hilandr451
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Posts: 3845
Loc: Houston, Texas
Reg: 010202

080107 11:17 AM  Post#1221837
reading coninuity & resistance using a VOM.
The ohm scale (second from bottom) on this meter is marked in 1 ohm increments.
On the X1 scale, the meter will read direct. If the needle points to 10 on the green scale, that's 10 ohms.
On the X10 scale multiply the numers on the green scale by 10. If the needle points to 10, that's 100 ohms.
On the X100 scale multiply the numers on the green scale by 100. If the needle points to 10, that's 1000 ohms.
Yes, the battery can be weak or the meter leads often break and cause an intermittent or false reading.
If the meter reads too high then that means there is a broken wire (open circuit).
If the meter reads too low, then it is shorted (in some fashion).
The resistance in the wire is dependent on it's makeup. Resistance in wire is usually ohms per foot  so if you have a small section of the wire you can measure so that you can get this ratio (for example, if you have 4 feet of it lying around above ground that you can test and it comes up with 4 ohms in 4 feet, you know that it has a resistance in general of 1 ohm per foot.) Then you can expand this to fit the length of the loop, so that you have a general idea of how much resistance you should be reading. The reading should be roughly within +/ 10 percent of the test loop figure.
Using an analog meter like this one though, you won't be able to see any resistance on a 4' piece of 16 gauge wire. Sixteen gauge has 4.08 ohms per 1000' so your meter should read so close to zero on a 4' section that you can't see it. (that's were a digital meter comes in handy)
Thanks to Don & Vaughn for this content
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