Your Place: A specialist discusses knob and tube wiring

I thought I'd finished with writing about knob and tube wiring - punch that phrase into the Philly.com search engine to read the articles - but readers raised a couple of good points this week, so I'll go one more time.

Knob and tube is the earliest of the electrical wiring, basically designed to power lightbulbs between 1880 and 1930.

Its presence in existing houses has become an issue for many lenders and home insurers, and it is serving to delay real estate transactions until after large amounts of money have been spent to replace the antiquated wiring.

Donald Miller is the CEO of Donald Miller Electric Services LLC in Havertown, which specializes in the removal and replacement of knob and tube wiring - which, when you consider the age of much of the Delaware County housing stock, must be a full-time job.

"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. "When the walls become home hazardous, debris is spread throughout the home."

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.

"Even worse, most electricians don't care about the plaster at all, so we are losing a piece of history," Miller said.

What he suggests is that a new home buyer test for lead before moving in, not just sign off on the fact that lead might be present.

The lack of education about knob and tube wiring concerns Main Line 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."

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.