[quote name='sunburstjazz1967' timestamp='1457031521' post='2994699']
I've seen this before, its pointless and a bit stupid really and here is why, the sticker is purely for users of the kit to see visually that its in date it MUST be accompanied by an actual certificate giving the full details of the item including the earth type,the certificate MUST show the company name and contact details on it.
Ok that's the paperwork side of it who cares you ask? Well EVERY band who's kit I have tested at least one item was found and repaired, many of our mass produced amps and musical kit have metal casings and high voltage transformers inside, often the only protection from a fault is a small ring terminal crimped to a banjo washer or bolted to the chassis, the bolts vibrate loose as do the locking nuts just like the ones on bass control pots so the earth is lost, any voltage trying to leak to earth (which is normal to a certain level) goes straight up your instrument lead and to your earthed bridge and strings, enjoy your ebay stickers though :-)
As a minimum a continuity test from the earth pin of the plug top to the chassis of the amp is worth doing, then check every iec lead from earth to earth, my own band used to get some terrible hum it various venues,when I tested our own kit I found a lead with no earth present, this was the cause of the hum and really dangerous when used to feed a PA system, life threatening really regardless of need or legality.
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OK, I'll take the risk. I'd like to make an observation, though - IME the people who go on about the importance of PAT testing the most are the people who get paid to do the tests.