Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 09-15-2012, 03:26 AM   #1
Newbie
 
Join Date: Sep 2012
Location: Oregon
Posts: 9
Rewards Points: 0
Share |
Default

Is my house adequately grounded, and what does that mean?


Hello,

I am a newish owner of an old (1941) home in Oregon. I know next to nothing about electricity, but am here to learn! Hopefully, you will entertain my relative naivete of electricity and how it affects me in my new (old) home.

My first question, if anyone would be so helpful to provide feedback is:

This old home had galvanized metal water pipes. They were corroding from the inside, reducing water pressure severely. We just had them replaced with PEX plastic pipes. In the process of having them replaced, the plumber removed 3 grounding connections to the metal water pipe (obviously). One was an exposed copper wire coming out of the electrical panel/circuit breaker box, clamped directly to a water pipe. One was a clamp from a light fixture to another water pipe. The third was a clamp from the natural gas line to a water pipe. He said to contact an electrician about what to do next (he was a friend of a friend working for cash, not doing anything with a permit. Sorry, I know, I know).

Anyway, I emailed about 50 electricians about this, asking if the can provide me with an estimate to come out and "re-ground" the house/re-attach the grounding clamps to something other than PEX plastic water pipe. I did look and see that there is another exposed copper wire leaving the electrical panel, going out through the wall, and attached to a grounding rod, directly beneath the meter outside. My "understanding" is that my house was grounded to both the water pipe, and this grounding rod outside. Now, it is only grounded to the grounding rod obviously.

Almost all of the electricians (other than the ones who had dispatchers/secretaries reply with "we can come diagnose your problem for $105/hr) said something similar to this "The current code requires two ground rods spaced 6' apart in lieu of the
metal water pipe. We are also supposed to bond to the gas pipe (if you have gas)."

So I thought, OK, I should have someone come out and install another ground rod. However, one electrician said this "The requirement for 2 ground rods is for new installations. If you have one existing ground rod that can be verified, as you stated in your first email, then you have a code compliant installation. If the existing cannot be verified, then 2 new rods would be required."

So either I am still code compliant with my one grounding rod (and no water pipes) or I need another grounding rod. Easy enough.

However, I started reading (and getting lost) in electrical forums, which start to utterly confuse this newbie. The crux of my questions is - what does this grounding rod (or two) do? What does it protect me from? A lot of the information I've read says it protects me from a ground fault (such as an appliance having a loose wire, coming in contact with a metal casing of said appliance, and becoming energized or hot). BUT, much other information I have read said a grounding rod (or two) only protects me from a static discharge - meaning if my house gets hit by lightning. Many of these sites also said that having two grounding rods 6 feet apart may or may not provide any additional benefit over 1 rod, depending on soil conditions, etc. But 2 rods is code, so.....

Anyway, sorry for being a windbag. I am just trying to figure out if:

a) I should get another grounding rod installed.
b) What situations/dangers this/these grounding rods would protect me and my family from.

Thank you any and all for your input.

lmark103 is offline   Reply With Quote
Old 09-15-2012, 06:38 AM   #2
Member
 
Join Date: Nov 2007
Location: Nashua, NH, USA
Posts: 6,951
Rewards Points: 16
Default

Is my house adequately grounded, and what does that mean?


If you already have one ground rod, adding a second ground rod is not a major undertaking (you can DIY) and you can extend the existing fat ground wire (grounding electrode conductor) from the panel from the first ground rod to the second as opposed to running a new GEC.

Nothing will protect against a direct lightning strike.

Between the two extremes above you can install additional ground rods or other esoteric gadgets (e.g. lightning arrestors with gaps or choke coils) to improve lightning protection.

"Can be verified" -- Means that, using special equipment, you measure less than 25 ohms between the GEC and the earth. You are not obliged to have more than two ground rods so after installing the second, there is no further need to measure or diagnose.

When the plumber removed the three grounding clamps from the water pipe that was also removed, the three respective ground wires should be clamped to each other (may be DIY), that's all you need to do there. (Just twisting them together is not good enough.) One of the three is almost certainly bonded to the ground rod (via #6 or larger copper wire not necessarily nonstop*); if not then you will need to add such a bonding jumper (more DIY).

To protect against electric shock, the various branch circuits have ground wires (equipment grounding conductors) accompanying the hot and neutral wires and also ground fault circuit interrupters are used. Code dictates which branch circuits need GFCIs but nothing prevents you from installing GFCIs on additional circuits or outlets.

