the design engineers should have figured that out! amps are gonna draw 1/2 to 3 amps, depending on manufacturer. the equipment should state it's draw. you can't (don't want to) exceed 80% of your power supply amp rating or you will have major problems. voltage may be sufficient at the amp but as soon as you insert the module the draw will knock out the system if it exceeds the amp rating. piggy backs are a temp fix to a bad design! Good luck! Mike M.
This is CABL.com posting #159531. Tiny Link: cabl.co/mPFf