Extech CT70 AC Circuit Load Tester Manual PDF
Contents
1. be present Double insulation AN This symbol adjacent to a terminal indicates that under normal use This WARNING symbol indicates a potentially hazardous situation which if not avoided could result in death or serious injury This CAUTION symbol indicates a potentially hazardous situation which CAUTION if not avoided may result damage to the product 2 CT70 V7 0 09 10 Description Meter Description 1 AC power cable connection 2 Measurement results menu 3 Hot Neutral Ground coded measurement result ON OF OY oe Primary reading display Secondary reading display Down arrow button Right arrow button GFCI test button Display Description A V Vd VL Z Hz Q mS ASCC Peak RMS GFCI EPD NEUT OL m M k Amperes Current Voltage Voltage Drop Percent Voltage Drop Voltage load Impedance Hertz cycles per second Ohms Resistance Milliseconds Available Short Circuit Current Ground to positive peak measurement Root Mean Square Ground Fault Equipment Protection Device test Neutral Overload 1 JE 2 tO m 4 210 bo scorers 6 T y cre gt 5 7 b 8 daad EPD HOH OU BoA Unit of measure prefixes milli mega and kilo CT70 V7 0 09 10 Operation Overview The CT70 AC Circuit Load Tester can test outlets or circuits under load for proper wiring reverse polarity and the presence o2. noise free sine waves the peak voltage should be 1 414 times the rms line voltage reading Ground to neutral voltage should be less than 2 VAC in which case the display backlight will appear blue in color if ground to neutral voltage is greater than 2 VAC the backlighting appears in red Higher ground to neutral voltages indicates excessive current leakage between the neutral and ground conductors Excessive ground to neutral voltage may result in inconsistent or intermittent equipment performance Voltage Measurement Troubleshooting Suggestions Problems Likely Causes Possible Solutions Out of tolerance Line Voltage Overloaded circuit Redistribute loads 4106 Aine shouldbe 120V 10 Connection within circuit or Repair high resistance at the panel has excessive connection resistance Utility company problem Contact the power utility company High Ground to Neutral voltage Neutral to Ground current Identify leakage check for Readings gt 2VAC indicated a leakage multiple bonding points problem Peak Voltage out of tolerance Supply voltage out of Contact power utility company For 120V Line Peak should tolerance measure petween 193 183V High peak loads on circuit Redistribute electronic devices Frequency out of tolerance Supply frequency out of Contact power utility company 50 60Hz tolerance 6 CT70 V7 0 09 10 Test 3 Voltage Drop Measurements To determine voltage drop the CT70 measures li
3. rewire or replace 8 CT70 V7 0 09 10 Test 6 GFCI Ground Fault Circuit Interrupter Testing A GFCF 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 Press the CT70 GFCI button to enter the GFCI test mode menu 3 GFCI is the default test and the letters GFCI should appear on the lower side of the meter s display If not press the button once to switch to GFCI 4 Press the GFCI button again to start the test The current that is leaked to ground will display The rotating display affect lets the user know that the test is in progress 5 The GFCI circuit should trip within the time specified by UL recommendations the meter s display will switch off because the power has been removed by the GFCI circuit 6 When the GFCI circuit is reset the CT70 will display the elapsed time from start of test to power down 7 Press the GFCI button again to return the meter to normal operation mode 8 If the GFCI circuit fails to respond in 6 5 seconds the CT70 stops the test automatically and OL will display on the meter UL Guideline T 20 I 1 43 Where T milli
4. FCI Ground Fault Circuit Interrupt feature performs two tests GFCI Faults a circuit when 6 to 9mA from hot to ground is detected EPD Equipment Protective Device For breakers equipped with an EPD the breaker trips for ground faults greater than 30mA To display the GFCI main menu window press the GFCI button To toggle the two tests use the gt button Once the desired test is selected press the GFCI button to start the test These tests are further detailed below 5 CT70 V7 0 09 10 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 For reverse polarity conditions open neutral or open hot conditions the meter will not display since power will not be available Notes e The meter cannot sense two hot wires in a circuit e The meter cannot display the results of more than one circuit issue at time e The meter cannot sense ground reversals Test 2 Voltage Measurements Warning Do not take measurements on circuits with voltages higher than 300VAC maximum voltage rating Line voltage measurements should be 120VAC 10 at 60Hz For
5. User s Guide EXTECH INSTRUMENTS A FLIR COMPANY AC Circuit Load Tester Model CT70 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 Circuit and wiring issues listed above can introduce shock hazards from grounding issues and can comprise performance of machinery and equipment from poor ground impedance lack of sufficient voltage under load and or high ground to neutral voltage In addition fire can result from the heat generated by high resistance points in a circuit Proper wiring habits have been shown to greatly increase power quality performance This meter is shipped fully tested and calibrated and with proper use will provide years of reliable service Features e True RMS measurements e Voltage drop measurements on 12A 15A and 20A loads e Voltage measurements Line ground to neutral and peak e Measures frequency of the voltage e Checks 3 wire receptacle configuration e Finds false grounds e Tests GFCI and EPD circuits Safety International Safety Symbols This symbol adjacent to another symbol or terminal indicates the user must refer to the manual for further information hazardous voltages may