The gas piping system needs to be bonded to the grounding electrode system (ground rods and accompanying fat ground wires). The gas pipe exiting the house does not count as a "grounding electrode". When there is at least one gas appliance that uses electricity and is grounded via its branch circuit, no additional bonding jumper is needed.

The water pipes, if metal, should to be bonded to the grounding electrode system. The water supply pipe exiting the house, if metal, must be so bonded.

* Bonding -- The making of an essentially resistance free electrical connection. If A is bonded to B and B is bonded to C then A is bonded to C. There is one rule that one ground rod or the (metal) water pipe exiting the house must have a nonstop GEC to the neutral bus bar in the panel with the first main disconnect switch or breaker.

Also: If A is bonded to B then B is bonded to A. However the intent is to bond the gas piping to the electrical ground (grounding electrode system), not the other way around.

__________________
Stop wasting time re-adjusting the pattern. Have several lawn sprinklers, one for each pattern.

Last edited by AllanJ; 09-15-2012 at 07:43 AM.
AllanJ is online now   Reply With Quote
The Following User Says Thank You to AllanJ For This Useful Post:
lmark103 (09-15-2012)
Old 09-15-2012, 08:51 AM   #3
Civil Engineer
 
Join Date: Mar 2009
Location: Boston
Posts: 4,203
Rewards Points: 2
Default

Is my house adequately grounded, and what does that mean?


That was an excellent summary by Allan J. I note that grounding is almost certainly the most misunderstood aspect of electrical wiring. You can look even on professional forums and find numerous incorrect statements, widespread misunderstanding, opinions authoritatively stated that are wrong, etc. The history of grounding is really pretty interesting, and modern code requires use of devices and techniques that are not necessary for the operation of electrical equipment, but do provide increased safety for users. In an older house such as yours, much of your installation likely does not meet current code, but may be grandfathered in, and may be safe (although not as safe as current code). What is grandfathered, and what must be updated when you make improvements, is the decision of the wiring inspector (or building inspector in some cases if they do both).
Daniel Holzman is offline   Reply With Quote
The Following User Says Thank You to Daniel Holzman For This Useful Post:
lmark103 (09-15-2012)
Old 09-15-2012, 08:54 AM   #4
Master Electrician
 
Join Date: Mar 2010
Location: Indiana
Posts: 2,867
Rewards Points: 4
Default

Is my house adequately grounded, and what does that mean?


If the water pipe entering the house is metallic it should be used as a groounding electrode. How old and what condition is our electrical service in general? Amperage, # of breaker slots, brand ?
brric is online now   Reply With Quote
The Following User Says Thank You to brric For This Useful Post:
lmark103 (09-15-2012)
Old 09-15-2012, 12:56 PM   #5
Newbie
 
Join Date: Sep 2012
Location: Oregon
Posts: 9
Rewards Points: 0
Default

Is my house adequately grounded, and what does that mean?


Thanks for the in depth info, you guys rock!

AllanJ - In regards to the grounding rods, you mentioned "nothing will protect against a lightning strike". I see. I am not particularly concerned about a lightning strike. Not asking for one though, ha ha, but here in Oregon we see lightning maybe once or twice a year. I've read a lot about how that is the only purpose of a grounding rod, but it sounds like they may not be. So I guess I am trying to ask what specifically the grounding rods will do. They will dissipate electricity into the earth in the event of __________. Or, they protect me from getting an electric shock from a _________ by doing __________. Does that question make sense. I am probably wording it poorly, you may have already answered it. I was under the impression the grounding rod would protect me from a ground fault, where an appliance shorted out or became energized (poor terminology?), etc.

Thanks for your input on what to do with the grounding clamps also, however none of the three are near enough each other to be clamped to each other. Would some sort of extension be in order?

Daniel Holzman - "I note that grounding is almost certainly the most misunderstood aspect of electrical wiring." Ha, that's the initial reason for my foray into this subject. So many conflicting things I have read on other sites.

"In an older house such as yours, much of your installation likely does not meet current code, but may be grandfathered in" - Interesting. In my case (with family, young kids), I am more interested in safety. So even if I am code compliant, or something can be grandfathered in, I would be interested in taking the time/money to make things safer, even if not required.

