Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Category ratings on test gear (maximum voltage)

  1. Sep 8, 2016 #1
    Hi all. What does the voltage rating in each category I/II/III/IV actually mean? For example, my multimeter is Cat III rated to 300V. Is this RMS? Peak? Peak-peak?

    Our supply here is 230V RMS AC, but this means the momentary peak is about + and - 330V (relative to neutral/ground) and the peak-peak is of course 660V.

    Can I therefore use it to measure mains voltage at a socket? My interpretation is:

    1. If RMS, yes.
    2. If peak, no.
    3. If peak-peak, definitely no.
  2. jcsd
  3. Sep 8, 2016 #2


    User Avatar
    Science Advisor
    Gold Member

  4. Sep 8, 2016 #3
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted