Understanding High-Voltage Circuit Breaker Nameplates - NETAWORLD JOURNAL (2023)

Along the extensive and complex electrical system infrastructure from generation to transmission and distribution, the wide variety of medium- and high-voltage circuit breakers (MV/HV CB) vary in size, interrupting medium, number of breaks per phase, and various other attributes. To help classify breakers and their attributes, they are all shipped with a nameplate stating the minimum information about specific mechanical, physical, and electrical characteristics that is required by IEEE Std. C37.04. Although manufacturers are only required to provide the minimum information, some provide more detailed information than others.

Viewing the nameplate will yield a variety of information concerning the CB’s function, electrical characteristics, and expected performance. For example, the same breaker may have different types of operating mechanisms, and this might not be apparent when first looking at the nameplate. Further investigation would be needed to fully understand the breaker’s mechanism specifications.

Understanding the information provided on the nameplate will provide a general description of the CB’s mechanism and operating conditions. Since there are many types of CBs, as well as numerous manufacturers, several questions can provide helpful information:

  • Do all nameplates provide the same information?
  • What is the minimum information that must be stated on the nameplate?
  • One important specification on the nameplate is interrupting time. Does this correlate to operating times measured while testing?
  • Will a quick glance at the nameplate tell you everything you need to test on the CB and what the expected values are?

This article focuses on the HV/MV CB nameplate information that is necessary for testing purposes. IEEE nameplate requirements and definitions are discussed. Parameters that are commonly tested in the field are described along with whether the parameter is verified or measured during the design, factory, or field phase of the breaker’s life cycle, and additional testing of parameters not shown on the nameplate is recommended. In the end, the reader will have a basic understanding of the CB nameplate and how it relates to the application, operation, and maintenance of the CB.


At a minimum, the CB nameplate will indicate the attributes of the CB and its mechanism. The manufacturer can choose to combine these into a single nameplate or provide separate nameplates. This article focuses only on the nameplates containing the attributes of the CB and the mechanism. However, certain additional nameplates are also required:

  • Nameplates must describe the operating characteristics of any current transformers (CT) or linear coupler transformers attached to the CB.
  • A nameplate indicating dielectric withstand capability must be provided for any self-contained components, such as current transformers (CTs) or bushings; this information could also be included on the CB nameplate.
  • Nameplates must be provided for any attached accessories indicating what they are, as well as any operating characteristics or relevant information.

Figure 1 and Figure 2 show examples of separate and combined CB nameplate configurations.

Understanding High-Voltage Circuit Breaker Nameplates - NETAWORLD JOURNAL (1)

Figure 1a: Separate Nameplates for CB

Understanding High-Voltage Circuit Breaker Nameplates - NETAWORLD JOURNAL (2)

Figure 1b: Separate Nameplates for Mechanism

Understanding High-Voltage Circuit Breaker Nameplates - NETAWORLD JOURNAL (3)

Figure 1c: Separate Nameplates for CT

Understanding High-Voltage Circuit Breaker Nameplates - NETAWORLD JOURNAL (4)

Figure 2: Combination CB and Mechanism Nameplate

The information required on the CB nameplate can be divided into four categories:

  1. Documentation provides general data identifying the CB manufacturer, CB type, serial number, and year of manufacture along with a parts list and the instruction book number.
  2. Physical characteristics listed on the nameplate describe the CB’s weight, operating pressure, and the volume of oil or weight of gas inside the tank.
  3. Electrical characteristics provide the general operating conditions of the CB along with insulation levels and other protection information.
  4. Operating characteristics refer to the minimum and/or maximum conditions for the mechanism to be able to operate and might include some electrical parameters related to the control of the breaker. In cases where the mechanism is hydraulic or pneumatic, the nameplate will show pressure rather than electrical parameters.

Table 1 and Table 2 provide the minimum CB and mechanism nameplate data required by IEEE Std. C37.04.

Understanding High-Voltage Circuit Breaker Nameplates - NETAWORLD JOURNAL (6)

Table 2: IEEE Std. C37.04 Minimum Mechanism Nameplate Data


CB characteristics include documentation, physical characteristics, and electrical characteristics. and operating characteristics.

Rated Maximum Voltage

IEEE Std. 37.04–2018 states:

The rated maximum voltage of a circuit breaker is the highest rms phase-to-phase voltage for which the circuit breaker is designed, and is the upper limit for operation.

