What exactly do I need to do to convert a phase 1 supply to a phase 3? (Commercial sunbed usage)

Depending on the size of the sunbed and what current it requires will dictate how much you need to spend. But you have two options really. Neither are cheap, but one more expensive than the other. Firstly the expensive option is to pay your electricity company to put in a three phase supply (i.e. dig up the street and physically lay in a new 3 phase cable to your home/shop) and also upgrade your single phase meter to 3 phase. This could easily cost two to three thousand pounds to do, plus you will also need a new 3 phase fuseboard and a 3 phase electrical circuit instllaed by your own electrician so that the sunbed can connect to it. The cheaper option is maybe to look at an "invertor" these are not as good as dedicated 3 phase supply, but will work. Take a look at; http://www.boost-energy.com/phase-converters/the-range/a-3-kw Hope this helps, please click on "like" if it does.

If there is no 3phase supply to the property you will need to contact the local supplier to install the new supply from the street.

You need to contact your supllier, ie EDF or UK power networks to upgrade your incoming supply