|
Home > Archive > Electrical Engineering > June 2005 > Dumping 1.5 Amps to ground
You are viewing an archived Text-only version of the thread.
To view this thread in it's original format and/or if you want to reply to
this thread please [click here]
| Author |
Dumping 1.5 Amps to ground
|
|
| SimonLW 2005-06-28, 12:25 pm |
| I put a clamp on meter on the main cable from the meter into the panel and
noticed an imbalance (should read 0). Next, I checked the ground cable going
to a water pipe and found the same current flowing. I checked the pipe from
the ground clamp side to the house and the clamp to the water main and all
the current was heading to ground.
The houses on the street are delivered power from a low voltage bus on the
poles. What I mean is each house does not have its own transformer. There is
a transformer on every other pole that is connected to the LV bus line. I'm
thinking, imbalance current on the neutral line is getting carried back to
the transformer through the water line (city water system), back up
someone's ground to the transformer since the other houses are connected on
a different part of the bus. Does this make sense? Is that excessive
current? Should the utility check it?
Thanks
| |
| SQLit 2005-06-28, 12:25 pm |
|
"SimonLW" <anon@anon.com> wrote in message
news:42c13d64$1_5@newsfeed.slurp.net...
quote:
> I put a clamp on meter on the main cable from the meter into the panel and
> noticed an imbalance (should read 0). Next, I checked the ground cable
going
quote:
> to a water pipe and found the same current flowing. I checked the pipe
from
quote:
> the ground clamp side to the house and the clamp to the water main and all
> the current was heading to ground.
>
> The houses on the street are delivered power from a low voltage bus on the
> poles. What I mean is each house does not have its own transformer. There
is
quote:
> a transformer on every other pole that is connected to the LV bus line.
I'm
quote:
> thinking, imbalance current on the neutral line is getting carried back to
> the transformer through the water line (city water system), back up
> someone's ground to the transformer since the other houses are connected
on
quote:
> a different part of the bus. Does this make sense? Is that excessive
> current? Should the utility check it?
> Thanks
>
Power going to ground indicates to me that your electrical service may be
improperly grounded, or loose connections, or improperly wired.
If someone used the ground you describe as a neutral, ( grounded conductor )
you would have the same result.
I hesitate to even comment on the concept of the imbalance traveling back
through the city water pipes to the utility. Usually there is no neutral
feeding the distribution transformers. If there is a connection to the city
water piping I would think it would be a mistake/accident.
Neutral the grounded conductor is established at the electrical service.
There may or may not be a ground at the transformer.
Does your electrical service have a ground rod, ufer, or some means of
grounding besides the water pipe?
Anything happening on the customer side of the meter is yours. At least it
is here. My suggestion is to hire a competent contractor to inspect/test
the installation. I am betting that the issue is on your side of the meter
and has nothing to do with the distribution.
Let us know what you find.
| |
| Charles Perry 2005-06-28, 6:25 pm |
|
"SimonLW" <anon@anon.com> wrote in message
news:42c13d64$1_5@newsfeed.slurp.net...
quote:
>I put a clamp on meter on the main cable from the meter into the panel and
> noticed an imbalance (should read 0). Next, I checked the ground cable
> going
> to a water pipe and found the same current flowing. I checked the pipe
> from
> the ground clamp side to the house and the clamp to the water main and all
> the current was heading to ground.
>
> The houses on the street are delivered power from a low voltage bus on the
> poles. What I mean is each house does not have its own transformer. There
> is
> a transformer on every other pole that is connected to the LV bus line.
> I'm
> thinking, imbalance current on the neutral line is getting carried back to
> the transformer through the water line (city water system), back up
> someone's ground to the transformer since the other houses are connected
> on
> a different part of the bus. Does this make sense? Is that excessive
> current? Should the utility check it?
> Thanks
Where are you located? That will help answer your question.
