How to Use a Multimeter (Latest Tips for Electrician)

This article presents the fundamental ideas of multimeters and discloses how to utilize them for essential estimations. Multimeters are a standout amongst the most valuable electrical and electronic guides accessible to us.

Viable they are our eyes to see power. The capacity to utilize a multimeter is fundamental in the event that you have to recognize what is happening electrically.

A multimeter is, as the name recommends, a meter equipped for different capacities. An essential meter will enable us to gauge and test AC voltages, DC voltages, DC extremity, opposition and regularly current.

Further developed meters additionally measure recurrence, capacitance, transistor gain, as well as inductance.

Analog vs Digital Multimeter

Multimeters come in many shapes and sizes. However, there are basically two

1. Analog
2.  Digital Multimeter

The basic differences are outlined in the following table:

Analogue meters	Digital meters
1. Indicate with a pointer that moves across the face of the meter.	1. Display the measured value in actual digits (numbers).
2. Not as accurate as a precisely calibrated digital meter.	2. Normally regarded as more accurate than analogue (only if they have been correctly calibrated).
3. Can require some practice to quickly read exact voltages, although they are very useful in showing that a voltage is present.	3. Easier to read exact values than on analog meters. However, this is often an overkill when all you need to know is if a voltage exists or not.
4. Especially suited to measuring voltages that very quickly. The pointer closely follows the voltage as it varies up or down quickly.	4. Display misleading results if the measured voltage varies quickly. This is because most digital meters require a second or more to read the measured voltage. If the voltage varies greatly during this time, then the reading will be wrong.
5. Only require a battery when measuring resistance.	5. Require a good battery to work on all settings.

On the off chance that you don't claim a meter, or can't promptly acquire one, at that point the time has come to put resources into one. An essential meter will most likely be sufficient for your necessities. That is one that basically peruses AC and DC volts, obstruction and DC current. The decision among simple and advanced is yours and will rely on accessibility as much as your financial plan and inclinations. It isn't prescribed to pay excessively cash for your first multimeter, as your utilization of it may not be advocated. Anyway, a meter that does the nuts and bolts is fundamental. 

On the off chance that you have to buy a multimeter, here is a connection to Amazon's scope of multimeters 

Advanced meters are ordinarily accessible in most electronic stores. Simple meters are frequently viewed as "old innovation". Anyway, much of the time a simple meter might be the main meter accessible that is working (since they don't expect batteries to peruse voltages). The two kinds of meters will be talked about in this part. In the event that you have a meter, if it's not too much trouble have it with you as you read this part. Read the directions for your specific meter to know about its capacities. Where conceivable utilize your meter to do the activities as reasonable models.

Measuring Voltages on your Multimeter

No matter what sort of meter you have, you need to know roughly what sort of voltage you are measuring. The first choice is between AC and DC. As a guideline, common sources are:

For AC:   transformers, alternators (often erroneously called generators), house wiring, light sockets, power outlets (wall sockets).

For DC:  batteries, solar panels, cars, electronic equipment.

Once you have determined if you will be measuring AC or DC, you need to select this on your multimeter. Refer to your meter instructions. Most meters will not be damaged by selecting AC instead of DC, or DC instead of AC. However, the meter won’t read correctly, if at all.

The next step is to consider roughly the magnitude of the voltage you will be testing. Then select on your meter a range that is bigger than that voltage.

Example 1: You want to measure the voltage at the wall outlet. It should be 220 or 240 volts, select the 250 or 300 volts range on AC.

Example 2: You want to measure the voltage of your car battery. It should be 12 volts. Select the 15, 20, 25, 30 or 50-volt range on DC, (depending on your meter’s ranges).

If you are not sure what the voltage should be, then start on the highest range.

Analogue Meter	Digital Meter
If the meter pointer only moves a tiny bit, then select a smaller range. Continue to select a smaller range until the pointer is midway or higher.	If the readout reads 0.01 or a similar very low reading, select a lower range until a more meaningful reading is displayed.
If the pointer goes off the scale (all the way over the right-hand side) then you need to quickly remove the probes, select a higher range, then measure again	If the range selected is too high, most meters will display OL or -1 or similar indicating overload or out of range.

Some (more expensive) digital meters have a feature called “auto-select” or “auto-ranging”. This means that the meter will automatically select the appropriate range for the voltage you are measuring. With these meters, all you need do is select AC or DC.

Measuring AC

When measuring AC, it doesn’t matter which probe goes to the phase (sometimes known as “active” or “hot”), and which probe goes to the neutral (sometimes known as the “cold”. That is, AC has no polarity (see the article on AC and DC  for more details).
Exercise 1: To measure the voltage at a wall outlet, insert one probe in one hole and the other probe in the other hole. It doesn’t matter which probe goes where. Try it with your meter:

1.   Select AC volts, 250 or 300 volts range (depending on your meter’s ranges).

2.   Being sure not to touch the metal points of the probes, put one probe in one of the holes in the wall outlet. Put the other probe in the other outlet hole. Your meter should read somewhere near what the voltage should be (110, 220 or 240 volts).

