New Conductivity Concept

By
Home Inspector with JRV Home Inspection Services, LLC HOI 394

An electric panel. Nothing appears amiss. As elementary school children we learn in science class the basic electrical principals of conductors and insulators. The strands of wire used in class show this concept in practice. The copper wire conductor is wrapped in a plastic insulator. The same is found in our homes, conductive wires wrapped in an insulating material of either cloth or plastic. 

As adults we understand this fundamental electrical law. We know that sticking a fork into an outlet will give us a electrified wallop we won't soon forget.

If that fork is metal. A plastic fork will yield not the tiniest slap.

Another fundamental, but confusing and in my experience not well understood electrical principal is grounding. 

Types of electrical grounding

Grounding is mostly thought of as a safety component of an electrical system. Most people I meet while inspecting homes believe that an electrical ground will prevent them from being "zapped". The fact is grounding will minimize the voltage to a sting, not eliminate it. Put simply, this is because electricity takes all paths. A solid and properly sized ground connection provides the path of least resistance for errant voltage. Meaning it dissipates a good deal of any wayward current within the system. Additionally grounding stabilizes line to ground voltage and limits voltage during abnormal surges such as lightning or accidental contact with higher voltage lines.

For the home inspector, checking the electrical grounding is a basic part of inspecting the electric system of the dwelling. One of the most common ground connections is made to the water supply pipe on public water systems. The copper pipe makes an ideal ground connection point. Other common means of system grounding are metal rods driven into the earth. The rods can be outside or inside the house. Another type of residential system ground is the Ufer. A Ufer is a metal rod, often the rebar encased in the concrete of the foundation.

While inspecting the electrical system of a relatively new (about 20 years) condominium recently, I found a curious ground connection. The ground wiring appears to be the original connection made when the system was installed. I followed the single wire from the panel box to locate the connection point in order to confirm that a good connection exists. I found the wire clamped to a copper water pipe up in the floor joists near the panel. 

Ground connection to water pipe

Because I usually check the electric panel last, I knew this connection was a problem. The issue wasn't with the clamp or the wire, it was with the pipe itself. 

As I had mentioned earlier, on publicly connected water systems, the main water pipe is often used as a ground connection. You will not see a system ground connection on a house with well water. The reason being the pipe coming from the well is plastic. What is becoming more and more common in modern construction is the use of plastic water pipes. Not just inside, but also outside to bring the water into the house. Plastic main water supply pipe

Thie water supply for this house is brought in by a plastic pipe. 

Unless this plastic pipe possesses an until now unknown conductivity, the electrical system in this house is not, nor likely has ever been grounded. 

 

 

Posted by

James Quarello
Connecticut Home Inspector
Former SNEC-ASHI President
JRV Home Inspection Services, LLC

 ASHI Certified Inspector

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Rainmaker
1,945,792
Andrew Mooers | 207.532.6573
MOOERS REALTY - Houlton, ME
Northern Maine Real Estate-Aroostook County Broker

Shocking, electrifying post on juice, power, current!

Feb 09, 2013 08:54 PM #1
Rainmaker
1,846,965
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

Specifics, specifics.

Actually, as you know, we see this a lot, particularly houses or condos built in the last 30 years.

If an Ufer rod is not found inside or outside, likely there is no grounding!

Feb 09, 2013 09:03 PM #2
Rainmaker
657,615
Pat & Wayne Harriman
Harriman Real Estate, LLC (203) 672-4499 - Wallingford, CT
Broker/Owners, Wallingford CT Real Estate

Very informative post, Jimmy. Well grounded in logic and fact. It's always good to keep up with what's current in the field of electricity. You always conduct yourself well and make a firm connection to your readers. When it comes to learning new things, you'll get no resistance from me! (OK, I'm done now...)

Feb 09, 2013 09:04 PM #3
Rainmaker
686,984
James Quarello
JRV Home Inspection Services, LLC - Wallingford, CT
Connecticut Home Inspector

Andrew, Thanks.

Jay, I see ungrounded, miswired electrical systems in many condos.

Wayne, Thanks. Punny :)

Feb 09, 2013 09:23 PM #4
Rainmaker
449,880
Scott Seaton Jr. Bourbonnais Kankakee IL Home Inspector
SLS Home Inspections-Bradley Bourbonnais Kankakee Manteno - Bourbonnais, IL
The Home Inspector With a Heart!

Grounding, shmounding. I can hear the electrician now. "I've been doing it that way for 30 years. You sure are a nitpicker." Yep, I guess I am. 

Feb 09, 2013 09:26 PM #5
Rainmaker
1,765,671
Tom Arstingstall, General Contractor, Dry Rot, Water Damage Sacramento, El Dorado County - (916) 765-5366
Dry Rot and Water Damage www.tromlerconstruction.com Mobile - 916-765-5366 - Placerville, CA
General Contractor, Dry Rot and Water Damage

Thanks for the detailed grounding topic. Too often, those that are strapping a grounding wire have not followed the pipe all the way to the ground, or even thought about where is goes.

Thanks for the Featured post James.

Feb 09, 2013 10:29 PM #6
Rainmaker
592,740
Than Maynard
Coldwell Banker Heart of Oklahoma - Purcell, OK
Broker - Licensed to List & Sell - 405-990-8862

Heh, grounding to a plastic pipe. Seems like a good idea to me, but then I'm not a licensed electrician....oh, wait, that should have been or was done by a licensed electrician.

Feb 09, 2013 10:42 PM #7
Rainmaker
490,619
Donald Hester
NCW Home Inspections, LLC - Wenatchee, WA
NCW Home Inspections, LLC

Jim, Ooops!!!! That is why the old "UFER" is the way to go. This maybe one of the most overlooked parts of the electrical system.

