The incoming electrical power must provide the proper voltage and be equipped to handle a minimum amperage. These values are determined by the boiler manufacturer.
Problems occur when the voltage is too high or too low, which can result in damage or destruction of the electrical components of the boiler. Voltage fluctuations can create instability and ultimately the failure of these same components. Modern boilers are especially vulnerable to these problems, as they utilize delicate internal circuitry when compared with boilers of yesteryear.