Amp Ratings, HP, Volts


Any Carling Technologies' switch that has agency approvals will have its ratings stamped on its base. Carling Technologies switch ratings are listed by amperes, volts, and horsepower (when applicable).

Electricity is the movement of electrons from one atom to another. The flow of electrons through an electrical conductor is called electrical current, which is measured in amperes or amps. The electrical pressure necessary to cause this movement is voltage. Voltage itself does not flow through conductors, but is the force that causes current to flow. Voltage is also called electrical potential, because if voltage is present in a conductor, there is potential for current flow.

Motors are rated in horsepower (HP) or fractions of horsepower (1/4, 1/3, 1/2, etc.) Mechanically, one horsepower (1HP) is equal to 33,000 pounds being moved 1 foot in 1 minute (or 33,000ft-lb/min). One horsepower (1HP) is also equal to 746 watts of electrical power.

The voltage rating is a function of a switch's ability to suppress the internal arc that occurs when a switch's contacts open. The voltage rating specified on Carling Technologies' switches represents the maximum voltage allowable for the switch to function properly at the rated current. The amp rating of a Carling switch is the maximum current in amperes the switch will carry continuously. So, in the example below the maximum amp rating for this switch at 250 volts AC (VAC) is 10 amps; the maximum amp rating at 125 volts AC for the same switch is 15 amps.

Switches that are going to be subjected to high-inrush inductive loads, such as an AC motor, will often be rated in horsepower in addition to volts and amps. This rating reflects the amount of current the switch contacts can handle at the moment the device is turned on. An AC motor will draw up to eight times its running current when first turned on or when held stationary while energized (stalled rotor). The switch in the example below would be rated for use with a 3/4HP motor at 125 through 250 volts AC.

Typical Carling Technologies' switch rating:
10A 250VAC
15A 125VAC
3/4HP 125-250VAC


Carling offers both AC (alternating current) and DC (direct current) switch voltage ratings. AC or alternating current is an electric current or voltage that reverses its direction of flow at regular intervals and has alternately positive and negative values, the average value of which over a period of time is zero. The number of times this value changes (or cycles) per second is it's frequency. Frequency is measured in Hertz (Hz). The more cycles per second, the higher the frequency. The electrical "grid" in North America is based on a very stable 60Hz frequency. Most European countries are based on a 50Hz frequency. All of Carling Technologies' AC voltage ratings are listed at 50/60Hz, and all Carling Technologies' agency approved switches will list specific AC voltage ratings.

DC or Direct Current is an electric current or voltage which may have pulsating characteristics, but which does not reverse direction. It's potential is always the same relative to ground, and it's polarity is either positive or negative. A battery is one example of a source of direct current.

A Carling AC rating is followed by "VAC", for example 125VAC is 125 volts AC. Carling AC/DC ratings are followed by "V" only, without the letters AC and DC following. For example a 125V rating would be read as 125 volts AC and 125 volts DC.

DC Rule of Thumb

For those switches that list an AC voltage rating only, the "DC Rule of Thumb" can be applied for determining the switch's maximum DC current rating. This "rule" states the highest amperage on the switch should perform satisfactorily up to 30 volts DC. For example, a switch which is rated at 10A 250VAC; 15A 125VAC; 3/4HP 125-250VAC, will be likely to perform satisfactorily at 15 amps up to 30 volts DC (VDC).

Types of Loads

An electric load is the amount of electric power delivered or required at any specific point or points on a system. The requirement originates at the energy consuming equipment of the consumers. More simply put, a load is the piece of equipment you turn on and off.

Resistive loads primarily offer resistance to the flow of current. Examples of resistive loads include electric heaters, ranges, ovens, toasters, and irons. If the device is supposed to get hot and doesn't move, it's most likely a resistive load.

Inductive loads are usually devices that move and normally include electric magnets, like an electric motor. Examples of inductive loads include such things as power drills, electric mixers, fans, sewing machines, and vacuum cleaners. Transformers also produce inductive loads.

High Inrush loads draw a higher amount of current or amperage when first turned on, compared to the amount of current required to continue running. An example of a high inrush load is a light bulb, which may draw 20 or more times its normal operating current when first turned on. This is often referred to as lamp load. Other examples of loads that have high inrush are switching power supplies (capacitive load) and motors (inductive load).

UL/CSA Ratings

Typical UL/CSA amperage rating is a single value which represents inductive/resistive loads. If a horsepower rating is listed, it indicates the switch is appropriate for use on motor loads that are rated at the given horsepower. If there is no horsepower rating listed, switches are tested to an inductive/non-horsepower load at 75% of the power factor.

A typical example of a UL/CSA Rating is listed below:
10A 250VAC
15A 125VAC
3/4HP 125-250VAC

European Ratings

The typical European rating will distinguish between resistive and inductive load ratings. Below is an example of a typical European rating:
16(4)A 250V ~ T85 µ

In this example the 16 = resistive load amperage; (4) = inductive load amperage; A= amperage; 250V= voltage; ~ = AC; T85= Maximum operating temperature in centigrade; µ = micro-gap (<3mm) approved.

If there is less than 3mm of air space between a switch's contacts in the open position, a micro-gap approval (µ) may be granted. This mark indicates that the switch has general application approval with a qualifier that another device, such as a cord and plug, must provide an alternate means of disconnection from the main power source.

L & T Ratings

An "L" rating denotes the ability of a switch to handle the initial high inrush characteristics of a Tungsten Filament Lamp on AC voltage only. A "T" rating is the equivalent lamp load for DC.

H Rating

An "H" rating denotes a non-inductive resistive rating. Ratings listed in Carling Technologies' product information may appear with the symbol "H" or with the words "non-inductive" or "resistive". "H" ratings are typically required for switches used in commercial oven applications.

Illuminated Switch Ratings

For illuminated switches with dependent lamps, line voltage should match the lamp voltage rating. For instance, if a 6 volt DC lamp is used, then the switch contacts should only be handling 6 volts DC line voltage; a 125Volt Neon lamp, should not be used on switches managing 250Volts AC. Mismatching these two ratings could result in much shorter than expected lamp life or lamp burn out, or dimmer than expected lamp performance.

Operating Temperature

All European certified switches have a maximum operating temperature of 85 degrees Centigrade, unless otherwise noted. Switches rated T85, if directly operated, should not be used in applications where the temperature of the actuating member inclusive of any temperature rise exceeds 85 degrees Centigrade.

Unless otherwise noted, all North American rated switches have a maximum material temperature rating of 105 degrees Centigrade.