What I'm Seeing Now

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The Old Knob And Tube Wiring

That's right - every now and then I run into the old knob and tube wiring.

The key word in that sentence is OLD.

Generally speaking, this older wiring system was used residentially in the United States from the 1880s to the 1930s.  I have found reports of it being used residential construction in some areas as late as 1950.  But that would be more on the unusual side probably.

When inspecting this house built in 1870 I found it everywhere, and still active, from the cellar to the attic.

Probably when the house was built there was no indoor electricity.

So, technically speaking, the listing for this house could have truthfully  said that the electrical system had been "upgraded."

I say that tongue in cheek because while it may have been an upgrade at some point, today it is considered clearly outside of modern electrical practices, very obsolete, and most insurance companies, if not all, consider it to be dangerous.  Many will not cover it, or a house where it is found.

I have had clients who purchased a house built in 1995 call me because their insurance application asked if the house had knob and tube wiring!  And they did not know.

The photo above shows that the knob and tube wiring in that house was still active and live.  It is still used, as I said, from top to bottom.

One problem I find in every house where it exists is that it is often tapped into and used to wire up new things!

Here, for example, the doorbell transformer is connected to it.

One problem with knob and tube wiring is that there is no conductor for modern grounding.

You can clearly see here how the ground wire that comes with the newer doorbell transformer has nothing to connect to!

My recommendation:  this is a clear example of why a home inspection should happen with every home.  And especially older homes!  Home inspectors have knowledge and tools to be able to show their clients the condition of the house being inspected, and what it contains.  When an odd circumstance exists, the home inspector will point it out! 

 

 

Jay Markanich Real Estate Inspections, LLC  

Based in Bristow, serving all of Northern Virginia.

Office (703) 330-6388   Cell (703) 585-7560

www.jaymarinspect.com


Comment balloon 24 commentsJay Markanich • February 19 2016 02:51AM

Comments

All - I just checked back on this post only to find that half of it had disappeared!  If you read it and did not see all three photos, or my recommendation, please read it again!  Hopefully this time it will stay around.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 2 years ago

I have had that happen too Jay Markanich and for many days in a row...and now the cybermonster seems to have disappeared...sigh. Maybe the site has been "rewired."

Posted by Sally K. & David L. Hanson, WI Realtors - Luxury - Divorce (EXP Realty 414-525-0563) over 2 years ago

Good morning Jay Markanich . Lordy, how many times have I seen that in some of the older properties in East Nashville. Oye Veh!!!

Posted by TeamCHI - Complete Home Inspections, Inc., Home Inspectons - Nashville, TN area - 615.661.029 (Complete Home Inspections, Inc.) over 2 years ago

Good morning Jay. Knob and tube is not unusual in this part of the country and in older homes everywhere. It was once in my home but no more. Good post.

Posted by Sheila Anderson, The Real Estate Whisperer Who Listens 732-715-1133 (Referral Group Incorporated) over 2 years ago

This type of wiring does still show up in home inspections - which is another reason home inspections are so necessary.

Posted by Kat Palmiotti, The House Kat (Grand Lux Realty, 914-419-0270, kat@thehousekat.com) over 2 years ago

Jay Markanich Seeing this wiring takes me back many years when I first started in this business back in 1880.

Posted by Sandy Padula and Norm Padula, JD, GRI, Presence, Persistence & Perseverance (Realty National) over 2 years ago

It's frustrating S&D.  Especially when it's a longer post and it has to be recreated.  I had taken to saving the post before loading it up and then checking back.  Today I forgot to do that!

I see it often, too, Michael.  It was time for a new post about it!

Sheila - what?  You upgraded!?  Can't imagine why...

Kat - for sure.  One of a zillion reasons...  At this house the insurance company wanted it replaced before coverage.

S&N - wow!  We should have met then - about the same time I started in business as well!

 

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 2 years ago

Good morning Jay,

Will be doing an inspection Saturday with a home here built in 1890. I will see if I can remeber to take pictures of the wiring as it looks like it is intact throughout the home but not working.

Make yourself an astonishing day.