Charles Perry P.E.
| |
| phil-news-nospam@ipal.net 2005-06-28, 6:25 pm |
| On Tue, 28 Jun 2005 12:05:03 -0400 Charles Perry <pipesandtobacco@hotmail.com> wrote:
|
| "SimonLW" <anon@anon.com> wrote in message
| news:42c13d64$1_5@newsfeed.slurp.net...
|>I put a clamp on meter on the main cable from the meter into the panel and
|> noticed an imbalance (should read 0). Next, I checked the ground cable
|> going
|> to a water pipe and found the same current flowing. I checked the pipe
|> from
|> the ground clamp side to the house and the clamp to the water main and all
|> the current was heading to ground.
|>
|> The houses on the street are delivered power from a low voltage bus on the
|> poles. What I mean is each house does not have its own transformer. There
|> is
|> a transformer on every other pole that is connected to the LV bus line.
|> I'm
|> thinking, imbalance current on the neutral line is getting carried back to
|> the transformer through the water line (city water system), back up
|> someone's ground to the transformer since the other houses are connected
|> on
|> a different part of the bus. Does this make sense? Is that excessive
|> current? Should the utility check it?
|> Thanks
|
| Where are you located? That will help answer your question.
|
| Charles Perry P.E.
His NNTP posting IP address suggests in or around the Dayton Ohio area.
--
-----------------------------------------------------------------------------
| Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ |
| (first name) at ipal.net | http://phil.ipal.org/ http://ka9wgn.ham.org/ |
-----------------------------------------------------------------------------
| |
| phil-news-nospam@ipal.net 2005-06-28, 6:25 pm |
| On Tue, 28 Jun 2005 08:06:39 -0400 SimonLW <anon@anon.com> wrote:
| I put a clamp on meter on the main cable from the meter into the panel and
| noticed an imbalance (should read 0). Next, I checked the ground cable going
| to a water pipe and found the same current flowing. I checked the pipe from
| the ground clamp side to the house and the clamp to the water main and all
| the current was heading to ground.
|
| The houses on the street are delivered power from a low voltage bus on the
| poles. What I mean is each house does not have its own transformer. There is
| a transformer on every other pole that is connected to the LV bus line. I'm
| thinking, imbalance current on the neutral line is getting carried back to
| the transformer through the water line (city water system), back up
| someone's ground to the transformer since the other houses are connected on
| a different part of the bus. Does this make sense? Is that excessive
| current? Should the utility check it?
| Thanks
Scenario 1:
There should be a connection between the neutral on the bus wires between
the poles, and the transformer neutral terminal, as well as a ground wire
to earth at the pole the transformer is on. If the connection between the
bus and the transformer is broken, then the only return path for imbalance
current is through earth. Since every house should have the neutral that
comes off the pole grounded, each one of those serves as a parallel path
through earth back to the earth ground wire at the transformer.
Scenario 2:
A neighbor has a broken or loose neutral in their service drop, but their
neutral in the panel is still grounded (perhaps through the water pipe).
Their current imbalance is flowing out the earth ground (maybe water pipe)
and using parallel paths back to the transformer, some through the ground
wire at the transformer, and some through each neighbor (and you) entering
via the ground and going back up the service drop to the transformer.
Scenario 2B:
Same as scenrio 2, but you are the one with the broken or loose neutral in
the service drop.
Scenario 3:
The neutral wire of the medium voltage distribution circuit connected to the
transformer primary is typically connected to the secondary neutral, and both
connected to ground. Thus, there is a metallic path between your neutral
wire and the neutral of the medium voltage distribution wires. If there is
a broken neutral between the transformer primary and the distribution, either
at the transformer, or further down the line, then the primary current trying
to return to the upstream source will flow through the ground wire on the
pole, and find parallel paths back to the source. In the simplest case, the
neutral is broken at that transformer, and each service drop, plus the pole
ground, are parallel paths through earth to other service drops of houses on
other transformers with OK neutrals, providing a working return path. At
medium voltages, typical earth resistances divided by all these parallel
paths can still result in a working system with little voltage drop.
--
-----------------------------------------------------------------------------
| Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ |
| (first name) at ipal.net | http://phil.ipal.org/ http://ka9wgn.ham.org/ |
-----------------------------------------------------------------------------
| |
| Charles Perry 2005-06-28, 11:25 pm |
|
"SQLit" <sqlit@qwest.net> wrote in message
news:C0dwe.16$jU.6814@news.uswest.net...
quote:
>
<snip>
quote:
> Power going to ground indicates to me that your electrical service may be
> improperly grounded, or loose connections, or improperly wired.
