anything electrical has added buyer restrictions...
Items that attach to electrical power have special issues with regard to safety and damage. These items may have the potential to deliver lethal electrical shock and burns, as well as the potential to start fires. They are also subject to damage if powered up incorrectly. The damage may not be visible and there is certainly no way for us to observe or control proper hookup.
A standard household electrical item is least restricted. However, if it looks like it might present a fire or shock hazard, we will want to determine the buyer's qualifications for dealing with these potential risks before shipping the item.
Electronic items are not particularly restricted in a safety sense but they are generally non-returnable as they are so subject to hidden damage from static electricity, reverse polarity and incorrect voltages.
In the USA, 220 volt (and higher) items are not consumer connectable. They must be wired/connected by a qualified licensed electrician. The key point is that these items may derive 110 volts internally by going between a hot leg and neutral. If the wire is not done properly, current could end up flowing through a ground wire or the frame of an item could become a shock or fire hazard.
3-phase items require installation and connection by a properly trained and qualified industrial power electrician (not just a home wiring expert). 3-phase has to deal with delta and wye connections where there can be issues is balanced versus unbalanced legs and hot versus standard legs. Hooking it up wrong has the potential for destroying the item as well as making possible shock, electrocution and fire hazards.
MAKE SURE YOU ARE QUALIFIED TO DEAL WITH THE POTENTIAL ISSUES OF THE ITEM BEFORE YOU COMMIT TO PURCHASE!!!