When the nameplate refers to continuous current and short-circuit current, it is the current at this rated maximum voltage.

A design test performing short-circuit current interruption and other current switching rating tests at the rated maximum voltage is used to verify this characteristic.

Rated Power Frequency

This is the frequency at which the CB is designed to operate. Typically, this frequency is 60Hz or 50Hz, but other frequencies exist (e.g., 25Hz or 16-2/3Hz). If the CB is operated at a higher frequency than its intended design, the CB will need to be de-rated, and the manufacturer should be contacted for consultation.

Rated Continuous Current

The rated continuous current is the maximum RMS current at rated power frequency that the CB can transmit continuously during usual service conditions (see IEEE Std. C37.04–2018 Section 5.5). The current ratings are designed around the temperature limits of all the parts used to construct the CB. The CB is designed to carry this current at an ambient temperature of 40°C. For the maximum internal temperatures of the individual components, see IEEE Std. C37.04–2018 Section 5.5.2. The rated continuous current is applicable at or below the rated maximum voltage.

Rated Full-Wave Lightning Impulse Withstand Voltage

Although the CB is designed to operate at a rated maximum voltage, it may be subject to environmental conditions that exceed the maximum voltage. The dielectric withstand capability of a CB is demonstrated by subjecting it to a power frequency, a lightning impulse test, and where required, a chopped-wave lightning impulse and switching impulse test at voltage levels equal to or greater than those specified in ANSI C37.06, Trial-Use Guide for High-Voltage Circuit Breakers Rated on a Symmetrical Current.

IEEE Std. 4–2013 Section 8 defines the standard lightning impulse as:

A full lightning impulse having a front time of (T1) of 1.2 and value (T2) of 50, and is described as a 1.2/50 impulse. The rated full-wave lightning impulse withstand voltage is the peak value of this wave. A new CB must have a 10% or less chance of external flashover when subjected to this wave.

Rated Switching-Impulse Withstand Voltages

In addition to the lightning impulse rating, CBs rated at 362kV and above are assigned a switching-impulse withstand voltage rating. These CBs can be subjected to transient overvoltages when they are switching open or loaded, or when faulted lines and equipment are present. To help alleviate these overvoltages, the CB are often equipped with pre-insertion resistors (PIR) or synchronous closing devices.

Rated switching-impulse withstand voltage is the voltage value at the peak of a standard 250x2500 switching-impulse wave (IEEE Std. 4–1995 Section 8) where 250 is the time to peak value and 2500 is the time to reach half-peak value. At this voltage value, the CB has a 10% or less probability of external flashover to ground in both wet and dry conditions.

Operating Duty Cycle

Also known as the rated operating sequence or rated standard operating duty, the operating duty cycle is a predefined sequence of operations in a specific period and interval. The sequence, period, and interval may be defined by industry standards, the manufacturer, or specific applications.

Per IEEE Std. C37.04, the standard operating duty of a CB is:

O – t – CO – t’- CO


O is Open

CO is Close-Open

t’ is 3 minutes

t is the minimum reclosing time

For CBs not rated for rapid reclosing, t is 15s and 0.3s for CBs rated for rapid reclosing duty.

In generator CBs, IEEE Std. C37.013 specifies that the rated short-circuit duty cycle shall be two operations with a 30-min interval between operations (CO–30 min–CO). In circuit switchers (IEEE Std. C37.016), the rated operating sequence is Close-Open (CO).

The sequence of operations shown on the nameplate is the maximum number of operations in a specific period that the breaker was designed for. This should not be exceeded in the regular operation of the breaker or during field testing. It is also an indication of what type of application the breaker is designed to handle.

The minimum operation a breaker should be capable of performing is the CO, and it is the sequence the breaker should follow when the breaker is requested to close but there is already a trip command from a fault in the system. The breaker should close completely and then open immediately. This is also a basic sequence that any breaker is designed and built to perform.

The reclose sequence OC is the capability of the breaker to clear a fault and close after a delay. Some applications, e.g., generator breakers in which the breaker might not be mechanically designed for this sequence, do not require this. It should not be simulated during testing, as it may break or get jammed.

When a CB is designed for the reclose function, it should also be capable of opening immediately after a reclose to interrupt the fault if the fault is still present after the first clearing attempt. This sequence of operation is known as the OCO, although it is not commonly tested.

It is important to test the sequence defined in the nameplate to verify that the breaker will be capable of performing as per the design, especially if the sequence is being fully used in the system, for example, the reclose function instead of just an open and close operation.