> If someone used the ground you describe as a neutral, ( grounded
> conductor )
> you would have the same result.
>
> I hesitate to even comment on the concept of the imbalance traveling back
> through the city water pipes to the utility. Usually there is no neutral
> feeding the distribution transformers.
???? Most distribution transformers in the US are fed from line to neutral,
not line to line.
Charles Perry P.E.
| |
| SimonLW 2005-06-29, 12:25 pm |
| "SimonLW" <anon@anon.com> wrote in message
news:42c13d64$1_5@newsfeed.slurp.net...
quote:
> I put a clamp on meter on the main cable from the meter into the panel and
> noticed an imbalance (should read 0). Next, I checked the ground cable
going
quote:
> to a water pipe and found the same current flowing. I checked the pipe
from
quote:
> the ground clamp side to the house and the clamp to the water main and all
> the current was heading to ground.
>
> The houses on the street are delivered power from a low voltage bus on the
> poles. What I mean is each house does not have its own transformer. There
is
quote:
> a transformer on every other pole that is connected to the LV bus line.
I'm
quote:
> thinking, imbalance current on the neutral line is getting carried back to
> the transformer through the water line (city water system), back up
> someone's ground to the transformer since the other houses are connected
on
quote:
> a different part of the bus. Does this make sense? Is that excessive
> current? Should the utility check it?
> Thanks
>
>
I shut off the main breaker and checked current through the ground lead.
The current dropped a little, but is still considerable, 1 amp. There is
another ground line that runs out to a ground rod. It looks properly
connected, but shows no current flow.
Since any conductor has resistance, there is a voltage drop across the
neutral line. This means the voltage on the neutral can be slightly
different between me an my neighbor's house if the neutral bus is carrying a
significant load. Since the neutral is bonded to the water line in each of
our houses, any potential difference on the neutrals between our houses will
be conducted through the metallic water supply line. There could be other
reasons, but considering the system has no faults, this is the best theory I
have.
-S
| |
| SimonLW 2005-06-29, 12:25 pm |
| "SimonLW" <anon@anon.com> wrote in message
news:42c13d64$1_5@newsfeed.slurp.net...
quote:
> I put a clamp on meter on the main cable from the meter into the panel and
> noticed an imbalance (should read 0). Next, I checked the ground cable
going
quote:
> to a water pipe and found the same current flowing. I checked the pipe
from
quote:
> the ground clamp side to the house and the clamp to the water main and all
> the current was heading to ground.
>
> The houses on the street are delivered power from a low voltage bus on the
> poles. What I mean is each house does not have its own transformer. There
is
quote:
> a transformer on every other pole that is connected to the LV bus line.
I'm
quote:
> thinking, imbalance current on the neutral line is getting carried back to
> the transformer through the water line (city water system), back up
> someone's ground to the transformer since the other houses are connected
on
quote:
> a different part of the bus. Does this make sense? Is that excessive
> current? Should the utility check it?
> Thanks
>
>
I shut off the main breaker and checked current through the ground lead.
The current dropped a little, but is still considerable, 1 amp. There is
another ground line that runs out to a ground rod. It looks properly
connected, but shows no current flow.
Since any conductor has resistance, there is a voltage drop across the
neutral line. This means the voltage on the neutral can be slightly
different between me an my neighbor's house if the neutral bus is carrying a
significant load. Since the neutral is bonded to the water line in each of
our houses, any potential difference on the neutrals between our houses will
be conducted through the metallic water supply line. There could be other
reasons, but considering the system has no faults, this is the best theory I
have.
-S
| |
| phil-news-nospam@ipal.net 2005-06-29, 12:25 pm |
| On Wed, 29 Jun 2005 07:29:56 -0400 SimonLW <anon@anon.com> wrote:
| I shut off the main breaker and checked current through the ground lead.
| The current dropped a little, but is still considerable, 1 amp. There is
| another ground line that runs out to a ground rod. It looks properly
| connected, but shows no current flow.
That suggests the broken neutral is on the pole between the LV bus and
the transformer. The transformer neutral is still connected to ground
and the bus is getting back to the transformer via each service drop's
ground electrode.
