Knob and Tube removal with help of a thermographic camera

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sully1975

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Have a prospective job and it is a 3100 sq ft house possibly half or more knob and tubed. Would a thermographic camera on the low end be worth investing in? Plaster and lathe of course and newer stuff for a small addition tied in to the old K&T.
 
sully1975 said:
Have a prospective job and it is a 3100 sq ft house possibly half or more knob and tubed. Would a thermographic camera on the low end be worth investing in? Plaster and lathe of course and newer stuff for a small addition tied in to the old K&T.
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Only if you have a safe and controlled way to overload selected wires so that they warm up enough to be detected by the camera.
Normal use currents may well not get the wires warm enough to detect, since they are in free air.
Even then detection through lath and plaster would be unreliable at best, and would require a fairly long heat soak to show any results.
 
hbiss said:
Why do you need to know where the old wiring is? Just forget about it and rewire.

-Hal
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Good point!

It is not as if knowing the location of the wire will be particularly useful in figuring a path for the new wiring, as the holes drilled in the framing for the ceramic tubes will probably not be large enough to be useful and the star/whatever configuration of the K&T will probably not be useful information either.
 
GoldDigger said:
Good point!

It is not as if knowing the location of the wire will be particularly useful in figuring a path for the new wiring, as the holes drilled in the framing for the ceramic tubes will probably not be large enough to be useful and the star/whatever configuration of the K&T will probably not be useful information either.
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Yeah, its better to just drill new holes and forget trying to reuse the old routes- the money spent on one of these gizmos would be put to better use getting some good bits for that drilling.

To the op: If you want to remove the old wiring- you can simply cut what you can loose and leave the unreachable in place.

And no, there is no NEC requirement that old vestiges of K&T wiring be removed.:)
 
sully1975 said:
It was more of a see where it is and where it is running to and connected with. At least that was the idea, instead of smashing holes everywhere.
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Why do you need to know that? Just wire the house like it was new construction. The old wiring may not make any sense especially if there are additions. Just start with a fresh design. Here's a hint: the receptacles and switches and fixture boxes and panel are going to be the end points for the wire.:)
 
sully1975 said:
It was more of a see where it is and where it is running to and connected with. At least that was the idea, instead of smashing holes everywhere.
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You are likely abandoning in place anything that is concealed anyway so why does it matter to know where it is?
 
sully1975 said:
It is a doctor's office and house under agreement of sale with the people still living in it and a practice going on. The last time and first time I did a K&T it was a disaster.
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I have rewired a house with people living in it. Didn't care for it.

I nomally try to get them to gut as much of the house as possible to cut electrical installation cost. That plus what they can save by installing proper insulation in the outside wall makes much more sense. Those old houses with plaster and lath don't have any insulation at all hear in the South. You all find quite a bit of damaged framming that's occured over the years ( wood rot, termites ).
 
growler said:
I have rewired a house with people living in it. Didn't care for it.

I nomally try to get them to gut as much of the house as possible to cut electrical installation cost. That plus what they can save by installing proper insulation in the outside wall makes much more sense. Those old houses with plaster and lath don't have any insulation at all hear in the South. You all find quite a bit of damaged framming that's occured over the years ( wood rot, termites ).
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Here in CA, it is much tougher to disturb existing knob and tube work. If you're planning surgical procedure to gain access to this type of wiring, it would be tough to do upgrades. These houses or institutional structures were built in the twenties right on to the early forties.

Plaster finishes over wood slats are mixed with asbestos aggregate that pose health hazard to both workers and occupants.

Structures with asbestos material can not be disturb. In my city, there was small school house that was abandoned and the owner couldn't even get a permit to raze the structure. Realizing that it was expensive to demolish it, the owner donated it to the fire department and used as fire fighting practice for new hires. The firefighters set it on fire.

I wish I had documented it but cell phone cameras were not available 30 years ago.

And yes, as the other poster says, just forget K&T and start from scratch.
 
sully1975 said:
It is a doctor's office and house under agreement of sale with the people still living in it and a practice going on. The last time and first time I did a K&T it was a disaster.
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Be careful. A Doctor's office must comply with article 517 and that definitely means no romex. Even if the new owner is not going to have a doctor's office, if the practice is going on while the work is, I would either get clarification from the AHJ or stay away from it.
 
A GOOD toner, tic-tracer, or underground locator.

A GOOD toner, tic-tracer, or underground locator.

I thermal camera would only tell you the temperature of the entire plaster wall.

with a good "toner" or adjustable non-contact voltage indicator, you might be able to follow the condutors.

I have also used a underground locator to follow submergered wires.

Best bet is to abandon K+T and run new...
 
myspark said:
Here in CA, it is much tougher to disturb existing knob and tube work. If you're planning surgical procedure to gain access to this type of wiring, it would be tough to do upgrades. These houses or institutional structures were built in the twenties right on to the early forties.

Plaster finishes over wood slats are mixed with asbestos aggregate that pose health hazard to both workers and occupants.

Structures with asbestos material can not be disturb. In my city, there was small school house that was abandoned and the owner couldn't even get a permit to raze the structure. Realizing that it was expensive to demolish it, the owner donated it to the fire department and used as fire fighting practice for new hires. The firefighters set it on fire.

I wish I had documented it but cell phone cameras were not available 30 years ago.

And yes, as the other poster says, just forget K&T and start from scratch.
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Firefighters practice on old buildings around here as well, but owner still needs to remove asbestos and other hazardous materials if present before they will burn it down, so owner still is stuck with the expensive hazardous material removal bill.
 
Strathead said:
Be careful. A Doctor's office must comply with article 517 and that definitely means no romex. Even if the new owner is not going to have a doctor's office, if the practice is going on while the work is, I would either get clarification from the AHJ or stay away from it.
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Psychiatrist office technically now, that part was remodeled 20 years ago. It is conjoined to a house which is under agreement of sale. Old house, older wiring.
 
sully1975 said:
Psychiatrist office technically now, that part was remodeled 20 years ago. It is conjoined to a house which is under agreement of sale. Old house, older wiring.
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article 517 applies to psychiatrist offices. Read the definition of health care facility.
 
Strathead said:
article 517 applies to psychiatrist offices. Read the definition of health care facility.
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Which opens the door to art 517. Type of care being given could still make a difference. An office where there is just counseling and no "medical procedures" being performed I could still see that not being considered a patient care area at all. In fact have been in some offices where the office is the Doctor's personal office so to speak and they also counsel patients in this room. If they need to do even mildly invasive procedures to the patient, they possibly need to do so in an appropriately equipped exam room.
 
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