Melco recommends using a Line Stabilizer/Power Conditioner for up to 4 Embroidery Machines at a time, based on peak usage. With that, you can safely power on/off up to 4 machines from one switch.
These two sizes of Line Conditioners are available on ShopMelco:
Single Machine: POWERVAR ABC302-11
Up to 4 Machines: POWERVAR ABC1000-11
Another option is the Tripp Lite LC1800 or Tripp Lite LC2400
We do not recommend connecting multiple machines to simple power strips as they do not reliably handle power spikes/surges, brownouts, or other variances in power.
Melco machine power specifications are available in the Technical Manual.