--
-----------------------------------------------------------------------------
| Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ |
| (first name) at ipal.net | http://phil.ipal.org/ http://ka9wgn.ham.org/ |
-----------------------------------------------------------------------------
| |
| phil-news-nospam@ipal.net 2005-06-29, 6:25 pm |
| On 29 Jun 2005 13:51:43 GMT phil-news-nospam@ipal.net wrote:
| On Wed, 29 Jun 2005 07:29:56 -0400 SimonLW <anon@anon.com> wrote:
|
| | I shut off the main breaker and checked current through the ground lead.
| | The current dropped a little, but is still considerable, 1 amp. There is
| | another ground line that runs out to a ground rod. It looks properly
| | connected, but shows no current flow.
|
| That suggests the broken neutral is on the pole between the LV bus and
| the transformer. The transformer neutral is still connected to ground
| and the bus is getting back to the transformer via each service drop's
| ground electrode.
Let me add that the transformer neutral would still be grounded even if
the ground wire on the pole itself is broken as part of the neutral being
broken. Since the neutral is connected between secondary and primary,
the return path to the transformer can very well be through earth to
other secondary systems (neighbors down the road on a different transformer)
and run back through the neutral wire of the primary lines.
There is an old saying "electricity takes the path of least resistance".
That's not true. The correct statement would be "electricity takes all
paths in parallel in proportion to the inverse of resistance of each path".
--
-----------------------------------------------------------------------------
| Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ |
| (first name) at ipal.net | http://phil.ipal.org/ http://ka9wgn.ham.org/ |
-----------------------------------------------------------------------------
| |
| Michael Moroney 2005-06-29, 6:25 pm |
| phil-news-nospam@ipal.net writes:
quote:
>On Wed, 29 Jun 2005 07:29:56 -0400 SimonLW <anon@anon.com> wrote:
quote:
>| I shut off the main breaker and checked current through the ground lead.
>| The current dropped a little, but is still considerable, 1 amp. There is
>| another ground line that runs out to a ground rod. It looks properly
>| connected, but shows no current flow.
quote:
>That suggests the broken neutral is on the pole between the LV bus and
>the transformer. The transformer neutral is still connected to ground
>and the bus is getting back to the transformer via each service drop's
>ground electrode.
Since the current through the water pipe is 1 amp but the current through
the ground rod is nil, I would have guessed that someone else's house
has a broken neutral, and its neutral current is going through their
water pipe ground, through the water piping, the O/P's water pipe ground
and through the O/P's neutral back to the transformer. And the other
ground is poor.
To the O/P: Does the current vary on its own even when you don't switch
anything on/off yourself? Also, if you switch a large 120V load (space
heater or something) on and off does the current change by the current
drawn by the device (rated wattage divided by 120) ? Experiment with
plugging it into outlets using different hot legs if possible.
| |
| phil-news-nospam@ipal.net 2005-06-30, 6:25 pm |
| On Wed, 29 Jun 2005 16:22:51 +0000 (UTC) Michael Moroney <moroney@world.std.spaamtrap.com> wrote:
| phil-news-nospam@ipal.net writes:
|
|>On Wed, 29 Jun 2005 07:29:56 -0400 SimonLW <anon@anon.com> wrote:
|
|>| I shut off the main breaker and checked current through the ground lead.
|>| The current dropped a little, but is still considerable, 1 amp. There is
|>| another ground line that runs out to a ground rod. It looks properly
|>| connected, but shows no current flow.
|
|>That suggests the broken neutral is on the pole between the LV bus and
|>the transformer. The transformer neutral is still connected to ground
|>and the bus is getting back to the transformer via each service drop's
|>ground electrode.
|
| Since the current through the water pipe is 1 amp but the current through
| the ground rod is nil, I would have guessed that someone else's house
| has a broken neutral, and its neutral current is going through their
| water pipe ground, through the water piping, the O/P's water pipe ground
| and through the O/P's neutral back to the transformer. And the other
| ground is poor.
That could very well be. As the pipe is likely metallic all the way,
it would be a good path between neighbors.
But the water pipe can also have a lot lower impedance to earth than a
single electrode, too, especially if it is leaking a slight amount.
--
-----------------------------------------------------------------------------
| Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ |
| (first name) at ipal.net | http://phil.ipal.org/ http://ka9wgn.ham.org/ |
-----------------------------------------------------------------------------
|
|
|
|
|