"What is grandfathered, and what must be updated when you make improvements, is the decision of the wiring inspector (or building inspector in some cases if they do both)." - Would you recommend I have a city inspector come out and analyze my electrical situation and suggest improvements, or would this be something I pay an private electrician to come out and do?

Sorry if these are stupid questions, I really am quite ignorant about a lot of these things currently, but want to learn.

brric - 18 individual breaker slots (some have an appliance taking up two spots - dryer, water heater, range). The there is the main breaker slots (incorrect terminology?), with 4 vertical switches connected together, to shut off all the power I assume.
The panel/breaker switches look to be Siemens. Every breaker says "15" on it except for:
Dryer/Water Heater = 30
Range = 40
I'm not sure what you mean by "electrical service" age. I know the wiring is original (house built in 1941). Replacing a few fixtures last year with a friend, it appears to have cloth covered wiring/no colors, so you have to keep track of which wire is hot, etc. But just now looking at the panel/circuit breaker box, there is a sticker that has the city inspection record, with a signature and date from December 1999. Also, we had a new gas furnace put in last year, so there is another sticker noting the addition of that from the electric company that hooked it up. Not sure if any of this helps.

The water pipe coming for the street into the house is metal, but as soon as it enters the unfinished basement, there is a valve and then the new PEX pipe starts immediately. So there is only about two inches of exposed metal water pipe entering the house before it takes a right angle and the PEX begins. This is on the opposite side of the house from the electrical panel, and not where the water pipe was previously grounded.
lmark103 is offline   Reply With Quote
Old 09-15-2012, 01:12 PM   #6
Civil Engineer
 
Join Date: Mar 2009
Location: Boston
Posts: 4,203
Rewards Points: 2
Default

Is my house adequately grounded, and what does that mean?


The City Inspector is not going to come out to look at your house unless you pull a permit for electrical modifications. If you are concerned about the condition of your wiring, you need an electrical contractor to look things over. As to the purpose of the grounding rods, think of it this way. Suppose you removed the grounding rods and the connection between the panel and the rods. What would change?

You would not notice any difference at all. Electrical current flows from the power company transformer through the meter, into the main panel, and to each device via your house wiring. The current returns to the transformer via the neutral if it is a 120 volt device. The fact that the neutral happens to be connected to the grounding rod at the main panel is irrelevant, but confusing to a lot of people. Since the grounding rods typically have resistance on the order of 25 ohms, and the neutral from the panel to the transformer has only a few tenths ohms resistance, the overwhelming majority of current return to the transformer is via the neutral, and a small portion returns to the transformer via the ground rod, into the earth, and then to the transformer via the transformer grounding cable. So you could pull your ground rods completely, and your system would not notice at all.

There are a few circumstances where the rods actually do something. One is in the event of a lightning strike, the rods may dissipate the electrical strike, reducing the chance of burning your house down or damaging equipment. Do not count on it. The only other case where the rods do anything that I can think of is in the event you lose the neutral to the transformer. In this case, the grounding rods should act like a 25 ohm series resistance for your device, so your electrical system would function as though each device had a 25 ohm resistor in series. This is equivalent to about 5 amps actual draw. Oddly, this might allow your house devices to function in the event the neutral to the transformer was completely severed. Not really sure, perhaps one of the electricians has personal experience with a situation where the neutral was cut, and the return current flow went through the ground rods.
Daniel Holzman is offline   Reply With Quote
Old 09-15-2012, 01:51 PM   #7
E2 Electrician
 
stickboy1375's Avatar
 
Join Date: Apr 2012
Location: Litchfield, CT
Posts: 5,091
Rewards Points: 4
Default

Is my house adequately grounded, and what does that mean?


Quote:
Originally Posted by Daniel Holzman View Post

The only other case where the rods do anything that I can think of is in the event you lose the neutral to the transformer. In this case, the grounding rods should act like a 25 ohm series resistance for your device, so your electrical system would function as though each device had a 25 ohm resistor in series. This is equivalent to about 5 amps actual draw. Oddly, this might allow your house devices to function in the event the neutral to the transformer was completely severed. Not really sure, perhaps one of the electricians has personal experience with a situation where the neutral was cut, and the return current flow went through the ground rods.
Untrue, the earth with not complete the path, Your service will become a 240v series circuit and destroy most electronics sensitive to high voltages.

stickboy1375 is online now   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.