Rated Interrupting Time

This is the manufacturer’s designated operating time limit for the opening of the contacts and interruption of the arc during the clearing of a fault. Rated interrupting time is measured from the energization of the trip circuit at rated voltage until the total interruption of current flow through the contacts. This interval includes the operation of the trip coil, actuation of the mechanism (travel), contact part separation, and extinguishing of the arc in all poles. This time depends on the speed of the breaker.

The standard rated interrupting time for CBs is 2, 3, or 5 cycles, but this might be exceeded under certain applications. In a CO operation, the interrupting time should not be more than 1 cycle for 5-cycle or higher CBs and ½ cycle for 3-cycle CBs. For out-of-phase switching, the time can be exceeded by 50% in 5-cycle CBs and 1 cycle in 3-cycle or faster CBs. In generator CBs, the typical values are between 60ms and 90ms.

This parameter is important during the design of the electrical network, especially when considering system stability and determining expected clearing times. The rated interrupting time is the main component of the total time it takes to clear a fault from its initiation to relay pickup and eventually arc extinction.

Rated Short-Circuit Current

This is the highest symmetrical component of short-circuit rms current at the instant of arcing contact separation that a breaker should interrupt at rated maximum voltage and standard operating duty without suffering damage of any nature in any of its components. This current includes the DC component, and it also establishes by fixed ratios the highest currents that the CB can close and latch against to carry and to interrupt.

ANSI C37.06 defines the preferred short-circuit current ratings for 123kV and above CBs as ranging from 31.5kA to 80kA. The typical values for generator CBs range from 63kA to 160kA as per IEEE Std. C37.013. These types of CBs are required to close in on a fault, latch, and carry current for at least 0.25s. The peak making current should not exceed 2.74 times the rated short-circuit current. This parameter is tested only at the factory.

Percent DC Component

This defines the portion of the total DC current that the breaker is capable of interrupting during an asymmetrical fault. It is an important parameter for CB specification and relay setting calculations. This specification cannot be verified in the field.

Short-Time Current Duration

This is the maximum time a CB can carry the rated short-circuit current without any damage. It is the maximum permissible tripping time delay (Y) for CBs.

The standards indicate a duration of 1s for HVCBs 123kV and above, for circuit switchers above 72kV, and for generator CBs. However, it is common to see breakers with a specification of 3s.

Ratings for Capacitance Current Switching

Capacitive currents are present during the switching of no-load overhead lines, no-load cables, capacitor banks, or filter banks. Energization of parallel capacitor banks and no-load lines can generate overvoltages or high currents, whereas the interruption of capacitive currents can generate voltage breakdowns across contact separation, known as re-ignition (less than ¼ of a cycle) and restrike (greater than ¼ of a cycle). Re-ignition can generate power-quality problems, while restrike will cause overvoltages of up to three times the peak value of the phase-to-ground voltage across the capacitive load for each restrike.

Breakers are designed to handle a certain amount of capacitive current under different system conditions like overhead line switching, isolated cable and isolated shunt-capacitor-bank switching, back-to-back cable and isolated shunt-capacitor-bank switching current, transient inrush current peak, and transient inrush current frequency. IEEE Std. C37.06 shows the preferred capacitance current switching ratings for indoor and outdoor CBs. This characteristic is tested at the factory, and IEEE Std. C37.09 and IEEE Std. C37.012 specify the proper procedures for testing.

Each capacitive current switching rating assigned to the breaker must have an associated class from the following categories:

  • Class C0: Unspecified probability of restrike during capacitive current breaking. Capability for one restrike per operation
  • Class C1: Low probability of restrike while breaking capacitive current
  • Class C2: Very-low probability of restrike while breaking capacitive current
Rated Out-of-Phase Switching Current

The out-of-phase condition is an abnormal situation in which the synchronism on either side of the CB is lost, creating a difference of potential where the phase angle of the voltages exceeds the normal values. In some cases, the voltages can be 180° out of phase. During out-of-phase switching conditions, a very large short-circuit current occurs.

The rated out-of-phase switching current is the current that the breaker should be capable of handling during an operation under a lack of synchronism. This is an uncommon situation, so not all breakers are designed for this. Whenever a breaker is designed with this capability, the preferred rating is 25% of the rated (symmetrical) short-circuit current expressed in kA, and the interrupting time is allowed to be greater than the rated interrupting time by 50% for 5-cycle breakers and by 1 cycle for 3-cycle breakers.


