Section 5—Performance Tests for Electronic Trip Legacy LE/LX, ME/MX, PE/PX, and SE Circuit Breaker

General Circuit Breaker Performance Tests

DANGER
Hazard of Electric Shock, explosion, or Arc Flash Apply appropriate personal protective equipment (PPE) and follow safe electrical work practices. See NFPA 70E or CSA Z462. This equipment must be installed and serviced by qualified electrical personnel. Turn off all power supplying this equipment before working on or inside equipment. Always use a properly rated voltage sensing device to confirm power is off. Replace all devices, doors and covers before turning on power to this equipment. Do not touch the circuit breaker terminals or the test leads while the circuit breaker is being tested. Failure to follow these instructions will result in death or serious injury.

DANGER

Hazard of Electric Shock, explosion, or Arc Flash

Apply appropriate personal protective equipment (PPE) and follow safe electrical work practices. See NFPA 70E or CSA Z462.
This equipment must be installed and serviced by qualified electrical personnel.
Turn off all power supplying this equipment before working on or inside equipment.
Always use a properly rated voltage sensing device to confirm power is off.
Replace all devices, doors and covers before turning on power to this equipment.
Do not touch the circuit breaker terminals or the test leads while the circuit breaker is being tested.

Failure to follow these instructions will result in death or serious injury.

Do the performance tests in the order given to maximize the accuracy of the test results.

NOTE: Never do the contact resistance test before doing the instantaneous primary injection testing. The primary injection testing will ensure the contacts are clear of resistive films, oxidation and foreign material.

The following tests are intended to verify that a circuit breaker is operating properly. Precisely controlled factory testing conditions are used to establish the characteristic trip curves. If field test results fall outside the characteristic trip curve tolerance band, carefully evaluate the test conditions and methods for accuracy.

When questionable conditions or results are observed during inspection and performance tests, consult your local field sales office. Circuit breakers with accessories or factory modifications may require special investigation. If it is necessary to return a circuit breaker to the manufacturing facility, use proper packaging and packing materials to avoid shipping damage. Repacking instructions are contained in the circuit breaker instruction manual.

NOTICE
Hazard of Equipment damage Do not apply test voltage to control circuits or accessory terminals; damage to electronic and/or low-voltage components can result. Failure to follow these instructions can result in equipment damage.

Insulation Resistance Test

Severe environmental conditions can reduce the dielectric strength of molded case circuit breakers. Check insulation resistance during electrical system testing.

To check the insulation resistance, perform the following steps:

De-energize the isolate the circuit breaker:
Clean the circuit breaker as described earlier.
Using a megohmmeter with a capacity of 500–1000 Vdc, apply voltage from:
1. Each phase-to-ground with the circuit breaker on (circuit breaker contacts closed).
2. Phase-to-phase with the circuit breaker on (circuit breaker contacts closed).
3. Between each line and load terminal with the circuit breaker off (circuit breaker contacts open).
Record resistance values. Resistance values of less than one megohm (1,000,000 ohm) should be investigated.

MicroLogic Electronic-Trip Circuit Breaker Tests

NOTICE
Hazard of Equipment Damage Circuit breakers are heavy and can be damaged with improper handling. Use care when handling and transporting circuit breaker to test equipment. Make connection to the circuit breaker carefully using rated cable and appropriate connection methods. Do not use clamps or other methods that can score or otherwise damage the finish of the connectors. Failure to follow these instructions can result in equipment damage.

NOTICE

Hazard of Equipment Damage

Circuit breakers are heavy and can be damaged with improper handling. Use care when handling and transporting circuit breaker to test equipment.
Make connection to the circuit breaker carefully using rated cable and appropriate connection methods. Do not use clamps or other methods that can score or otherwise damage the finish of the connectors.

Failure to follow these instructions can result in equipment damage.

Long-time Trip Test

The long-time ampere rating defines the maximum level of current the circuit breaker will carry continuously. MicroLogic electronic-trip circuit breakers pick up and begin timing when a phase current exceeds 110% ± 10% of the ampere rating. The long-time delay feature permits variations of the circuit breaker inverse-time delay characteristic. This delay determines how long the circuit breaker will carry a sustained overcurrent before initiating a trip signal. Performance of the inverse-time overcurrent functions of the circuit breaker can be tested using a high-current, low-voltage ac power supply.

