Can Half of a Home be Grounded?

Specific Inspection Topics Electrical Inspections
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Hey guys, I wrote this in response to something I read earlier. It wasn’t actually a report, but I wanted to keep it simple.

What do you think?

As a home inspector, I have to constantly improve my understanding of the interdependent systems that make up a home. I invest a lot of time digesting articles, books, and other informative resources to ensure that the quality of my inspections is above par.

The electrical system is one of the harder systems for inspectors to understand. This was again evident as I read another inspector’s report. In the electrical section, it read: “Most of the home is not on a grounded system,” continued with, “Only the kitchen and the master bath had a grounded system,” and ended with “The home’s [electrical] system is not working properly.” The inspector was referring to the outlets not having the “ground” wires installed.

Let’s work backwards and get something out the way first. The electrical system does not need the “ground wires” to work properly. During normal operation with a properly functioning system, the “ground wires” do not carry any current. The proper term for what most people commonly describe as a “ground wire” is an equipment grounding conductor (EGC). EGCs bond non-current-carrying equipment, such as metal conduit, junction boxes, and outlet/switch boxes, to the service panel, and the neutrals and EGC’s within the panel. In the event that a “hot wire” comes into contact with equipment, the EGC will allow enough current to flow back to the panel and trip the breaker (or blow the fuse). If the EGC was not there and a person came in contact with the equipment, and was also in contact with the ground, s/he could complete the circuit and receive the flow.

Notice that the EGC is not connected to the ground at all. It is, however, bonded to the grounding electrode system, which brings us to my next point.

You generally cannot have half the home or only a few circuits on a grounded system. The grounding system is designed to protect your electrical system and home in the event of a lightning strike, line surge, or other electrical event. The neutral is grounded at the transformer and then again at your service panel. The grounding system creates a low-resistance path to the ground so that excessive voltage can dissipate away from the house. A structure has one ground system. The assertion that “most of the home is not on a grounded system” does not really make any sense.

Lastly, the correction for “ungrounded” three-prong receptacles is quite simple. The NEC allows these circuits to be upgraded with GFCI protection. In other words, a three-prong receptacle with an “open ground” that is GFCI-protected is acceptable, per the NEC.

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While permitted it does nothing to deal with equipment that requires a grounded outlet such as computers and equipment with metal exterior enclosures.

GFCI protection is not a substitute for a properly grounded receptacle.

GFCIs protects people from shock hazards but do nothing to deal equipment needs.

3

Lets assume the home was built with two wire Romex and had an unfinished basement . Time marches on and a new home owner want to finish the basement and uses the newer two wire with ground in basement .
You now could have main floor all ungrounded and finished basement with all circuits are a grounded system.
1/2 and 1/2

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Thanks. I’ve read many of the discussions here on the matter. I think It’s a big enough topic for its own blog post.

Maybe I’ll tackle it later, or leave it to you, Jeff, or Paul.

5

You are missing the point. Grounded is a misnomer.

One of my points is that you can’t have half of the home grounded, as the other inspector wrote.

Do you see anything in my post that is inaccurate?

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I think I understand the point…
Also…
Something being “grounded”, as applied to electrical installation, is commonly understood as having a groundING conductor present (If unsure why I capitalized the ING, Google the distinction between the a groundED and groundING conductor).
But further to your point, it would make more sense when calling ***branch circuits ***grounded, not the entire house.
The way I would word that is “Half of the house branch circuits do not have have a grounding conductor”

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The way I read it there was still confusion between the EGC and GEC.

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Can you elaborate?

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This can mean many different things since the person who wrote it doesn’t really understand the terminology or how the system is supposed to work. It could be as simple as someone (correctly) used self-grounding receptacles without a bonding jumper to a grounded metal box.

I would clarify that the neutral and EGC’s are connected by a main bonding jumper.

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Is everything else accurate?

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Although the principle of the statement above holds merit it is not completely correct. A higher voltage such as lightning is able to push current through earth easier than the 240 volts that supply our homes the earth is not a low impedance path for current to flow.

With our homes the total amount of voltage that could ever go to ground (earth) would be 120 volts. Should somehow both of the legs hit the grounding electrode at the same time this would equal a short circuit and the impedance would be the resistance of the conductors and the winding of the transformer which will be really low and the over current device opens.

At 120 volts with a resistance of 25 ohms (the requirement to allow only one rod) only 4.8 amps would flow and not enough to open the over current device. Should the primary of the transformer short (surge) or the primary supply break and hit the service drop at 7200 volts then there would be 288 amps that would flow through earth and be more than enough to open the over current device of the power company.

In the event of a lightning strike the voltage will be super high and the current returns or leaves one of the differences of potential. Lightning is a cloud to earth or earth to cloud event so the current is getting to where it needs to go instead of through our appliances via the neutral conductor which is bonded to the grounding electrode conductor. You are correct there is no such thing as an ungrounded system in our homes no matter the type of receptacle or cable used. The term “ungrounded” would mean that the neutral is not connected to earth which has always been a requirement of the NEC

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I think I get it Mr. Whitt

Basically, the ground isn’t a low resistance path, it’s just the path the lightning needs to take?

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Juan,
Here’s an article I recommend that may help us better understand the subject matter.

It talks about grounding and bonding, and explains the distinction between the two.
The bigger purpose of the groundING conductor is bonding, i.e. to “… provide a low-impedance fault-current path to facilitate the operation of overcurrent protection devices, and how to remove dangerous voltage potentials between conductive parts of building components and electrical systems.”
The bonding aspect of the grounding conductor is what matters most for safety. That is why you can and should say that “half of the house is not grounded,” provided [size=2]you word it correctly[size=2], [size=2]e.g. [/size][/size]if you point out that half of the house branch circuits do not offer a grounding conductor. The rest of the theory behind grounding and bonding, while may be interesting to us, is not nearly as important to our customer – the home buyer.

Here’s the article: [/size]http://www.mikeholt.com/mojonewsarchive/GB-HTML/HTML/Grounding-Part-1-of-12~20041005.php

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So how would you say it? My house is the one that Roy has described, 2 wire romex upstairs and 3 wire down. How would you write that up?

note to Michael, while you are correct in theory re ground protection, I have lived with ungrounded outlets since 96 and always had one to three PCs going since, not to mention TV, stereo, guitar amps, electronic key boards etc. all with 3 prong plugs in ungrounded receptacles and have never had anything fail yet.

One interesting thing is a 1951 gas stove with an unpolarized plug for an oven light, the kitchen electrics have been upgraded to three wire grounded, plug in the stove one way and kaboom there goes the breaker, turn the plug around and no problem. This could not happen with an ungrounded receptacle btw, the stove is also grounded through the gas line so if the plug is reversed instant short. I should change that plug, shoe makers kids :wink:

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Please read the manufacturer instructions.

Statement 2 is incorrect.

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I have to agree with what Michael is saying here.

Many homeowners might think or feel that everything is protected just because of an GFCI.

Having a whole home protector installed for bout $100 bucks doesn’t hurt

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What is a whole home protector?

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I have no idea either.

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I have seen some that come in 12 gauge and 9 mm.

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Sorry guys… I was using voice on my phone and it left out the surge part.

A whole home surge protector.