TWD means one of these.


http://www.amazon.com/Electrical-Receptacle-Outlet-Ground-Tester/dp/B0012DHVQ0

You guys are on 110 volts and as such don't rely on the earthing we have in EU and UK we need serious earthing.
Make sure you buy the right voltage for your country...

Tony
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Tyros 4/Pair SR 350/ PC with a i8 intel chip, XENYX 802, Ford Focus 2 litre/Tascam DR07/Brother printer/Designjet 500/ our Doris/5 Grandchildren/ white boxers short Kymart shipped over and Typhoo Tea Earl Grey