Mechanism characteristics include documentation and operating characteristics.

Control Voltage Range

This is the designated control voltage range required for operation of the mechanism at the connecting point of the control circuit. The high end of the range corresponds to the open-circuit voltage. The low end of the range corresponds to the voltage when the maximum operating current is flowing through the control circuit. The control circuit includes operating coils, auxiliary relays, and compressor, hydraulic pump, or spring charging motor.

IEEE Std. C37.06–2009 defines various ranges based on DC/AC signals, indoor or outdoor applications, and closing/tripping operations. For a DC voltage, various ranges are defined from 24V to 250V. Ranges below 48V are not recommended for breakers that might experience a voltage drop during operation, such as being far from the source or where the cabling is not adequate.

Control Current

This is the maximum current at nominal voltage that should flow through the control circuit during the operation of the CB. Each element in the control circuit has its own nominal current and maximum current.

In some cases, e.g., in the tripping coil or the spring-charging motor, a characteristic current curve provides valuable information on the condition of the element or its associated part of the mechanism. For example, the tripping-coil current reveals information on the condition of the latching system, and the spring-charging motor current indicates the condition of the spring mechanism.

Rated Operating Pressures

CBs might require pressurized systems for hydraulic or pneumatically operated mechanisms and/or for interrupters that use a pressurized gas as the interrupting medium. Each of these has a rated pressure range as per the CB design and construction that should be guaranteed at any time for the breaker to be operated safely.

The pressure refers to the standard atmospheric air conditions of +20°C and 101.3kPa (absolute)(or density), which may be expressed in relative or absolute terms, to which the mechanism or the interruption chamber should be filled before being operated.


CB nameplates contain basic information on how a breaker was designed and built, and it is useful to many different audiences. System engineers and operators use nameplate information for system calculations and to determine appropriate applications of the CB. System installers use it to verify conditions prior to installation. Testing and commissioning personnel use it to properly prepare testing procedures and evaluation criteria. Although the information displayed on the nameplate might not be complete for every audience’s need, especially for field testing purposes, most of the information is in the CB manual or instruction book, which is referenced on the nameplate.

For information on testing procedures that can confirm the expected performance of the CB, watch for Part 2 of this article in the Spring issue of NETA World.


IEEE Std 4–2013, IEEE Standard Techniques for High-Voltage Testing.

IEEE Std 100–2000, The Authoritative Dictionary of IEEE Standard Terms – Seventh Edition.

IEEE C37.04–2018, IEEE Standard Rating Structure for AC High-Voltage Circuit Breakers.

IEEE C37.06–2009, IEEE Standard for AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis – Preferred Ratings and Related Required Capabilities for Voltages Above 1000V.

IEEE C37.09–1999, IEEE Standard Test Procedure for AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis.

IEEE C37.010–1999, IEEE Application Guide for AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis.

IEEE C37.012–2005, IEEE Application Guide for Capacitance Current Switching for AC High-Voltage Circuit Breakers.

IEEE C37.013–1997, IEEE Standard for AC High-Voltage Generator Circuit Breakers Rated on a Symmetrical Current Basis.

IEEE C37.016–2006, IEEE Standard for AC High-Voltage Circuit Switchers Rated 15.5kV through 245kV.

Understanding High-Voltage Circuit Breaker Nameplates - NETAWORLD JOURNAL (7)Volney Naranjo joined the Technical Support Group at Megger in 2011 as an Applications Engineer focusing on the products for transformer, low-voltage and high-voltage circuit breakers, batteries, and power quality testing. He participates in the IEEE Energy Storage and Stationary Battery committee and has published articles in conferences such as TechCon, PowerTest, TSDOS, BattCon, and EIC as well as technical magazines. Volney received his BSEE from Universidad del Valle in Cali, Colombia. After graduation, he worked in the areas of electrical design and testing and commissioning of power systems as a field engineer and project manager.


What do the letters mean on a circuit breaker? ›

A means Standard Rating, C stands for Extra High Rating, H is High Rating, and I is for Current Limiting Rating. The third letter shows the type of lug a breaker has. There are three possible types: L, which means both ends have lugs; P, which denotes lugs for one end; and F, which means the breaker has no lugs.

