Aluminum Wire: White = Negaive?

[rwidman]

Originally Posted by Gone2long

Hi again,

I tested the wire with an Ohm meter (spelling?) and when I connected the red wire to the red (positive) meter probe and the white wire to the black (negative) meter probe, I got a reading of 12 or so volts.

When I switched them I got no reading, so I assume that this test "proves" that the white is negative.

Thanks to all,

G2L

It proves nothing but it suggests that you don't know how to use a meter.

Please, get an electrician to check your boat's wiring and tell you what is going on.

[Garrettw]

Originally Posted by Gone2long

Yes, that could be. Do not really know how to tell the difference.

The original boat owner is 9,000 miles away, and got nobody to ask.

Thanks for your help,

G2L

When tinned cable is cut, if the strands are not super fine, you can usually see the copper exposed.

[bobofthenorth]

Originally Posted by rwidman

It proves nothing but it suggests that you don't know how to use a meter.

Please, get an electrician to check your boat's wiring and tell you what is going on.

Excellent advice. A VOM in the hands of an amateur is at best useless and often dangerous.

R.J.(Bob) Evans
www.travellingwithgeorge.blogspot.com

[skipmac]

Originally Posted by Garrettw

When tinned cable is cut, if the strands are not super fine, you can usually see the copper exposed.

Another way to tell if the wire is copper, stick the ends in bilge water for a few days and see if they turn green.

[Gone2long]

Originally Posted by jeepbluetj

Nope. That proves absolutely nothing, as your report of what the voltmeter is doing doesn't make all that much sense. (I assume you're measuring DC volts, not ohms)

Even with an analog meter, one way will be +12 volts (red on +, blk on -) and the other way will move the meter 'negative' -- i.e. 'left' of 0.

With a DMM (digital multimeter) reversing the leads would show -12v as opposed to 12v. If it's nothing the 'other' way, something is wierd, or you have the worlds strangest meter.

Let me clarify. I used a "multimeter". I set it to read DC current. When the red prob was connected to red wire, I got a positive voltage reading of over 10 volts. "Yes" not exactly accurate.

When I connected red prob to white wire I got no reading.
Thank you all for your invaluable assistance.

G2L

[Gone2long]

Originally Posted by rwidman

It proves nothing but it suggests that you don't know how to use a meter.

Please, get an electrician to check your boat's wiring and tell you what is going on.

... Obviously, I am not an expert at this, but I am in the boonies of Southeast Asia, the prior owner is in Cuba, and that is why I am asking the experts and not hiring a non-existant one.

I sincerely appreciate the advice of everyone on the thread.

Regards,

G2K

[Wotname]

G2L
Let me try to help without being critical.
First set your multimeter to read DC volts (and not DC current or ohms or anything else)
Put the black lead on this unknown wire.
Put the red lead on some other wires until you get a reading of about 12 volts.
If you are using a ditigal meter and it reads about 12 volts, then the unknow white is negative.; however if the ditigal meter reads -12volts, then the unknown white is positive.

If you are using a analogue meter and it reads 12 volts, then the unknown white wire is negative.
If all you can get on the analogue meter is a very slight deflection below zero (ie against the needle stops), then the unknow white wire is probably positive. To be sure, reverse the leads and if you now get 12 volts with the red lead on the unkown white wire and the black lead anywhere else, then that will confirm the unknown white is positive.

In essence, a digital meter doesn't care which way the leads are connected and it will display either a positive or negative result. The analogue meter does care and will only display a positive result. The color of the leads will then determine polarity.

Good luck

[Gone2long]

Originally Posted by skipmac

If the strands of the wire are very fine, like a little larger than a hair then it is almost certainly copper. It may exist but I am not aware of stranded aluminum wire that is fine stranded since the metal would be too weak to hold up.

Proper wire will usually be marked on the insulation with the gauge and if it's certified UL, etc.

If you have enough slack on the end of the wire scrape some of the strands with the edge of a blade and look at the wire closely to see if it looks yellowish inside. You might have to use a magnifying glass as shiny copper might be hard to tell.

I agree with the meter question. If you are using a digital meter it would show +12 one way and -12 the other when you reverse the leads. If it is an analog meter (has a needle) then it won't show -12 but you can see the needle bounce slightly to the left when you connect the leads backwards.

I used an analog meter, and "yes" the readings were as you noted above.

Thanks for your reply, it really helped clarify the situation.

G2L

[Gone2long]

Originally Posted by Garrettw

When tinned cable is cut, if the strands are not super fine, you can usually see the copper exposed.

Thank you sir.

Your enlarged photo certainly makes the difference obvious. I will cut some ends and do a close check.

