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Old 27-03-2015, 20:36   #46
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Re: Clarification

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Originally Posted by Gone2long View Post
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
Does "Multimeter" mean DMM (digital multimeter) or analog multimeter? They're both multimeters. One (dmm) is far more common at this time. I can't remember last time I used an analog one, but I have. (I've been a stupid engineer for something like 30 years.. hehehe but now I do software with that aging EE degree...)

If you did have it set to current (DC amps) and the wire you're looking at has battery voltage on it, you've blown the fuse in the meter. No biggie, I've done that dozens of times. But since you didn't say the meter pegged then went to zero, I'm guessing you had it on DC volts, which is what you want to measure - and "over 10" sounds like volts.

Reversing should move the meter to the left on an analog meter or show negative on a digital meter. If not, something (process, or the meter, or something) is off, and that's a red flag to those of us who deal with electrons very often, which is why you got lots more replies.

I concur with trace the wire. That's good advice. If you trace it and find a red on a breaker, and the white on a ground buss - you have a definitive answer.

Oh, and what overall are you trying to do? That may help get you better information to solve your issue. And may get advice to "just try it" (for something like a light fixture) to "that'll fry stuff" (for electronics)
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Old 28-03-2015, 17:15   #47
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Re: Aluminum Wire: White = Negaive?

Using a meter on two wires, even if done correctly tells you nothing unless you know where the wires originate, especially if the colors are not standard (or may not be standard). In this case, it's entirely possible that the red wire is the positive conductor to one device (say a radio) and the white wire is the positive conductor to something else (say a cabin light). Also, without a load and with a sensitive meter, it's possible to read phantom voltages, that is voltages that will disappear when a load is placed on the circuit.


Trying to measure something without knowing what you are measuring will get you nowhere or in trouble.


I don't understand the OP's reluctance to trace the wires to see where they originate. Or answer the question about the size of the conductors.
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Old 22-04-2015, 03:40   #48
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On corrosion Re: Aluminum Wire: White = Negaive?

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Originally Posted by Wotname View Post
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.
good point. that is exactly what I have found w. this wire at various points in the boat. thankfully, most had already been disconnected from any current power source.

g2l
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Old 22-04-2015, 03:47   #49
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Re: Aluminum Wire: White = Negaive?

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Originally Posted by rwidman View Post
Using a meter on two wires, even if done correctly tells you nothing unless you know where the wires originate, especially if the colors are not standard (or may not be standard). In this case, it's entirely possible that the red wire is the positive conductor to one device (say a radio) and the white wire is the positive conductor to something else (say a cabin light). Also, without a load and with a sensitive meter, it's possible to read phantom voltages, that is voltages that will disappear when a load is placed on the circuit.


Trying to measure something without knowing what you are measuring will get you nowhere or in trouble.


I don't understand the OP's reluctance to trace the wires to see where they originate. Or answer the question about the size of the conductors.
Did you mean PO?
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Old 22-04-2015, 03:58   #50
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Latest Re: Aluminum Wire: White = Negaive?

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Originally Posted by Gone2long View Post
Gang,

Have some aluminum wire on my boat. It is white and red. My voltmeter seems to indicate that the white is negative.

Is it usual for negative aluminum wire covering to be colored white?

Or is this some kind of regional or other phenomenon?

Thanks,

G2L
The white and grey wires were all neg. Most had no power to them. The ones that do, are relatively large= 16awg or so. They are bitter ends, connected to 20 or 22 copper wire feeding LED bulbs or appliances rated at 12v, dc, each pulling no more than 15 watts. I never draw more than 80 watts from the entire solar system at any time, and each of my 5 parallel panels is rated at 85.

Seems relatively safe to an ignorant newbie like me.

Comments welcomed.

g2l
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