What would you recommend about finding out where wires are broken?

[Rohan]

Not really sure what forum is the best for this, but since it concerns wiring, I'll put it here.

I have several wiring issues on my boat in the forward section. Neither my water tank gauge or my bow light are working.

After checking every other possible cause, I stripped the wire a little in both locations and used a volt meter to see if there was any electricity flowing and there wasn't. This means there's a break in the wires somewhere between and the unit and the batteries back in the aft section. But it is difficult to get access and find where the problem is. The wiring runs behind paneling and under headliners. I tried to unscrew these and get access best I could, but some of it is either glued or fastened in another way I can't figure out, and even gently pulling it back I already did a little cosmetic damage. If I pull it out, I am worried I will do some real cosmetic damage that would be hard to fix and might be more costly than hiring a pro.

Another solution would be to forget the old wires, leave them there and run new wires. But since I can't good access behind the headliner, that would mean having exposed wires running along the inside and would look really trashy. For now, I'm just going to strap on red and green flashlights for my bowlight. Not an elegant solution, but good enough for the time being.

So I ask the forum, in this situation, what would be your next step, short of calling a professional?

[Cheechako]

I would likely try a 12V light style tester with a sharp point first. Push the needle sharp point into the wires and work your way forward until you find the spot where it lights the tester light and then doesnt light it a foot away. Then splice properly, well sealed.
Or just run new wires forward, can you run them under the floor instead of overhead?

However, I will say it's not that usual for a wire to be simply "broken" unless a screw went through it or etc.

You checked the bow light right at the bow light? Those outdoor lights are often bad inside. Does the wire run through the pulpit tubing? If so you checked in the anchor locker etc where the wire goes into the tubing?

You checked the back of the electrical panel right? You just have to start there and check often.
Where DO you have voltage? Possible hidden connectors or terminal strips?

As far as tank level gauges, I never try to keep them working, they seem to never work long. Many of them you can replace the float gauge with one that reads directly on the top of the tank requiring no electricity.

[sailah]

What I would do is take your voltmeter, set it to ohms (omega symbol). Then take a spare piece of wire as long as you need (15-20'?). I have a piece designed specifically for this task with alligator clips on each end out of 12AWG. Then connect the wire to your voltmeter in such a way to make a loop. You are reading the resistance in the wire (as well as your new wire). But if you get a lot of resistance you've found that likely your wire in place has a break or just corroded. Keep checking in all areas that you can reach with this jumper until you've found the bad section.

Then I'd cut this bad section and see if I could use old wire to pull new wire like a fish tape. This may or may not work depending if it was secured behind things with zip ties. You can buy a fish tape at home depot that is a flat metal band on a reel designed to feed wires. It's a trial and error process.

Then reconnect with butt splices.

A better option is just to run a new wire to the fixture. Wire is cheap and you know you have a better fix. But it's more effort.

EDIT: Realized this may have been a bit confusing so I drew a crude pic. In this diagram I have a brown wire from 18AWG that I happen to have a 500' spool of. 1 end you connect to the bow light etc and either wrap around 1 of your voltmeter leads. You can make this as long as you need. Doesn't matter which lead of VM you connect to. The other lead, in my case Black, you are probing along wire. Can start at panel and just keep moving along wire as far as you can reach. The other end attached to my red lead, you do the same. You might need to pierce the wire sheathing with the tip or test at terminal blocks along the way. All you need is good contact.

You are reading the resistance of the circuit in ohms of the brown jumper wire, the multimeter leads AND your existing wire. In my case it's 0.16 ohms which is basically nothing, and what you'd expect from new wire and high quality meter. Mine I can even zero this out on my meter so I'd connect the 20' loop, zero the meter and then check existing wire. This will give me actual resistance of wire in place and already calibrated for resistance of my test setup but this isn't necessary for your purposes.

The nice thing about the jumper wire is it lets you check wiring without having 20' long arms.

[Rohan]

Originally Posted by Cheechako

I would likely try a 12V light style tester with a sharp point first. Push the needle sharp point into the wires and work your way forward until you find the spot where it lights the tester light and then doesnt light it a foot away. Then splice properly, well sealed.

Not really an option. There just isn't any exposed wiring for me to test this way. Even if I pull back the headliner as far as I can, the wiring is also inside another tube. And even if it wasn't, I can't check anything or insert any needle while I'm using all my strength with one arm just holding the headliner open. It's very frustrating.

Or just run new wires forward, can you run them under the floor instead of overhead?

Maybe... but since I can't follow the wires all the way back, I'm not totally sure where they originate.

You checked the bow light right at the bow light? Those outdoor lights are often bad inside.

I actually pulled the wires out of the bowlight and tested them there.

Does the wire run through the pulpit tubing? If so you checked in the anchor locker etc where the wire goes into the tubing?

Yes it does, but the wires aren't exposed in the anchor locker.

You checked the back of the electrical panel right?

Sure did. But that is such a concentrated mass of wires I am totally overwhelmed.

Many of them you can replace the float gauge with one that reads directly on the top of the tank requiring no electricity.

Interesting idea, I'll look into that.

[Rohan]

Originally Posted by sailah

What I would do is take your voltmeter, set it to ohms (omega symbol). Then take a spare piece of wire as long as you need (15-20'?). I have a piece designed specifically for this task with alligator clips on each end out of 12AWG. Then connect the wire to your voltmeter in such a way to make a loop. You are reading the resistance in the wire (as well as your new wire). But if you get a lot of resistance you've found that likely your wire in place has a break or just corroded. Keep checking in all areas that you can reach with this jumper until you've found the bad section.

Thank you so much, but even with the photo, this is way beyond my level of understanding.

[CharlieJ]

OP: You are going to hate this suggestion; Hire a professional.

[AndyEss]

Originally Posted by Rohan

It's very frustrating.



Maybe... but since I can't follow the wires all the way back, I'm not totally sure where they originate.


Sure did. But that is such a concentrated mass of wires I am totally overwhelmed.

.

Well, if you feel totally overwhelmed in tracing out your own wiring from standing on your boat immediately in front of them,, just what do you expect from total strangers possibly thousands to tens of thousands of miles away?

BTW paying a professional to do what amounts to housekeeping chores should prove quite expensive. Tracing wires isn’t rocket science, but it involves patience, dogged determination and attention to detail. A lot of things in life are like that.

[Lake-Effect]

To the OP - it's essential that you're able to access all wiring runs, for service, additions and repairs. And most boat manufacturers have allowed for this... some better than others. So it might be that you just haven't found all the accesses that would facilitate repair or running new wire.

Depending on your patience and time, it shouldn't be a hard problem to resolve. But if you're in a hurry or it's impacting your safety or enjoyment, it might be worth paying a pro for the couple of hours it should take to find and fix the problem.

Some boat electricians have begun using portable TDR (time-domain reflectometry) gear which locates wiring faults very quickly.

[chris mac]

Buy a fox and hound. (Only name I know for it) I bought one at harbour freight, for 20 bucks or so. Clip the power source on your exposed wire end, and ground to either a ground wire or metal on boat. Then with the wand end you wave it close to any exposed wires you can access. It beeps louder as you get close to the wire in question.
It really simplifies things . It will even work through headliners so you can trace it to the break point
It's not fool proof, but I consider it essential. Our boat has almost 30 years and 4 owners worth of refits, with dead wires everywhere. Its allowed me to easily trace and remove/replace a lot of wire

[AndyEss]

TDR is useful if wiring runs in a known conduit or path.
Further, from the little I used TDR in industrial settings, it not only has an appreciable error band, it is a bit limited in time scale resolution.

I barely skimmed the used TDR unit I purchased off of Ebay - but I believe electrical current runs through wiring at some sizeable fraction of the speed of light. Using TDR on short wiring harnesses gives a very high uncertainty.

I tried TDR on wiring harnesses several hundred feet long, and only was accurate to 20-40 ft.

I think usual TDR uses are in copper wire telephony where runs are in the thousands of feet to multiple miles.

The technology may have improved since my use. Still, knowing that a break is 10-12 ft away from the test point doesn’t mean much if you don’t know where the wiring runs.

[sailah]

Originally Posted by Rohan

Thank you so much, but even with the photo, this is way beyond my level of understanding.

You can do this, it's not difficult. Perhaps I wasn't very good explaining it. Do you have a basic voltmeter with an ohms setting? It's the omega symbol. The only other thing you want is a 30'(? or how ever long it is from your panel to the bow of your boat) piece of good wire. I put alligator clips on mine to make it easy to attach.

https://www.youtube.com/watch?v=SJRy...ature=youtu.be

[AKA-None]

We used to have a tool that you could connect to a wire and use it as an antenna. It had a separate receiver that could then show where the signal stopped. Eg where the wire was broken. It’s been some time and I don’t recall if we made that tool or if we bought it. I was doing r&d in the super computer industry and we made most of the tech we used, but we did buy stuff too.

[Lake-Effect]

Originally Posted by AndyEss

TDR is useful if wiring runs in a known conduit or path.
Further, from the little I used TDR in industrial settings, it not only has an appreciable error band, it is a bit limited in time scale resolution.

I barely skimmed the used TDR unit I purchased off of Ebay - but I believe electrical current runs through wiring at some sizeable fraction of the speed of light. Using TDR on short wiring harnesses gives a very high uncertainty.

I learned about this application of TDR from Ed Sherman (ABYC) during a seminar, and later from one of his books on electrical servicing.

The unit he refers to has a claimed resolution of 0.1 ft. They're still over $500 to buy, but for a busy service pro who doesn't want to be on their back all day chasing out basic wiring issues, it could be a time- and back-saver.

AKA-None - the unit you're referring to is the "fox & hound" mentioned earlier by chris mac. I have one of the cheap ones too and they are a help when tracing wires from one place to another.

[YANDINA]

I made my own wire tracer.
I wired a spare 12 volt relay through its normally closed contact to make an electrical buzzer. With my portable radio on AM off-station it would pick up the static.
For tracing the path of a cable or finding where the cable was broken I would put 12 volts on the wire with the buzzer and trace it with the radio.

[jamhass]

I know this should be obvious, so I apologize in advance, but...

I see no mention of fuses in any of the posts.