Feb 10, 2013 12:10 AM #8
Rainer
171,130
Robert Butler
Aspect Inspection - Montreal West Island, QC
Montreal Home Inspector | Aspect Inspection

We always look for electrical grounding clamps at the water pipe entry. Anywhere else is iffy.

Feb 10, 2013 12:12 AM #9
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Fernando Herboso - Broker for Maxus Realty Group
Maxus Realty Group - Broker 301-246-0001 - Gaithersburg, MD
301-246-0001 Serving Maryland, DC and Northern VA
I guess that's a easy fix by installing a few grounding rods?..
Feb 10, 2013 02:53 AM #10
Rainer
284,418
Steven Cook
No Longer Processing Mortgages. - Tacoma, WA

James -- hmmm, that is an interesting approach to things.  When I put up my television antenna I put a ground rod down for it, separate from the one for the electrical system.

Feb 10, 2013 03:26 PM #11
Rainer
408,223
Jeremy Wrenn
Winslow Homes - Youngsville, NC
C.O.O., Winslow Homes

James, I did see the word Ufer in your post.  So you were on the same wavelength as Donald and Jay!

I've never heard that word before last week, and now I've read it in 3 blogs in 3 days!

Feb 10, 2013 08:33 PM #12
Rainmaker
686,984
James Quarello
JRV Home Inspection Services, LLC - Wallingford, CT
Connecticut Home Inspector

Scott, Hard to imagine any electrician arguing over this "grounding" of the system.

Tom, That does seem to be the casr in this house. It makes me wonder about the others in the complex. 

Than, Yep, I believe it was. A real head scratcher for sure.

Don, The Ufer is a superior grounding system, however we have millions of existing houses with the other types of grounds. 

Robert, The water pipe ground has really fallen out of favor for the Ufer or ground rods. 

Fernando, Yep, that should do the trick.

Steven, TV antennae? I hope you mean satellite dish my friend :)

Jeremy,  Weird how we all get on the same wave length. It's happened several times in the past. 

Feb 10, 2013 08:52 PM #13
Rainmaker
840,674
David Popoff
DMK Real Estate - Darien, CT
Realtor®,SRS, Green ~ Fairfield County, Ct

A very detailed and informative post to be shared with all homeowners, thanks James.

Feb 10, 2013 10:10 PM #14
Rainer
408,223
Jeremy Wrenn
Winslow Homes - Youngsville, NC
C.O.O., Winslow Homes

James, it is pretty interesting how you guys seem to get on the same "current" topic.  Yes, pun intended.

Feb 10, 2013 10:37 PM #15
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Charles Buell
Charles Buell Inspections Inc. - Seattle, WA
Seattle Home Inspector

Jim, at 20 years old I would be willing to bet that the receptacles still tested as "grounded."  That is because the whole system is required to be grounded both at the house service and then it is also protected again back at the transformer.  Therefore the wire back to the transformer will be acting as the only ground for the system.  Redundancy is a good thing with grounding:)

Feb 11, 2013 12:01 AM #16
Rainmaker
686,984
James Quarello
JRV Home Inspection Services, LLC - Wallingford, CT
Connecticut Home Inspector

David, Thanks. 

Jeremy, It is, like were wired together.

Charlie, They did. And yes the neutral/ground is as you say grounded. In this instance it appearred there was a ground at the meters (condo). The ground inside the house might actually be referred to as bonding for the water pipes. Still not right. 

Feb 11, 2013 01:22 AM #17
Rainer
408,223
Jeremy Wrenn
Winslow Homes - Youngsville, NC
C.O.O., Winslow Homes

Indeed! 

And I think we could be grounded in electric puns for quite a while, if we so choose.

Feb 11, 2013 01:37 AM #18
Rainmaker
220,844
Jim Mushinsky
Centsable Inspection - Framingham, MA

Electrical grounding is an interesting topic.

Especially when meeting people from countries that distribute electricity in a "Wye" configuration instead of the "Delta" configuration in the USA.  

Comment #16 from Charles and Comment #17 from James are of interest to me.  Circuits and Nodes are two significant terms with respect to electricity.   What is the purpose of an electrical ground?  Is it really good to have "redundancy" with grounding (Charles #16) ?   Ground loops may be dangerous.   When there are two (or more) ground points (or nodes) it may be possible for a voltage potential between the two nodes.  A voltage potential is a risk of shock.  "Redundancy" as in a stranded wire is OK with me.  "Redundancy" as in multiple ground circuits is NOT OK with me.

Bonding of the copper water pipes (James #17) being referred to as "not right" does not read well to me.  It is important to bond copper water pipes to the electrical ground of the dwelling.  A common area of concern is the absence of a bond wire across a water meter or other device (water filter).

Consider the home (dwelling) as a node with respect to the electrical circuits within the home.  I want the exposed conductors in my home (metal) all bonded to the electrical ground of the home (dwelling).  When the insulation around the electrical wire deteriorates, and makes contact with another conductor, I prefer the fuse or circuit breaker to open circuit and reduce my risk of shock or worse.

Of course a blog is not a substitute for the many years of training required to be an electrician or home inspector.  Electricity is dangerous.  Partial information is also dangerous. 

Would you be concerned if there were 0.5 amps, 5 amps, or 50 amps of current passing through your ground wire?

 

Feb 12, 2013 02:12 AM #19
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Charles Buell
Charles Buell Inspections Inc. - Seattle, WA
Seattle Home Inspector

@jim, redundancy is the connection of multiple GEC's to the same system EGS---everything in the grounding system needs to be at same potential.  For example connecting the phone system ground wire to an underground water pipe coming to the house that is not connected to the EGS is bad, wrong and dangerous.

Feb 12, 2013 04:18 AM #20
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