Maybe you have been confused by what the markings on circuit breakers suggest? Comprehending the markings on electric gear is a simple must ensure a secure and dependable installation that is electrical. Circuit breaker marking demands are established by the needs based in the NEC plus the UL 489 product standard. This short 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 needs to be marked from the circuit breaker and also the location where you will discover those markings. Bear in mind the UL® standard specifies requirements that are minimum. 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 eliminating trims or covers. This location is normally named the handle escutcheon (see picture 1).
Picture 1. Markings visible with trims or covers set up
Markings Visible with Trims or Covers Removed
UL 489 requires other markings be noticeable for a circuit that is installed with trims or covers eliminated. This location is normally known as the face associated with circuit breaker (see pictures 2, 3, 4).
Picture 2. Markings noticeable with trims or covers eliminated
Other markings that should be dating sites for seniors 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 typical journey, where all poles are mechanically tripped whenever one of many poles trips, or a completely independent journey construction where just the pole that is a part of the overcurrent condition trips. Then it should be marked “Independent Trip” or “No Common Trip. If your 2-pole circuit breaker won’t have an interior common journey feature, ” NEC 240.20(B) may be the foundational requirement of a typical journey function in a circuit breaker; but, additionally continues on to explain where separate journey is allowed.
For Replacement utilize Only not-CTL –The Class CTL (circuit limiting) 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 built to reject significantly more than the appropriate quantity of circuit breakers that may be set up when you look at 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 designed 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 might be a violation associated with the report on the construction NEC 110.3(B).
Markings Found in Other Places
The markings we shall discuss below can happen in almost any location except the relative straight straight back of this circuit breaker. These markings consist of:
40°C –This marking suggests 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 they’ve been just suited to a 25°C ambient, in which particular case they need to be marked 25°C. As soon as the ambient heat rises above 40°C, the designer could need to consult the producer 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 compared to true quantity which is why the gear 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-con and refrigeration gear. TheNEC2005 no further has this marking requirement. The electric industry determined that circuit breakers are believed appropriate use with such gear with no further screening, consequently, the HACR marking isn’t any much much much much longer required on air cooling and refrigeration equipment or in circuit breakers to be used in these applications. The necessity because of this marking has additionally been taken from the UL 1995 product standard for HVAC gear (see product 3 in picture 1).
Maximum cable size –Circuit breakers are usually marked by having a cable range, nonetheless that marking just 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 utilizing the connectors that are proper terminal kits needed in just about any location except the straight straight straight back (see product 8 in picture 3).