The MAX2982 digital baseband and its companion device, the MAX2981 analog front-end (AFE) with integrated line driver, offer a complete high speed powerline communication solution fully compliant with HomePlugM 1.0 Powerline Alliance Specification. The HomePlug Power Line Networking system is specified only for operation on residential AC power lines carrying nominal AC voltages from 120 V to 240 V.
Please see page 3 of the document below:
http://read.pudn.com/downloads114/ebook/479147/HOMEPLUG.pdf
However, you can use the MAX2982 at 480V. Just make sure high voltage capacitors of coupling circuit have a rating higher than 480VAC.