Mystery electrical system problem - not sure how to proceed.

[Sunbeam]

Hi folks,

I have a mystery (to me anyway) electrical problem. My maine fuse has blown twice within the past two weeks. Without it, I have engines and bilge pumps, but no instruments, helm stuff, lights, etc. What scares me about it is that it's not in my area of expertise, and it's seemingly random (so I don't even begin to know how I would have a pro find/fix it; and anyway I would rather understand it and figure it out myself, just for the knowledge). I'd really appreciate your help or ideas.

So, beginning of the problem:

A week or so ago (after three weeks of full time cruising/living aboard without any electrical problem), my main, 30-amp fuse blew. At the time the trim tabs were auto-retracting, as I had just shut the engine down, and I was fiddling with the depth sounder (another story... blasted transducer...). The chartplotter (Garmin 2006c) and VHF were also on, although not doing anything special. Nothing unusual really, although the tabs do draw a fair amount when retracting (but I had been using them regularly, which is the same draw, and all is fine. Plus, my friend and I wired them, so there is no mystery there. [Edited to add: Looked this day up in the log. We were drifting in a pool in Labyrinth Canyon, just enjoying the quiet, when the depthsounder transducer started reading "2.3'" -- which it has an annoying habit of doing at random times. I had figured out that sometimes putting the boat in reverse, then going into neutral, then shutting off and turning back on the depth sounder would "shake it loose," so that's what I was doing. I had all the instruments on the whole time, but the engine shut down. Then I started the engine, reversed, shut it off (trim tab auto retract went into action) and was just reaching up to cycle the depth sounder on and off when "all went black." I may have had my laptop plugged into the cigar lighter charging (computer off and not same plug/adapter as in the current iteration.) I didn't write that in the log, but we had been adding up power and thinking that maybe, maaaaybe, things could have got slightly close to 30 amps with any surge from the trim tab retractor firing up - as events today proved, that was not the issue).]

System info:

The way my system is wired, current goes from the house battery through a Blue Sea Safety Hub (which has a 30 amp fuse in it; the one that blew), then to the battery switch (Blue Sea On/off/combine -- the combine is for emergency paralleling; normally the switch is just left "On" while boat is in use). From there power to a positive bus (has a wire to the trim tabs with 20 amp inline fuse; plus one wire going to helm for helm stuff (original wire, 10 gauge I think.)

(The bilge pumps go straight into/out of the Safety Hub and don't involve that 30 amp fuse.)

Not sure if there is any other info that would help, but moving along with the problem....

So, the day that first fuse blew, we put in my spare 30 amp fuse and went merrily on our way. I did disconnect the trim tabs auto retractor at that time - mostly because I find it annoying and not a function I really need (it's noisy and goes on for 15 seconds, trying to retract, even if they are already retracted - I want peace and quiet when I shut the engine down).

Now it's a week later. We've been running around using everything - and all has been fine (except that depth sounder transducer..... but that's another thread - I don't think that's an electrical issue anyway). Today we pulled up to one of the "potti islands" on Powell and tied up. I shut down the engine but left the chartplotter/depth sounder/VHF on. My buddy had his phone plugged into the 12 volt cigar lighter outlet. Nothing else was on (heck, we hardly have anything else). We went about our business on the dock for a half hour or so, and then came back on the boat while I checked a few things online (computer not plugged in; just running on its internal battery). At one point we noticed..... hmmm.... the instruments are all off - no power to any of them. :cry Pulled the replaced-last-week 30 amp fuse from the Safety Hub and... it's blown again. Now I'm really motivated to figure this out because okay, once could be a flawed fuse, but twice? I don't think so. And before I was thinking "well, why was there a 30 amp fuse chosen in the first place; maybe a 40 would be more appropriate? (Not that I just "raise" fuse sizes willy nilly; I would have researched it; just that I don't know why 30 amp was chosen initially).

But okay, sitting at a dock with nothing much on, shouldn't blow a 30 amp fuse, even if a 40 would be better in the grand scheme of things. We were tied up on a calm day, so not really even agitating anything.

I did find that there is no fuse on the wire leading to the (I believe original installation) of the cigar lighter outlet, so that will be remedied (I had already bought new Blue Sea versions anyway). But I can't exactly understand how that would have blown the fuse (that said, I'm no Reddy Kilowatt).

We put an electrical meter across the fuse contacts and then turned on the instruments that were on at the time, plus had the phone plugged into the cigar lighter (so just how things were when the fuse blew this time). Total draw: 2.5 amps, just like you would expect. I wiggled the USB adaptor that was in the cigar lighter just to see, but... no change.

So... what could blow a 30 amp fuse while we sit tied to a calm dock with the VHF/depth sounder/chartplotter/phone charger on and nothing else? (Before at least we were "doing" several things including the trim tab retractor which is over 10 amps.)

And... how do I try to find this? We can get back to the launch ramp if we need to, but.... were planning another night/day first, and plus, now the boat is effectively "broken." Noooo! That does not give me a warm fuzzy feeling.

Thanks ahead for any help or ideas you can give me.

