grounding electrode

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zappy

zappy

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if you lose the grounded conductor at the service of a home will the the grounding electrode provide the path to the transformer or will the ohms be to much?
 
zappy said:
if you lose the grounded conductor at the service of a home will the the grounding electrode provide the path to the transformer or will the ohms be to much?
Click to expand...

It does provide a path but as you guessed it will have to much resistance to do much good.
 
It depends on the electrode. For example, if the service hapens to be grounded to a common metal water pipe that is shared by a neighboring service, it is very possible to lose the grounded service conductor and it never be noticed. At least until the continuity of the water pipe is lost.
 
Here's a good graphic of a scenario similar to what Bryan mentioned. Although the loss of the grounded conductor at one service would put all of the neutral current on the rebar. It's hard to say how long that would go unnoticed without a problem.

1113920421_2.jpg
 
Sticky,

the ecm article you posted brings back memories. The below article-copied from the article link posted by sticky-tells exactly what happen to me: Part of article: the case of an open neutral with a low-resistance ground path, the open neutral may never be detected. Currents may continue to travel this path for years until an unsuspecting person opens the ground circuit, potentially placing them in harm's way.


We where doing service upgrades for a mobile home site. I was hit by the EGC through a pair of working gloves I was wearing. An experience I will never forget!
:rolleyes:
 
glad i asked!

glad i asked!

i never really thought about the grounding electrode conductor being hot!you guys might have saved me from being zapped or worse!thank you!
 
I submitted a proposal to revise the requirement 250.58 to be similar to that as required for ungrounded system. The idea was to provide an open neutral monitoring system that activate upon an open neutral. It was rejected.

5-176 Log #386 NEC-P05 Final Action: Reject
(250.58)
____________________________________________________________
Submitter: Bryan P. Holland, Holland Electric
Recommendation: Add new text as follows:
Where separate services, feeders, or branch circuits supply a building and are
required to be connected to a grounding electrode(s), the same grounding
electrode(s) shall be used and the provisions of (1) are met:
(1) An approved audible or visible alarm shall be installed at each service to
indicate the grounded conductor brought to the service has opened.
Exception No. 1: In industrial installations, with written safety procedures,
where conditions of maintenance and supervision ensure that only qualified
persons service the equipment.
Exception No. 2: Where electric service and electrical maintenance are
provided by the building management and where these are under continuous
building management supervision.
Substantiation: Upon the opening of the grounded (neutral) conductor at one
service, potentially dangerous current will flow between the common
electrodes to both services. Any person who comes in contact with exposed
metal parts at the service equipment or grounding electrode system could be
exposed to lethal current.
Panel Meeting Action: Reject
Panel Statement: The submitter has not provided any technical substantiation
to require monitoring grounding electrode and grounding electrode conductor
integrity by audible and visible alarms. The Code is not structured to protect
against abnormal conditions such as open neutrals that may develop.
Number Eligible to Vote: 15
Ballot Results: Affirmative: 15
Click to expand...
 
Current on grounding electrode...

Current on grounding electrode...

After reading the link provided by Stickyboy, I read a small amt of current on my water pipe where it leaves the building, @ .03Amps. (Using a Fluke 33) Anything to be concerned about?
daddyray
 
daddyray said:
After reading the link provided by Stickyboy, I read a small amt of current on my water pipe where it leaves the building, @ .03Amps. (Using a Fluke 33) Anything to be concerned about?
daddyray
Click to expand...

.03 amps?

Heck no, as a matter of fact I would expect more current then that.

The grounding electrodes are part of parallel paths (the neutral is the other part) back to the source. (the Power company transformer)
 
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