May 12, 2008 Your Grounded! Well, not really - but many machines out there are. An easy way to tell if a machine is grounded is to look at the plug. If there is a third pin on the plug, it's grounded. In this case, you must use a transformer with a grounding power cord and receptacle. If a machine is not grounded, you can use a less expensive transformer with a 2 pin format. Transformers with a third pin ground can be used with both grounded and ungrounded machines. The opposite, however, is not acceptable - a 2 pin transformer can only be used with a machine that is not grounded. For simplicity's sake, if a transformer is going to serve multiple purposes and be used with different pieces of machinery, it's a good idea to choose a 3 pin transformer which can be used with both (provided, of course, its VA rating is sufficient). Back to FAQ home page