Maybe you have been confused as to what the markings on circuit breakers mean? Knowing the markings on electric gear is a simple must make sure a safe and dependable electric installation. Circuit breaker marking demands are founded because of the needs based in the NEC while the UL 489 product standard. This short 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 beetalk 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 where you will see those markings. Bear in mind the UL® standard specifies minimal needs. Circuit breaker manufacturers may possibly 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 getting rid of trims or covers. This location is normally known 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 on a circuit that is installed with trims or covers eliminated. This location is usually described as the face of this circuit breaker (see pictures 2, 3, 4).
Picture 2. Markings noticeable 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 constructed of either a trip that is common where all poles are mechanically tripped whenever among the 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 won’t have an inside 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; but, in addition continues to explain where separate journey is allowed.
For Replacement utilize only–The that is not-CTL class (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 doing the NEC for many years. CTL panelboards have actually a rejection means made to reject a lot more than the number that is appropriate of breakers which can be set up within the panel. The marking “For replacement utilize just Not CTL Assemblies” means that the circuit breaker doesn’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 must not be set up in a panelboard marked “Class CTL Panelboard” since that could be a breach associated with set of the construction NEC 110.3(B).
Markings Found in Other Areas
The markings we shall discuss below can happen in just about any location except the relative straight straight back associated with the circuit breaker. These markings consist of:
40°C –This marking suggests the most temperature that is ambient that your circuit breaker could be used at its marked ampere rating without rerating the ampacity for 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. As soon as the temperature that is ambient above 40°C, the designer may prefer to consult the maker 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 apparatus is rated.
HACR type –This marking suggests the circuit breaker would work to be used aided by the combined team engine installations 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 appropriate usage with such gear without having any further evaluation, consequently, the HACR marking is not any much longer required on ac and refrigeration equipment or in circuit breakers for usage in these applications. The necessity because of this marking has additionally been taken out of the UL 1995 product standard for HVAC gear (see product 3 in picture 1).
Optimum wire size –Circuit breakers are usually marked by having a cable range, nonetheless that marking isn’t 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 shipped connectors –If connectors aren’t factory installed on a circuit breaker, then it should be marked because of the appropriate connectors or terminal kits needed in every location except the straight straight back (see product 8 in picture 3).