3.    Now, still being sure not to touch the metal points of the probes, swap the probes over. That is, remove both probes from the outlet holes, swap them over and carefully re-insert them. Your meter should read the same as it did before. This shows it doesn’t matter which way the probes go when measuring AC.

 Measuring DC

When measuring DC, you need to put the red probe to the positive(+), and the black wire to the negative(-) of the voltage being measured. If you mix this up and reverse the wires, then the meter will read backward. That is, on analog meters, the pointer will quickly move off the left-hand side of the scale. If this happens, no permanent damage normally occurs, simply reverse the way you have the probes. On digital meters, all that happens is that a “-” sign appears in front of the numbers indicating a negative voltage.

Exercise 2: To measure the voltage of a car battery.

1.   Select 15, 20 or 50 volts DC on your meter.

2.   Place the red positive probe on the battery positive terminal.

3.   Place the black negative probe on the battery negative terminal.

4.   A good battery should read between twelve and fourteen (12-14) volts.

A common use for a multimeter is to detect which lead from a battery or power supply is positive and which is negative. When you don’t know which is which, hold one probe on one of the leads to be tested, and then momentarily touch the other lead with the other probe. If, on an analog meter, the pointer moves off to the left, then swap the probes over. When the meter reads correctly, the red probe is connected to the positive wire (or positive battery terminal). On a digital meter, if the “-” sign appears, then reverse the probes for the red lead to be connected to the positive.

Some common terms

Short Circuit: When there is zero resistance in the circuit, it is said to be a “short” circuit. This is shown on all meters by reading “0” (zero ohms) – or close to zero ohms.

Open Circuit: When there is so much resistance that the meter can’t register it, it is said to be an “open” circuit. This usually indicates that there is no connection between the probes.

Note: When there is an open circuit, the meter can sometimes suggest some resistance (often measured in Mega-ohms). This is normally caused by touching the probes with your hands, and the meter is actually measuring your skin resistance.

Practical Uses of Measuring Resistance

As mentioned earlier, knowing the exact resistance in a circuit is often not as important as knowing if there is a circuit at all, if there is a short circuit, or if there is an open circuit. Try the following exercises as examples.

Exercise 5: Test a lead to see if it is faulty or not. This could be a lead from your HiFi, a power extension lead or a microphone lead.

1.   Select Resistance and the Ω x 1 scale. If using an analog meter, calibrate it to read 0Ω when shorting the probes together.

2.   Check the lead for short circuits. Using only one end of the lead, place a probe on each connection. Your meter should read infinitive resistance, saying there is no circuit between the two probes. If your meter shows close 0Ω, (a short circuit), then it needs to be fixed or replaced. The most common places for “shorts” to appear are in the plugs at either end.

3.   Check the lead for continuity. Using both ends of the lead, place one probe on the same point at each end. Your meter should show a short circuit (0Ω). Now do the same for the other connection on each end. If on either connection you do not get a short circuit, then there is not a continuous circuit in the lead where there should be. It probably means the lead is broken. The normal way to fix this is to cut 10cms off either end of the lead, check that the lead now has continuity, and then rejoin the connectors. This is recommended because the greatest wear on the lead is where it bends at the exit of the plugs. If after replacing the ends there still is no continuity then it is probably best to replace the lead.

Note: Some stubborn leads will only show an open circuit after bending the lead severely at either end. This suggests the lead is broken but still making an intermittent connection. It also should be cut shorter and re-joined.

Exercise 6: Check a light bulb to see if it is OK. If a flashlight doesn’t work it is good to know if the batteries are flat if there is a bad connection or the bulb is blown.

1.   Select resistance and the Ω x1 range. If using an analog meter, calibrate it to read 0Ω when shorting the probes together.

2.   Place a probe on each connection on the light bulb. Your meter should show a circuit. Often it shows the resistance is almost zero ohms, this is normal and suggests a good light bulb.

Note: the resistance of a light bulb increases greatly when power is applied. This is because, as with most resistances, the resistance increases with temperature.

If the light bulb checks out OK, select DC volts on your meter and check that the batteries are also OK.

Exercise 7: Check if a fuse is blown or not. If you think a fuse is blown, the best way to know for sure is to remove the fuse (with the power off!) and test it with your multimeter.

1.   Select resistance and the Ω x1 range. If using an analog meter, calibrate it to read 0Ω when shorting the probes together.

2.   Place a probe on each end of the fuse. Your meter should show a short circuit (no or very low resistance). If there is very high or infinitive resistance, then the fuse is blown.

SUMMARY

To avoid electric shock when measuring voltage or current, always hold only the plastic insulation on the probes.
DO NOT touch the metal pins

When measuring AC, it doesn’t matter which way the probes go.

When measuring DC voltages, the red positive probe goes to the positive side of whatever is being tested.

When measuring resistance, ensure there is no power applied to the resistance being tested. It doesn’t matter which way the probes go.

When measuring current, it is necessary to break the circuit in an appropriate place and insert the probes in series with the circuit under test. The black probe goes to the positive side of the break.

So there you go, grab a multimeter and start “looking” at electricity – but do it carefully!

Credit: https://geoffthegreygeek.com