Low Voltage Module 2 Part 4

Ammeters

Plug the black test leads in parallel with the circuit across the voltage source. Turn on the power in the circuit being measured. For the 2.5V range, read the value directly on the AC scale marked 2.5V. For the 10V, 50V and 250V ranges, read the red scale marked AC and use the black figures immediately above the scale. For the 500V range, read the red scale marked AC and use the 0-50 figures. Multiply the readings by 10.

Intro to Analog Multimeters

Show the measurements (voltage, current and resistance) through a corresponding physical movement of a pointer, needle or other indicator that moves over a graduated scale on the meter. The most common analog meters are the ammeter, the voltmeter and the ohmmeter. All three of these meter functions have been combined into a multifunctional tester called the multimeter.

Functions and Calibration

Functions of Analog Multimeters Ammeters Voltmeters Ohmmeters Calibrations Procedures ensure: Effectiveness of the instrument Compliance with standards Safety of the equipment

Stud Finder

Identifies studs behind drywall Some will detect wood and metal, and perform a deep scan for electrical wiring or plumbing All have limitations which you should know before putting any holes in the wall

Safe Use of Power Tools

If the GFCI option is chosen, all 120-volt, 15- and 20-ampere receptacle outlets, which are not part of the permanent wiring and in use by employees, must have approved ground-fault circuit-interrupters for personal protection regardless of the type of tools plugged into them. If the assured equipment-grounding conductor program is the chosen option, then all cord sets, receptacles that are not part of the permanent wiring and cord-and-plug-connected equipment that is required to be grounded must be covered by the program.

Ammeters

In so doing, you ensure that the current will flow through the ammeter from minus (-) to plus (+). If you connect the ammeter incorrectly (polarities reversed), the meter coil (a current-sensitive element called the galvonometer) will move in the wrong direction. This wrong direction will cause the pointer to deflect downward, possibly striking the retaining pin and damaging the meter.

Shop Vacuum

Keep a job site clean for safety and aesthetics Maintain shop vacuum and empty it regularly Turn on the vacuum outside for a minute or so after cleaning the filter to ensure no dust is spread back onto the site

Ammeters

Measuring AC Voltage 0-2.5 through 0-500 V Set the function switch to AC. Set the range switch to one of the five voltage range positions marked 2.5V, 10V, 50V, 250V, or 500V. If you know the voltage is within a lower range, set the switch to the next range above it in order to have a more accurate reading. If you are not sure about the actual voltage, however, start with the highest voltage range in order to protect the instrument. Plug the black test lead into the - (common) jack and the red test lead into the + jack.

Analog Multimeters

Multimeters are equipped with two probes that allow you to get circuit readings by touching contact points in the circuit. These instruments are used to determine electrical problems in appliances, audio equipment and security systems. You can also test batteries with multimeters. No matter what type of test instrument you use, you must take into consideration specifications (specs) and calibration.

Label Maker

Neatness is important, do not overlook Label all wires before being pulled and for the final installation Labeling devices and cable allow you to identify cables and devices in such a way that they are easy to read now and in the future

Analog Multimeters

Output voltage functions are used for measuring AC components that mix AC and DC voltages, occurring primarily in amplifier circuits. Analog multimeters rely on knobs and needles to indicate measurements. Both analog (VOMs) and digital multimeters (DMMs) allow the user to measure volts, amperes and resistance in the same instrument.

Ammeters

A popular type of ammeter is the clamp-on ammeter. Moveable set of jaws that you can use to open and clamp onto the wires to be measured, one at a time. Take current measurements without interrupting the circuit by fastening the ammeter clamps directly to the wire. By clamping the instrument directly to the wire, you can also take higher current measurements. The clamps allow you to measure the system's total AC current.

Analog Multimeters

Analog multimeters, also known as volt-ohm-milliammeters (VOMs), are generally used in the following applications: Observing changes Adjusting peak or dip indications Viewing instantaneous responses Typical VOMs are simple, yet accurate and easy-to-use instruments. Used to take accurate measurements of DC and AC voltages, current resistance, decibels, and output voltage

Soldering Iron

Creates a permanent bond between two metal conductors by melting a lead/tin material, which bonds with both conductors

Hole Saws

Designed for larger holes, 1½" to over 4" Typically make a semi-smooth cut in the wood, but are prone to splintering and burning the wood

Reciprocating Saw

Designed for quick, rough cutting of wood and metal Commonly used during demolition Can cut through wire and cable of almost any size Ensure that all electrical power is off in the area where saw is cutting

Safe Use of Power Tools

Do not rely on rubber-insulated gloves Double-insulated equipment marked by symbol Two methods of ground fault protection: Ground-fault circuit-interrupter (GFCI) Assured equipment-grounding conductor program

Safe Use of Power Tools

Double-insulated tools have no required grounding, but a visual inspection of the attached cord and plug is still required. All other applicable requirements of the program, however, apply to the extension cord and must be complied with for the protection of exposed employees. Applicable requirements include: Employer must have a written description of the program One or more competent persons must have been designated to carry out the program. No damaged or defective equipment will be used The required tests must be performed These tests must be recorded

Laser Level

Ensure two objects are same height over a relatively long distance Know how your device works, some will lose their accuracy relatively fast Be sure to follow all safety rules to avoid eye damage Helpful for mounting boxes and equipment

Ammeters

The moving-coil meter movement limits most analog ammeters to measure only small amounts of current, because they have a limited resistance (Rm) and can only handle a certain maximum current The maximum current is called the full-scale deflection current and causes the pointer to move all the way to the end of a scale. These older ammeter styles, however, have largely been replaced by meters that use digital readings.

Powder-Actuated Tools

Use a .22 caliber cartridge (actual powder shot) and special nails Secures bottom plates and other objects, such as metal gang boxes to concrete Eye and ear protection required as is manufacturer training Powder-actuated nailers use a firearm-like charge to drive a fastener into hard materials like concrete.

Ammeters

Used to detect and to measure electrical current. When using older ammeters, you must connect the ammeter in series with the current path being measured. You must also observe the proper polarity when measuring a DC circuit by doing the following: Connect the negative terminal (denoted by the "─" sign or the color black) of the ammeter to the negative or low-potential point in the circuit. Connect the positive terminal (denoted by the "+" sign or the color red) of the ammeter to the positive or high-potential point in the circuit.