Originally Posted By: mwright1 This post was automatically imported from our archived forum.
Ok…I’ve got to ask because I keep hearing conflicting stories. I inspected a house that had knob and tube wiring in addition to new modern wiring. Two bedrooms had Knob and tube outlets and light switches, in addition to current 110 outlets. Is this ok? I was under the impression that once you updated the wiring, all knob and tube wiring had to be replaced. Help!
Originally Posted By: pdacey This post was automatically imported from our archived forum.
The problem with active knob and tube is the unknown:
The integrity of the wire sheathing
Have the wires fallen off of the knobs
Are the wires in contact with any combustibles
Are the splices between the old and new system done correctly
etc...
Most (if not all) insurance companies will not cover a home with known active knob and tube. Too much potential for a problem.
Originally Posted By: lkage This post was automatically imported from our archived forum.
pdacey wrote:
The problem with active knob and tube is the unknown:
The integrity of the wire sheathing
Have the wires fallen off of the knobs
Are the wires in contact with any combustibles
Are the splices between the old and new system done correctly
etc...
Add to above: insulation encasing knob and tube wires.
It presents an overheating problem because they're designed to be air cooled.
-- "I have never met a man so ignorant that I couldn't learn something from him."
Galileo Galilei
Originally Posted By: mwright1 This post was automatically imported from our archived forum.
Does any one know if this is against code? I wrote it up as a hazard, and should be fixed immediately. Later an eletrician came in and told the buyer that I was wrong, that it’s fine, as long as it’s spliced in a junction box.
Originally Posted By: syared This post was automatically imported from our archived forum.
Quote:
Most (if not all) insurance companies will not cover a home with known active knob and tube. Too much potential for a problem.
Never heard of any clients in this area having trouble getting insured. I live in a historic district, inspect many homes with K & T and have it in my own home, the insurability has never come up as an issue
-- Steve Yared
The Home Examiner, LLC
(616) 776-7725
Originally Posted By: lkage This post was automatically imported from our archived forum.
As long as it has been maintained properly, is in good condition, is not overloaded and is not buried in insulation I believe it can be considered safe even today.
Regarding encasing it in insulation:
"The concern over insulation of attics with this type of wiring arose with a recent change in the National Electrical Code (NEC). Prior to 1987, the NEC did not mention thermal insulation with knob-and- tube wiring at all. With the 1987 edition, however, NEC Section 324-4 was revised to say "Concealed knob-and-tube wiring shall not be used in... the hollow spaces of walls, ceilings and attics when such spaces are insulated by loose or rolled insulating material."
Originally Posted By: roconnor This post was automatically imported from our archived forum.
I would flag any K&T wiring as a “concern” (potential for deterioration and insurance issues in some areas), and red flag any of the issues Patrick and Larry noted as a “safety hazard”.
Note that there are provisions for repairs and extensions of K&T wiring in the current NEC, but it's pretty limited. Also insulating the spaces around the K&T wiring is a big issue, and would not comply with the current model electrical code under NEC 394.12.5 ... and therefore would be a "safety hazard" according to current standards in my book.
I think it is better to flag K&T wiring as either a "concern" or "safety hazard" that requires further evaluation and possible repair by a licensed electrician. If a qualified electrician checks things out, and puts it in writing that they have examined the installation and it's acceptable then your job and obligation to your client is done.
Just my opinion and 2-nickels ... 
-- Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee
I am absolutely amazed sometimes by how much thought goes into doing things wrong
Originally Posted By: jkormos This post was automatically imported from our archived forum.
I would write it up as potential for future upgrade and that they should budget for such an upgrade. With something like that with the demands of a modern appliances and so forth bla bla bla, and above all the safety concerns. But as long as it performing as intended, and no visible defects are noted then the system is viable, just my thoughts
Originally Posted By: lkage This post was automatically imported from our archived forum.
roconnor wrote:
I think it is better to flag K&T wiring as either a "concern" or "safety hazard" that requires further evaluation and possible repair by a licensed electrician. If a qualified electrician checks things out, and puts it in writing that they have examined the installation and it's acceptable then your job and obligation to your client is done.
Sounds like the best plan to me.
-- "I have never met a man so ignorant that I couldn't learn something from him."
Galileo Galilei
Originally Posted By: roconnor This post was automatically imported from our archived forum.
I also like Joseph’s suggestion of recommending that a client budget for future upgrade, as that could become a reality with a new family’s electrical demand on an old wiring system …
– Robert O’Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee
I am absolutely amazed sometimes by how much thought goes into doing things wrong
Originally Posted By: lkage This post was automatically imported from our archived forum.
roconnor wrote:
I also like Joseph's suggestion of recommending that a client budget for future upgrade, as that could become a reality with a new family's electrical demand on an old wiring system ... 
I agree.
I would also add it to the "deferred cost items"...items that have reached or are reaching their normal life expectancy or show indications that they may require repair or replacement anytime during the next five (5) years.
-- "I have never met a man so ignorant that I couldn't learn something from him."
Galileo Galilei
Originally Posted By: William Dorsey This post was automatically imported from our archived forum.
The NEC still permits existing knob and tube wiring properly installed and in good working condition to coexist with new wiring. However you cannot use old knob and tube runs to feed new wiring.
I have seen some pretty bad amateur additions to knob and tube wiring especially in accessible areas like basements and attics. It always made me wonder what else was hidden away out of sight and mind. In my opinion one of the worst problems with knob and tube wiring other than amateur additions and repairs is the effects over time of being exposed to excessive heat. So many older homes in the colder parts of the united states had insulation blown in over the past 30 years. The old knob and tube wiring in these homes has now been buried in insulation for years, which is essentially equivalent to being operated under overload conditions since it greatly hampers the wiring's ability to dissipate heat. The rubber and cloth jacketing of this buried wiring must all be greatly compromised.