What does the 15 and 20 mean on a circuit breaker? ›

The standard for most household circuits are rated either 15 amps or 20 amps. An important note to remember is that circuit breakers can only handle about 80% of their overall amperage. That means a 15-amp circuit breaker can handle around 12-amps and a 20-amp circuit breaker can handle about 16 amps.

What does 10KA mean on a circuit breaker? ›

"10KA" means 10,000 amps. Is is an extreme conditions rating for the breaker. It means that if your range suddenly has a massive problem, and causes a dead short, causing thousands of amps to flow, the breaker is certified to be able to interrupt it if it's less than 10,000 Amps.

What are the nameplate ratings? ›

Rated output, also known as Nameplate Rating, is determined by the wind turbine manufacturer, based on their chosen wind speed. The rated output can be a high number or a low number, depending on the wind regime chosen for performance calculations.

What do the letters and numbers on a circuit board mean? ›

The letters indicate the type of component, and the number, defines which particular component of that type it is. An example may be R13, or C45, etc.. By having meaningful abbreviations, it helps identifying the components much easier and it makes the circuit diagrams and board layouts more meaningful.

What are the three types of circuit breakers and what are their characteristics? ›

The three main types of circuit breakers are standard, GFCI and AFCI. Some models have dual functionality. Each handles different amp capacities and operates in different locations in the home. Standard circuit breakers monitor amp capacity of the devices they operate.

How are breakers numbered? ›

If you open the circuit breaker panel cover, you'll notice the layout of circuit breakers. The left side is the odd-numbered circuit breakers that are in a sequence of 1, 3, 5, etc. and the right side is the even numbered circuit breakers in a sequence of 2, 4, 6, etc.

What happens if I replace a 15 amp breaker with a 20 amp breaker? ›

You should never just upgrade from a 15-amp breaker to a 20-amp one just because the current one is tripping. Otherwise, you may burn your house down via electrical fire. To help you understand why this is so dangerous, you need to know what the circuit breaker is for.

Is it OK to use a 20 amp outlet on a 15 amp circuit? ›

For instance, it is crucial that the amperage of an outlet doesn't exceed the amperage of the circuit it uses. As a result, both 15 amp and 20 amp electrical sockets can be installed to a 20 amp circuit, yet only 15 amp receptacles should be used for 15 amp circuits.

What is the difference between 6kA and 10kA? ›

The capability of the MCB to operate under these conditions gives its short circuit rating in kiloamps (kA). In general for consumer units a 6kA fault level is adequate whereas for industrial boards 10kA fault capabilities or above may be required. MCBs are offered in types B , C and D characteristics.

What does 6kA mean on a circuit breaker? ›

For example, a value of 6kA means that the circuit breaker can withstand 6,000 amps of current during the brief time it takes to trip.

What does 65k AIC mean? ›

The interrupting rating at nominal circuit voltage of the main breaker is 65 kAIC (65,000 available interrupting current). A 200A circuit breaker, also rated 65 kAIC, supplies power to a downstream panelboard located more than 200 feet from the main distribution panelboard.

What is the 80% breaker rule? ›

This rule states that an OCPD can be loaded to only 80% of its rating for continuous loads. Remember that 80% is the inverse of 125% (0.80 = 1 ÷ 1.25) and, as such, the rules are indeed identical in their end requirement.

What are the ratings and specifications of a circuit breaker? ›

Rated voltage of circuit breaker depends upon its insulation system. For below 400 KV systems, the circuit breaker is designed to withstand 10% above the normal system voltage. For above or equal 400 KV system the insulation of circuit breaker should be capable of withstanding 5% above the normal system voltage.

What is an 80% rated breaker? ›

The 80% (standard-rated) breaker can only be applied continuously (defined as 3 hours or more by the NEC) at 80% of its continuous current rating (or Ir setting; e.g. if a 150 A H-frame is dialed to 100 A, the 80% rating applies to the 100 A setting).

How many types of name plates are there? ›

Nameplates have different types such as metal, plastic, aluminum, stainless steel, and brass. All these types of nameplates have unique advantages. And these nameplates are durable, long-lasting, perform well through extreme temperature, outdoor exposure, chemical exposure, and cleanings.

What are nameplate details? ›

The nameplate contains information about the construction characteristics and performance of the motor. The types of information that are shown include the number of phases, rated operating voltage, service duty, efficiency code, frame size, IP rating, insulation class and more.