Sunbeam (partly cloudy now)

 

[ghone]

Hi Sunbeam. Good write up sorry about the issue. First thing on my mind when things have been running well for a long time and then issues show up is.....what did I add to the load lately? Or what did I push into the lazarette to dislodge a wire? Anything fall off the panels behind the helm? A lotta wires in there. Anything new aboard plugged in? It's likely a wire loosened up or a poor crimp perhaps. As usual start at the batteries and trace each wire for firm connections. Anything worked on at panel or breakers where a wire forgotten? Those auto retractors are gimmicky in my humble opinion. They haven't been super dependable. I power off instrument prior to engine start to avoid spikes in voltage. Maybe? I'm suspecting the charging laptop, thru an inverter or 12v? With all the draw you may have pulled too much. Fridge on too perhaps? Maybe an old battery on the house side getting erratic? Maybe switch to start battery as house for a while to see if the problem re occurs. Alternator putting out too much all of a sudden? Don't panic I'll bet it is minor once located. Enjoy the day. George

 

[Ray]

I will think a bit more on this, but at first glance....

30A is *A LOT* of power. It is not likely due to one too many USB chargers or a specific mode of a VHF or anything. As you found out, these things are 1 or 2 amps at best.

If something is blowing a 30A fuse, something big is going on - something that you may be glad is fused in the first place.

I would look for a gross problem - a direct short (or close to it) somewhere. Something intermittent in the DC power system?

Maybe try to CAUSE the fuse to blow by, for example, starting the engine, moving the battery switch to all positions, fiddling with the DC panel, messing with battery connections, etc. Maybe keeping a current meter in line with the battery lead(s) to observe any anomalies....

Just some thoughts - curious to hear the outcome!!!

Ray.

 

[Will-C]

I would start by running new wires directly to the battery for your 12vdc outlet with an in line fuse rated to match the proper sized wire. I have a male plug for our 12vdc outlet with foot long pig tails for power should something else soil the bed so to speak electronics wise so I could temporarily power a device/s or two ie. radar, gps, vhf until I could isolate the problem . Maybe you have some mice aboard who has chewed up some wire insulation causing an occasional dead short. I would think that most of the individual items have their own lighter amp rated fuses. I'd be looking for a loose wire on a larger sized wire or cable. Maybe a whole buss bar in a fuse box is getting shorted Thirty amps is a pretty heavy fuse and would just seem to me to be related to items that have heavy gauge wire running to them. 12 gauge wire I think is only rated for twenty amps. Just a thought.
D.D.

 

[Sunbeam]

Hi again,

Thank you so much for responding. It means so much to have the C-Brat gang "on my side" giving suggestions and thinking it over "with" me.

Let me answer some of your questions, but first, tell you what my buddy and I have done in the meantime.

I first made of a list of every electrical item on the boat (around 20 - yay for simple boats). Then we traced each wire to see if it had an inline fuse, where said fuse was located, and what the amperage was (I will check to see they are correct later on, just because).

Every wire was fused but one. Some with fuses a bit larger than necessary, but nothing out of line. The one unfused wire was the cigar lighter. That has been unplugged for now. The only other glaring weirdo thing (not that it's the problem) is that the fan wire was spliced into the VHF wire and they were fused together. I'll change that later on.

On to some of your thoughts:

1) The heavy cabling to the batteries was all new Ancor put in by me last summer. That's not to say I'm infallible (hardly!) but just to note that it is not old or cruddy wire. Likewise the battery switch, safety hub, ACR, batteries were all new then. I can't switch the batteries around because I have a large, deep cycle house battery and a smaller cranking start battery (but I also think that this means my electronics are isolated from spikes when I start the engine). Essentially all the electricals in the lazarette are new. The wiring behind the helm is as-came (but I don't think there is anything "huge" back there, and that is what we just traced) (not that it is perfect - far from it and it is on my list to "sanitize" in future).

2) I have not added anything new since before this trip (been out a month as of today, running/living aboard). I did add the trim tabs, new depth sounder transducer, new lazarette electrical system/batteries/monitor in the past months, but those have all worked fine up to now (of course everything works fine until it doesn't....but I just mean those were not just added in the last week).

3) We did have one mouse on the outside of the boat, but (thank heaven!!) it never got inside (I barricaded the boat until the mouse was gone) and there is no sign in the lazarette (I combed the thing regularly, no turds, no sign - I detest mice).

4) The lazarette with the electronics has not been opened except to check it for mice and/or change the fuse. There is nothing stored in it - it is only to house the batteries/electrical. I like to keep that locker "clean" and uncluttered just because it is the electrical lazarette. Nothing in there is not strapped or fastened down (or should be!)

5) As far as loads.... the first time I had just shut the engine down and the tabs retractor was running, plus the chartplotter/depth sounder/VHF/cigar lighter.

Today the boat was shut off and nothing was on except the chartplotter/VHF/depth sounder/cigar lighter. So same as last time but this time the boat was just sitting tied to a dock, and the trim tabs were not in use at all ( (I disconnected the tab retractor last week when the first fuse blew -- so it is not a current player.)

6) I have not wiggled every wire - that is a good idea. We have no more big fuse (used the spare - of course MORE spares will be on board in future), but we can jumper that with the voltmeter and try wiggling things.... I think?

Funny, because the boat never even had a "big" fuse before I re-wired it. Now I'm wondering if it's a good thing - I guess it must be and maybe I avoided a worse fate.

I do have a brand new Blue Sea cigar lighter new in the package aboard - so maybe I can rig that up temporarily to charge my laptop if necessary. (Kicks self for leaving all spare wire spools and etc. back in the van when lightening up load - pack rate may be hard to stop next trip )

Again, I really appreciate your thoughts and input. Thanks!

