What safety precaution must be taken before performing maintenance inside the PipeWorx 400?

Before performing any internal maintenance, you must turn off the power source, disconnect the input power, and verify the residual voltage on the input capacitors according to Section 7-6. A dangerous DC voltage remains present on the capacitors after power is cut, so you must wait at least 5 minutes or measure the capacitor voltage to confirm it is near zero before touching any internal components. (Pages 9, 16)