Current and Voltage Rating of Liquid Level Switches
Above ratings are for resistive loads only.
Maximum voltage ratings: SPST Switches – 240 VAC; SPDT Switches – 120 VAC
Please note: Nominal VA is Volts x Amps and is the term used for Apparent Power in AC circuits. It is simply the product of voltage and current, without taking into account the type of load (resistive or inductive). In this chart we use the Nominal VA with resistive load in conjunction with the applied AC voltage to determine the current – we are stating currents with a resistive load. Watts and VA can be used interchangeably in the charts above.
We recommend that switches stay below these ratings for non-resistive loads.
Current and Voltage ratings are for resistive loads only. For inductive loads, maximum life will be achieved if appropriate arc suppression is used.
Maximum voltage ratings: SPST Switches — 240 VAC; SPDT Switches — 120 VAC
Each switch has a power rating in watts. These power ratings are for resistive loads that are at a steady state and are calculated as Power (Watts) = Voltage (AC/DC) * Current (Amps-resistive load). Most devices have other things to consider, such as current or voltage spikes caused when powering up or shutting down. Common devices such as pumps, coils and light bulbs can create these types of spikes. For these more complex cases, one must remember to stay within the maximum current and voltage ratings of the switch regardless of the power rating.
For example, our 30-watt standard switches have a maximum switching current of 1 Amp and a carrying current of 2.5 Amps. If the switch is connected to a 12 V circuit that spikes to 2 Amps and runs at a steady state of 1 Amp, the power spike exceeds the switch rating although the steady state running power is 12 Watts. Due to the heat and type of power dissipated during the spike, the contact may be damaged or even welded together, causing switch failure.
Custom designs have other elements to consider and even alternative ground paths that may affect the power delivered to a switch. It is important to consult your engineering department before assuming the system's power requirements. Contact the factory for additional assistance.