Sunbeam

 

[therevdr]

For several years I have intermittently had the top three circuits on my main
(factory installed) switch-and-fuse array go out . . . you might be able to tell by my precise description that I don't know much about this stuff!!!.
WHAT I DO KNOW IS . . . the those switches are set-up in in chain-like sequence (with wires jumping from one switch-fuse station on down the line); and so, when the pounding on the black switch array no longer works, it is necessary to jiggle-and-reattach the wiring at the back of the array.
[My usual failure is for the horn, anchor light, and running lights (which is also the instrument lights at the helm) . . . which are the top three circuits on
that board.]
THEREVDR on Driftwood Drei
2002 22' Cruiser

 

[Sunbeam]

A bit more info. NOT that I "expect" anyone to slog through it, but more for the sake of completeness (and for anyone who does want to follow along).

We went through the electrical lazarette one more time with a fine-toothed comb. Wiggled and looked at all the "big" wires (all tight, no obvious issues). Double checked for no signs of mice (none found, no turds, no dust or dirt or piles of wiring insulation). The locker is pretty clean and white, so easy to see if anything "new" in there.

I have no fridge or anything else that would have "come on on its own" that I can think of. So my current thinking is that maybe it IS that cigar lighter plug. I think we had something plugged into it last time (I did not write that down, but buddy remembers it as my computer was plugged in charging); this time his phone/tablet were plugged into it. Occam's Razor says it would not be both my inverter and his USB adaptor, but the unfused cigar lighter was implicated both times.

If I don't find anything else, I think (does this sound like a good plan?) I'm going to wire in the new Blue Sea socket I already have, with proper wire and the right size fuse (for now it is disconnected), then put in a new (as yet to be purchased) 30 amp main fuse, and basically wait to see if it happens again.

Here, for the sake of it, is my list of all electrical items aboard, where they are fused, and what size fuse (maybe this will help someone in future). I laid hand on all these earlier today. I will check them against equipment mfg'rs recommendations later.

1) Sidelights, all around light, and compass light (10 amp fuse on factory fuse block).

2) VHF antenna (not "electrical" in the load sense).

3) Cabin lights (one fixture in V-berth, one in cabin) (10 amp fuse on the factory fuse block)

4) Fan (spliced into VHF wire and thence to 10 amp fuse on factory fuse block - this will be improved).

5) VHF (10 amp fuse on factory fuse block)

6) Depth sounder (3 amp fuse on factory fuse block)

7) Depth sounder transducer (does not draw separate load but comes through depth sounder above helm; see #6)

8 ) Chartplotter (5 amp fuse on factory fuse block)

9) Chartplotter (GPS) antenna (1 amp inline fuse)

10) Cigar lighter (unfused - ugh - looks like 12 gauge wire).

11) Trim tab switch (indicator part at helm, not relay) (two wires both with inline 1.5 amp fuses as specified).

12) Trim tab relay (20 amp inline fuse on way to positive buss in lazarette).

13) Trim tab HPU (comes off relay; see #11)

14) Auto pilot (15 amp fuse on factory fuse block)

15) Bilge pump manual switches (auto is wired directly to power, not through the blown 30-amp fuse at all). (Mid pump manual switch has 5 amp fuse on safety hub; transom pump manual switch has 5 amp fuse in factory fuse block.)

16) Cockpit spotlight (10 amp fuse in factory fuse block)

17) Victron battery monitor (1 amp inline fuse as came with product).

18 ) Horn (10 amp fuse on factory fuse block)

Thanks again for all ideas - even if I "refute" them it's just to provide info and clues - not to say any ideas themselves are not helpful!

Edited to add:

For several years I have intermittently had the top three circuits on my main
(factory installed) switch-and-fuse array go out . . . you might be able to tell by my precise description that I don't know much about this stuff!!!.
WHAT I DO KNOW IS . . . the those switches are set-up in in chain-like sequence (with wires jumping from one switch-fuse station on down the line); and so, when the pounding on the black switch array no longer works, it is necessary to jiggle-and-reattach the wiring at the back of the array.

Hi THEREVDR, I was just looking at those switches and wires. I don't think they are my problem (none of those things were in use either time), but having just figured out what they all were doing (at least as much as I know), I can tell you sort of why they are jumpered like that.

The reason is that you have the all-around white light, which can be used separately as an anchor light, and then you have the SAME all-around white light, that can come on as part of the nav lights (along with the sidelights, and in my case the compass light). So it has a double-pole single throw switch arrangement, which allows the one all-around white light to work for both functions (but not have the sidelights on when you want it to work as an anchor light, which would be wrong). Hence the many jumpered wires (and the many spade terminals to possibly corrode or fail - maybe one of those is your problem).

Sunbeam

PS: If my problem is the cigar lighter (and I hope it is as I can fix that) the irony is that I wondered about that fixture a few times ("is that thing all wired up properly" but did not check it (mostly due to my non-handy-feeling around electrical stuff). Just goes to show, if you are thinking about reefing.... (and a head slap to me..... geez).

