Perhaps you have been confused as to what the markings on circuit breakers mean? Comprehending the markings on electric gear is a simple must make sure a safe and dependable electric installation. Circuit breaker marking requirements are founded because of the needs based in the NEC and also the UL 489 product standard. This informative article will talk about the many markings that are common where they may be found.
The UL 489 product standard for Molded Case Circuit Breakers specifies the given information to be marked on circuit breakers and where it really is become situated, so let’s talk about what information should be marked in the circuit breaker therefore the location in which you will discover those markings. Bear in mind the UL® standard specifies minimal demands. Circuit breaker manufacturers might provide more information or offer information in an even more location that is convenient.
Markings Visible without Eliminating Trims or Covers
UL 489 requires that some markings be noticeable without getting rid of trims or covers. This location is normally 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 visible for a circuit that is installed with trims or covers eliminated. This location is normally known as the real face regarding 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 made from either a typical journey, where all poles are mechanically tripped whenever one of many poles trips, or a completely independent journey construction where just the pole this is certainly a part of the overcurrent condition trips. In case a 2-pole circuit breaker won’t have an inside typical journey function, then it should be marked “Independent Trip” or “No Common Trip. ” NEC 240.20(B) may be the foundational requirement of a typical journey function in a circuit breaker; but, in addition continues on to explain where separate journey is allowed.
For Replacement utilize Only not-CTL –The Class CTL (circuit restricting) panelboard has only held it’s place in existence for approximately 25 years, although the illumination and appliance branch circuit panelboard has been around the NEC for many years. CTL panelboards have a rejection means made to reject a lot 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 doesn’t have CTL rejection provisions and it is designed for replacement in older equipment pre-dating the CTL requirements for circuit breakers and panelboards. Circuit breakers using this designation must not be set up in a panelboard marked “Class CTL Panelboard” since that could be a breach associated with report on the construction NEC 110.3(B).
Markings Found in Other Areas
The markings we are going to discuss below can happen in just about any location except the straight back for the circuit breaker. These markings consist of:
40°C –This marking suggests the most temperature that is ambient that your circuit breaker may be used at its marked ampere rating without rerating the ampacity regarding 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 adam4adam be marked 25°C. Once the temperature that is ambient above 40°C, the designer might need to consult producer 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, together with Class CTL circuit breakers, avoid more circuit breaker poles from being set up compared to the true quantity which is why the apparatus is ranked.
HACR type –This marking suggests the circuit breaker would work to be used aided by the 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 appropriate usage with such gear with no further evaluating, consequently, the HACR marking isn’t any much longer required on ac and refrigeration equipment or in circuit breakers to be used during these applications. The necessity with this marking has additionally 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, 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 every 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 because of the connectors that are proper terminal kits needed in virtually any location except the back (see product 8 in picture 3).