The majority of X-10 units are available only for the USA market where the mains supply is 115 volts at 60 Hz but the UK mains supply is 230 volts 50 Hz. It is however possible to modify some USA modules to operate at 230 volts. Most of the pages on this site provide details of modifications actually performed by the author from X-10 modules bought from Smarthome.
This information is provided for information only and is not guaranteed to be correct, and I urge you not to attempt these modifications unless you are technically competent. I accept absolutely no responsibility for any modifications you perform or the effects of any such modifications.
Performing these modifications will invalidate your warranty and could render the modules in a dangerous condition and without CE approval. Finally, make sure all installed modules have appropriate fuses and cable to reduce the likelihood of fire.
For further details, please: