User's Guide 99 Washington Street Melrose, MA 02176 Phone 781-665-1400 Toll Free 1-800-517-8431 Visit us at www.TestEquipmentDepot.
Introduction Congratulations on your purchase of the CT70 AC Circuit Load Tester. This device can detect circuit and wiring problems such as: Poor ground impedance, false grounds, missing ground fault protection, low voltage availability under load, and high ground-to-neutral voltage. In addition, the CT70 tests GFCI and EPD circuits.
Description 1 Meter Description 1. AC power cable connection 2. Measurement results menu 2 3. Hot-Neutral-Ground coded measurement result 3 4 4. Primary reading display 5 5. Secondary reading display 6 7 6. Down arrow button 8 7. Right arrow button 8.
Operation Overview The CT70 AC Circuit Load Tester can test outlets or circuits under load for proper wiring, reverse polarity, and the presence of a ground. The CT70 uses a simple menu-driven display to allow the user to quickly see line voltage, voltage drop under full load, ground-toneutral voltage, and line impedance. The GFCI testing utility is performed separately per UL-1436, disrupting the flow of electricity if a functioning GFCI is present.
The Voltage menu displays the True RMS line voltage. Use the ► button to scroll the Voltage sub-menu (line voltage, ground-to-neutral voltage, Peak Voltage (P), and Frequency (Hz)). The Voltage Drop (Vd) window indicates percent voltage drop (with 15A load) and the Loaded Voltage (Vl). The voltage drop sub-menu offers a load voltage result for 20A and 12A loads. Use the ► button to scroll the sub-menu. The Impedance (Z) window indicates the impedance in ohms of the hot conductor.
Testing Procedures Test 1: Wiring Verification The wiring configuration is the first test result that is displayed. Refer to the table presented earlier in the user guide for the test result key. For wiring conditions other than normal, the CT70 is limited in the type of tests it can perform on a circuit until the circuit’s wiring issues are resolved. For ‘no ground’ conditions, only the line voltage and voltage drop tests can be made.
Test 3: Voltage Drop Measurements To determine voltage drop, the CT70 measures line voltage, factors in the load, measures the loaded voltage, and then calculates the voltage drop. Results for 12A, 15A, and 20A loads are provided. For nominal efficiency, a voltage drop of 5% is the maximum recommended by the National Electrical Code (NEC) board. When a voltage drop measurement of less than 5% is made, the meter’s display backlight turns blue in color.
Test 5: Impedance (Z) Measurements The impedance measurement capability of the CT70 is used to check Hot and Neutral impedance when voltage drop measurements are too high (greater than 5%). To determine where the problem is, measure the impedances and analyze the data as follows: • If one impedance measurement is exceedingly higher than the other then the problem is with the conductor that shows the higher impedance.
Test 6: GFCI (Ground Fault Circuit Interrupter) Testing A ‘GFCI’ can protect personnel from shock hazards. The CT70 tests GFCI circuits by forming a Hot-Neutral imbalance, leaking small amounts of current (6 to 9 mA) from Hot to Ground through a fixed resistance. A good GFCI circuit will sense this imbalance and switch off the power. The CT70 displays the current value in mA. To test a GFCI circuit: 1. Plug the meter into the receptacle under test. 2.
Test 7: EPD (Equipment Protective Device) GFCI Testing An EPD device can protect equipment as well as personnel. The CT70 tests EPD circuits by forming a Hot-Neutral imbalance, leaking current from Hot to Ground through a fixed resistance. A larger amount of current (30mA) is used than would normally be used to test a standard GFCI (6 to 9mA). A good EDP/GFCI circuit will sense this imbalance and switch off the power. The CT70 displays the current value in mA. To test an EPD/GFCI circuit: 1.
Specifications Measurement Specifications Range and Resolution Accuracy Line Voltage 100.0 to 250.0 VAC ± (1.0% + 0.2V) Peak Line Voltage 121.0 to 350.0 VAC ± (1.0% + 0.2V) 45.0 to 65.0 Hz ± (1.0% + 0.2Hz) 0.1 to 99.9% ± (2.5% + 0.2%) 10.0 to 250.0 VAC ± (2.5% + 0.2V) 0.0 to 10.0 VAC ± (2.5% + 0.2V) 0.00 to 3.00 Ω (Hot) ± (2.5% + 0.02Ω) >3 Ω (Neutral, Ground) Unspecified GFCI Trip Current 6.0 to 9.0mA ± (1.0% + 0.2mA) EPD Trip Current 30.0 to 37.0mA ± (1.0% + 0.
Maintenance WARNING: To avoid electrical shock, remove all inputs before opening the case. Cleaning and Storage Periodically wipe the case with a damp cloth and mild detergent; do not use abrasives or solvents to clean the instrument. Pack the meter away safely when not in use. Do not allow the meter to remain connected to live circuitry when not in use.