Completely de-energize and remove the circuit breaker from service.
Before testing, record pickup and delay settings for all functions. Important: reset the trip unit to these same settings after the test procedure is completed.
If the MicroLogic circuit breaker has the integral ground-fault protection function, see test procedures for circuit breakers with integral ground fault, Circuit Breakers with Integral Ground Fault Protection, before continuing with the test procedure.
Use the following settings for the test:

Long-time/Ampere Rating = Max

Long-time/Overload Delay = Min.

Short-time/Short Circuit = Max.

Short-time/Short Circuit Delay = Max. (I²t IN or ON)

Instantaneous = Max.

NOTE: Labeling and trip unit functions are specified by the circuit breaker series and catalog numbers. Series and catalog numbers are printed on the circuit breaker.
Connect the circuit breaker to a high-current, low-voltage ac power supply. Connect the circuit breaker to the test power source with any convenient length of adequately sized wiring.
Test all phases of the circuit breaker individually, or in pairs, for integral ground-fault equipped circuit breakers as required in the special test procedure on Circuit Breakers with Integral Ground Fault Protection.
Use the slow “run-up” test method to determine the pickup level. Slowly increase the current until the long-time pickup light glows steadily; this is defined as the pickup level.

NOTE: All MicroLogicelectronic-trip circuit beakers are equipped with Long-time/Overload Memory or thermal imaging. The Long-time/Overload Memory can be reset by using the appropriate memory reset module. See the local field sales office for additional information of the memory reset modules and test kits. If the memory-reset module is not used, wait at least 15 minutes to allow the memory to clear and reset before proceeding with the tests.
To determine the delay time, set the current to 300% of the ampere rating value. Monitor the time from this pickup point until the circuit breaker trips; this is the delay time.
Record pickup and delay values and compare them to the appropriate trip curve.

The long-time trip test can also be done using the UTS3 secondary injection test kit. These secondary injection test sets do not test the current transformers and connections.

Short-Time Trip Test

The short-time pickup characteristic of a MicroLogic electronic-trip circuit breaker adjusts the level of current at which the short-time delay begins timing. Short-time pickup levels are multiples of sensor size times the rating plug multiplier. The short-time delay function determines how long the circuit breaker will wait before initiating a trip signal during a short circuit. Performance of the short-time functions of the circuit breaker can be tested using a high-current, low-voltage ac power supply.

If testing a circuit breaker that is equipped with zone-selective interlocking, follow the Procedure to Defeat Zone-Selective Interlocking on Procedure to Defeat Zone-Selective Interlocking. If you are using a secondary injection test kit for these tests, carefully read and follow the test kit instructions about zone-selective interlocking.

NOTE: Failure to defeat zone-selective interlocking will result in tripping with no intentional delay.
If the MicroLogic trip unit is equipped with the integral ground-fault protection function, see test procedures for circuit breaker with integral ground-fault, Circuit Breakers with Integral Ground Fault Protection, before continuing.
SE drawout circuit breakers with the integral ground-fault protection function require an adapter plug (catalog number SEPITK2) when completely removed from the cradle. The adapter plug makes the necessary jumper connections on the secondary circuit. These jumper connections are normally made when the circuit breaker is in the connected position. Follow the instructions provided with the plug to ensure proper application.
Use the following settings for the test:

Long-time Pickup/Ampere Rating - Max.

Long-time/Overload Delay = Max.

Short-time/Short-circuit Pickup = Min.

Short-time/Short-circuit Delay = Min.

Instantaneous = Max.

NOTE: For LE Series 1B, ME Series 3, 4, 5, 5A, 5B, NE Series 1, 2, 3, 3A, 3B, PE Series 4, 5, 6, 6A, 6B, and SE Series 2, 3, 3A, 3B trip units, the Min. Short-time/Short-circuit setting will be 0.1 I²t OUT.
Connect the circuit breaker to the test source with any convenient length of conductor.
For non-ground-fault circuit breakers, test all poles of the circuit breaker individually. For circuit breakers with integral ground-fault, test each pole of the circuit breaker as noted in the special test procedure on Circuit Breakers with Integral Ground Fault Protection.
Short-Time Pickup Test

After the circuit breaker is properly connected, inject the phase under test with a current value just below the minimum pickup value indicated by the trip curve. Test current duration must exceed expected delay time (determined from the trip curve). The circuit breaker should not trip. Repeat the test using the maximum pickup value indicated by the trip curve. The circuit breaker should trip, indicating an acceptable pickup level. If the circuit breaker does not trip within the expected time, terminate the test to prevent thermal damage to the circuit breaker. If the precise pickup value is desired, repeat the test at current levels between the maximum and minimum. The lowest current value at which the circuit breaker trips is the pickup value.
Short-Time Delay test

After the circuit breaker is properly connected, apply 150% of the nominal short-time pickup value. The circuit breaker should trip within the time limits defined by the trip curve. If the circuit breaker does not trip within the expected time limits, disengage the power supply to prevent thermal damage to the circuit breaker.

