Gardner Bender GCM-500 AC Clamp Meter User Manual

1. Introduction

The Gardner Bender GCM-500 is a versatile clamp-on analog multimeter designed for electrical measurements. It features 4 functions and 8 ranges, allowing for precise measurement of AC Current, AC/DC Voltage, and Resistance. Its unique Lockjaw feature enhances safety by ensuring the jaws only open when the meter is set to Amps mode. This manual provides essential information for the safe and effective operation of your GCM-500 clamp meter.

2. Safety Information

WARNING: Always exercise extreme caution when working with electricity. Failure to follow safety guidelines can result in serious injury or death.

• Always ensure the meter is set to the correct function and range before making any measurements.
• Do not attempt to measure voltages or currents exceeding the meter's specified maximum ratings.
• Inspect test leads for damage before each use. Replace if insulation is cracked or wires are exposed.
• Wear appropriate personal protective equipment (PPE), such as safety glasses and insulated gloves.
• Do not use the meter if it appears damaged or is not operating correctly.
• Always reference the National Electric Code (NEC) and local electrical codes before performing any type of electrical work.
• The GCM-500 is fuse and diode protected for enhanced safety.

3. Product Overview

Components and Controls:

• Clamp Jaw: Used for non-contact AC current measurement. Features a 1.5-inch opening.
• Lockjaw Feature: Prevents misuse by only allowing the jaws to open when the meter is set to the Amps mode.
• Rotary Dial: An 8-position smooth rotary dial for selecting measurement functions (AC Current, AC/DC Voltage, Resistance).
• Digital Display: Easy-to-read display for showing measurement readings.
• Data Hold Switch: Maintains the current reading on the display for convenient recording.
• Zero Ohms Adjustment Dial: Used to calibrate the resistance measurement for accuracy.
• Test Lead Inputs: Jacks for connecting the red and black test leads for voltage and resistance measurements.

4. Setup

Battery Installation:

The Gardner Bender GCM-500 requires one (1) AA battery for operation. The battery is not included with the meter.

1. Locate the battery compartment cover on the back of the meter.
2. Use a screwdriver to remove the screw securing the battery compartment cover.
3. Carefully remove the cover.
4. Insert one AA battery, ensuring correct polarity (+ and -) as indicated inside the compartment.
5. Replace the battery compartment cover and secure it with the screw.

Note: Remove the battery if the meter will not be used for an extended period to prevent battery leakage.

5. Operating Instructions

Before operating, ensure the battery is installed and the meter is in good condition. Always refer to the safety information in Section 2.

5.1 Measuring AC Current (Amps)

The GCM-500 measures AC current using its clamp jaw, allowing for non-contact measurement without breaking the circuit.

1. Turn the rotary dial to the "A~" (AC Amps) setting. The Lockjaw feature will allow the clamp to open in this mode.
2. Open the clamp jaw by pressing the trigger.
3. Enclose a single conductor (wire) within the clamp jaw. Ensure the jaw is fully closed around the conductor.
4. Read the AC current value on the digital display.
5. To hold the reading, press the "HOLD" button. Press it again to release.

Note: For accurate readings, ensure only one conductor is inside the clamp jaw. Clamping around multiple conductors carrying current in opposite directions will result in an inaccurate or zero reading.

5.2 Measuring AC/DC Voltage (Volts)

Use the provided test leads for voltage measurements.

1. Insert the black test lead into the "COM" (common) jack.
2. Insert the red test lead into the "VΩ" (Volts/Ohms) jack.
3. Turn the rotary dial to the desired voltage range: "V~" (AC Volts) or "V-" (DC Volts). Select a range higher than the expected voltage.
4. Connect the test probes across the circuit or component to be measured.
5. Read the voltage value on the digital display.
6. To hold the reading, press the "HOLD" button. Press it again to release.

5.3 Measuring Resistance (Ohms)

Use the provided test leads for resistance measurements.

1. Insert the black test lead into the "COM" (common) jack.
2. Insert the red test lead into the "VΩ" (Volts/Ohms) jack.
3. Turn the rotary dial to the "Ω" (Ohms) setting.
4. Before measuring, short the test leads together (touch the metal tips) and adjust the "Zero Ohms Adjustment Dial" until the display reads zero.
5. Connect the test probes across the component whose resistance you wish to measure. Ensure the circuit is de-energized before measuring resistance.
6. Read the resistance value on the digital display.
7. To hold the reading, press the "HOLD" button. Press it again to release.

6. Maintenance

Cleaning:

Wipe the meter casing with a damp cloth and mild detergent. Do not use abrasives or solvents. Keep the display clean and free of scratches.

Battery Replacement:

Replace the battery when the low battery indicator appears on the display or if the meter does not power on. Refer to Section 4 for battery installation instructions.

Storage:

Store the meter in a cool, dry place away from direct sunlight and extreme temperatures. If storing for extended periods, remove the battery.

7. Troubleshooting

• Meter does not power on: Check battery installation and ensure the battery is fresh.
• Inaccurate readings:
  • Ensure the correct function and range are selected.
  • For AC current, ensure only one conductor is within the clamp jaw.
  • For resistance, ensure test leads are properly zeroed.
  • Check test leads for damage or poor connection.
• Display shows "OL" (Overload): The measured value exceeds the selected range. Switch to a higher range or a different function if applicable.

8. Specifications

9. Warranty and Support

Specific warranty details for the Gardner Bender GCM-500 AC Clamp Meter are not provided within this manual. For information regarding warranty coverage, technical support, or service, please refer to the official Gardner Bender website or contact their customer service department directly. Keep your purchase receipt as proof of purchase for any warranty claims.