 

[AstoriaDave]

Sunbeam,

I agree with Ray. 30 A surge is pretty substantial. An ammeter inline during testing is a good idea, but make sure it can handle a 30A surge. Good on ya to have that 30 A fuse on the main supply! Two suggestions:

1. If easy to do, replace that 30 A fuse with a same amperage marine breaker. Blue Sea makes some which are compact, easy to reset, and show clearly when they have been tripped.

2. If there was a short somewhere you may see a damaged wire, if it was smaller diameter (altered color of insulation, etc.). Or, a spot on a crimp that shows melting. A thorough visual check, which you may have already done, sounds like, will buy peace of mind, and perhaps identify wires which need chafe protection.

The intermittent nature of the problem suggests a wire that swings or slaps into trouble.

 

[AK Angler]

First: The 30A fuse is there to protect the wire from an overload scenario that could cause a fire. Please don't consider bypassing that fuse because it's blowing. There's definitely a problem here that needs fixed, and bypassing the fuse could be catastrophic.

Second: With the electrical loads you have, the only real way to pull enough current to blow that 30A main fuse is if there is a short to ground. And it is likely a short in that main house wire.

Your secondary circuits should all be fused with much smaller fuses (maybe up to 10 amps for most circuits, or 20 amps for big loads like trim tabs), which would have blown if there were problems "downstream" of the main fuse block. (If you discover any un-fused circuits, now is the time to address that.)

But, if one of the wires in the secondary or tertiary circuits did happen to be un-fused (or over-fused) and was drawing that much current, they would very likely have melted some insulation at this point, and should be easy to identify as the bad circuit.

So, if it were me, I'd start looking for wire chafing, or otherwise compromised insulation on the main wire (and others, while I'm at it), especially at any locations where the wires may come in contact with anything hard and relatively sharp. I would also make sure that all secondary circuits are fused, and that those fuses are properly sized for the wire they are connected to. And, I would take a good hard look at that 12v plug for any corrosion or other irregularities in the outlet.


EDIT:

10) Cigar lighter (unfused - ugh - looks like 12 gauge wire).

Just noticed this... Yeah - I think you've discovered your problem.

 

[Sunbeam]

Hi again,

Thank you for the continued, valued input. Now that I have some juice back in my laptop, I thought I would write about what we have done for now (until we get back to shoreside supplies tomorrow).

1) I won't be removing the 30-amp fuse, but thank you for confirming that it's a good idea. I did so some research before putting this system in, but certain parts of it I partly "took on good faith" from experts were a good way to go. So it's good to have confirmation of that.

2) I removed the original cigar lighter fixture, and put in place the new Blue Sea one I had brought onboard.

3) So now to fuse the wire (and I drastically lightened up my electrical kit, so did not have much here with me). I had one empty fuse block on the factory block behind the helm, just adjacent to the cigar lighter. This had a 20 amp fuse it it and was used for the washdown pump, which I temporarily removed from the boat until I finish re-doing my water system. I took that out and put in a spare 10 amp fuse I had aboard, then re-used the spade connectors that went to the original cigar lighter fixture on one end, then used a butt connector I had aboard to connect that to the spade connectors that were on the fuse block terminal. So this means there is a new cigar lighter fixture, and the original wire but that wire is now 10-amp fused. I will not plan to use it much until I re-do it all, but wanted to be able to charge my laptop at least partially.

4) Okay but we still have no power to the boat (except the engines and bilge pumps which do not run through that fuse). First of all, did we need it? What are our options?

a) We are safely tied to a "potti island" on Powell, and I doubt there would be a problem if we stayed here overnight, so that is one option.

b) We could have gone to anchor in a small cove nearby, or another anchorage we have used already and "know." We have an LED lantern (actually two) that we power with AA batteries (lots to spare) so we could have fashioned an anchor light (although they are not used much here anyway, as people are usually tied to shore or near shore).

c) We could have made it to the launch ramp during daylight if we had really wanted to. We know the way and could have just followed the main channel even without chart or depth.

d) We have a freshly charged tablet with Navionics on it.

That said, we were not planning to "take out" until tomorrow, and our vehicle is in storage for which we need to make arrangements to get a ride to. So taking out today would not have been handy. But we could have taken a slip too, if necessary.

Instead, we decided to rig a temporary solution to be able to use power. I will not use the trim tabs or autopilot, and nothing else we have draws nearly as much as those two items (we can monitor draw underway via the Victron battery monitor).

What we did was use one of the "upper" terminals in the Safety Hub (uses a car style flat fuse -forget the name - and not the "big" type - forget that name too at the moment), and put a 20 amp fuse in it (the former washdown pump fuse rides again). This is now powering everything (but as stated, we will only use lower draw items, and we are prepared for it to "go south" again. Tomorrow we'll haul out, and these items will be addressed before boating again.

Okay, better head to the anchorage as I would like to get there during daylight, just in case.

Sunbeam

PS: If the cigar lighter was the culprit - yay! But I will still spend some time looking over every wire. I have tried hard to chafe guard everything, but the fact remains that there is still much "factory" wiring on the boat that I have not re-done. On the other other hand, this last "blow" was while the boat was sitting motionless, so maybe it is (was) the cigar lighter....

 

[AK Angler]

You should be fine running your basic navigation circuits off of the temporary 20A fuse. (Good workaround, by the way. :thup)

I would suggest putting a piece of tape over any switches that run the big power draw circuits (trim tabs, auto pilot, etc.) so that you don't use those systems out of habit and end up popping the temporary main fuse.

