Exactly Just Just Just What Perform Some Markings on Circuit Breakers Suggest?

Perhaps you have been confused by what the markings on circuit breakers mean? Comprehending 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 additionally the UL 489 product standard. This informative article will talk about the many markings that are common where they may 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 talk about what information has to be marked regarding the circuit breaker plus the location for which you will discover those markings. Bear in mind the UL® standard specifies requirements that are minimum. Circuit breaker manufacturers might provide more information or provide information in a far more convenient location.

Markings Visible without Eliminating Trims or Covers

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

Picture 1. Markings noticeable with trims or covers in position

Markings Visible with Trims or Covers Removed

UL 489 requires other markings be noticeable on an installed circuit breaker with trims or covers eliminated. This location is normally known 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 removed

Multi-pole circuit breakers are constructed of either a typical journey, where all poles are mechanically tripped when one of many poles trips, or an unbiased journey construction where just the pole this is certainly involved in the overcurrent condition trips. In case a 2-pole circuit breaker won’t have an inside typical journey function, then it must be marked “Independent Trip” or “No Common Trip. ” NEC 240.20(B) could be the foundational requirement of a typical journey function in a circuit breaker; nevertheless, in addition continues on to explain where separate journey is allowed.

For Replacement utilize Only not-CTL –The Class CTL (circuit restricting) panelboard has just held it’s place in existence for around 25 years, although the illumination and appliance branch circuit panelboard has been doing the NEC for a long time. CTL panelboards have actually a rejection means built to reject significantly more than the number that is appropriate of breakers that may be set up within the panel. The marking “For replacement utilize just Not CTL Assemblies” means the circuit breaker won’t have CTL rejection provisions and it is designed for replacement in older gear pre-dating the CTL requirements for circuit breakers and panelboards. Circuit breakers with this particular 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 installation NEC 110.3(B).

Markings Found in Other Places

The markings we are going to discuss below can happen in almost any location except the straight straight straight back regarding 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 regarding the circuit breaker. This marking is necessary for thermal-magnetic circuit breakers and it is optional for electronic journey circuit breakers they must be marked 25°C unless they are only suitable for a 25°C ambient, in which case. If the temperature that is ambient above 40°C, the designer could need to consult the producer to acquire rerating information (see product 4 in photo 3).

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

HACR type –This marking suggests the circuit breaker would work to be used because of the team engine installments typically present in heating, ac 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 the further evaluating, consequently, the HACR marking is not any much longer required on ac and refrigeration equipment or on circuit breakers to be used in these applications. The necessity because of this marking has also been taken from the UL 1995 product standard for HVAC gear (see product 3 in picture 1).

Optimum cable size –Circuit breakers are generally marked with a cable range, nevertheless that marking is certainly not mandatory. Then the maximum wire size must be marked in any location except the back (see item 5 in photo 3) if the circuit breaker cannot accept the next larger wire size required for the ampere rating,.

Individually delivered connectors –If connectors aren’t factory installed for a circuit breaker, then it should be marked utilizing the connectors that are proper terminal kits needed in every location except the back (see xcheaters dating product 8 in picture 3).