Given an input of 120VAC, the ER4 will draw a maximum of 8 Amperes -- 2 Amperes per option module or processor.
ETC recommends feeding the ER4 with a dedicated 15 or 20A breaker or disconnect.
Given that the Power (Watts) does not change for higher input voltages, we can use the formula W=VA (or P=IE) to determine max amperes at other voltages.
Voltages other than 120VAC
The ER4 will draw a maximum of 4.2 Amperes at 230VAC. A CME will draw approximately a maximum of about 1.1 Amperes at the same voltage.
Using the same calculations at 277VAC, the ER4 will draw a maximum of ~3.5 Amperes at 277VAC. A CME will draw appoximately .875 Amperes at the same voltage.