Good Luck!

 

[Sunbeam]

You should be fine running your basic navigation circuits off of the temporary 20A fuse. (Good workaround, by the way. :thup)

Thanks. I can tell you know your stuff, too.

I would suggest putting a piece of tape over any switches that run the big power draw circuits (trim tabs, auto pilot, etc.) so that you don't use those systems out of habit and end up popping the temporary main fuse.

That's exactly what I did! I haven't been using the autopilot (and have to reach down to even power it up), so I left that; but I did put a piece of blue tape over the trim-tab controls, so I wouldn't use them out of habit. Probably could have, but no need so planned not to.

We are now snug in our anchorage, 70' or so of rode out in 10' of water. Just watched an amazing full moon rise from behind a dramatic butte. So things could be worse. Now, just to be realistic, we are having olives, bad (mild, rubbery) cheddar cheese, and pickles for dinner, with sardines on the side. And coffee or milk? Ha, but a memory. But to the good, "cleaning the food off the boat" will be a one-handed affair

I'm still mulling over the issue though, and while hopeful it's solved, not at all sure. We fiddled around with the original (now replaced) cigar lighter fixture, but could not get it to do anything funky while hooked up to the meter. My laptop inverter (may have been hooked up the first time; was not today) has its own 15 amp fuse inside, which is fine. I don't know of a way to test the USB adapter we had plugged into the cigar lighter today - although we did wiggle it around in the removed cigar lighter to try to make something happen (nothing did).

The wire (that was unfused) from the cigar lighter was about 10" long, and went directly to the power post where the main wire running forward also connects (to power fuse block, etc.). So I don't know.... not exactly miles of wire to have a problem (and that wire is what we have in there now again, temporarily, albeit this time fused). But... maybe. It WAS in use both times the big fuse blew (and little else).

I am still going to take your (all's) advice to look over every wire for melted spots, chafe, etc. Not a bad idea anyway to check these things over. I'm sure there are places that I have not had my mitts on that could use better chafe protection (one actually comes to mind as I type this; where the wires come in through the boot back by the splashwell, that fiberglass hole is not well protected. I meant to start by putting a "ring" of TrimLok around it, plus some additional chafe guard such as split hose, but had not done it yet. There is still the fact that we were sitting tied to a dock on glassy seas, but .... I'm going to check and double check the wiring and chafe protection. It is one of the few (partial) "mystery areas" left on the boat, and I don't like those.

And of course I'll be ordering more 30-amp fuses to install and have as spares! (I like the breaker idea, but I don't think one would fit in the safety hub, and darnit, I would like to just solve the problem. But it never hurts to look at the Blue Sea catalog now, does it?

Any more thoughts, bring them on. Likewise I will keep the thread updated.

Sunbeam

PS: As you can probably tell, I'm a big fan of Blue Sea products. However, so far I am not thrilled by the new cigar lighter fixture I just installed, The original, a Marinco, held the (small) inverter in snugly, as it did my Maha battery charger plug and the USB adapter. The Blue Sea socket is slightly larger, and the fit is loose on all three items. Boo! (I'm surprised; may call Blue Sea and mention it to them.)

 

[AK Angler]

Well, if it wasn't the 12V outlet, you'll find out soon enough. :shock:

But... since it was the only non-fused load running through the main fuse, I'd bet dollars to doughnuts that it's either a ground fault in that 12V outlet, or the main house feed is shorted to ground. (My money's on the outlet.) The short 12g non-fused wire powering the 12V outlet could certainly carry a ground short long enough to trip the 30 amp fuse at the SafetyHub, without melting the insulation off of it.


And as a side note (because you mentioned the splashwell boot), last year I found a trim tab wire (that has a very thick outer insulation protecting the inner insulated wires) almost rubbed through where it went through the hole in the splashwell on my Arima. It's a good area to keep an eye on.

 

[anchorout]

Sunbeam:
I have many yrs experience in electronic repair. I know, we all find it hard to believe that something could short out on a boat tied to a calm dock. We call it FM F......g Magic in the business and I assure you it happens. A change in temperature causes a wire to stretch or shrink. A change in humidity causing moisture to drip into a component. Vibration. The boat hull itself reacting to heat or a passing boat's wake.

Intermittent shorts are very difficult to find until they finally short long enough to trace them with a meter. As the other Brats have said, to blow a 30 amp fuse you need almost a direct short. Obviously, the short will be AFTER the fuse, not back towards the battery source. You have isolated most equipment with appropriate fuses. You have turned most items off and had the master fuse blow, that tells me it is not from having to many devices drawing to many amps. Look for wires NOT protected by secondary fuses. Look for wires where +12v and Ground may be switched (your cig lighter plug should have +12v on the center terminal). Look for old wires that have been snipped and just tucked behind the bundle, where they can touch ground. The problem may be behind the fuse panel itself, a broken terminal or stray piece of wire or loose washer sliding around. Check between your hot panel and ground strip, nothing flopping between to short them together. Also, a sloppy crimp where the insulation gets into the crimp, or a loose crimp or terminal which can cause a surge or spark which will blow your fuse.

You say you have not checked out the older wiring circuits. Isolate the ones not protected by fuses. Pull them off of the terminals, label and insulate each until your problem goes away. Then connect one at a time until the problem returns.

