The 110V (Not 120V) supplies used on construction sites in the UK are actually governed by a series of EU safety directives.
The transformers are isolated and center tapped with 55V to earth on each side and appliences are connected using yellow CeeForm plugs.
220-230 (or 240)V is completely illegal for handheld use on building sites or in any similar hazardous work areas. Using it in Ireland would be a very serious breech of Health and Safety regulations and the HSA (Health and Safety Athority) could potentially shut a site for such an infraction.
Most hired powertools are also 110V systems.
It should be extended to garden equipment too in my opinion. RCDs are only a partial sollution.
Here's a list of voltage regulations for sites: http://www.niceic.org.uk/specifiers/consites.html
Other "Extra low" voltages are required for things like hand lamps etc.
As for your US equipment. It should be ok if:
1) its ok with 110V-120V at 50Hz rather than 60Hz.
and 2) Arn't US outlets are 110V to ground not two 55V to ground centre tapped?
I though the centre tapped stuff applied to the 220V outlets? Where you've 2 110V hots taken from the centre tapped transformer giving you 220V(ish)
NEMA plugs are not used and wouldn't not be allowed as they do not conform with EN (Euro standards) or BS. The system is also only used in hazardous heavy use areas so standard NEMA would be unacceptable.
I've seen situations where people have installed hardwired 110V transformers to feed US equipment here where people had moved to Ireland and generally because NEMA fittings are simply unavailable they just used non-standard UK fittings. (smaller BS 546 in one case and BS1363 with keyed pins in another, I could see the fuse being a problem though if it was a high wattage applience/peaky applience..) It was just for audio equipment and both systems worked fine, actually they said better then NEMA. No sparking!
Fit yellow CeeForm plugs to your powertools. They're a MUCH safer more robust option and will plug directly into a transformer and only cost around ¬£1 each http://www.axminster.co.uk/default.asp?sub=100
[This message has been edited by djk (edited 05-28-2003).]