Electrical testing services
Circuit Breaker Testing
Comprehensive acceptance and maintenance testing for low-voltage, medium-voltage, and SF6 circuit breakers — verifying that your protection devices will operate correctly when it matters most.
Your Last Line of Defense Deserves Verification
A circuit breaker that fails to trip during a fault can turn a manageable electrical event into a catastrophic equipment failure, fire, or injury. Circuit breakers are the last line of defense in any power system — and like any mechanical and electrical device, they degrade over time. Contacts wear, mechanisms bind, and trip coils weaken. Without periodic testing, there is no way to know whether a breaker will operate correctly until it is called upon in an emergency.
J. Wesley Services Group performs circuit breaker testing in accordance with NETA ATS and MTS standards on new installations and in-service equipment. Our technicians are experienced with the full range of low-voltage, medium-voltage, and SF6 breaker types found in industrial, utility, and commercial applications.
Tests We Perform
Contact Resistance Testing
Measures the resistance across breaker contacts using a micro-ohmmeter. Elevated contact resistance indicates worn, pitted, or oxidized contacts that increase heat generation and reduce interrupting capacity. Results are compared against manufacturer specifications and NETA acceptance criteria.
Insulation Resistance Testing
Megger testing of breaker insulation across open contacts and from each pole to ground. Identifies insulation degradation, moisture ingress, and contamination that could cause tracking or flashover under operating voltage.
Primary Injection Testing
Applies high current through the breaker's primary circuit to verify the operation of overcurrent trip elements at specified pickup and time-delay settings. Confirms that the breaker will trip within the required time at the currents it is designed to interrupt.
Secondary Injection Testing
Tests the electronic trip unit or relay by injecting test signals into the secondary control circuit. Verifies pickup settings, time-delay curves, and instantaneous trip functions without requiring high primary current.
Trip and Close Timing
Measures the mechanical operating time of the breaker from trip signal to contact separation and from close signal to contact make. Verifies that operating times are within manufacturer specifications and NETA acceptance criteria.
SF6 Gas Pressure Verification
For SF6 circuit breakers, verifies gas pressure and checks for leaks. SF6 gas provides both insulation and arc interruption — low pressure compromises both functions and must be identified before the breaker is returned to service.
Breaker Types We Test
- Low-voltage molded case circuit breakers (MCCB)
- Low-voltage insulated case circuit breakers (ICCB)
- Low-voltage power circuit breakers (LVPCB)
- Medium-voltage vacuum circuit breakers
- Medium-voltage SF6 circuit breakers
- Air magnetic circuit breakers (legacy equipment)