Perhaps you have been confused as to what the markings on circuit breakers suggest? Comprehending the markings on electric gear is a simple must make sure a safe and dependable electric installation. Circuit breaker marking demands are founded by the needs based in the NEC as well as the UL 489 product standard. This informative article will talk about the many markings that are common 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 really is become situated, so let’s talk about what information has to be marked in the circuit breaker and also 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 extra information or offer 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 noticeable with trims or covers in position

Markings Visible with Trims or Covers Removed

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

Picture 2. Markings visible with trims or covers eliminated

Other markings which will be noticeable with trims or covers eliminated are:

Photo 3. Markings visible with trims or covers eliminated

Multi-pole circuit breakers are made from either a typical journey, where all poles are mechanically tripped whenever one of many poles trips, or an unbiased trip construction where just the pole this is certainly involved in the overcurrent condition trips. If your 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) could be the requirement that is foundational a typical journey function in a circuit breaker; nonetheless, 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, even though the illumination and appliance branch circuit panelboard has been doing the braziliancupid NEC for many years. CTL panelboards have actually a rejection means made to reject a lot more than the appropriate amount of circuit breakers that may be set up into the panel. The marking “For replacement utilize just Not CTL Assemblies” means the circuit breaker won’t have CTL rejection provisions and it is meant for replacement in older gear pre-dating the CTL requirements for circuit breakers and panelboards. Circuit breakers with this specific designation ought not to be set up in a panelboard marked “Class CTL Panelboard” since that could be a breach of this set of the construction NEC 110.3(B).

Markings Found in Other Areas

The markings we are going to discuss below can happen in almost any location except the straight straight back of this circuit breaker. These markings consist of:

40°C –This marking shows the most ambient temperature in that your 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 unless these are typically just ideal for a 25°C ambient, in which particular case they have to be marked 25°C. As soon as the ambient heat rises above 40°C, the designer could need to consult the maker to have 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 for which the apparatus is ranked.

HACR type –This marking suggests the circuit breaker would work to be used with all the combined team engine installments typically present in heating, air cooling and refrigeration gear. TheNEC2005 no further has this marking requirement. The electric industry determined that circuit breakers are believed ideal for usage with such gear without the further evaluation, therefore, the HACR marking isn’t any much much much longer required on ac and refrigeration equipment or on circuit breakers to be used during 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 usually marked having 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 using the connectors that are proper terminal kits needed in almost any location except the straight back (see item 8 in picture 3).