Knob and tube is the earliest electrical wiring, basically designed to power light bulbs between 1880 and 1930.
Its presence in houses has become an issue for many lenders and home insurers, and it causes delays in real estate transactions until large amounts of money are spent to replace it.
Donald Miller is the CEO of Donald Miller Electric Services in Havertown, Pa., which specializes in removing and replacing knob-and-tube wiring.
“The problem I am seeing is with the rewire,” Miller said. “Too many electricians are trying to rewire homes without proper safety measures.
“Most of the older homes are filled with lead, as well as other hazardous materials, locked into the plaster walls,” he said.
His company has been certified to deal with lead paint hazards, “and it scares me the bids we lose due to hazardous rewire techniques,” he said.
The lack of education about knob-and-tube wiring concerns Realtor John Duffy.
“Two recent inspections by approved inspectors stated there was knob-and-tube wiring,” he said.
One buyer requested $32,000 for rewiring the house, he said, but because both houses were built after World War II “it signaled some doubt” that it really was knob and tube.
After licensed electricians inspected the properties, “it turns out both were Romex (a later generation of wiring) wrapped in cloth,” he said.
A licensed electrician can tell the difference.