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

Maybe you have been confused in what the markings on circuit breakers suggest? Comprehending the markings on electric gear is a simple must make sure a secure and dependable electric installation. Circuit breaker marking demands are founded because of the needs based in the NEC plus 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 given 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 additionally the location for which you will discover those markings. Bear in mind is bbwdesire free the UL® standard specifies minimal needs. Circuit breaker manufacturers may possibly provide extra 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 eliminating trims or covers. This location is normally known as the handle escutcheon (see photo 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 a circuit that is installed with trims or covers eliminated. This location is normally named the face of this circuit breaker (see pictures 2, 3, 4).

Picture 2. Markings noticeable with trims or covers eliminated

Other markings that ought to 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 among the poles trips, or a completely independent journey construction where just the pole that is involved in the overcurrent condition trips. In case a 2-pole circuit breaker won’t have an interior typical trip function, then it should 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; nonetheless, in addition continues 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 approximately 25 years, although the illumination and appliance branch circuit panelboard has been around the NEC for many years. CTL panelboards have actually a rejection means built to reject a lot more than the appropriate amount of circuit 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 rejection that is CTL and it is designed for replacement in older gear 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 violation associated with the report on the construction NEC 110.3(B).

Markings Found in Other Places

The markings we are going to discuss below can happen in virtually any location except the relative straight straight 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 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 have been just suited to a 25°C ambient, in which particular case they need to be marked 25°C. Once the ambient heat rises above 40°C, the designer might need to consult the maker to acquire rerating information (see product 4 in photo 3).

Class CTL –Circuit breakers marked Class CTL have 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 because of 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 evaluating, consequently, the HACR marking is not any much longer required on air-con and refrigeration equipment or in 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 by having a cable range, nonetheless that marking just isn’t mandatory. In the event that circuit breaker cannot accept the following bigger cable size necessary for the ampere score, then the utmost wire size must certanly be marked in just about any location except the rear (see product 5 in picture 3).

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