NOTE: All MicroLogic electronic-trip circuit breakers are equipped with Long-Time/Overload Memory or thermal imaging. The overcurrent pulses used to test Short-time Pickup and Delay add to this memory. If the circuit breaker trips at a lower than expected current value after several overcurrent pulses, it may be tripping on the long-time function. The Longtime/Overload Memory can be reset using the appropriate memory reset module. If the memory reset module is not used, wait at least 15 minutes to allow the memory to clear and reset before proceeding with the tests.

The short-time trip test can also be done using the UTS3 secondary injection test kit. These secondary injection test sets do not test the current transformers and connections.

Instantaneous Trip Test

The instantaneous trip function of a MicroLogic electronic-trip circuit breaker determines the level of current at which the circuit breaker trips with no intentional delay. Performance of the instantaneous function of the circuit breaker can be tested using a high-current, low-voltage ac power supply.

If the MicroLogic circuit breaker is equipped with the integral ground-fault protection function, see test procedures for circuit breaker with integral ground-fault, Circuit Breakers with Integral Ground Fault Protection, before continuing.
For non-ground-fault circuit breakers, test all poles of the circuit breaker individually. For circuit breakers with the integral ground-fault function, test each pole of the circuit breaker as noted in the special test procedure on Circuit Breakers with Integral Ground Fault Protection.
After the circuit breaker is properly connected and adjusted, apply current in approximately 10-cycle pulses. Start at 70% of the expected trip value, increase the current in each succeeding pulse until the circuit breaker trips.

NOTE: All MicroLogic electronic-trip circuit breakers are equipped with Long-time/Overload Memory or thermal imaging. The overcurrent pulses used to test Short-time Pickup and Delay add to this memory. If the circuit breaker trips at a lower than expected current value after several Overcurrent pulses, it may be tripping on the long-time function. The Long-time/Overload Memory can be reset by using the appropriate memory reset module. If the memory reset module is not used, wait at least 15 minutes to allow the memory to clear and reset before proceeding with the tests.
Compare the pickup value to the trip curve for the tested circuit breaker.

The instantaneous trip test can also be done using the UTS-3 secondary injection test kit. These secondary injection test sets do not test the current transformers and connections.

Circuit Breakers with Integral Ground Fault Protection

Special Overload and Short-circuit Test Procedures

MicroLogic electronic-trip circuit breakers with the integral ground-fault protection function require special attention when testing overload and short-circuit functions. The single-pole primary injection tests for the inverse-time overcurrent, short-time and instantaneous functions will cause ground-fault trips due to the return current path not going through the circuit breaker. To overcome this difficulty, use the looping method for MicroLogic circuit breakers with the integral ground-fault feature.

Looping Method:

Looping the current as shown in Special Overload and Short-circuit Test Procedures, balances the amount of current entering and leaving the circuit breaker. This, in effect, eliminates ground-fault trips by keeping the internal ground-fault transformer balanced. Verification of successive poles can be made by varying the connections (loop AC, AB, BC).

Exceptions:

For SE fixed-type circuit breakers, connect terminals 16, 17, 18 and 19 together to defeat ground fault for test purposes. For SE drawout circuit breakers, use the adapter plug SEPITK2 to make the necessary connections.

Procedure for Circuit Breakers Used with PowerLogic Systems

LE, ME, NE, PE and SE circuit breakers connected to a PowerLogic system are connected via a communications adapter (catalog number CIM3F). If the circuit breaker is tested by the primary injection method, the PowerLogic system can remain connected to the circuit breaker during testing without affecting the results.

NOTE: Testing a circuit breaker connected to a PowerLogic system causes the PowerLogic system to react as if the circuit breaker were experiencing the actual faults.

When performing secondary injection testing using the UTS3 test set, the PowerLogic system must be disconnected from the circuit breaker. This is done by disconnecting the 4-pin plug connection on the adapter. The test set will indicate testing failed if the PowerLogic system is left connected when testing. After testing, reconnect the 4-pin plug to the adapter. Follow the instructions for the version of the PowerLogic software that is installed on the system to verify that communication has been re-established with the circuit breaker.

