PAGE 10, Standards for the administration of ECT (UK)
http://www.rcpsych.ac.uk/PDF/The%20ECTAS%20Standards%20Dec%2006.pdf
"...The ECT nurse ensures that the machine function and maintenance is checked and recorded at least every year or according to machine guidance..."
Your local electrical maintenance psychiatric nurse might have a bit of a problem though if your machine has no serial number, no documentation, no manufacturer's information, no wiring instructions and no means of callibrating/testing its accuracy or faults.