Originally Posted by Cherryville Chuck View Post
I don't understand how you use +55v and -55v power.
The potential difference between +55 volts and -55 volts is 110 volts, which is what our industrial site power tools run on. I've found that most 115 volt US tools with universal motors will run on that quite happily unless they have some sort of frequency-based speed controller. The UK and Ireland are probably the only places in the EU which have 110 volt power tools on building sites (and other restricted areas such as railway lines, etc). My understanding is that if one live is exposed and you accidentally touch it the 55 volts earthing through your body cannot kill you, but as some people are killed every year testing 9 volt bicycle batteries on their tongues, maybe I'm wrong there. So it is supposedly intrinsically
safer. Maybe. The rest of the EU, however, doesn't play that game and instead insists on the standard 220 volts (live + neutral) with an RCD to protect each circuit. We normally get an MCB or RCD per circuit on larger transfornmers so maybe the health and safety brigade/insurance brigade are a bit more belt and braces here in the UK. What I do know is that it costs me more to buy some of my work tools and that not everything is available in 110 volt form.
The only other thing I can say about 110 volt site tools is that they are useable outside safely
when it's a bit damp with minimal risk of electrocution. By that I don't mean standing up to your oxsters in water core-drilling a wall in the middle of a monsoon, but certainly I've been out there jigsawing a hardwood shop frontage to scribe it in whilst the rain is spitting and the pavement is still wet. So far, at least, without problems!
I suppose that it's the transient nature of construction work (be it domestic kitchen fitting, commercial bar fitting or building a skyscraper) which means that most of the problems will occur in the extension cables which do tend to get dragged all over the place, run-over by trucks, etc rather than problems in the tools themselves