230v / 110v / 110v centre tapped earth / 50vdc / 50vac pelv / 50v selv / 12v etc etc, the voltage is totally irrelevant, the environmental rating is what matters. its complicated but if you intend to use the equipment in rain then it needs to be ipx4 rated. all equipment that is ce marked has a rating. the 'x' is to do with dust and solid foreign objects. the second letter is to do with liquids and droplets, eg, ipx1 allows all liquids in therefore is not suitable for any liquids, but ipx7 is totally waterproof and submersible. the industry standard for vertical to 45 degree droplets of water falling from above is ipx5 usually ip65 (sometimes the ip index is replaced by water droplet symbols 1 droplet not so good water protection, 3 very good etc etc) is what you will see on the rating plate. the reason 110v centre tapped earth's is used on buildings site is because of the harsher conditions and higher risk assessments, ie., more chance of equipment being damaged in between 3 monthly checks. however personally if i have an option of buying 110v equipment i prefer to use this (maximum of 55v between me and earth which is where all electricity wants to get back too, either thru green / yellow or your wet socks, whichever is the easiest route), however a 30ma rcd protected circuit will keep you safe, you may feel a little jolt but only lasts for a maximum of 0.4 seconds.