I have a 12V DC switch. How many V AC can it handle?

R

RobertStorm

New member
Joined
Jun 11, 2008
Messages
2
Reaction score
0
Points
1
Or can it handle any VAC at all? I'm not sure, but I thought that a switch was just a mechanical way of closing a circuit. It has an LED, and it's rated at 12V DC (and some amperage, I forgot what). I need to know what V AC it can handle.
How do I know?
 
I would expect a 12 VDC switch to work fine with any low-voltage AC, like 12 VAC.

I would not use it for 120 VAC.

"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)."
 
A good rule of thumb is that the RMS voltage of an AC signal can be approximately compared to the the DC voltage. This works perfect with pure resistive circuits, but if safety alone is your concern it will work with any other circuit.

The switch is rated at said voltage because this is the maximum permissible voltage across it when open. This is the maximum permissible voltage across the air gap before miniature lightning occurs. In theory, when closed, there is no voltage across it.

RMS voltage stands for "root-mean-square". You don't need to know what a "root", a "mean", or a "square" is to understand the calculation of this.

Formulas below are applicable to sinusoidal AC signals (the default). Any other waveform will be more complicated.
In terms of mid-line to peak of an AC signal (Vamp, the amplitude), Vrms = Vamp/sqrt(2).
In terms of peak to peak of an AC signal (Vpp), Vrms = Vpp/(2*sqrt(2)).

Just solve for Vamp or Vpp, which ever is of interest to you.

Frequency should not be an issue, as long as it is reasonably low.
 
Back
Top