I am really surprised by the responses here.
If the equipment says it must get 230 volts then it must get 230 volts. If I am installing it I do not concern myself with the reasons why. It could be a bunch of BS....I don't care, I was hired to hook it up professionally and IMO part of being a professional is following instruction like this.
I also see it as a way for the manufacturer to pass the buck.
Do not follow the directions and phone call like this could be in the future.
Customer: My $25,000 tanning bed stopped working.
Bed Manufacturer: We are sorry to here that, did you supply it with 230 volts as we require.
Customer: Heck no, my electrician said it was a waste of money and it did not matter, we supplied it with 240.
Bed Manufacturer: Well that voids any warranty we provide, we can repair it, bill you and you can go after your electrician for the costs.
It won't matter if the 240 volt supply had anything to do with the problem it will still be the excuse to put the costs back at the EC.
I wired a 7-11 store and the two frozen drink machines both required buck boosts per the manufacturer to get closer to 230 volts, they also had a very low tolerance for voltage variations between phases.
Was it really needed?
Would the machines worked fine without the buck boosts?
Who cares? I did not spec the equipment but I will install it correctly and charge for it.