# Tying multiple VDC minus power supply outputs together



## IslandWire (Aug 3, 2013)

Of coures, first check with the transformer literature(driver) and see if the manufacturer recommends or prohibits making the reference ground connection. If they don't mention it, call the tech support. Or, use an ohm meter on the transformer alone from each AC input to each DC output (4 measurements total). I would think that if you have any of them less than 25ohm, you dont have electrical isolation from AC to DC in the transformer(driver). You must be cautious if there is no isolation, particularly if you might end up having different phases feeding the AC side of the transformers.


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