Perhaps you have been confused as to what the markings on circuit breakers suggest? Knowing the markings on electric gear is a simple must make sure a safe and dependable installation that is electrical. Circuit breaker marking demands are founded by the needs based in the NEC as well as 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 information to be marked in circuit breakers and where its become situated, so let’s talk about what information has to be marked in the circuit breaker plus the location in which 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 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 usually known as the handle escutcheon (see picture 1).

Photo 1. Markings noticeable with trims or covers set up

Markings Visible with Trims or Covers Removed

UL 489 requires other markings be noticeable on an installed circuit breaker with trims or covers eliminated. This location is normally described 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 trip that is common where all poles are mechanically tripped whenever one of many poles trips, or an unbiased journey construction where just the pole this is certainly involved in 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 foundational need for a typical journey function in a circuit breaker; nonetheless, in addition continues on to explain where separate journey is allowed.

For Replacement utilize Only not-CTL –The Class CTL (circuit restricting) panelboard has just experienced 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 which can be set up when you look at the panel. The marking “For replacement utilize just Not CTL Assemblies” means the circuit breaker won’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 ought not to be set up in a panelboard marked “Class CTL Panelboard” since that might 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 every location except the straight back of this circuit breaker. These markings consist of:

40°C –This marking suggests the most ambient temperature in that your circuit breaker may be used at its marked ampere rating without rerating the ampacity of this 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. Once the ambient heat rises above 40°C, the designer may prefer to consult the maker 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 number which is why the apparatus is ranked.

HACR type –This marking suggests the circuit breaker would work for usage utilizing the 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 ideal for usage with such gear without the further screening, consequently, the HACR marking isn’t any much much 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 out of the UL 1995 product standard for HVAC gear (see item 3 in picture 1).

Optimum cable size –Circuit breakers are generally marked with 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 using the connectors that are proper terminal kits needed in just about any location except the straight straight back (see item 8 in picture 3).

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