While re-wiring the Backfire sign to make use of 2 PB (thanks for the sync feature!), I’m also redoing all the wiring and this is my progress so far. (Need to order another PB and expander for the other four letters)
One thing I wanted to do, just to make the sign a bit more safe since its all aluminum frame, is to properly ground the frame.
I can screw down and run ground wires from the frame, but to where? the V- ground on the 5V side, or the earth ground on the 120V side? Anyone know?
Since your frame is already screwed to power supply, it should already be grounded to the earth ground through the case of the power supply. You could use a multimeter to confirm that your sign frame is attached to the earth ground already.
If for some odd reason the case of the power supply isn’t grounded… I’d ground your frame to the earth ground.
Nice work! Hey I know you’re not going for UL approval or anything, but the best practice is to connect your incoming earth ground wire to a secure screw on the frame, then run a separate jumper (with it’s own crimp lugs) from that screw to your power supply. This ensures that the frame remains grounded even if the power supply comes loose or falls out.