I hope you find this problem soon, but if not, a temporary 30amp breaker, as others suggest, will make life easier in the mean time even if you just hang it to one side with a tyewrap. Typically these type problems increase in frequency and become easier to find. I hope I have helped.

 

[ghone]

Hi Sunbeam. Since this is your main fuse I'm wondering if it is on the small side. I would like the main protector to be a resettable breaker. Like in airplanes reset it once and then investigate. Mine was wired with a Blue Sea breaker (pretty sure it's 50 amp). The boat is in the canvas shop so a couple days till I can check. It's the same breaker as the windlass uses 50 amp. Alternator on the Yamaha 90 puts out 25 amps. I kind of think that laptop into the 12 ga socket is part of the issue though. Best of luck. George

 

[thataway]

Looks like you are "OK" for now, and should be fine getting home. I have read and re-read the above posts, and most likely have missed somethings.
As I recollect you added up all of the amps a few days ago in a tablet form.
You have the Victron monitor/ ammeter, so can determine loads.
We also have to all keep in mind that Sunbeam is currently on Lake Powell--not at some place where tools and supplies are all available.

I share your question about a 30 amp fuse for a modern boat. From what you describe on the boat it would be easy to exceed 30 amps. You have the relay trim tabs at 20 amps, and the auto pilot at 15 amps--just there you are over 30 amps. Are these going to draw 35 amps at the same time?You are close to the limit with 30 amps. The Chart plotter / depth sounder are fairly low draws--the radio can be more; 5 to 6 amps on transmit. Stereo? Lights can be a large draw. A cigarette lighter is alway a big question. There are all sorts of things which plug into them, and can have a short, loose connection or high current draw (such as a spotlight or 300 watt inverter!) Conclusion from this is that 30 amps is not enough.

I have found that most of the C Dorys are not adequately wired. I usually double the size of the wires to the console bus bars (both positive and negative!). I also go with a 60 amp breaker for the main breaker at the battery. I then put in more fuses at the console. With the current C Dory we utilized the one 6 fuse present and added a second 12 fuse block.

I am not familiar with a "Blue Seas 30 amp Safety hub". There are 100 to 250 amp safety hubs (with a AMI large fuse), with up to six ATO or ATC fuses up to 30 amps each. When Sunbeam gets back on land, she can clarify if this is one of the 100 amp safety hubs with a single 30 amp ATC fuse in it; (most safety hubs are more designed for a center console boat which does not have a fuse block.)

Although this may not apply here, but when you start the engine, since the starting battery and house battery are always combined (I believe you said), you can drop the voltage at the console, and thus increase amperage draw.

For now--stay away from the cigarette lighter. Have a good rest of the trip--and sort out the electrical later. Are you using a VSR?

 

[AK Angler]

Regarding the size of the main fuse, it may - or may not - be undersized. Just remember... fuses are there to protect the wire. If needed, electronics or other components will have dedicated fuses in - or very near - the unit itself. As such, trunk and branch circuit fuses should be sized relative to the size of the wire between the fuse and the load. If there's too much load for the wire, upgrade the wire and then increase the fuse size accordingly. Never just bump up the size of a fuse because there's more load present than it can handle. The latter is a recipe for disaster.

Sunbeam - What size wire do you have connected to that 30A fuse? Is it tinned marine wire, or non-tinned copper?

 

[AK Angler]

You have the relay trim tabs at 20 amps, and the auto pilot at 15 amps--just there you are over 30 amps. Are these going to draw 35 amps at the same time?You are close to the limit with 30 amps.

Not so. Those circuits are FUSED for 15 and 20 amps. They should never draw anywhere near that much unless there's a problem with those components, which would then blow those fuses before they blow the larger main fuse.

However, I do agree that a 30 amp main fuse may be undersized for the total load. But if that's the case, wire size needs to be considered FIRST.


And for the record, I'm running a 60A main fuse to protect the 6ga tinned marine wire running to the helm on my Arima. A 30A fuse shouldn't be used on anything smaller than (I think - I'm going by memory here) 10ga wire. I had a 10ga main run before I rewired my boat, but I found it to be marginal for the load(s) I had, and the associated voltage drop to be problematic. So, I upgraded all the wiring when I repowered last year.

 

[Sunbeam]

Everyone:
You are definitely helping! I was baffled and lost when this happened (again) today. Now I am feeling a bit more confident. As I mentioned, this is not my strong suit, so this is a learning experience. I'll try to answer some of your questions - and maybe that will lead to something (plus, it's polite to answer anyway).

... since [the cigar lighter socket] was the only non-fused load running through the main fuse, I'd bet dollars to doughnuts that it's either a ground fault in that 12V outlet, or the main house feed is shorted to ground.

I am going to take a close look at that main house feed. Even though it is "supposedly" large enough, it is the original one as far as I know (which I don't believe would be proper marine tinned wire), and... well, it just "seems" like it should be larger (and maybe also fused?). I realize I can calculate it, so I may not act just on "seems," but I will trace it up through the bundle and give it a close look-see. It is 10 gauge, by the way.

And as a side note (because you mentioned the splashwell boot), last year I found a trim tab wire (that has a very thick outer insulation protecting the inner insulated wires) almost rubbed through where it went through the hole in the splashwell on my Arima. It's a good area to keep an eye on.

