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Perhaps you have been confused in what the markings on circuit breakers mean? Knowing the markings on electric gear is significant must make sure a secure and dependable installation that is electrical. Circuit breaker marking demands are founded by the needs based in the NEC therefore the UL 489 product standard. This informative article will talk about the many typical markings and where they could be discovered.

The UL 489 product standard for Molded Case Circuit Breakers specifies the information to be marked in circuit breakers and where it’s become situated, so let’s discuss what information has to be marked regarding the circuit breaker while the location for which you will see those markings. Bear in mind the UL® standard specifies minimal demands. Circuit breaker manufacturers may possibly provide extra information or provide information in a far more location that is convenient.

Markings Visible without Eliminating Trims or Covers

UL 489 requires that some markings be noticeable without eliminating trims or covers. This location is usually described as the handle escutcheon (see picture 1).

Picture 1. Markings visible with trims or covers in position

Markings Visible with Trims or Covers Removed

UL 489 requires other markings be noticeable on a circuit that is installed with trims or covers eliminated. This location is normally described as the real face for the circuit breaker (see pictures 2, 3, 4).

Picture 2. Markings noticeable with trims or covers eliminated

Other markings that should be noticeable with trims or covers eliminated are:

Photo 3. Markings visible with trims or covers eliminated

Multi-pole circuit breakers are constructed of either a trip that is common where all poles are mechanically tripped whenever one of many poles trips, or a completely independent journey construction where just the pole that is associated with the overcurrent condition trips. In cases where a 2-pole circuit breaker doesn’t have an interior typical journey function, then it should be marked “Independent Trip” or “No Common Trip. ” NEC 240.20(B) may be the foundational need for a typical journey function in a circuit breaker; nonetheless, in addition continues on to explain where separate trip is allowed.

For Replacement utilize Only not-CTL –The Class CTL (circuit restricting) panelboard has only experienced existence for around 25 years, although the illumination and appliance branch circuit panelboard has been around the NEC for a long time. CTL panelboards have actually a rejection means made to reject a lot more than the appropriate quantity of circuit breakers that may be set up within the panel. The marking “For replacement utilize just Not CTL Assemblies” means the circuit breaker doesn’t have rejection that is CTL and it is meant for replacement in older gear pre-dating the CTL requirements for circuit breakers and panelboards. Circuit breakers using this designation ought not to be set up in a panelboard marked “Class CTL Panelboard” since that might be a breach of this report on the construction NEC 110.3(B).

Markings Found in Other Areas

The markings we’ll discuss below can happen in almost any location except the straight straight straight back for the circuit breaker. These markings consist of:

40°C –This marking suggests the most temperature that is ambient that the circuit breaker could be used at its marked ampere rating without rerating the ampacity associated with the circuit breaker. This marking is needed for thermal-magnetic circuit breakers and it is optional for electronic journey circuit breakers unless they truly are just suited to a 25°C ambient, in which particular case they have to be marked 25°C. Once the temperature that is ambient above 40°C, the designer could need to consult the company to acquire rerating information (see product 4 in photo 3).

Class CTL –Circuit breakers marked Class CTL have actually a rejection means created in to the circuit breaker. Class CTL panelboards or assemblies, along with Class CTL circuit breakers, avoid more circuit breaker poles from being set up as compared to quantity which is why the gear is ranked.

HACR type –This marking suggests the circuit breaker would work for usage aided by the team engine installments typically present in heating, air cooling and refrigeration gear. TheNEC2005 no more has this marking requirement. The electric industry determined that circuit breakers are thought ideal for usage with such gear without having any further evaluating, consequently, the HACR marking is not any much much longer required on air cooling and refrigeration equipment or in circuit breakers for usage in these applications. The necessity because of this marking has additionally been taken off the UL 1995 product standard for HVAC gear (see product 3 in picture 1).

Optimum cable size –Circuit breakers are generally marked by having a wire range, nonetheless that marking is certainly not mandatory. In the event that circuit breaker cannot accept the second bigger cable size needed for the ampere score, then the utmost wire size needs to be marked in virtually any location except the rear (see product 5 in picture 3).

Individually delivered connectors –If connectors aren’t factory installed for a circuit breaker, then it should be marked aided by the connectors that are proper terminal kits needed in virtually any location except the straight straight back (see product 8 in photo 3).