I have a 3d printer with a 12vdc-30A power supply (PS). The PS has a common +/- rails with three screw connectors for positive and three for negative. The printer has two sets (+/-) of wires coming from the PS to a junction block. Then there are two sets of wires (+/-) going to two screw terminals on the controller card.

I recently bought a clamp meter that does DC-Amps, pretty clever and seems to be very accurate when compared with an in-line Amp meter.

So here's the issue.
If I clamp around one wire from the PS when both the heated bed and nozzle are drawing current I get 11A on one wire and 9A on the other. If I clamp around both wires I get about 14A so I am confused.

Can I clamp around both wires for a total current reading?
If I clamp one, is it showing a true reading?


ASCII Art

0-vdc ----+-+ +-+----- 12vdc [ PS
| | | | [ measure each 11A and 9A
| | | | [ measure both 14A
+---+ +---+
| | | | [ Junction block
+---+ +---+
| | | | [ measure each 11A and 9A
| | | | [ measure both 14A
Hotbed --+ | | +--
Nozzle ----+ +----

Thoughts?

Thanks