Ground Rod For Residence ?

[Robert11]

Hello:

Was just wondering about this a bit.
Live in the Boston area, in a typical Colonial built about 30 yrs ago.

Have the "standard" 220 V line coming into the house from the street line
Appears to be 3 conductors, the 2 phases and the neutral.

My question is that I keep reading about houses needing, and the NEC
requiring, a ground (or grounding) rod right outside
the house.

Don't seem to have one.

Is an actual ground rod required ?
Where would it be ?

If not, why not ?

Thanks,
Bob

 

[[email protected]]

Hello:

Was just wondering about this a bit.
Live in the Boston area, in a typical Colonial built about 30 yrs ago.

Have the "standard" 220 V line coming into the house from the street line
Appears to be 3 conductors, the 2 phases and the neutral.

My question is that I keep reading about houses needing, and the NEC
requiring, a ground (or grounding) rod right outside
the house.

Don't seem to have one.

Is an actual ground rod required ?
Where would it be ?

If not, why not ?

Thanks,
Bob

You are grounded to the water pipe coming in the house. As long as the
water company doesn't replace it with plastic you are fine. The new
code requires another electrode beside the pipe for that reason.

 

[daestrom]

Hello:

Was just wondering about this a bit.
Live in the Boston area, in a typical Colonial built about 30 yrs ago.

Have the "standard" 220 V line coming into the house from the street line
Appears to be 3 conductors, the 2 phases and the neutral.

My question is that I keep reading about houses needing, and the NEC
requiring, a ground (or grounding) rod right outside
the house.

Don't seem to have one.

Is an actual ground rod required ?
Yes.

Where would it be ?

Usually not far from the main service entrance. You should see an
uninsulated conductor leading from the ground rod into the main service
panel.

If not, why not ?

Ah, there's the question now isn't it? In the past, it was acceptable to
use the incoming cold water pipe for a ground. The reasoning was that
iron/copper (even old lead) piping made an excellent ground by
interconnecting with all the other water pipes in town. So you might find
an uninsulated conductor running from your main service panel over to a cold
water pipe in the basement/crawlspace.

But times change. With the advent of PVC and plastic water meters and other
things, using the cold water pipe as the sole grounding rod is no longer
permitted. So if you have any major work done, you will have to also put in
a new ground rod to bring it up to current code.

daestrom

 

[[email protected]]

A ground "rod" isn't the only viable ground. The "UFER" ground is
supplanting the ground rod as the method of choice in most Western states. A
UFER is either a copper conductor poured in it's own concrete, or in the
foundation concrete of the building. Often a piece of re-bar is turned up
from the foundation under the service for this purpose. Check this link out,
if you're interested.
http://www.psihq.com/iread/ufergrnd.htm

This is how we do it in SW Florida.

http://members.aol.com/gfretwell/ufer.jpg

 

[ehsjr]

This is how we do it in SW Florida.

http://members.aol.com/gfretwell/ufer.jpg

Nice pictures!
Ed

 

[Bud--]

This is how we do it in SW Florida.

http://members.aol.com/gfretwell/ufer.jpg

I always pictured copper wire coming out of the footing. Rebar up makes
the thing look indestructable. Presume green is anti-rust and doesn't
impair conductivity?

The link above from Long Tom seems to say you can't use Ufer alone
without a rod. Can't you use Ufer alone without anything else?

I just looked at info that included Ufer. Original test was over 18
years with resistance range from 2.1 to 4.8 ohms average 3.6 ohms. Would
think these would replace rods.

There was also info from a Mike Holt video from Orlando where he drove a
10' rod with a water table about 3' down, connected 120V and got a
current of about 1.5A (implies 80 ohms). He added lengths do a depth of
50' where the current was 14A (implies 8.6 ohms). Any idea why such
dismal results? Oddity of Florida?

bud--

 

[[email protected]]

Presume green is anti-rust and doesn't
impair conductivity?

They just shoot it green so it won't get confused with the dowel rods
and get the cell in the block poured solid. That is a water based
paint they wash off before the connection in the last picture is made.
The hole in the block gets a mud ring at stucco and a stainless blank
cover so it stays accessible.

The rest of those vertical #5s go up through the block, get tied to
two #5s across the top 2 courses and all of that gets poured solid.
This ends up being a virtual faraday cage.

The sany soil makes "Ground" in Florida is a fairly ambigous thing and
the difference between 2 buildings can spike 35v or more on a Dranitz
monitor.
The Ufer just insures an equipotential grid in the building you are
in. When they build a radio tower or a toll booth they go to
extraordinary lengths to get a good ground. Typically a tool booth
gets a Ufer, a ground ring around the whole plaza and several 40 foot
rods along the ring. A radio tower gets all that plus buried radials.
It may still not be "ground" but it is a stable reference.

 

[[email protected]]

There was also info from a Mike Holt video from Orlando

Haqve you ever watch the shows about the University of Central
Floirida/ Florida Powere & Light project to study lightning?
They shoot rockets up into charged clouds to induce a controlled
strike and analyse the result.
It does somewhat debunk the idea that a buried power line is safe trom
ligntning. The lightning is still making glass out of sand 5 or 6 feet
down. Still plenty of energy to spike a power line.

 

[Don Kelly]

----------------------------

Haqve you ever watch the shows about the University of Central
Floirida/ Florida Powere & Light project to study lightning?
They shoot rockets up into charged clouds to induce a controlled
strike and analyse the result.
It does somewhat debunk the idea that a buried power line is safe trom
ligntning. The lightning is still making glass out of sand 5 or 6 feet
down. Still plenty of energy to spike a power line.

Whether or not it will damage a buried power line depends on a number of
factors, including shielding and grounding. What is most important is the
potential difference between the "live" and the "grounded" conductors or
objects. A low ground resistance certainly is beneficial and it doesn't
require an excessively large conductor to handle the very short duration
current without overheating.

Given all that, the flow of lightning current in the ground is very often
not predictable.

 

[Bud--]

They just shoot it green so it won't get confused with the dowel rods
and get the cell in the block poured solid. That is a water based
paint they wash off before the connection in the last picture is made.
The hole in the block gets a mud ring at stucco and a stainless blank
cover so it stays accessible.

The rest of those vertical #5s go up through the block, get tied to
two #5s across the top 2 courses and all of that gets poured solid.
This ends up being a virtual faraday cage.

A grounded ring in the foundation and top of the wall? Sounds like great
lightning protection. Steel reinforced concrete block tied to the
foundation sounds like a bomb shelter but is probably for hurricanes?

The sany soil makes "Ground" in Florida is a fairly ambigous thing and
the difference between 2 buildings can spike 35v or more on a Dranitz
monitor.

If the water table is high why don't disolved minerals give high
conductivity?

bud--

 

[Bud--]

Haqve you ever watch the shows about the University of Central
Floirida/ Florida Powere & Light project to study lightning?
They shoot rockets up into charged clouds to induce a controlled
strike and analyse the result.

If it is where the rockets trail fine wire I saw an hour program. IIRC
the program had interesting information on the electrical findings;
seems like science programs now are dumbded down and a lot less
frequent. Looked like it would be real interesting to watch the tests.
From inside a good shelter.

bud--

 

[[email protected]]

Steel reinforced concrete block tied to the
foundation sounds like a bomb shelter but is probably for hurricanes?

Yup that is the coastal wind code. It is even more stringent in south
Dade county and the Keys.

We saw the value when Wilma came and some folks who didn't get their
tie beams poured lost their walls.
When you see the pile of rubble that used to be a block wall it will
conmvince you wind is powerful stuff.
Once you get steel and concrete in there you got ya something.