Multiple PSU in single case for Bench Supply - Ground Question

Arcygenical

Fully [H]
Joined
Jun 10, 2005
Messages
25,056
Hey guys,

I'm building a 1500w 12v bench supply using 2 750w PSUs (yes, I know I won't get the full 1500w, but let's just ignore that for now). I'll be using it for 12v audio output testing (car audio testing)

I know both supplies will be case grounded to the chassis... But would it be better to open the supplies up, and actually physically connect the green AC ground together, then to the main chassis, rather than relying on screws, case grounding, multiple grounds etc.

Will I have any issues if I connect all the AC grounds together, and ground directly to the chassis its self, or should I leave the grounds attached to their respective PSUs and just go about it that way.

The reason I ask, is both supplies AND the chassis is powdercoated, and I don't really want to have two separate floating grounds. Although, to be fair, two separate floating grounds may be smarter since this is for audio. Basically, what would you do?

Cheers,
 

Mohonri

Supreme [H]ardness
Joined
Jul 29, 2005
Messages
5,751
The case of the PSU is wired to the ground pin on the power cable in each power supply, and those grounds are all connected at the power strip (or outlet pair). In any case, they are only there as a safety measure. Normally, you'll have no current going through the ground lead. It's there so that if a live wire gets lose inside the enclosure and contacts the case, the rogue current will be safely routed out through the ground wire, rather than shooting through your body when you touch it. In other words, as long as you're using three-prong outlets and cables, you're safe.

That said, given that you are running these two supplies in parallel, you definitely need to ground their 0VDC lines (the black wires on a molex connector, which are often called "ground" but really should be called "common") together.
 

JoBUSH

Weaksauce
Joined
May 21, 2014
Messages
103
Most AC rectifiers bond the 0v to the ground anyway. You can test continuity between the AC side ground and the 0v on the DC side of the PSU.
 
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