New Low-Power Limit for ARRL HF Contests Goes into Effect on January 1, 2022
ARRL has set a new standard for what counts as low power for ARRL-sponsored HF contests. The new limit is 100 W, which is down from 
the 150 W limit that has been permitted in some events, including the ARRL November Sweepstakes.
With the exception of ARRL Field Day, this change goes into effect on January 1, 2022, for all ARRL-sponsored HF contests, as well as the IARU HF World Championship.
This change has been implemented to standardize low-power categories within the contesting community. However, on a more practical level, the typical modern HF transceiver has a maximum power output of 100 W.
For more information, contact the ARRL Contests program. — Thanks to The ARRL Contest Update