Best regards,

G2L

[Gone2long]

Originally Posted by Wotname

G2L
Let me try to help without being critical.
First set your multimeter to read DC volts (and not DC current or ohms or anything else)
Put the black lead on this unknown wire.
Put the red lead on some other wires until you get a reading of about 12 volts.
If you are using a ditigal meter and it reads about 12 volts, then the unknow white is negative.; however if the ditigal meter reads -12volts, then the unknown white is positive.

If you are using a analogue meter and it reads 12 volts, then the unknown white wire is negative.
If all you can get on the analogue meter is a very slight deflection below zero (ie against the needle stops), then the unknow white wire is probably positive. To be sure, reverse the leads and if you now get 12 volts with the red lead on the unkown white wire and the black lead anywhere else, then that will confirm the unknown white is positive.

In essence, a digital meter doesn't care which way the leads are connected and it will display either a positive or negative result. The analogue meter does care and will only display a positive result. The color of the leads will then determine polarity.

Good luck

Thank you for the advice. Please see my earlier posts.

Also, I think that the wire very well may be aircraft related as some other parts and items left in the boat (a parachute, for instance) suggest that the previous owner had at least an interest, if not a vocation related to aviation. And, in this part of the world, it is not uncommon to simply scavage around and attach anything to anything which may, at least for the short term, function.

Of course, not exactly safe, which is exactly why I am asking.

Thanks again for your help,

G2L

[CarinaPDX]

Adding to the previous critiques of aluminum wire, there are several failure modes possible - and not just at the terminals. While it is no longer code for use inside residential spaces (as previously noted it was a very short-lived experience) it is allowed to use from the meter back to the transformer (or at least was until the '90s). My parents' home had a buried aluminum supply line that simply burned open one phase. Being underground it is not deemed a fire hazard I guess. The power company guy explained that they use aluminum to save money, and eat the cost of the occasional repair. The failure point was underneath a concrete driveway that had been tinted a peach color, so after cutting it open and repairing it no longer matches. Not appreciated.

The point is that aluminum wire can fail anywhere along its length, and when it does it creates a lot of heat (at least with 120VAC). IMHO it shouldn't be used on land or sea - I'll leave the air to others.

Greg

[rwidman]

Originally Posted by Gone2long

Let me clarify. I used a "multimeter". I set it to read DC current. When the red prob was connected to red wire, I got a positive voltage reading of over 10 volts. "Yes" not exactly accurate.

When I connected red prob to white wire I got no reading.
Thank you all for your invaluable assistance.

G2L

That pretty much verifies my suspicion. You should have set it to read "voltage".

The real problem here is, you don't know (or are not saying) what you measured. That is, where are the wires connected at each end. You could even have been measuring from one circuit to another.

Put the meter down for a few minutes and follow the wires to where they get their power from. The battery, a circuit breaker or distribution panel, a buss bar, etc. Also, are these "big wires" (usually called cables), 1/4" or larger in diameter or "small wires, more like 1/8" in diameter? There should be writing or markings on the cable insulation. Write down what you see and post it here.

[Wotname]

Originally Posted by CarinaPDX

Adding to the previous critiques of aluminum wire, there are several failure modes possible - and not just at the terminals. While it is no longer code for use inside residential spaces (as previously noted it was a very short-lived experience) it is allowed to use from the meter back to the transformer (or at least was until the '90s). My parents' home had a buried aluminum supply line that simply burned open one phase. Being underground it is not deemed a fire hazard I guess. The power company guy explained that they use aluminum to save money, and eat the cost of the occasional repair. The failure point was underneath a concrete driveway that had been tinted a peach color, so after cutting it open and repairing it no longer matches. Not appreciated.

The point is that aluminum wire can fail anywhere along its length, and when it does it creates a lot of heat (at least with 120VAC). IMHO it shouldn't be used on land or sea - I'll leave the air to others.

Greg

The only advantage in aviation as far as I cantell is weight saving but come to think of it, I don't recall any recent builds using Al. I might check the latest regs to see if it still approved. However still see it some older aircaft.

My biggest objection to Al wire in the maritime world is that where the Al meets Cu (and of course it must meet somewhere), the Al will corrode rapidily in a damp possibily salty environment due to electrolysis.

[CarinaPDX]

I am not a fan of aluminum in the marine environment at all. If I were building a boat again I would avoid it as much as possible, including paying for carbon fiber spars. Favorite gripes are powder-coated things like anchor windlasses, and stainless bolts threaded into aluminum parts without any anti-corrosion treatment. Where needed, as in outboard motors, why on earth can't the manufacturers use a little Tef Gel?

Greg

[skipmac]

Originally Posted by CarinaPDX

Favorite gripes are powder-coated things like anchor windlasses, and stainless bolts threaded into aluminum parts without any anti-corrosion treatment. Where needed, as in outboard motors, why on earth can't the manufacturers use a little Tef Gel?

Greg

I have asked that question a hundred times. As in every time I have to drill out a screw or bolt in a mast or outboard or whatever aluminum part I'm working on.