Posted by Raymond E. Camp, Licensed Real Estate Salesperson Greater Rochester (Howard Hanna Real Estate Services) over 2 years ago

Good morning Jay. The only place I have seen this is in old photographs! Enjoy your day!

Posted by Wayne Martin, Real Estate Broker (Wayne M Martin) over 2 years ago

Raymond - here is another photo of what it looks like.  That is from this house also.

Wayne - and here is a new photograph!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 2 years ago

I have been copying all my posts before I try to publish them, I have had the same problem, it's frustrating!

Oh, nice Knob & Tube! 

Posted by Fred Hernden, CMI, Albuquerque area Master Inspector (Superior Home Inspections - Greater Albuquerque Area) over 2 years ago

You'd think glitches like this would be taken care of immediately, but I guess not.  Thanks, Fred.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 2 years ago

Jay, I run into my share of the old knob and tube also. Still quite a bit of it out there.

Posted by Donald Hester, NCW Home Inspections, LLC (NCW Home Inspections, LLC) over 2 years ago

And that's absolutely amazing to me, Don.   Maybe Joe Bonamassa could do a blues song about it.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 2 years ago

I remodeled a home back in 2003 that still had live knob and tubing.  There was evidence of a fire in the attic from the old wiring.  This job required a complete gutting of the house: new insulation, wiring, plumbing and drywall.  It was a big job, but rewarding.

 

Posted by Stephen Weakley (Nationwide Mortgage Services) over 2 years ago

Those kinds of houses are labors of love, Stephen.  They aren't homes - they are projects!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 2 years ago

Hi Jay - We do a fair amount of OLD houses and have seen this regularly over the years - the fix isn't easy or cheap, but almost always something the seller has to address if he wants a sale.

Posted by Dick Greenberg, Northern Colorado Residential Real Estate (New Paradigm Partners LLC) over 2 years ago

Dick - this seller thinks he is selling an historic house with "charm."  He wants top dollar.  I don't think he's going to get it.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 2 years ago

Hi Jay, thanks for another informative blog article on areas of a home with deferred maintenance/repair.

Be careful with the tem "not grounded". 

"One problem with knob and tube wiring is that it is not a grounded system."

Knob & Tube is a two conductor branch circuit with one ungrounded conductor ('hot' wire). and one grounded conductor ('neutral' wire).

Knob & Tube wiring is absent of an equipment ground conductor.  Current/modern "Romex(R)" brand wiring includes an additional equipment ground conductor to provide an equipment ground current path.

As you emphasize the characteristic of "old" its important to recognize the additional safety risk of a failed neutral conductor with knob & tube wiring compared to the failure of a neutral conductor with a more modern Romex(R) cable (which includes an equipment ground conductor).

In addition to the AC voltage sensor that you show in your blog photo, I have also adopted the use of a clamp meter to further investigate the potential for active knob & tube wiring.  I have observed "renovations" where only the neutral wire of the knob & tube is active.  You can imagine the controversy when seller believes that all the knob & tube is inactive and I demonstrate current on the knob & tube wiring when lights/appliances are active.

You write very well and your photos are fantastic.  I always enjoy reading your posts when I have some "spare time'.

Posted by Jim Mushinsky (Centsable Inspection) over 2 years ago

Thanks Jim.  Clunky wording corrected.  My client wants to buy this home intending to make it "new" insofar as possible.  Certainly the electrical will need a complete redo.  They didn't know there was knob and tube, and certainly that it was still being used!  This house was a mish mash of old and new.  And dangerous in my opinion.  But that's why they wanted an inspection!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 2 years ago

Maybe the doorbell will get "grounded" when the home burns to the ground Jay Markanich 

Posted by DEANNA EARLY - ( NMLS #268590 ), Virginia Mortgage Loan Originator (American National Bank and Trust) over 2 years ago

Bada boom, Deanna!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 2 years ago

Knob and tube wiring is a main stay in my area the arverage home I inspect is suspect of knob and tube, thanks for the blog. 

Posted by Fred Sweezer Sr., Certified Home Inspector (Hud Certified 203K Consultant) over 2 years ago

Wow, Fred!  That's an amazing thought!  I have never seen more than an old home here or there, and few and far between.  This house was way out in the boonies, surrounded by a lot of property.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 2 years ago

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