While wiring my shop, I noticed something very disturbing. My house
is not grounded. I open my main panel and there are the two hots and
Ground bus and neutral bus are connected and both ground and neutral
wires share the same bus.
My house is newer, only about 8 years old.
Why is there no ground? I know when I did the same work in FL I was
required to put in two ground rods.
Is this a concern or normal?
If your ground goes to a water pipe check it out a bit. In my previous
house I was doing some other remodeling when I discovered that the
water line coming into the house had at some point been re-done in
plastic. I had a ground to the galvanized pipe in the house, but
effectively no real ground since what actually went into the ground
was non-conductive. I drove an 8' rod and properly grounded things -
it was amazing, both my phone system and my computer worked better
Usually, the neutral is grounded at the transformer, and the meter and
entrance panel share a common ground with the neutral in the entrance
panel bonded to ground. Any subpanels should have the neutral isolated
"It has been a source of great pain to me to have met with so many among
[my] opponents who had not the liberality to distinguish between
Son in law discovered the same on their "new" (20yr old) house. Might have
been because the subdivision is on an old lakeside dune, and a driven rod
would have trouble gaining a ground. His dad, who works for a power
company, came up with ten feet of rod to drive. Next time the weather gets
dry, we'll see.
Guard tower they built at the airbase, also in sand, had to have an
extensive grid buried to keep St Elmo and lightning away.
Don't know much about this but it seems like I remember that the code
most places prohibits more than one ground. Aren't you required to have
a ground for the main service or panel and no secondary ground at any
Bob Peterson wrote:
Generally you are required to have another grounding electrode (typically a
ground rod) but not necessarily a connection between earth and neutral at
that subpanel. the ground rod is for lightning protection.
Err... I guess I was unclear/incomplete. It is a convoluted subject,
but here is the entire run-down as per the 2002 NEC.
When the sub-panel is located in the same building, you use the ground
provided in the main panel, and DO NOT bond the ground and neutral
together in the sub-panel - requiring a 4 wire feed.
A detached structure with no metallic paths between it and the main
building, MAY use a 3 wire feed, but MUST use a grounding electrode
with the neutral to ground UNbonded in the sub-panel.
A detached structure with no metallic paths between it and the main
building, MAY ALSO use a 4 wire feed, but MAY also use a grounding
electrode, with the neutral to ground UNbonded in the sub-panel. It
is highly recommended to have a secondary ground rod, and must NOT
bond the ground and neutral in the sub-panel when the sub-panel is
located in a separate building.
Any detached structure that has an existing non-current carrying
metallic path such as water pipes, intercoms, telephone lines, etc.
installed between the main structure and the detached structure MUST
have an equipment grounding conductor installed with the feeders
installed between the two buildings AS WELL as using the water pipe as
a ground, AND a supplementary grounding rod, even if an
interconnecting metallic water pipe is also connected as ground.
Article 250-32-B-1 & 2
It is primarily to prevent telephones, water pipes, intercoms and such
from presenting a shock hazard when they are at differing earth
potentials, aggrevated by charged atmosphere/earth conditions.
If there is no grounding electrode system serving the detached garage,
then you must install a new grounding electrode system as described in
Article 250-50. If none of those listed in Article 250-50 is
available, then you may use a made electrode as found in Article
250-52. Article 250-50 lists any metal water pipe in direct contact
with earth, any rebar in concrete, any grounding rings, and many more
as an approved grounding electrode to be combined as a grounding
electrode system. If available all of those grounding electrode
sources listed in Article 250-50 must be connected together to make
the grounding electrode system. Most likely, if you have a metal water
pipe run underground between the two buildings, then you have a water
pipe in direct contact with earth and that metal water pipe, and any
other grounding method listed in Article 250-50 must be connected
together to make that grounding electrode system. If that metal water
pipe is installed between the two buildings, then you must use that as
part of the grounding electrode system but you must also supply a
supplemental grounding electrode to back up that water pipe in case
that metal water pipe is removed at a later date. Article 250-50-A-2
Remember, if any non current carrying metal connection is existing
between that main building, and the detached building, then you must
install an equipment grounding conductor between the two buildings,
with that feeder and as a part of that feeder installed between the
two buildings. Article 250-32-B-1 & 2
You cannot connect the neutral to earth except at the service point. Most
often this is done either by using the neutral bar as the earth connection
point and as a combined ground bar/neutral bar, or in newer panels via a
bonding jumper between the equipment ground bus and the neutral bus in the
You can have as many ground rods as you want interconnected with each other
either directly or through an equipment grounding conductor.