6. de and measure the current on the branch circuit If a voltage drop reading changes significantly from one receptacle to the next then the problem could be a high impedance point at or between two the receptacles It is usually located at a termination point such as a bad splice or loose wire connection but could also be a faulty receptacle Voltage Drop Measurement Troubleshooting Suggestions Problems Likely Causes Possible Solutions Voltage drop gt 5 Overloaded circuit Redistribute loads Wrong wire gauge size for Check code and rewire if length of cable run necessary High resistance connection Locate bad connection and in the circuit or at the panel rewire or replace Test 4 ASCC Measurements The CT70 calculates the ASCC Available Short Circuit Current that a branch circuit can deliver through a breaker in a dead short circuit condition The ASCC is calculated by dividing the line voltage by the circuit s line impedance See equation below ASCC Line Voltage Hot impedance Neutral impedance Use the gt button to simulate a situation where all three conductors hot neutral and ground are shorted together Note that this second test will trip a GFCI 7 CT70 V7 0 09 10 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 m
7. easure the impedances and analyze the data as follows e f one impedance measurement is exceedingly higher than the other then the problem is with the conductor that shows the higher impedance e If both impedances are high the problem could be an undersized conductor a faulty load or poor connections Ground impedance should be less than 1 Q preferably in the 0 25 Q region to ensure that the ground conductor can safely return current when necessary Surge suppressors require good grounding to adequately protect against transient voltages Note A small amount of current is applied to the ground conductor during impedance measurements and can trip a GFCI circuit High Impedance Troubleshooting Suggestions Problems Likely Causes Probable Solutions High hot and or neutral impedance ee Limit 0 0480 ft of 14 AWG wire Excessive loading Redistribute loads High hot and or neutral impedance Undersized wirin Check code and rewire if Limit 0 03 a ft of 12 AWG wire 9 necessary High hot and or neutral impedance High resistance connection Locate bad connection and Limit 0 01 a ft of 10 AWG wire in the circuit or at the panel rewire or replace High Ground impedance Limit 10 Undersized wirin Check code and rewire if for personal protection 9 necessary High Ground impedance Limit High resistance connection Locate bad connection and 0 250 for equipment protection in the circuit or at the panel
8. f 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 to neutral 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 Note To avoid the buildup of heat during load testing allow at least 20 seconds to elapse between tests In addition to the safety benefits this will allow the meter to maintain its stated accuracy during repeated tests Warning To avoid damage to the instrument do not use this device on the output of a UPS system a light dimmer or a square wave generator Warning Use only the supplied power test cord CT70 AC with this equipment Interpreting Measurement Results Important note The CT70 is a microprocessor controlled device that prioritizes its tasks Taking a reading and analyzing the results are its top priorities This is why at times the keypad may not respond immediately The internal computer places a higher priority on completing a test than on recognizing a keystroke To minimize this effect press and hold a key until the display menu changes In addition to the main Wiring Configuration icon shown on the meter display the measurement modes are accessed using the four 4 menu items shown on the left side of the display The menu items are 1 Voltage V 2 Voltage drop Vd 3 ASCC Available short circuit cur
9. nance 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 Warranty EXTECH INSTRUMENTS CORPORATION A FLIR COMPANY warrants this instrument to be free of defects in parts and workmanship for one year from date of shipment a six month limited warranty applies to sensors and cables If it should become necessary to return the instrument for service during or beyond the warranty period contact the Customer Service Department at 781 890 7440 ext 210 for authorization or visit our website www extech com for contact information A Return Authorization RA number must be issued before any product is returned to Extech The sender is responsible for shipping charges freight insurance and proper packaging to prevent damage in transit This warranty does not apply to defects resulting from action of the user such as misuse improper wiring operation outside of specification improper maintenance or repair or unauthorized modification Extech specifically disclaims any implied warranties or merchantability or fitness for a specific purpose and will not be liable for any direct indirect incidental or consequential damages Extech s total liability is limi