Procedure to Defeat Zone-Selective Interlocking

Zone-selective interlocking is a method of communication between electronic-trip overcurrent protective devices. Zone-selective interlocking allows interlocked devices at different levels to work together as a system in which a short circuit or ground fault is isolated and cleared with minimum time delay. The purpose of defeating zone-selective interlocking is to verify the characteristics of the specific circuit breaker short-time and ground-fault trip delay functions. This is accomplished by disconnecting restraint wiring and installing jumpers as required. This self-restrains the circuit breaker being tested. Label any restraint wires before disconnecting.

Self-Restraint Settings outlines self-restraint (jumper) instructions for each of the MicroLogic circuit breakers. Use wire size 14–18 AWG (1–2.1 mm).

Self-Restraint Settings

Circuit Breaker Type/Trip Unit Series	Function (ST or GF)	Connect Terminal (Restraint IN)	To Terminal (Restraint OUT)
LE 1B	Short-time	#5	#6
LE 1B	Ground-fault	#7	#8
ME 3	Both	Violet wire	Violet wire
ME 4, 5, 5A, 5B	Short-time	#5	#6
ME 4, 5, 5A, 5B	Ground-fault	#7	#8
NE 1	Both	#6	#7
NE 2, 3, 3A, 3B	Short-time	#5	#6
NE 2, 3, 3A, 3B	Ground-fault	#7	#8
PE 4	Both	#6	#7
PE 5, 6, 6A, 6B	Short-time	#5	#6
PE 5, 6, 6A, 6B	Ground-fault	#7	#8
SE 2, 3, 3A, 3B (Fixed and Drawout)	Both	#23	#24
SE 2, 3, 3A, 3B (Fixed and Drawout)	Ground-fault	#20	#21
SE Drawout (Fully Removed From cradle)	Both	Use SEPTIK2 (see Primary Injection Test Kit)	Use SEPTIK2 (see Primary Injection Test Kit)

NOTE: If self-restraint jumpers are installed to defeat zone-selective interlocking for testing purposes, remove jumpers when testing is complete. Any restraint wires disconnected for the test should be reconnected at this time.

Ground-Fault Protection and Indication Only Tests for Radial Systems

DANGER
Hazard of Electric Shock, explosion, or Arc Flash Apply appropriate personal protective equipment (PPE) and follow safe electrical work practices. See NFPA 70E or CSA Z462. This equipment must be installed and serviced by qualified electrical personnel. Turn off all power supplying this equipment before working on or inside equipment. Always use a properly rated voltage sensing device to confirm power is off. Replace all devices, doors and covers before turning on power to this equipment. Failure to follow these instructions will result in death or serious injury.

DANGER

Hazard of Electric Shock, explosion, or Arc Flash

Apply appropriate personal protective equipment (PPE) and follow safe electrical work practices. See NFPA 70E or CSA Z462.
This equipment must be installed and serviced by qualified electrical personnel.
Turn off all power supplying this equipment before working on or inside equipment.
Always use a properly rated voltage sensing device to confirm power is off.
Replace all devices, doors and covers before turning on power to this equipment.

Failure to follow these instructions will result in death or serious injury.

Ground-Fault Trip Test

The ground-fault function of a MicroLogic electronic-trip circuit breaker provides ground-fault protection for equipment with adjustable pickup and delay values. the ground-fault delay feature determines how long the circuit breaker waits before initiating a trip signal during a ground fault. Performance of the ground-fault functions of the circuit breaker can be tested using a high-current, low-voltage ac power supply.

SE drawout circuit breakers with the integral ground-fault test feature require an adapter plug (Square D catalog number SEPITK2) when the circuit breaker is completely removed from the cradle. The adapter plug will make the necessary jumper connections on the secondary circuit. These jumpers are normally made when the circuit breaker is in the connected position. Follow the instructions provided with the adapter plug to ensure proper application.

Test Procedure

Completely de-energize and remove the circuit breaker from service.
Before testing, record pickup and delay setting for all function. Reset the trip unit to these same settings after the test procedure is completed.
If testing a circuit breaker that is equipped with zone-selective interlocking, follow the procedure to defeat zone-selective interlocking on Procedure to Defeat Zone-Selective Interlocking. If you are using a secondary injection test kit for these tests, carefully read and follow the test kit instructions about zone-selective interlocking.