Yeah, on my boat is it just a raw fiberglass edge on the hole. Now, the wires do go through there in a semi-protective mesh sleeve, and none of them are routed right over the edge itself, but still.... things move and shake in a boat. I like them closer to bulletproof. So I think I will line the cut edge with Trim lok and plus add chafe guard (hose or something).

Sunbeam:
I have many yrs experience in electronic repair. I know, we all find it hard to believe that something could short out on a boat tied to a calm dock. We call it FM F......g Magic in the business and I assure you it happens.

I do believe you - and all of your reasons why it could happen sound perfectly valid to me (plus you have experience). I guess it only seems odd because we've spent a good portion of the last month running along in chop, wakes, etc. And the first time the fuse blew we were at least floating in a calm pool untied, and doing something (albeit not much). But still... everything that breaks "just worked" right before it broke and boats are so hard on stuff!

You have isolated most equipment with appropriate fuses. You have turned most items off and had the master fuse blow, that tells me it is not from having to many devices drawing to many amps. Look for wires NOT protected by secondary fuses. Look for wires ....(great list of things to check here in the original reply).

Thanks, that's a good list. I will look at all those things. I've been wanting to "clean up" behind the helm anyway (and get a new/larger fuse block), so this is a good time for that.

You say you have not checked out the older wiring circuits. Isolate the ones not protected by fuses. Pull them off of the terminals, label and insulate each until your problem goes away. Then connect one at a time until the problem returns.

I don't think I have any of these anymore (now the cigar lighter is fused). I did have two cut wires stuffed into the bundle where I removed the washdown pump temporarily, but then those were fused (fuse was still in place, slot now re-purposed for cigar lighter with a smaller fuse), plus they were not touching or rubbing on anything (they were taped). I wish that had been it! However there are still things to check and improve.

I hope I have helped.

Absolutely!

Hi Sunbeam. Since this is your main fuse I'm wondering if it is on the small side.

Me too. I didn't choose the fuse (electrical tech I had helping me at the time did, but I don't know why that size was chosen). The way the Safety Hub works I don't think a resettable breaker would fit into it, but then I am not married to the Safety Hub (chosen by said tech - I could change it). I can see why something resettable would be handy. I even have a couple of Lewmar (IIRC) resettable breakers, albeit in storage (but I can get something else once I know what I want).

Alternator on the Yamaha 90 puts out 25 amps.

I think my 80 puts out 20 amps, but I don't know if that relates to this problem as I don't think the engine is connected to this fuse at all (engine still works fine even with fuse blown).

I kind of think that laptop into the 12 ga socket is part of the issue though.

I'm hoping that outlet was it, but not real confident yet. Also my laptop was not plugged in today when the fuse blew (my buddy's tablet/phone was instead -- with a USB adapter vs. the inverter my laptop uses). My laptop charging draws about 4 amps, so should be fine at any rate (socket rated for up to 15 amps; now fused with 10 amp fuse). I think the phone/tablet draws a couple of amps. BUT, that was the one thing not fused, so it is a wild card (and it was in use both times, albeit for different things).

Thanks for your thoughts. Interesting that you haven't had good luck with the trim tab retractors, btw. Mine just came along with the indicator light kit, but I didn't like them so now have them disconnected (I like the indicator lights though).

Looks like you are "OK" for now, and should be fine getting home. I have read and re-read the above posts, and most likely have missed somethings.

Thanks, yes I think so, since we are taking out tomorrow. Still, I may leave the boat here in storage for awhile, and hate to leave it "broken" if I can avoid it.

I did write quite a bit, so don't blame you if you missed something. I'll respond below.

Re loads:

Stereo?

I don't have one.

Lights can be a large draw.

The boat does have two small cabin lights (single bulbs), but I have not used them (and probably won't unless/until I change them to LED's. I tend to use my headlamp, an LED lamp I have, or a candle lantern.

A cigarette lighter is alway a big question. There are all sorts of things which plug into them, and can have a short, loose connection or high current draw (such as a spotlight or 300 watt inverter!)

True enough, and it was a question mark for me even before this trip. As it stands currently though, I have only plugged in smallish loads, all of which I have measured with the battery monitor (laptop, phone, tablet, 12 volt dry cell charger). Of course that's no reason not to have the socket up to snuff and capable of larger tasks. Kind of like having strong grabrails - you just KNOW you will lunge and grab them sometime, even if not planned.

I have found that most of the C Dorys are not adequately wired. I usually double the size of the wires to the console bus bars (both positive and negative!).

I have been thinking those wires leading to the helm panel could stand review/upgrading.

With the current C Dory we utilized the one 6 fuse present and added a second 12 fuse block.

After going over everything today, I was thinking a larger or added fuse block would be nice. I'd rather have things organized in one place vs. more inline fuses (right?). So it's nice to hear how you upgraded your 22 along those lines.

I am not familiar with a "Blue Seas 30 amp Safety hub". There are 100 to 250 amp safety hubs (with a AMI large fuse), with up to six ATO or ATC fuses up to 30 amps each. When Sunbeam gets back on land, she can clarify if this is one of the 100 amp safety hubs with a single 30 amp ATC fuse in it; (most safety hubs are more designed for a center console boat which does not have a fuse block.)

