The Scottish Fire and Rescue Service (SFRS) said in some cases fixed equipment needed to get water to firefighters tackling a blaze had been vandalised.
It issued the warning as it hosted a major summit on how to tackle the threat to public safety and the economy. British Transport Police (BTP), Police Scotland, utilities providers and Scottish Government representatives also attended the summit in Cambuslang, South Lanarkshire.
SFRS assistant chief officer Lewis Ramsay said: "Anyone engaged in metal theft is risking lives. These are not victimless crimes and we are working closely with police and others to protect our communities.
"Thieves' interference with power infrastructure has caused surges of electricity resulting in fires breaking out and flames and toxic smoke taking hold within homes. We have also seen cases where high-rise buildings have been left at severe risk due to thieves vandalising fixed equipment needed to get water to firefighters tackling a blaze.
"It isn't hard to imagine the terrible consequences of a fire within a block where there is significant delay getting water to our crews.
"Those involved in metal theft must know their actions put the public at risk, as well as the firefighters and our fellow emergency responders who are called to emergencies."
In November, fires broke out in four homes in Greenock, Inverclyde, after thieves stole copper wire from an electricity substation, leaving 280 homes without power. A family-of-four, including two young children, had to flee their home and the father was treated for smoke inhalation.
Justice Secretary Kenny MacAskill, who attended the summit, said: "Along with proposals for tougher legislation, more effective enforcement has been introduced including the British Transport Police team dedicated to tackling metal theft."
BTP chief superintendent Ellie Bird said: "These crimes not only cause immense inconvenience and upset to the public, they can also put them in real danger."