How do you calculate nameplate capacity? ›

The formulas we use is: Nameplate Capacity (kW) = (Percent of Building Load * Annual Building Load (kWh)) / (8760 * Capacity Factor ).

What does Q stand for on a circuit board? ›

DesignatorComponent type
PSPower supply
QTransistor (all types)
RNResistor network
41 more rows

What are the abbreviations on a circuit board? ›

Common Printed Circuit Board Abbreviations
OCMOriginal Component Manufacturer
OEMOriginal Equipment Manufacturer
PCBPrinted Circuit Board
PCBAPrinted Circuit Board Assembly
60 more rows

What are the 5 electrical symbols? ›

There are five commonly used symbols in Electrical – Switch, Wire, Contactor, Motor, Transformer. These symbols can be used in any electrical drawings. Switches are used for ON/OFF any control circuit.

What is a high voltage circuit breaker? ›

High-voltage circuit breakers are mechanical switching devices which connect and break current circuits (operating currents and fault currents) and carry the nominal current in closed position.

How do you classify the circuit breakers and briefly explain each of them? ›

There are two types of circuit breakers based on the voltage level. They are: Low Voltage Circuit Breakers, which are intended to be used at voltages up to 1000V. High Voltage Circuit Breakers, which are intended to be used at voltages greater than 1000V.

How do you identify different types of breakers? ›

Standard circuit breakers – regular breakers just have a switch that flips up and down. GFCIs – GFCI breakers look similar to regular breakers, but they have a test and on/off button on the front of the breaker and usually have pigtails.

How are circuit breakers organized? ›

Most circuit breaker panels have two vertical rows of breakers. Above (or sometimes below) these two rows is a large breaker called the main breaker. This breaker controls the power to all of the branch circuit breakers. If you switch off the main breaker, you turn off all the circuits in the house at once.

Is it OK to oversize a breaker? ›

Oversizing a circuit breaker can be a safety concern. If there is a direct short in an appliance a breaker will kick off even if oversized, but if there is simply a crossed or burned wire it may not turn off. This would cause a possible shock hazard.

How many watts will a 15 amp circuit breaker on a 220V circuit allow? ›

On average, a 15 amp breaker can run a one 1K light each without blowing or about 1800 – 2000 watts. The only issue with relying on this formula is that it is advisable to only load a breaker up to 80 percent of its capacity.

Is it OK to use a higher amp circuit breaker? ›

When the breaker is tripping, it is almost never a good idea to replace it with a larger one. Here's why: It increases the risk of fire. If the breaker is tripping because it's overloaded (say, drawing 25 amps on a 20-amp breaker), increasing the size may cause the wire or the receptacle to overheat.

Does a 15 amp breaker trip at 15 amps? ›

As you add up the electrical loads, keep in mind that a wire rated at 15 amps can carry 15 amps all day long. However, 15-amp breakers and fuses can only carry 12 amps—80 percent of their rating—on a continuous basis.

Can I have 10 outlets on 15 amp circuit? ›

Technically, you can have as many outlets on a 15 amp circuit breaker as you want. However, a good rule of thumb is 1 outlet per 1.5 amps, up to 80% of the capacity of the circuit breaker. Therefore, we would suggest a maximum of 8 outlets for a 15 amp circuit.

Can a 20 amp circuit have 20 amps of equipment running on it? ›

The NEC states that a circuit cannot supply more than 80% of the circuit breakers limits. This protects the circuit breaker from constantly tripping and protects your home from electrical failure. Based on the information above, a 20 amp circuit breaker cannot provide a current of more that 16 amps (80% of 20 is 16).

Can I use 12 gauge wire on a 15 amp circuit? ›

However, 12-gauge wire is acceptable on both 15- and 20-amp circuits, so some electricians use it exclusively when wiring a house. This avoids the potential for mixing wire gauges in future repairs or additions, which is prohibited by the National Electric Code because it's a fire hazard.

Can you use 14 gauge wire on a 20 amp breaker? ›

You cannot use any 14 gauge wire on a 20 amp circuit. This is true, even running to a light fixture that has smaller wires built in. The wires built into the fixture are allowed as part of a manufactured assembly. However, any added wire must be appropriate to the circuit breaker protecting the wire.

Why can't you use a 14 gauge wire on a 20 amp circuit? ›

What happens if you use a 14 gauge wire on a 20 amp circuit? 14 gauge wire is rated for 15 Amps. A 20Amp breaker/fuse would risk fire. The wire gets hot enough to melt the insulation and start fire.

