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drynoc 04-24-2005 07:42 PM

The previous owner of my Santana 35 had three wire systems running from the masthead and anchoring lights on the mast (black, white and red, and black, white and green) connected to a bus. From the bus back to the electrical panel, he had only two wires (black and white in each case). Is there a reason for this, or did someone simply not know what they were doing? It seems like the third wire ought to be superfluous.

Irwin32 04-24-2005 10:02 PM

Disconnect the 3rd wire and see what happens.

drynoc 04-25-2005 06:25 AM

It''s already disconnected. I''m trying to decide how (and whether) to put it back together. I know of no situation in DC wiring, and the boat has no AC capability, where you need a three wire setup.

TomS 04-25-2005 04:31 PM

Is your "steaming light also a deck light? If it is, two wires carry power to there respective lights, and the other is a ground. There isn''t any way to decide which is ground and which carries power using a meter; there is a path for current flow thru the bulbs. If you have a simple steaming light fixture, only two of them will be used. The third wire is for future use. Thank the previous owner profusely.

If you have a tri-color/anchor light fixture on top of your mast, this would require the three wires as well. If there is nothing but a standard anchor light, perhaps he planned to add one and pre-wired for it.

drynoc 04-26-2005 10:10 AM

Thanks, TomS. That is exactly the kind of help I was looking for. I''ll call the manufacturer and see what the standard was when the boat was built. Let''s assume for a moment that you are right, and the lights are dual purpose. What would the procedure be to connect the three wires coming down the mast to the two wires leading back to the panel?

TomS 04-30-2005 10:48 AM


Sorry to be so long in getting back to you.
If you have two bulbs, each is going to require power. Now, you already have one power wire and a ground. All you need to add is another power wire leading from your breaker panel to the mast step. Add a breaker to the panel to switch and protect the circuit. Two additional power wires means you need two empty spaces on the panel. If this method proves to be too difficult, you could consider adding a pair of breakers at the existing terminal panel at the mast. Then the existing wiring will become a feed for both lights. Since you have two two bulb systems that you are feeding, you will wind up with four breakers at the mast.

If you have called the manufacturer, he probably has told you that black and red are probably power and white is ground. The blk, wht, and grn wires are probably standard 110vac cable, and the person used it because its what he had. It will work fine, but you make up your own color code. I always use green for ground, white for anchor, and black for tricolor. That is assuming of course that it goes to the top of the mast. If it goes to the deck light/steaming light, green is probably ground, but after that, you are on your on. Check out the color codes used in the rest of the boat. Whoever did it, probably used the same code throughout.

A meter will show you which of the boat wires is positive and which is negative.

I am curious, have you ascertained if you have multiple bulb fixtures on your mast? When you flip the switches on, do you have any lights showing?

Hope all this helps you.

shmangasarian 04-30-2005 11:55 AM

before you start making any assumptions, read the code stamped on the insulation. If the insulation has BC stamped on it you are dealing with boat cable and DC wiring rules apply. Black is negative and red is positive, (although more current ABYC standards now make yellow negative). DO NOT confuse DC wiring with AC - different color coding rules could create a potentially deadly situation. I would suggest you read up a bit on boat wiring - Both Calder and Casey have excellent books on the subject. And if I may say, making up your own color codes invites disaster. As far as breakers go, I have all my nav. lights powered from the same (properly sized) breaker and then to separately fused switches.

drynoc 05-03-2005 12:00 PM

Thanks again for your replies. At present the batteries are not on the boat. I spent the winter re-powering, and am now in the process of hooking up the electrics. So I can''t flip the switches at the moment to see what happens. But you are right that someone did use standard AC wiring which has no markings on it, so I can''t tell from that what they were trying to do. What I will end up doing is solving the problem via trial and error when I put the batteries back in. But it sounds as though I will have to install three wire cable from the bus to the panel to match the three wire cable from the lights to the bus. True?

shmangasarian 05-06-2005 06:45 AM

If, as you said, only two wires from the 3 wire cable are connected at the mast bus, then you would run 2 wire cable to the panel. You mentioned "standard AC wiring" -- hopefully you (and whomever wired previously) are working with multi-strand, tinned, properly AWG sized boat cable.

drynoc 05-06-2005 10:41 AM

Thanks again for the reply. I am using multi-strand etc. etc., but that was not necessarily the previous owner''s habit. There is quite a bit of AC wire throughout the boat which I am gradually getting rid of. None of the wiring under discussion in this thread is currently hooked up. What I have are three wire AC cables running down the mast and clearly meant to attach to a terminal bus. Two wire AC cables run aft from, but not connected to, the same bus to the wiring panel. I was just trying to understand whether there was a reason for that, or if he had used the three wire cable because it was lying around available, and only used two wires. I will do some trial and error to find the answer. Thanks again for the help. It has been valuable.

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