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 installation that is electrical. Circuit breaker marking demands 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 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 located, so let’s talk about what information has to be marked in the circuit breaker while the location in which you will discover those markings. Bear in mind the UL® standard specifies minimal demands. Circuit breaker manufacturers may possibly provide more 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 normally known as the handle escutcheon (see picture 1).
Picture 1. Markings noticeable with trims or covers set up
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 known as the real face associated with 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 constructed of either a trip that is common where all poles are mechanically tripped whenever among the poles trips, or an unbiased journey construction where just the pole that is a part of the overcurrent condition trips. In case a 2-pole circuit breaker doesn’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 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–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 appropriate wide range of circuit breakers which can be set up into the panel. The marking “For replacement utilize just Not CTL Assemblies” means the circuit breaker doesn’t have rejection that is CTL and it is meant for replacement in older gear pre-dating the CTL requirements for circuit breakers and panelboards. Circuit breakers using this designation ought not to be set up in a panelboard marked “Class CTL Panelboard” since that might be a breach for the set of the construction NEC 110.3(B).
Markings Found in Other Places
The markings we’re going to discuss below may appear in just about any location except the relative straight straight back associated with the 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 associated with 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 ambient heat rises above 40°C, the designer could need to consult the maker to have rerating information (see item 4 in photo 3).
Class CTL –Circuit breakers marked Class CTL have a rejection means created 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 true quantity which is why the gear is ranked.
HACR type –This marking suggests the circuit breaker would work to be used using 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 thought appropriate usage with such gear without the further evaluating, consequently, the HACR marking isn’t any much longer required on ac and refrigeration equipment or in circuit breakers to be used in these applications. The necessity with this marking has additionally been taken off the UL 1995 product standard for HVAC equipment (see product 3 in picture 1).
Optimum cable size –Circuit breakers are usually marked by having a cable range, nevertheless 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 delivered connectors –If connectors aren’t factory installed on a circuit breaker, then it should be marked using the appropriate connectors or terminal kits needed in almost any location except the straight straight back (see product 8 in picture 3).