# Multimeter question

• posted on June 28, 2003, 8:27 am
Just got a Sperry Digital Multimeter - the Pocket-Pro, and I am trying to figure out how to test a wall receptacle with it. There is only a positive and a negative probe, no ground. What do I do to test it? What voltage do I look for? The instruction manual was totally unhelpful.
Complete newbie into electrical matters, so any advice is appreciated.
Pete
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• posted on June 28, 2003, 10:49 am

Select VOLTS and AC, select highest range, connect +ve to LIVE, -ve to NEUTRAL, measure value.
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• posted on June 28, 2003, 10:58 am
That is not likely your best tool for checking wall receptacles. A small one use plug in tool is likely to be better.
In any case. be careful. It would not be difficult to injure yourself here.
You need to set the meter to AC and if it has ranges make sure the range includes 100 - 250V. Next make contact with the leads to each side of the spades (the two long skinny sockets) you should get about 120V. You still will not know if there are any poor connections however. Next check each spade to the ground connection (the small round one) You should get one 0V and one about 120V.
With most modern meters you are likely to get a reading where you would think it would be 0V because they are very sensitive. You may also get a reading, often 10-40V where you would expect 120 when you don't have any connection. These , safety and other reasons are why I suggest a standard outlet tester may be better, unless you really understand what is going on.
--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math
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• posted on June 28, 2003, 2:27 pm
What are you trying to test the outlet for? Voltage?
It measures the voltage between two points. Between hot and neutral, hot and ground, ground and neutral.
A normal outlet has 120v H-G or H-N and 0v G-N.
Anything else?
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• posted on June 28, 2003, 9:09 pm

Well, we really haven't eliminated anything from the list because the meter in the "proper hands" can test all that and more. Your best bet might be to get a good book or take a course at a local tech school if you really want to get comfortable using that meter.
Bobby
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• posted on June 28, 2003, 11:50 pm
Meters don't care about ground. They have two leads. They tell you the voltage difference between two points. Any two points. Stove and sink. AC plug and light fixture. Black wire and green wire. Meter simply tells voltage between each pair of points.
You have two options. To read AC voltage difference or DC voltage difference. Which one? An AC outlet would measure some AC voltage and no DC voltage. A battery would measure a DC voltage and show no AC voltage. Simply tell the meter which voltage to measure. Then touch leads to two different wires or whatever. Meter will simply report the voltage difference between those wires (or two whatevers).
That meter is, by far, the best device to test an outlet. Simply put meter to AC voltage mode, set range to Auto, and let the meter tell you the voltage difference between any two wires in that outlet. The thing even auto ranges so that you don't even have to tell it what voltage you are expecting.
Meter is smart. As long as the measured voltage does not exceed 450 volts, then you cannot even destroy the voltmeter section. IOW just don't try to measure voltages inside a TV. Measure voltages anywhere else.
hedrew3 wrote: