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Thread: Tips to read a Multimeter Electric Tester

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    Tips to read a Multimeter Electric Tester

    Hello Guys,

    Multimeters are electrical test meters that can be used as voltmeters, ammeters, or ohmmeters. Basically, a voltmeter measures the volts of an electrical system and a multimeter can be set for DC or AC voltage. Similarly the AC or DC current (ammeter) measured in amps can be measured with a multimeter as well. Finally the resistance (measured in Ohms) of an electrical system can be measured by a multimeter. When you first hold a multimeter it may look confusing to read, but it is really quite simple. By following a few easy steps you can be testing electrical circuits like a pro in no time.

    1. Determine what type of circuit you will be testing. If you are testing a circuit in your home, it most likely is AC and thus you would want to set the multimeter to AC. However, if you are testing car, boat, or RV circuits you should choose the DC setting.

    2. Determine the suspected range of circuit resistance and set the multimeter to a resistance of at least 10 times that of the circuit resistance. Connect the red wire to the positive connection and the black wire to the negative or ground connection.

    3. Read the number from the scale you are working with. The red scale is for AC and the black is for DC currents. If you are interested in the DC voltage and you have the multimeter set to DC 10V you will read the first line of black numbers labeled "DCV,A" for DC voltage and amperes. However if you have the multimeter set to DC 50V, read the second line. If set to AC 10V read the first row of black numbers, but use the red line scale to determine the exact reading.

    4. Read the resistance by determining the Ohm reading from the very top scale of black numbers, and amps are determined in the same manner as voltage.

    Thanks and Regards
    Steven Brooks

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    Diamond Member AndyD's Avatar
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    Hi Steven, are you trying to sell multimeters or are you trying to reduce the population?

    Quote Originally Posted by Steven Brooks View Post
    Hello Guys,

    Multimeters are electrical test meters that can be used as voltmeters, ammeters, or ohmmeters. Basically, a voltmeter measures the volts of an electrical system and a multimeter can be set for DC or AC voltage. Similarly the AC or DC current (ammeter) measured in amps can be measured with a multimeter as well. Finally the resistance (measured in Ohms) of an electrical system can be measured by a multimeter. When you first hold a multimeter it may look confusing to read, but it is really quite simple. By following a few easy steps you can be testing electrical circuits like a pro in no time.
    When you say 'testing like a pro' you actually mean connecting the tester to a circuit and getting it to display a number on the screen hopefully without damaging the tester or giving yourself a shock. The problem arises in interpreting what the number means. Without the knowledge to interpret the result on the tester screen you're not really 'testing like a pro'...are you?


    Quote Originally Posted by Steven Brooks View Post
    1. Determine what type of circuit you will be testing. If you are testing a circuit in your home, it most likely is AC and thus you would want to set the multimeter to AC. However, if you are testing car, boat, or RV circuits you should choose the DC setting.
    Okay, lets stop there a minute. Some circuits in homes are at main supply voltage, some are ELV or SELV or even PELV (12V lighting etc). Same with boats and RV's, you often find some circuits at normal domestic supply voltage and some at battery voltages. If you can't tell which circuits are which it would be better for your health if you didn't try to use a multimeter on them.


    Quote Originally Posted by Steven Brooks View Post
    2. Determine the suspected range of circuit resistance and set the multimeter to a resistance of at least 10 times that of the circuit resistance. Connect the red wire to the positive connection and the black wire to the negative or ground connection.
    I see your plan here... I think. If you don't mention the fact that you must isolate all circuits before you attempt to measure resistances or impedences there's a 50/50 chance the customer will require a new multimeter. My first thought was that the other 50% who get killed trying to do a live resistance test won't be return customers but I suppose they won't be in a position to bad mouth your multimeter or your half-assed instructions so overall it could be a solid marketting strategy I suppose.


    Quote Originally Posted by Steven Brooks View Post
    4. Read the resistance by determining the Ohm reading from the very top scale of black numbers, and amps are determined in the same manner as voltage.
    Amps are not determined in the same manner that voltage is determined. To measure a voltage with probes the circuit is left in tact. To measure current with a multimeter you need to split the circuit somewhere and connect the multimeter in as a part of the circuit.

