Electrical miracle ?

Volkhard · #1 (**permalink**) 12-31-2008

Hello everyone.

Do I have a secret powersource?

My bowlight is giving me problems(Aquasignal combined red/green with 10W Bulb).
Sternlight on same circuit is fine and indicator LED,s on E-Panel at Nav station is fine. I checked the bulb: tested working.

When I measure Voltage at the light fixture contacts without bulb I am getting ~13.6 V with bulb installed just ~2V. Funny thing is, my house bank is at 12.5 V right now. Where is the extra voltage coming from and why does it go down when the bulb is installed?
I am cruising right now and using my web-enabled Cellphone (better than nothing.
Whether I will make a nightsail into the New Year or stay at anchor depends on whether I get this figured out or not.
Any thoughts?

FarCry · #2 (**permalink**) 12-31-2008

Are you measuring 12.5 volts on your house bank with the same meter that you are using to get 13.6v at your bowlight?

Regarding your bowlight not working, it would seem that you have a very bad connection someplace. There is enough conductivity to provide adequate voltage to register on your meter until a small load is put on it, in this case just 10 watts. I would suggest working backwards from your bowlight fixture checking all connections for voltage with the bowlight on and the bulb installed.

If you have another length of wire and know how to check for continuity, you could determine if the problem is the positive or ground which would narrow down your troubleshooting to just one conductor.

SEMIJim · #3 (**permalink**) 12-31-2008

Quote:

Originally Posted by Volkhard

When I measure Voltage at the light fixture contacts without bulb I am getting ~13.6 V with bulb installed just ~2V. Funny thing is, my house bank is at 12.5 V right now. Where is the extra voltage coming from and why does it go down when the bulb is installed?

The 2nd part is easy: Load. (Btw: Is is 2V or 0.2V?) The 1st part is trickier. I would start by disconnecting both hot and ground for that light at the source end and see what you get. Then I'd reconnect one, then the other, and see what happens. My guess is you're not seeing what you think you're seeing.

Like FarCry suggested: Check continuity by connecting both hot and ground to a long, known-good wire that'll reach the light.

I don't suppose you can get to the wiring for that light from end-to-end, can you?

Jim

Rockter · #4 (**permalink**) 12-31-2008

Volkard :

The voltage drop you describe is the classic symptom of a corroded connection somewhere.
When you mesure the voltage with your multimeter, you read close to battery voltage, because the multimeter draws very little current in order to measure it.
When you try to draw a curent for a bulb load, the voltage chokes off because of the high resistance of the corroded connection. Trace it back and you will find it.

I don't know why the voltage is above battery voltage... that is a mystery to me. The laws of physics say that it should not happen. Voltage does not run uphill in a conductor.

Volkhard · #5 (**permalink**) 12-31-2008

There are 2 wires going from the panel to the anchor locker.From there (crimp connected) 2 smaller wires go thru the deck into the tubing if the stainless bow pulpit. Up to the anchor locker everything is okay. The problem must be in the hidden run within the tubing (perhaps some chafing). I connceted the bulb at the end of the main wires in the anchor locker.
Light!
I made a good and solid new temporary connection to the thinner wires and tried the same bulb direct at the other end of the thinner wires (after disconnected from Aqua signal) no light at the end of the thinner wires. Therefore the thinner wire pair is the culprit.
Would it work to try to pull a messager line while pulling the thin wires out? I have no idea whether the makers of these pulpits are doing it in a way that makes it possible to re-wire thru the tubing ...
I am still baffeled by the high voltage reading on my meter. When I am back from my holiday cruise I will double check with a second meter ...
Any comments on re-wiring a bow pulpit?

Thanks and Happy New Year everybody!

SEMIJim · #6 (**permalink**) 12-31-2008

Quote:

Originally Posted by Volkhard

Would it work to try to pull a messager line while pulling the thin wires out?

I guess the only way to find out is attach a messenger line, securely, give the wires a gentle pull, and see if they're inclined to move.

Glad to see you've at least identified the source of the problem.

Good luck and Happy New Year!

Jim

camaraderie · #7 (**permalink**) 01-01-2009

Yeah...a messenger line should work but you never know if it will get hung up. Sometimes you have to simply replace the wire. One useful "tool" in doing such jobs is the wire used inside engine control cables as it is flexible yet spring steel that you can force past the rough spots without kinking. Most yards have a supply of the old cables they have removed doing repairs and once I learned the trick, I carried a coiled cable with the spare parts. Very handy.

Another tip if you can't get the new wire past the pulpit tubing and in through the deck is to drill a hole at the base of the tubing and hook the wire out. Then drill a deck hole and pass the wire through a connection block down below. Doing this, you will need a plastic anti-chafe grommet to install on the tube, some tubing to cover the exposed wire on deck and a cable clam to insure the deck penetration is waterproof (after you've potted the hole with epoxy of course!) .

Hope this gives you some options if the messenger doesn't work.

FarCry · #8 (**permalink**) 01-01-2009

Cam's points are good, as usual.

Things I've learned from fishing wires as an electrician...
Gravity is almost always your friend
Make the connection to the old wire very strong so that it won't fail
Make the transition from existing wire to pull wire as smooth and seemless as possible
Do not jerk, but use a steady pull
Two people, one feeding the wire and one pulling would be best if possible
If it gets stuck pull back and try again
If it is pulling hard sometimes dish soap can work wonders as a lubricant
Be very careful not to chafe the new wires when you feed them or you will end up right back where you started soon enough
If all else fails use Cam's suggested process of drilling a new hole etc...

Good luck and tell us how it works out.

Volkhard · #9 (**permalink**) 01-02-2009

Thank's for all you input. I will try to attach the new wires to the old one by creating a sacrificial soldered joint, soldering all 4 ends together. That should give me a rather strong joint without increacing the diameter much. Than , very carfully pull from the anchor locker with someone leading the new wire in atop for least resistance. I will try as soon I am back in home portand keep everyone posted how it went.
Yesterday I enjoyed a 10 hr run broad reach at almost 7kts up the SW coast of Florida. We are in Sailing Paradies here in Florida ...

sailingdog · #10 (**permalink**) 01-02-2009

Volkhard—

The problem with that approach is that it also creates a hard spot in the wires...that may make it less willing to negotiate any bends or obstacles it may encounter... I generally prefer to use messenger lines, since pulling on the wire itself will help harden the wire and make it more likely to fatigue.

YMMV. 3mm line or parachute cord works well for messenger lines.

Quote:

Originally Posted by Volkhard

Thank's for all you input. I will try to attach the new wires to the old one by creating a sacrificial soldered joint, soldering all 4 ends together. That should give me a rather strong joint without increacing the diameter much. Than , very carfully pull from the anchor locker with someone leading the new wire in atop for least resistance. I will try as soon I am back in home portand keep everyone posted how it went.
Yesterday I enjoyed a 10 hr run broad reach at almost 7kts up the SW coast of Florida. We are in Sailing Paradies here in Florida ...