I don't think the phrase "secondary ground" has any defined meaning in the
A subpanel (another term that I don't recall being defined in the NEC) could
have its own ground rod but may or may not have a connection from the ground
rod to neutral at that panel. Most often in most residential settings it
would not have that connection.
To summarize or correct many responses. Every utility wire
entering the building must connect to same single point earth
ground before or as it enters the building. That means AC
electric neutral (one type of ground) must connect to earth
ground (what the code calls a ground electrode) where it
enters the building (called service entrance). This earthing
wire could be at meter or at breaker box with the mains (100
amp or 200 amp) circuit breaker. Meter or breaker box is
often unique to local utility requirements and typically is a
6 AWG or larger bare copper wire.
All other utilities (phone, cable TV, etc) must also make a
less than 20 foot connection to this earth ground.
This earth ground is required for human safety. NEC that
requires these earthing connections is only concerned with
human safety. However this earthing system must meet or be
enhanced to also provide transistor safety. No earth ground
is why plug-in protectors do nothing effective - another topic
beyond the scope of this discussion.
Water pipe is no longer acceptable for earthing as of 1990.
The water pipe must connect to breaker box safety ground
(where earth ground, receptacle safety ground wires, AC
neutral wire all meet) for human safety reasons - not to be an
earth ground connection. Furthermore, no wire may connect to
water pipes with the intent of dumping electricity into that
pipe. Wire connections to pipes are only to remove
electricity from those pipes - a fundamental change in code.
In addition, some jurisdictions require any metallic bathtub
be hardwired (again 6 AWG wire) from drain pipe to breaker box
safety ground. Further information on safety grounding is
summarized by volts500 in the newsgroup alt.home.repair
entitled "Grounding Rod Info" on 12 July 2003 at
How to find the earth ground? Again, every utility must
connect to that earth ground. Follow the wires. All utilities
must be earthed to same grounding electrode. If not, then an
important electrical upgrade is necessary and may require an
electrician. No earth ground means no human protection and no
As noted, remove sub panels - those powered by the mains
breaker box - would have safety ground and neutral wire
separate and would not connect to earth ground.
Consider geology. For example, if constructed in sandy soil
or on a boundary line between different geologies, then
consider more earthing than just a few earth ground rods.
Well pump protection may also require additional
considerations. Again, reasons involve facts beyond this
What will a plug-in ground tester report? Which ground is
it testing for? Tester can only detect bad breaker box safety
ground connection. It will not report a good safety ground
connection nor will it test for any other grounds such as
earth ground. Anyone recommending tests using "one of those
plug testers into a wall socket" should have known this before
Then another earth ground that is essential to safe home.
Note the failures exampled here:
Happy earthing. Don't get your knees too dirty.
Insufficient information.... The ground might well be present, but
connected in the meter base rather than the main panel. This is common
practice - check it before you panic.
Also, if there is an outside main breaker mounted on a ppole with the
meter enclosure, the ground could be there.
On Wed, 03 Nov 2004 05:03:40 GMT, "Dave"
your local lowes, HD, Orchard supply, etc. will have fairly
inexpensive testers available..
I think the one we carry in our rv was about $20...
(lots of rv parks have bad grounding or inverted polarity)
There probably is a ground. In the main breaker box (but not in any
sub-panels), the ground and the neutral are tied together. If you look on
the neutral/ground bus bar, you will probably see one fairly large wire (#4,
#6, #8 (hopefully no smaller)) that goes into a conduit or out through a
cable clamp. That larger wire probably ends up at a good earth ground.
However, it is possible, that the electrician is relying on the utility
neutral as a ground. THAT is not a good thing.
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