# Understanding power rating of switches at 5V

I have a hard time selecting a switch for my 5V project (somewhat of a newbie to the field). I would like to power a LED strip that consumes up to 1.2A at 5V. A typical load is usually lower at about 600mA at 5V.

I have come across some nice switches such as this one. Which states that it supports 0.4VA maximum @ 28V AC/DC maximum.

What does that mean for my use-case? How can I convert such ratings to 5V?

It is not suitable. Keep reading:

0.4VA maximum @ 28V AC/DC maximum
(Applicable Range 0.1mA ~ 0.1A @ 20mV ~ 28V)


.1A or 100mA is not high enough for your application.

In general for a certain voltage on a resistive load, the max current is

$$0.4VA / 5V = 0.08A = 80mA$$

• Ok, that explains it nicely. Another switch also provides a 'Power Level Rating' of '6A @ 125V AC or 3A @ 250V AC or 6A @ 12V DC for silver'. Would this mean that it would be suitable for 12/5*6=14.4V? – Felix Lamouroux Oct 10 '15 at 2:24
• +1 for Daniel. That one is suitable, for as many as 5 pieces of 1.2A strips in parallel (it's the 6A current rating that matters in this case not the VA), but you must choose the W01 version with silver contacts rather than the gold option. Not sure what you mean by 14.4V. – Spehro Pefhany Oct 10 '15 at 2:38
• My question for the second rating was: given that it can sustain 6A @125V, how much can it sustain at 5V: is it a simple equation or does the maximum current not change with the applied voltage. Sorry for the follow-up question in the comment section. – Felix Lamouroux Oct 10 '15 at 8:17
• The difference there is between AC (125V) and DC(12V) - at both of these it'll take 6A. The higher voltage AC rating reflects the fact that the AC waveform crosses through 0V to break any arc that develops when switching off. On DC, it's not guaranteed to do this (for 6A) above 12V. At 5V its rating is probably still only 6A. – Brian Drummond Oct 10 '15 at 9:45