Knob & Tube - All or nothing?


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Old 12-02-07, 04:12 PM
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Knob & Tube - All or nothing?

I am renovating a circa 1940's house and found a bunch of Knob and Tube wiring. My electrician has quoted me $3K to redo all wiring from the electrical panel to the receptacles but he says that there's no need to rewire the light fixtures b/c they don't pose a hazard with K+T. Is this true? Or is replacing K+T an all or nothing prospect? I am a bit new to all this, but I understood that a light switch was being powered by the nearest receptacle anyway so presumably if I pay to have all receptacles grounded then isn't the light fixture effectively grounded too? The panel itself has been updated and is 100amp service.

Anyone have advice?
 
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Old 12-02-07, 04:25 PM
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Is your electrician bringing the house up to the requirements of your city? Some city's around here when you update the panel you must also upgrade the house with 2 kitchen small appliance circuits, GFCI's in bathrooms and ground light fixtures near water sources. (kitchens and baths) Also minimum spacing for outlets per square foot of a room (I think is was one outlet per 70 sq ft) and smoke detectors. Be sure to check what all is included before they start the job to avoid any surprises. 3K seams pretty fair to me.

As far as your light fixtures go, they will only be grounded if there is a ground wire from the switch to the light (or vice versa) K & T has no ground therefore a new cable or wire would need to be installed to ground the fixture


.
 
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Old 12-02-07, 07:04 PM
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No, this will not ground the lighting fixtures. But since the lighting fixtures are typically not within reach, it's not as important.

Be sure to talk with your insurance agent before you proceed. Some insurance companies will refuse to insure homes with K&T. Others will simply charge you a premium. If you remove part but not all of the K&T, you'll want to ask your insurance agent what this does to your coverage and rates.

You might also want to get a quote from your electrician for replacing it all. And make sure you understand how many holes will be cut in the wall and who will be responsible for patching them.

Make sure a permit will be pulled and inspections will be done.
 
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Old 12-02-07, 07:42 PM
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Some K&T is often left for the less accessible location such as ceiling fixtures, etc. Since they are generally low wattage (2 or 3 60w lamps), it's less of an issue. But on the other hand, if you're doing all the work to pull out most of the K&T, I'd seriously consider doing it all. That way you know the house is up to date and you don't have to worry about it in the future. Also now is a good time to possibly add recessed lights if you want any, reconfigure other fixtures, etc.

If you are planning on selling your house anytime soon, having replaced all the K&T will be a good feature. (one less thing for the next inspector to highlight as a problem).

Good luck!
 
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Old 12-02-07, 10:10 PM
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And many newer light fixtures require wire with a higher temperature rating then K&T so you will be some what limited on choice of new fixtures.
 
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Old 12-03-07, 07:54 AM
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Just to point out, if you have those 90c fixtures already installed and don't end up replacing ALL the K&T, installing CFL's can significantly reduce heat (and the "baking" of the wires in the fixture). Also to consider is the design of the fixture.

This is not to say you should INSTALL 90c fixtures on 60c wire, as CFL's or no CFL's, it's not appropriately listed in most, if not all, cases (except for 60c specific fixtures, which can be hard to find).

But if you have them in place, or want to be on the safe side with 60c fixtures, using CFL's is a GREAT idea. And they'll lower your electric bill too!
 
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Old 12-03-07, 09:02 AM
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I once pulled a CFL from a sealed (weather proof) fixture that had significant indication of possible heat damage to the base of the bulb. The base had turned from white to brown. That makes me not so confident in the heat lowering ability of CFL though probably it was just the wrong type of CFL for the fixture.
 
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Old 12-03-07, 09:04 AM
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Ray,

When a CFL eventually burns out the base sometimes turns brown and sometimes even the bulb smells like it is burning. This is normal of CFLs and is nothing to get all concerned about.
 
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Old 12-03-07, 10:38 AM
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Originally Posted by racraft
Ray,

When a CFL eventually burns out the base sometimes turns brown and sometimes even the bulb smells like it is burning. This is normal of CFLs and is nothing to get all concerned about.
Thanks for the info. Sometimes us old timers who learned way back when electric was made by squirrels running on exercise wheels need a bit of info on these new fangeled devices. (-:
 
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Old 01-18-08, 11:49 AM
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I just updated my insurance-issue survey, in my area (Chicago), as best I can tell knob and tube wiring is now getting flagged for additional scrutiny by *all* major home owner's insurance companies. I'm also seeing more concern about fuse based panels, even if 100A service:

http://www.paragoninspects.com/visua...-problems.html
 
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Old 01-18-08, 12:02 PM
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Another big concern with leaving K&T in place is that you cannot cover it with any type of insulation. So if you plan on adding cellulose or fiberglass to your attic to meet energy efficiency standards, all of the K&T up there must be replaced.
 
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Old 01-18-08, 02:47 PM
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Originally Posted by Michael Thomas
I just updated my insurance-issue survey, in my area (Chicago), as best I can tell knob and tube wiring is now getting flagged for additional scrutiny by *all* major home owner's insurance companies. I'm also seeing more concern about fuse based panels, even if 100A service:

http://www.paragoninspects.com/visua...-problems.html
Dear Lord, please tell me you didn't make that web page.
 
 

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