Contact ratings are not max power related, but rather specific max voltage and current ratings. You have to stay under both values no matter what the load power is.
The max voltage rating has to do with the contact spacing when open such that there is no 'flash over'. The max current rating is that which the contacts can handle without 'burning' material off the contacts.
On contact current ratings, if you look over enough relay spec sheets you will sometimes see examples where the contact current spec is higher if switching AC current Vs DC current. That is because the AC current is always passing through 0 amps/volts at 50/60 Hz and that helps extinguish the contact arc as the contacts open and close. However unless that is stated in the contact ratings you should always stay under whatever spec they do state.
That make sense?
Lefty