How To Check Circuit Breakers?

Virtually every building you’ll ever be in runs on electricity. While things tend to run smoothly most of the time, that isn’t always the case. Sometimes, there can be changes in the flow of the electric current. Depending on the severity of such changes, there is a risk of severe damage to the system and building, and danger to those within it. Circuit breakers are intended to protect the electrical circuit from damage caused by an overload, ensure efficient current conduction when closed, and effectively insulate contacts from one another when open. That only works when the circuit breaker itself performs properly. If a circuit breaker’s performance is in doubt, it should be tested without delay. So how do you test a circuit breaker?

Type Tests

Type tests help prove a circuit breaker’s capabilities. There are multiple types of type tests including mechanical, thermal, dielectric, and short-circuit tests. Type tests are designed to make sure that the circuit breaker’s rated characteristics are accurate. Such a thing is necessary to ensure that the circuit breaker can properly perform as it is meant to. These tests are done in a testing laboratory specifically intended for that purpose, so they should already have been done well before any electrician gets to a breaker. Other tests are performed where the circuit breaker is located on the property.

Circuit Breaker Trip Test

Trip tests are designed to analyze the current the trip coil consumes as the breaker operates. This helps identify any mechanical or electrical issues the circuit breaker might have. These issues can then be localized to identify the root cause of the problem at hand. If the tripping batteries are the problem, that can be identified by monitoring the tripping supply’s voltage.

Insulation Resistance Test

The insulation that makes up a molded case circuit breaker should also be tested periodically to ensure that it is performing as it should. A megger is used to test the insulation resistance by applying a known DC voltage to a specific wire over a predetermined period of time. This tests the resistance of the insulation on that individual wire. In order to be effective, the load and line conductors should be disconnected. That way, you can avoid including the characteristics of the connected circuit in your test values. Take care not to use a voltage that is too high for the insulation to withstand, as that could damage the insulation.

Contact Resistance Test

Extended use of a circuit breaker will inevitably result in contact wear and tear. A contact resistance test can identify signs of weakening so any weak points can be addressed before the circuit breaker no longer functions properly. To test contact resistance, quantify the resistance across each of the breaker’s poles and watch for excessive millivolt drops across the breaker. That is indicative of abnormal conditions such as contact contamination and erosion.

Overload Tripping Test

It’s important to know if a circuit breaker will trip if there is an electrical fault that could damage the circuit. An overload tripping test can help determine if the circuit breaker will perform properly. To do an overload test, input 300% of the breaker rating into each pole. This will determine if it will open automatically. Refer to the manufacturer’s manual for a specific breaker’s characteristics and NETA standards for acceptable overload tripping test trip times.

Circuit breakers should be tested on a regular basis so that any problems with them can be identified and rectified as quickly as possible. These important parts of a building’s electrical system are meant to protect expensive equipment and anything else that can be damaged by a surge of electricity. Considering how much trouble can be avoided simply by testing a circuit breaker, it’s easy to see how valuable and worthwhile such a task can be.

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