Wikipedia says just "Low voltage, phase B". The tape I bought has no specification about such property on the package. About how much voltage can one layer of such tape block? If one layer can block X volts, does using two layers block 2X volts?
UL 510 rating for "low voltage" applications specifies a 600 volt (!) dielectric withstand. You can reasonably assume any good quality vinyl tape will at least be able to withstand (household) mains voltage. If you buy cheap unrated clone tape of unknown material/construction, all bets are off. Good quality tape will have some kind of stated rating.