Why North Carolina gets caught out
The state does not get sustained deep cold, so plumbing is often run through crawlspaces, unheated garages and exterior walls in ways that would never survive further north.
Then a hard freeze arrives for three days and the calls start. The damage is rarely from the freeze itself - it is from the split that appears when the ice thaws and pressure returns.
What actually works
Insulate the runs that are exposed: crawlspace lines, garage walls, anything against an exterior wall. Foam sleeve is inexpensive and effective.
Close crawlspace vents before a freeze and open them again afterwards.
Disconnect hose bibs. A hose left attached traps water in the bib and splits it.
Open cabinet doors under sinks on exterior walls so household heat reaches the pipes.
Let one faucet drip on the far end of the run. Moving water is much harder to freeze, and a dripping tap also relieves the pressure that actually causes bursts.
What does not work
Leaving the heat off while away to save money. Set it no lower than 55F.
Space heaters aimed at pipes unattended. This causes fires.
Open flames to thaw a frozen line - the most common cause of house fires during cold snaps.
If a pipe freezes anyway
Open the faucet the line feeds so melting water has somewhere to go. Apply gentle warmth with a hair dryer, working from the faucet back toward the frozen section.
Stay near the main shutoff. Most splits become obvious the moment the ice releases.