I'm anchored with Internet here (whee!) so can respond now. It is a Blue Sea Safety Hub 100, Blue Sea part #7725. The 30 amp part is the size of the main fuse that happened to be installed in one of the slots, which take AMI fuses. There is room for three of them on the hub, but I'm only utilizing one slot (for the 30-amp one that blew). Then there are spaces for ATO (blade) fuses up above on the hub - those are not routed through the main fuse/main switch and are where I have my bilge pumps (I think there are five slots there and I'm using two). Really, I'm not exactly sure why this was chosen, but the fellow helping me set up the electrical system was using it on other, similar installations, and it sounded like a decent way to go about it; but it's not like I could argue cogently about why it was "the way to go" at this point (in other words, it made sense when I heard the reasoning, but I can't remember the exact details). Here is what Blue Sea has to say about it:

"SafetyHub 100 Fuse Block, PN 7725
--The SafetyHub 100 combines an ignition protected fuse block and an integrated connecting plug. It is safe for use on gasoline powered boats, reduces wiring connections, and consolidates up to seven fused circuits.

--Three 30A−200A MIDI®/AMI® fuses ideal for high-amp circuits including panel feeds, windlasses, and
stereo amplifiers

--Four 1A−20A ATO®/ATC® fuses ideal for circuits including bilge pumps, alarms, and clock memory

--Sealed cover protects fuses from the harsh marine environment: IP66 rating—protected against powerful
water jets

--Integrated connector plugs eliminate loose wires and provide a secure, waterproof connection."



http://www.bluesea.com/products/7725/SafetyHub_100_Fuse_Block

Although this may not apply here, but when you start the engine, since the starting battery and house battery are always combined (I believe you said), you can drop the voltage at the console, and thus increase amperage draw.

For now--stay away from the cigarette lighter. Have a good rest of the trip--and sort out the electrical later. Are you using a VSR?

I have the Blue Sea ACR - the 7610 model if memory serves. Blue Sea's product literature for this says "Protects sensitive electronics by temporary isolation of house loads from engine circuit during engine cranking," so I think I'm okay on that front.

http://www.bluesea.com/products/7610/SI-ACR_Automatic_Charging_Relay_-_12_24V_DC_120A

Regarding the size of the main fuse, it may - or may not - be undersized. Just remember... fuses are there to protect the wire….
Sunbeam - What size wire do you have connected to that 30A fuse? Is it tinned marine wire, or non-tinned copper?

I think by this you mean the wire on the "other" side of the fuse (i.e. not the house loads and such), right? If so, then that is #6 Ancor tinned wire - all new within the past 6 months or so, and put in by me (for better or worse). I did have the lugs put on by someone with a proper crimper though (I don't have one that large). The lugs are also Ancor brand. These #6 wires are what all the wires leading from the batteries, through the Safety Hub, ACR, and to the main battery switch are (size and type). Hopefully this is good.

... a 30 amp main fuse may be undersized for the total load. But if that's the case, wire size needs to be considered FIRST.


And for the record, I'm running a 60A main fuse to protect the 6ga tinned marine wire running to the helm on my Arima. A 30A fuse shouldn't be used on anything smaller than (I think - I'm going by memory here) 10ga wire. I had a 10ga main run before I rewired my boat, but I found it to be marginal for the load(s) I had, and the associated voltage drop to be problematic. So, I upgraded all the wiring when I repowered last year.

Okay, so if all the wiring on the "other" side of my equation is #6… that seems like it is plenty good for a larger-than-30-amp fuse. But….I only have 10 gauge running from the positive bus up to the helm panel (and that is wire that came with the boat, so probably nothing special in the quality department). However now I'm getting confused I now think I know that all the individual fuses (mentioned in my list) protect the "small" wires running from the components to the fuse block (behind the helm), or the switches (by the helm). But does the 30 amp main fuse protect the "other" wires "behind" it (house battery/ACR/Safety Hub/main switch in lazarette, all #6 wire), OR does it protect that "supply" wire running from the positive bus to the helm area? I should be able to figure this out but…. maybe my brain has too small a fuse tonight

(I never liked the size of that "supply" wire to the helm area anyway, so would jump at a reason to replace it with better/larger wire.)

Okay, whew, sorry to write so much, but I wanted to respond to everyone who took the time to think it over and write back with their ideas and questions. I hope others (non-pro's, like me) reading along can also benefit :thup

Sunbeam

 

[AK Angler]

Sorry for the confusion, Sunbeam. Let's see if I can clear things up a bit...

Your 30A fuse protects the main wire that runs from the SafetyHub, up to the fuse/distribution block at helm. And, if both legs of that circuit are made up of 10ga wire (both the positive, and the ground wire), the 30A fuse is correct, and a larger fuse would not offer adequate protection for that circuit. If EITHER of those wires are smaller than 10ga, you need a smaller fuse. If BOTH of the wires are larger than 10ga, you MAY use a larger fuse.

Regardless, the 10ga wire in your house trunk circuit (and subsequently, the fuse) may be too small (marginal at best) to actually run all the house branch loads. That's how my boat was wired, and I was getting low voltage issues cropping up, so I upgraded to 6ga for that run and haven't had any problems since.

And, if you're wondering what protects the wires connected directly to the battery and switches (on the battery side of the SafetyHub) the answer is... nothing. If they are short runs made of large wire (I don't have the specifics sitting in front of me at at the moment), the ABYC says that they can be unprotected without raising red flags, or causing any safety issues.