Overvoltage potential difference is easy but there are many kinds of them internal, external, and immediate. When the internal is focused on household security, external you need to protect but in a short of time because electric city provider is good but possible damages from immediate and current are protected by equipment and stabilizer. Heat is monitored but it required multiple sources of input since there is a possibility over the area and compare of working area and comfort area required not because of high temperatures but determine comfort equipments.