The only way to resolve the problem is to contact a professional electrician to diagnose and repair the problem. Often, it results from a variety of factors including overloaded circuits, poor wiring, or external disruptions. For most residential circuits, the standard is 120 volts (V), with a larger 240V supply for major appliances like ovens and clothes. Here are seven possible reasons why you may have low voltage in your house. These issues can be caused. The causes of low voltage in a house are usually linked to increased electrical resistance, neutral path degradation, long circuit runs, undersized wiring, or load imbalance rather than a weak electricity supply.