the studs on the backs of battery switches or ANY other large amp cable terminals with post caps!!

#3 Any wire in the vicinity of HOT terminals needs to be secured so there is NO WAY, even if it came disconnected, to touch a HOT component. Zip ties are CHEAP!! This wire was zip tied within 6" of the cigarette lighter but it was still not enough to prevent it from falling onto the battery post!!!

#4 And finally the MOST important component is that ALL battery banks MUST have a fuse as close to the battery as possible!! ABYC suggests 7" but I know mine are about 9" to 10" (of total cable length for strain relief reasons) as it is the closest I could get them..

DO NOT wait, as my buddy did, to fuse your batteries!! If this has been on your list please, for your own sake, MOVE IT TO THE TOP!!!!!

BTW the post this wire came in contact with was the direct to the battery and even turning off the switch DID NOTHING. The only way we prevented a fire was because the wire melted in half and acted as a fuse because it was a light 14
gauge run . If this had been a 10 ga wire, for say the macerator, we may have burned the boat to the water line last night..!!!

Think about it!!!!!

Call me an alarmist but if you witnessed what I saw last night you'd have been buying fuse blocks TODAY!!!

Here's a picture of my ANL fuse block so it can be visualized.

With cover off:

With cover back on:


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Old 19-07-2008, 05:37   #2

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I couldn't agree more. I have battery cable fuse blocks, in addition to the regular breaker panel - they are a MUST!

The idea is to shield your positive cables and any positive junctions/terminals in every way possible. The other issue here is that the battery selector post needs to be completely shielded, being a positive conductor. ALL positive conductors should be shielded for exactly this reason.

It's dangerous to have any exposed positive posts anywhere on the boat. They make plastic shields for just this purpose.

Glad to hear the situation didn't lead to any more severe damage.

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Old 19-07-2008, 05:38   #3
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WOW ! That post gets me thinking and hopefully off my lazy butt to work on my half-assed wiring.

Thanks for posting the story and the fuse block photos.

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Old 19-07-2008, 05:41   #4
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Thankyou.. the thought of a serious fire along way from anywhere fills me with dread. Bit hard to hit the Epirb if it is melting in front of your eyes.
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Old 19-07-2008, 05:50   #5
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80% of boat fires come from electrical sources. Shore power and home quality AC devices being number one but DC wiring is right up there too.

We have a lot of good material on electrical systems and working with them in the forum so adding this post is great since it even has pictures. It's always nice to have a story that goes with it as well.

The last two boats we purchased both had a lot of home done terrible wiring. It's easy to wire a boat and make it work. It takes some serious thought to do it right. You really don't want to use your battery compartment like a toaster oven.
Paul Blais
s/v Bright Eyes Gozzard 36
37 15.7 N 76 28.9 W
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Old 19-07-2008, 09:30   #6
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Watch out for AC Wiring, Too!

I agree with Paul...most boat fires are caused by electrical problems, usually DC. However, AC can be a problem, too. If you've ever spent much time around a liveaboard marina, you've seen lots of horror stories, with haphazard wiring to dockside plug-ins, melted 30A connectors, etc.

In 1984 I moved aboard a seven-year old 43' houseboat, which was to become my primary home for the next 15 years. The PO told me there were "some electrical problems". Indeed, there were!

The boat was outfitted with a full-size kitchen refrigerator, a 4-burner with oven electric stove, a 20-gallon hot water heater, a large RV-type air conditioner/heater in the main cabin overhead, and assorted other 110VAC lights and appliances.

All these circuits were routed to a standard household-type fusebox. Fuse sizes generally were appropriate for the respective circuits (except the stove...see below). Wire size was adequate, if not tinned copper marine wire. However, believe it or not the entire fusebox -- except for the lighting -- was connected directly to one of the boat's two 30A outlets!!!

In other words, it was easily possible to try to draw 20A for the air conditioner/heater, plus 15A for the hot water heater, plus 5-10A for the refrigerator, plus 30A or more for the electric stove (which, it turned out, never got hot because it had 220V elements installed and was connected to a 110V circuit!).....for a grand total of 70A or more!!!

And, we all know that the 30A connectors typical of small boat use are not really capable of handling 30A at all, except perhaps when conditions are absolutely favorable: new, clean tight connections, low ambient temperature, etc. Typically, if you try to routinely draw 30A thru a 30A "marine" connector, it's gonna heat up badly and will soon have a meltdown. Worse, the 30A splitters in common use for 3-phase systems are connected to a 50A breaker on the power pole, so protection is totally inadequate from that source.

Bottom line: learn about and be very careful about your electrical systems onboard, both DC and AC.


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