10. ne 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 If the voltage drop is higher than 5 the meter display appears in red An efficient branch circuit should have less than 5 voltage drop at the furthest receptacle from the breaker panel at the termination of the cable run A steady decrease in the voltage drop should then be measured for each receptacle tested in sequence towards the breaker panel If the voltage drop is higher than 5 and does not noticeably decrease as the testing moves closer to the first device on the circuit then the problem lies between the first device and the breaker panel Visually check the terminations at the first device the wiring between the device and the panel and the circuit breaker connections High resistance points can be identified as hot spots using an infrared IR thermometer or by measuring the voltage across the breaker If a voltage drop measurement exceeds 5 but noticeably decreases as the testing moves closer to the panel then the circuit may have an undersized wire too long of a cable run or excessive current on the circuit Check the wires to ensure that they are sized per co
11. ow follow steps 4 through 8 in Test 6 GFCI above 10 CT70 V7 0 09 10 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 Frequency 45 0 to 65 0 Hz 1 0 0 2Hz Voltage drop 0 1 to 99 9 2 5 0 2 Voltage under load 10 0 to 250 0 VAC 2 5 0 2V Neutral to Ground Voltage 0 0 to 10 0 VAC 2 5 0 2V 0 00 to 3 00 Q Hot 2 5 0 020 Impedance gt 3 Q 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 2mA General Specifications Display Voltage display update rate Over range indication Equipment Power Rating Operating Temperature Storage Temperature Operating Humidity Storage Humidity Case construction Altitude Dimensions Weight Safety approvals General safety 128 x 64 LED with backlighting 2 5 seconds max OL display 100 to 250 VAC 3 9 VA 45 to 65Hz 18 0mA 32 F to 122 F 0 C to 50 C 32 F to 122 F 0 C to 50 C Max 80 Max 80 ABS UL 94V 0 5VA rated 6561 7 ft 2000m 8 x 2 8 x 2 203 x 71 x 51 mm 11 2 oz 317 5g CE ETL For indoor use and in accordance with the requirements for double insulation to IEC1010 1 2001 EN61010 1 2001 Overvoltage Category II 300V Pollution Degree 2 11 CT70 V7 0 09 10 Mainte
12. rent 4 Impedance Z Use the VW button to scroll the menu list The wiring configuration screen shows correct wiring reverse polarity wiring and no ground conditions The three circles on the wiring configuration icon indicate the wiring status The circles are coded changing appearance clear solid and flashing to indicate the measurement results A table is provided below for interpreting the circle code Correct Blue Display No Ground Red Display H N Reversed Red Display Blink Open Hot No or Display Open Neutral Blank Display H G Reversed 4 CT70 V7 0 09 10 The Voltage menu displays the True RMS line voltage Use the gt 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 VI The voltage drop sub menu offers a load voltage result for 20A and 12A loads Use the gt button to scroll the sub menu The Impedance Z window indicates the impedance in ohms of the hot conductor The impedance sub menu displays the neutral N and ground G conductor impedances Use the gt button to move through the sub menu Note that testing ground impedance will trip a GFCI circuit The ASCC window indicates the Available Short Circuit Current that the branch current can move through a breaker in a short circuit situation GFCI Button The G
13. seconds ms and milliamps mA Notes 1 To test a GFCI circuit on a two wire system a three to two wire adaptor must be used with the adaptor manually connected to ground cold water pipe for example 2 Appliances connected to the circuit under test should be disconnected to avoid measurement errors GFCI Troubleshooting Suggestions Problems Likely Causes Probable Solutions Verify that the wiring complies GFCI may be installed with the manufacturer s GFCI does not trip within trip time incorrectly directives and with NEC Check ground and other GFCI does not trip Defective GFCI wiring Replace GFCI if necessary 9 CT70 V7 0 09 10 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 Plug the meter into the receptacle under test 2 Press the CT70 GFCI button to enter the GFCI test mode menu 3 GFCI is the default test and the letters GFCF will appear on the lower left side of the meter s display Press the gt button once to switch to EPD 4 N
14. ted to repair or replacement of the product The warranty set forth above is inclusive and no other warranty whether written or oral is expressed or implied Calibration and Repair Services Extech offers repair and calibration services for the products we sell Extech also provides NIST certification for most products Call the Customer Care Department for information on calibration services available for this product Extech recommends that annual calibrations be performed to verify meter performance and accuracy Saw amp Support line 781 890 7440 Technical Support Extension 200 E mail support extech com Repair amp Returns Extension 210 E mail repair extech com Product specifications subject to change without notice For the latest version of this User Guide Software updates and other up to the minute product information visit our website www extech com Extech Instruments Corporation 285 Bear Hill Road Waltham MA 02451 1S09001 Certified Copyright 2009 Extech Instruments Corporation a FLIR company All rights reserved including the right of reproduction in whole or in part in any form 12 CT70 V7 0 09 10
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