NOTE: Failure to defeat zone-selective interlocking will result in trip time inaccuracy.
Use these settings for the test:

Long-Time Pickup/Ampere Rating = Max.

Long-Time/Overload Delay = Max

Short-Time/Short-Circuit Delay = Max. (I²t IN or ON)

Instantaneous = Max.

Ground-Fault Pickup = Min.

Ground-Fault Delay = Min. (I²t OUT of OFF)

NOTE: Do not use the INSTANT setting for ground-fault delay. On Series 2 SE circuit breakers, use ground-fault delay setting “2.”

Follow the hookup procedure appropriate to the test application.

For circuit breakers without a neutral current transformer, go to step 8.

For circuit breakers with the integral ground-fault function in a three-phase, four-wire system, an externally-mounted neutral current transformer (CT) must be used. The neutral CT is connected to the circuit breaker by a shielded cable (#14 AWG [2.5 mm] wire is recommended).

Test Hookup Diagram for Neutral CT Phasing Test

See circuit breaker instructions bulletin for connections to circuit breaker and neutral CT.

Test Hookup Diagram for Neutral CT Size Test

See circuit breaker instructions bulletin for connections to circuit breaker and neutral CT.

Verify correct phasing of the neutral CT (three-phase, four-wire systems) by performing a No Trip Test as follows:

Connect the circuit breaker and neutral CT as shown in Test Hookup Diagram for Neutral CT Phasing Test. The jumper must go from the load connection on the circuit breaker to the H1 connection on the neutral CT (or the side of the neutral CT that has the red dot). Connect the secondary of the neutral CT according to the circuit breaker instruction manual or the neutral CT instructions.
Apply current above the ground-fault pickup level and maintain longer than the ground-fault delay.
The circuit breaker must not trip. No trip indicates that both the phase CT and neutral CT are phased properly.

Test Hookup Diagram for Circuit Breaker Without Neutral CT

Test Hookup Diagram for Ground-fault Pickup and Delay Test

Verify the correct size of the neutral CT (three-phase, four-wire systems) by performing a Trip Test as follows:
1. Connect the circuit breaker and neutral CT as shown in Test Hookup Diagram for Neutral CT Size Test. Connect the polarity (+) terminal of the high current injection unit to the load side of the circuit breaker. The jumper must go from the line connection on the circuit breaker to the H1 connection on the neutral CT (or the side of the neutral CT that has the red dot). Connect the non-polarity (-) terminal of the high current injection unit to H2 on the neutral CT (on the line side of the circuit breaker). Connect the secondary of the neutral CT according to the circuit breaker instruction manual or the neutral CT instructions.
2. Apply current.
3. The circuit breaker must trip at half the value of the ground-fault pickup. Tripping indicates that both the phase CT and neutral CT have the same turns ratio (same size).
Test ground fault pickup and delay by performing a trip test as follows:
1. Connect the circuit breaker as shown in Test Hookup Diagram for Circuit Breaker Without Neutral CT, (three-phase, three-wire systems) or Test Hookup Diagram for Ground-fault Pickup and Delay Testor (three-phase, four-wire systems).
2. After the circuit is properly connected and closed, apply current in short pulses of 10-cycle duration. Starting at 70% of the expected trip value, increase the current on each succeeding pulse until the circuit breaker trips.
3. Reclose the circuit breaker and reduce the current level; pulse again to determine if the pickup level found was overshot.
4. Repeat steps b and c to further isolate the pickup point.
5. To determine delay time, test each pole of the circuit breaker individually at 150% of the ground-fault pickup setting. Monitor the time from this pickup point until the circuit breaker trips to obtain the delay time.
6. Record pickup and delay values and compare the results to the trip curve.

The ground-fault test can also be done using the UTS3 secondary injection test kit. These secondary injection test sets do not test the current transformers and connections.

Tests for Ground-Fault Alarm Only: LE, ME, NE, PE and SE Circuit Breakers

All LE, ME, NE, PE, and SE circuit breakers with the ground-fault alarm feature are supplied with an integral ground-fault test feature. A 120 V power source is required to operate the integral test feature. The test circuitry simulates a ground-fault when the test button on the front of the circuit breaker is depressed. The ammeter in the circuit breaker will indicate a current value while the push-to-test button is engaged.

NOTE: The ground-fault alarm only circuit breaker will not trip or indicate a trip when the push-to-test button on the front of the circuit breaker is pressed.

When connected to a PowerLogic system via a communications adapter (Square D catalog number CIM3F), the PowerLogic system will indicate a ground-fault current value while the push-to-test button is engaged. The PowerLogic system indicates an alarm condition if the push-to-test button is pressed for two seconds. The circuit breaker takes a maximum of one second to communicate an alarm condition. The PowerLogic system updates the condition only as frequently as the scan time is set on the PowerLogic system.

Instructions for the ground-fault trip test, Ground-fault Trip Test, can be applied to ground-fault alarm only circuit breakers with the following exceptions:

Ground-fault alarm only circuit breakers have no trip or delay features. Therefore the Universal Test Set (catalog number UTS3) will display no time values.
Ground-fault zone-selective interlocking is not available on ground-fault alarm only circuit breakers.
If the pulse test method is used, the pulse signal must be long enough for the PowerLogic system to recognize the alarm condition.

When secondary injection testing using the UTS3 test set, the circuit breaker must be disconnected from the PowerLogic system. To disconnect the circuit breaker from the PowerLogic system, detach the 4-pin plug connection on the adapter. The test set will indicate the circuit breaker failed if the PowerLogic system remains connected when testing. After testing, reconnect the four-pin plug to the adapter. Follow the instructions for the version of PowerLogic software that is installed on the system to verify that the communication has been re-established with the circuit breaker.

NOTE: Testing a circuit breaker connected to a PowerLogic system causes the PowerLogic system to react as if the circuit breaker were experiencing the actual faults.

Maximum Micro-Ohms Per Pole

Circuit Breaker		Micro-Ohms (u ohm)	Circuit Breaker		Micro-Ohms (u ohm)
Type	Rating	Micro-Ohms (u ohm)	Type	Rating	Micro-Ohms (u ohm)
LE, LX	300	477	NE, NX	600	112
	350	416		700	106
	400	250		800	85
	450	310		900	81
	500	286		1000	66
	600	169		1200	56
ME, MX	125	1,600	PE, PX	600	106
	150	1,500		700	100
	175	914		800	81
	200	725		1000	63
	225	593		1200	53
	250	488		1400	49
	300	344		1600	41
	350	261		1800	35
	400	200		2000	31
	450	146		2500	33
	500	114	PE, PX	600	106
	600	94		700	100
	700	78		800	81
	800	68		1000	63
				1200	53

Contact Resistance Test

Circuit breaker pole resistance tests are not reliable indicators of circuit breaker performance because the resistance values are influenced by a number of transient factors including contact surface oxidation, foreign material between the contacts, and testing methods. NEMA AB 4 paragraph 6.4.1 states: “The millivolt drop of a circuit breaker pole can vary significantly due to inherent variability in the extreme low resistance of the electrical contacts and connectors. Such variations do not necessarily predict unacceptable performance and shall not be used as the sole criteria for determination of acceptability.”

High pole resistance may also be caused by eroded contacts, low contact force, and loose termination. The only one of these factors likely to be present on a new circuit breaker is a loose termination, since the contacts are new and there has been no opportunity for contact pressure to have drifted from the factory setting. A loose termination can be corrected in the field.

If a contact resistance test is done, it is important to do it after the contacts have been conditioned by instantaneous primary injection testing to ensure the contacts are clear of resistive films, oxidation and foreign material. If the circuit breaker has been in service with no performance issues, (overheating or nuisance tripping), contact resistance measurements are redundant and of little value.

Square D recommends that a DLRO (Digital Low Resistance Ohmmeter) be used, using a 10 A dc test current for circuit breaker ratings below 100 A, and using 100 A dc for circuit breakers rated 100 A and above. the median (middle) value of three readings (toggling the circuit breaker between each reading) should be recorded for each pole tested. If this value is equal to or less than the value listed in Maximum Micro-Ohms Per Pole, the pole is acceptable. If the reading is higher, the cause should be investigated and corrected if possible. Contact your local field office for more information.

Remove Test Connections

Upon completing testing:

Remove test connections from circuit breaker.
Inspect connections for damage caused by testing.
Reset the long-time pickup switch to original settings, as recorded in above.
If an auxiliary power supply is being used for the MicroLogic trip unit, reconnect the auxiliary power supply.

Additional Information

For more information concerning Square D circuit breakers, refer to the appropriate instruction manual. These manuals contain installation instructions, mounting information, safety features, wiring diagrams, and troubleshooting charts for specific circuit breakers.