5 second intervals between EmonLib samples?

In that case, if you use calcIrms( ), you’ll need to work out the sample rate for yourself. The way I do it is record the time before and after calling the function, then change the number of samples and record a new time. Then take the difference in the number of samples and the time difference to work out the rate (gets rid of overheads that way - assuming they don’t change significantly).