Camp on Multitester

[fred1949]

I just bought a clamp on multitester with "peak-Hold" & I thought it would give me a readout in amps as in how many amps the wire is using over a period of time. I hooked it around a romex that runs to a fridge & a very small deep freeze. The reading was 3.33. The dial on the tester was set on ACA 20 (horseshoe sign). I guess I just gave myself away. I'm not a electrician. Is this tester capable of doing what I need? Also can you tell me in laymens terms how to use it, because the manual just tells me what it offers not how to use it. All I want out of it is to see under load how much "juice the wire is carrying.

Thank you,
Fred

[HayZee518]

The horseshoe sign indicates ohms. Using the internal battery and the probes you can measure ohms. Volts is a direct reading using the appropriate scales. Amps are read when the clamp around jaws are applied around one conductor. If you try to read amps around a pair of conductors this won't work.

[fred1949]

By one conductor do you mean one romex? Or one wire in the romex?

If it is not too much trouble please tell me how I can measure how many Amps that are being used through a particular No. 14 wire using the clamp on multimeter?

I am trying to determine if having a freezer & a fridge is overloading a wire. So if I could see how many Amps these two are using when both compressors kick on.

Thank you for your help,
Fred

[LazyPup]

A single wire is referred to as a conductor.

Whenever two or more conductors are combined in a common casing such as Romex or an appliance cord it is technically called a cable.

A snap on amp meter can only measure the current on a single conductor, therefore when it is necessary to measure the current on a cable the inner conductors must be separated so you can measure one conductor.

Kirchoffs law states that the amount of current leaving a circuit is equal to all applied currents, therefore when measuring the amperage on a motor circuit, such as a AC compressor, that has both a start and run winding you can measure the current to either winding by attaching the amp meter to the wire to the winding, or you can measure the total combined amperage by measuring on the common conductor.

A snap on ammeter is an instantaneous reading device and will not measure current over a period of time.

When a motor starts it requires a surge of current to overcome inertia and start the rotation of the armature. That instantaneous start currant if called "LRA" or Locked Rotor Amperage, and is typically 3 times the "FLA", Full Load Amperage for the motor.

The "LRA" normally only occurs for a fraction of a second during motor start. When measuring with an analog snap on ammeter you can see the indictor needle peak one "LRA" then fall back to "FLA"

Digital meters use an electronic circuit to average a reading, therefore most digital meters cannot function fast enough to measure the "LRA" current.

Some high quality digital meters have both a liquid crystal numeric display and a bar graph display the mimmics an analog meter. The bar graph type meters do react fast enough to display the "LRA"

Some meters also have a "Peak-Hold" function. When you select the peak hold function the internal circuit will measure the instantaneous peak of the "LRA" and display that reading.

If you take a reading while a motor is running with the peak-hold setting on, it will measure the current and hold the reading on the display until you manually clear it. This can be a very handy feature when you must take a reading in a tight spot where you cannot see the display. You can reach the meter in, take the reading, which is then held on the display as you pull the meter out to read it.

[fred1949]

Do you know a website where I could read up on how to use a snap on multitester?

Fred

[kactuskid]

"There are three easy ways to do this. One way is to purchase a line separator designed specifically for this purpose. It is a plastic device that plugs in between the appliance and the outlet and splits out the legs in the circuit.

http://www.omnicontrols.com/lists/n_extech234.html

The second way is to build a short extension cord and separate either the hot lead (black) or neutral lead (white) out in a section so that the amp meter can be installed around it.
Do not remove, cut, or nick the insulation from any of the wires! It is not necessary and is very dangerous. You could cause a fire or be killed!

http://www.applianceaid.com/images/ampmeterhowto.JPG

"The third place to gain access to the lines feeding the branch circuit is in the main electrical panel that contains the circuit breakers for the house. Please note that working in the electrical panel can be extremely dangerous. You could start a fire, or be injured or killed if you don’t know exactly what you are doing. Make sure that the power is turned off to the panel before removing the cover. If you are not qualified to do any of this work, call a licensed electrician!"

For a 120 V branch circuit, the amp meter can be installed around the wire coming out of the circuit breaker that feeds the branch circuit."

[fred1949]

I think I understand the wire separation to get the reading. The most confusing part is what do I set the dial on the multitester to. It has five different settings that the dial can be turned to & the several choices within these 5.
ACA
DVC
A Ohms settings
ACV
External Unit
Within these 5 there are various numbers. I wish I could find some instructions for this. I just want to do basic testing.
It also has 3 plug in holes at the bottom...V Ohms...COM...EXT.

Any help to understand how this works will be greatly appreciated.

[HayZee518]

For amps as well as voltage measurement start out at the highest range and adjust downscale. Voltage measurment is at the jacks of volts and common.
Some amprobes have amp ranges - mine made by greenlee have amp scales of 2, 20, 200, 2000. AC Volts start at 1000, 600, 200, Ohms is 2, 20 and 200 and 2K

[LazyPup]

changing the settings on the dial selects the different types of tests you can perform with this meter:

ACA= Alternating current Amps- When set in this position and the snap on jaws are snapped around one conductor the meter will indicate the amperage flow on that wire. Some meters have multiple scales for ACA- I.E. 0-60, 0-30, 0-15 etc. For the most accurate reading you select the scale that has the maximum at or slightly above the circuit under test. As an example, when checking a residential general outlet circuit which is fed by a 15A breaker you would select the 0-15A scale, attach the meter on a single conductor on the line, usually at the breaker and the meter will show the actual current draw on that circuit at the moment of the test.

On the base or side of your meter you will have three input jacks to connect external test probe leads. Normally the center jack is marked "C" which is the common and that is where you plug in the black test lead wire.

A second jack will be marked "V"

You connect the Red test lead into the "V" plug and the black in the "C"
Set your meter on "VAC" or "ACV" and you can now test the voltage between any two points of a ciruit by touching the test probes at the points in question in the circuit.



You will then have a jack that has an unside down U shaped symbol (Greek Letter Omega) that indicated "Ohms" or resistance. You plug the Red test lead into the OHMs jack, then set the meter to the OHMS scale. You can then test the resistance in between any two points of a circuit by touching the points with the tips of the test probes and reading the resistance on the scale. (A word of caution--Absolutely Do Not make a resistance measurement on a live circuit because it can and probably will burn out your meter.)

[fred1949]

Thank you very much for your help. With your information I think now I can use the multitester to find out what I need to know.

Thank you very much Lazypup.

Fred

[fred1949]

I ran several test letting the fridgerator & the small freezer start up at the same time. The multitestor read 18.4 in all tests. Does that mean that the no. 14 wire (15 Amp circut is wrong?

[HayZee518]

Is the 18.4 reading initial at start up or did it record the amp reading during normal run? You said you had a peak lock clamp around. Every motor at start up will read at least 125% more than nameplate reading - this reading is the LRA [locked rotor amp]
If the 18.4 is normal run amps then the 14 gauge wire is definitely too small.

[fred1949]

It was when both are starting up from the circut off, doors open then turning the breaker on. Both running at the same time then in a couple of minutes it drops way down.

Thank you,
Fred