    Have you actually used the multimeter you're talking about?

    You are obviously a scientist. Do you have any more electrical tutorials? I thoroughly enjoyed this one and I'd be interested to see any others you have written as well please.
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    vieome (08-Nov-12)

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    LOL,I think if someone doesn't know how to work a multimeter they certainly should not be using one.

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    Site Caretaker Dave A's Avatar
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    Quote Originally Posted by roryf View Post
    LOL,I think if someone doesn't know how to work a multimeter they certainly should not be using one.
    +1
    The trouble with opportunity is it normally comes dressed up as work.

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    Gold Member vieome's Avatar
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    http://www.ehow.com/how_4894886_read...ic-tester.html His post is an exact copy of the e-how page, given AndyD reply makes one wonder how many people have been fried if the ehow page has wrong advice too.

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    Diamond Member adrianh's Avatar
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    My wife is a qualified heavy current electrical technician (yes, its true) She worked in JHB many years ago and one of the things she did during her training was to assist with repairing ESKOM multimeters. The techs would blow them up all the time because they would forget to move the probe to the Amp socket when testing current. A Fluke 77 does not appreciate having lots of amps going through its voltage measuring circuit. If you ever wanted to know what a PCB looks like with a hole blown through it then this is the perfect way to see
    How easily someone is offended is directly proportional to how stupid they are.
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    Site Caretaker Dave A's Avatar
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    Quote Originally Posted by vieome View Post
    http://www.ehow.com/how_4894886_read...ic-tester.html His post is an exact copy of the e-how page
    Maybe Steven's next "how to" should be how to copy and paste text from the internet

    Not often I get inspired to hand out negative reputation...
    The trouble with opportunity is it normally comes dressed up as work.

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    Diamond Member Justloadit's Avatar
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    Quote Originally Posted by adrianh View Post
    My wife is a qualified heavy current electrical technician (yes, its true) She worked in JHB many years ago and one of the things she did during her training was to assist with repairing ESKOM multimeters. The techs would blow them up all the time because they would forget to move the probe to the Amp socket when testing current. A Fluke 77 does not appreciate having lots of amps going through its voltage measuring circuit. If you ever wanted to know what a PCB looks like with a hole blown through it then this is the perfect way to see
    Hi Adrian,

    I think you meant to say that the technicians would forget to move the leads from the current position when they decided to measured voltage. The voltage side is quite resilient, however if you were measuring current and now place the leads across a supply to measure voltage, you effectively connect the multimeter shunt across the supply, causing a dead short, and off course a destroyed instrument. A very dangerous position to be in, as the flash from the short could cause severe injury to the technician. I prefer to use a clamp tester when measuring amps than using a series based measuring instrument, as this is an intrusion free method of measuring current.
    Last edited by Justloadit; 08-Nov-12 at 08:20 PM. Reason: verb and grammer
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    Diamond Member AndyD's Avatar
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    Steven, I actually semi regretted the reply I made late last night, I wasn't in a particularly good mood and your new thread on multimeter instructions for people who shouldn't be attempting to use one in the first place was like a red rag to a bull.

    I actually wasn't sure if it was a spam post or not but I since see you posted an intro etc so I should maybe have given you the benefit of taking your thread as being in good faith at least, even if it was somewhat innacurate and a copy/paste job from elsewhere. I can't apologise for my stance or the factual content I posted but I do apologise for the tone and the sarcasm.

    Quote Originally Posted by roryf View Post
    LOL,I think if someone doesn't know how to work a multimeter they certainly should not be using one.
    Also +1 and this is probably how I should have replied first time around.
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    Andy, I must say i was rather suprised by your reply, the reason i say this is because your replies are normally educational and informative, you would expect a reply like that from other members including myself. We will let you off this time, just dont do it again , otherwise we will have to get Dave to clean it up, dont want to tarnish your good reputation .

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