Old, wood frame office building needs 3-phase power to run the new elevator. The only space available for the phase converter is on the second floor. The electrician set the phase converter on a rubber pad and bolted it to the wood floor, which is now acting like a big sounding board. You can hear the vibration throughout the building.

I was thinking that some type of neoprene or rubber vibration isolating mounts would help, but I doubt that the mounts will solve the problem completely. Should we put pour a small concrete pad under the phase converter? I was thinking that the mass of the concrete would eliminate some of the vibration.

Any thoughts or suggestions?