Installing heat tape on water pipes to prevent freezing isn't needed on most properly constructed homes. Construction methods are used that in the area are good enough to prevent pipes from freezing. Water supply lines are buried below frost lines and are run into the home and throughout the home where they typically will not freeze. However, there are many homes where the water supply is exposed to the elements such as mobile homes, pier and beam homes, and homes with crawl spaces where the temperature may drop low enough to freeze pipes. Insulating pipes can help by slowing the rate at which the pipes cool thereby slowing down the freezing process but when the temperatures take a deep dive the protection offered by insulation just isn't enough. In addition there are many homes in warmer areas of this country where freezing temperatures are very unusual and only happen every 20 years of so like the extreme southern row of states and down into the Florida peninsula. When an artic blast descends down through the south and Florida it can be a catastrophic event! The homes in those areas are constructed with very little or, no consideration of being exposed to freezing temperatures. In fact it is not unusual to see a water line come out of the ground and run up the outside of a home going through the side of the home into an attic where it gets distributed.
Fortunately there is an answer to prevent frozen pipes, installing heat tape on water pipes will prevent freezing. The pipe must be in the open and not surrounded by combustibles or, heat tape cannot be used. Heat tapes plug into a 120-vac outlet or extension cord generating heat by resistance to keep the pipes warm and prevent freezing and are sold in fixed lengths. Most have a thermostat on them so they only turn on as temperatures drop close to freezing. For most heat tapes they are wrapped around the pipe a specified number of turns per foot and secured in place then fiberglass pipe insulation is applied over the wrapped pipe. The heat tape cannot overlap or it may burn itself out. The heat tape is plugged in and when the temperatures drop close to freezing the thermostat turns on the heat tape and a small amount of electricity runs through the wires warming the pipes enough that they do not freeze.
There is another type of heat tape that I prefer, called Frostex. This is a unique product that does not use a thermostat to control the heating but instead uses a special polymer that changes its resistance as the temperature changes. The lower the temperature, the higher the amount of heat, the Frostex cable produces to prevent a freeze up. In addition the Frostex cable is not wrapped around the pipe but runs straight down the length of the pipe greatly reducing the installation time. That is not the only convenience Frostex offers. Frostex because it is self regulating can overlap and will not burn out, and can be cut to any length you desire so there is no running short or having extra to contend with. When you buy Frostex all you have to do is know how long the pipe is that you are installing the Frostex heat tape on and figure out how many time you have to run the cable down the pipe based on its diameter and buy the length you need. You also need to buy the Frostex #9800 flex plug kit that has a power plug that you install on one end and a gel filled cap that goes on the other end. The only tools you will need to install Frostex are a #2 phillips screwdriver, wire cutters, and electrical tape and whatever you need for installing the fiberglass wrap over the pipe and heat tape. Installing heat tape and insulation on water pipes to prevent freezing is an excellent way to keep the water running when your home is not prepared for the cold.