What is the difference between 4.5 kA and 6kA? ›

4.5kA means the RCD can handle 4.5kA of 'fault current. ' Commercial and industrial RCDs rated at 6kA or more can handle 6kA of 'fault current. ' If the fault current is exceeded, the RCD will most likely be damaged and subsequently not operate as it's intended.

What does 10KA mean on a breaker? ›

"10KA" means 10,000 amps. Is is an extreme conditions rating for the breaker. It means that if your range suddenly has a massive problem, and causes a dead short, causing thousands of amps to flow, the breaker is certified to be able to interrupt it if it's less than 10,000 Amps.

What does 10A 250VAC mean? ›

10A 250VAC is the max Voltage, Current the relay can handle.

How do you read a circuit breaker? ›

Each switch has an ON and OFF position. When the ON side is pushed in, the circuit is active. If the circuit is off or the breaker trips, it will be in the OFF position. Breakers are reset by switching them back to the ON position when you're ready to restore power.

What do the markings on circuit breakers mean? ›

Breakers are marked with either a slash or straight system voltage rating that indicates their capability to interrupt fault currents. Voltage markings for breakers with slash voltage ratings are separated by a slash — for example, 208/120V or 480/277V.

What does B32 mean on a circuit breaker? ›

A B32 circuit breaker is a miniature circuit breaker with a “B” trip curve. That means that is is for ordinary resistive loads, that do not cause surge currents. not inductive loads, like motors, that do cause surge currents (that would call for a “C” trip curve).

What is the AIC rating of a 400 amp panel? ›

* 400 Amp, 120/240 V, Single Phase Panels: Second breaker is an CRA-ES requirement and needs to be minimum 22K AIC rated.

What is the AIC rating of a 200 amp panel? ›

An example would be a 200-amp circuit breaker or fuse with an ampere interrupting capacity (AIC rating) of 42k AIC or 42,000 amps, installed in a panelboard where there is 38,000 amps of available fault current.

Is fault current the same as AIC? ›

AIC stands for Ampere Interrupting Capacity. The AIC rating indicates the maximum fault current (in amps) that an overcurrent protection device (circuit breaker, fuse, etc.) will safely clear when a fault is applied at the load side of the overcurrent protection device.

How do I identify a circuit breaker brand? ›

Circuit breakers have markings stamped on the side of them and are usually located inside the panel cover door. There is a label that will tell you what type of breaker is needed for installation in that particular panel.

What is nameplate data of electrical equipment? ›

A nameplate giving the following information shall be attached to the outside of the enclosure, or on the machine immediately adjacent to the enclosure: (1) Name or trademark of supplier (2) Model, serial number, or other designation (3)*Rated voltage, number of phases and frequency (if ac), and full-load current for ...

What is the purpose of a name plate? ›

Name plates are generally used by organizations to identify the occupants of the office spaces, desks, or cubicles. They are usually made of materials such as specialty plastic, aluminum, stainless steel, wood, and occasionally, bronze or multi-layered plates of acrylic.

How can you tell if A motor is AC or DC? ›

The most obvious difference is the type of current each motor turns into energy, alternating current in the case of AC motors, and direct current in the case of DC motors. AC motors are known for their increased power output and efficiency, while DC motors are prized for their speed control and output range.

What does SF amps mean? ›

Service Factor Amps, or S.F.A., represents the current the motor will draw when running at its full Service Factor. In the example nameplate, the S.F.A. is eight amps at 230 volts. Continually exceeding the S.F.A. shown on the nameplate can shorten motor life.

What are the 3 types of breakers? ›

The three main types of circuit breakers are standard, GFCI and AFCI. Some models have dual functionality. Each handles different amp capacities and operates in different locations in the home.

What important information must be listed on the electrical tags? ›

Tags can contain information such as the date of the test, the name of the tester, and are often colour-coded according to the level of risk. All tags should be non-metallic and non-reusable.

How is nameplate power calculated? ›

The formulas we use is: Nameplate Capacity (kW) = (Percent of Building Load * Annual Building Load (kWh)) / (8760 * Capacity Factor ).

What is ASME nameplate? ›

All pressure vessels we build are manufactured in accordance with the ASME Code. According to this standard, the vessel must be built with a nameplate. Once the pressure vessel passes its final inspection, the ASME Code mark is stamped onto the nameplate, proving the vessel was built in accordance with this standard.

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