| Author |
Message |
Howard Knight
Guest
|
 Posted:
Sat Jun 11, 2005 2:39 am Post subject:
Power Strip Causing Ground Loop? |
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|
First, let me tell you that I'm a retard when it comes to electronic
stuff. Anyway...
I was fiddling around behind my computer and got a nice shock. I'm
trying to figure out this problem and am hoping you folks could
help me out.
I get the shock when I touch any part of the back of my computer or
wires, and also touch the metal part of the cable that comes in and
connects to my cable modem. Here's the deal:
I live in an older house that is not grounded. The ground prong on
the outlets isn't connected to ground or anything else. Also, I've
determined that the coax cable coming in to my cable modem is
grounded. Somthing seems to be making the ground prong on my outlet
hot. I've narrowed down the problem to my power strip. I've
unplugged everything from my outlet and I check the outlet for
voltage. Neutral to hot gives me 110V. Neutral to ground give me
nothing (actually, for some odd reason, there does seem to be a
slight voltage (less than 2V). Hot to ground also gives me nothing.
As one would expect.
Now, if I plug in a power strip and do the same check on one of the
outlets on the power strip, I get: neutral to hot 110V, neutral to
ground around 60V and hot to ground around 60V. Is this right?
I've checked this with two power strips and I get the same results.
What would cause this? Is the polarity on my outlet wrong? Or,
am I just a dummy and am misintepreting what is going on. This
misterious 60V is what give me the shock.
Howard
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Todd H.
Guest
|
| Posted:
Sat Jun 11, 2005 2:39 am Post subject:
Re: Power Strip Causing Ground Loop? |
|
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howardkinsd@yaEXPUNGEhoo.com (Howard Knight) writes:
| Quote: | I get the shock when I touch any part of the back of my computer or
wires, and also touch the metal part of the cable that comes in and
connects to my cable modem. Here's the deal:
I live in an older house that is not grounded. The ground prong on
the outlets isn't connected to ground or anything else.
|
Red flag. This is problem #1. This isn't a ground loop. This is an
absence of ground. The former is an inconvenience, the latter can
kill ya.
| Quote: | Also, I've determined that the coax cable coming in to my cable
modem is grounded.
|
Typically staked at the junction box by the cable company.
| Quote: | Somthing seems to be making the ground prong on my outlet hot. I've
narrowed down the problem to my power strip. I've unplugged
everything from my outlet and I check the outlet for voltage.
Neutral to hot gives me 110V. Neutral to ground give me nothing
(actually, for some odd reason, there does seem to be a slight
voltage (less than 2V).
|
The odd reason is that if we believe what you're telling us (i.e. that
your ground on your outlet is completely floating) I'd believe any
voltage you'd tell me between ground and the neutral of the outlet.
| Quote: | Hot to ground also gives me nothing. As one would expect.
|
As one would expect in Danger World where ground is left completely
floating. :-)
In the Safe World, neutral and ground should be the same potential
with 0V, and hot to ground should measure in the 110-120V range.
| Quote: | Now, if I plug in a power strip and do the same check on one of the
outlets on the power strip, I get: neutral to hot 110V,
|
Good.
| Quote: | Neutral to ground around 60V
|
Wee! This is a Big Problem.
| Quote: | and hot to ground around 60V. Is this right?
|
Oy. No.
You gotta remember here, your ground in your outlets is completely
floating, and someone should tell you this is Very Bad.
| Quote: | I've checked this with two power strips and I get the same results.
What would cause this? Is the polarity on my outlet wrong? Or, am
I just a dummy and am misintepreting what is going on. This
misterious 60V is what give me the shock.
|
Call an electrician. Today. You've got potentially lethal problems
with your home's electric wiring. You may also have some power
strips in need of replacement.
60V on your third wire ground is Not Good (tm). Since your computer
is a metal enclosed 3-wire appliance, it's presenting allcomers with
60V ready to shock the crap out of em.
Most aren't aware that surge suppressing power strips do nothing
without a real third wire ground, and it appears that they might also
be creating a rather hazardous situation. I suspect that these may be
surge suppressing power strips with some circuitry that is potentially
faulty (burned out MOV's for instance) and is therefore creating a
more hazardous situation than you have at your outlet to begin with
because your outlet is heinously miswired.
Don't take offense, but do call an electrician.
Best Regards,
--
/"\ ASCII Ribbon Campaign | Todd H
\ / | http://www.toddh.net/
X Promoting good netiquette | http://triplethreatband.com/
/ \ http://www.toddh.net/netiquette/ | "4 lines suffice." |
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Howard Knight
Guest
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| Posted:
Sat Jun 11, 2005 4:31 am Post subject:
Re: Power Strip Causing Ground Loop? |
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Todd H. (bmiawmb@toddh.net) wrote:
: ...your outlet is heinously miswired.
Not miswired, just wired 40+ years ago with no ground. Couldn't I
just ground the outlet myself? Run a wire from the ground in the
outlet to a water pipe outside? Would that solve my problems?
Howard |
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CJT
Guest
|
| Posted:
Sat Jun 11, 2005 4:44 am Post subject:
Re: Power Strip Causing Ground Loop? |
|
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Howard Knight wrote:
| Quote: | Todd H. (bmiawmb@toddh.net) wrote:
: ...your outlet is heinously miswired.
Not miswired, just wired 40+ years ago with no ground. Couldn't I
just ground the outlet myself? Run a wire from the ground in the
outlet to a water pipe outside? Would that solve my problems?
Howard
|
There are electrical codes with which you should comply.
--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form che...@prodigy.net. |
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Rich Grise
Guest
|
| Posted:
Sat Jun 11, 2005 4:44 am Post subject:
Re: Power Strip Causing Ground Loop? |
|
|
On Fri, 10 Jun 2005 21:39:09 +0000, Howard Knight wrote:
| Quote: | First, let me tell you that I'm a retard when it comes to electronic
stuff. Anyway...
I was fiddling around behind my computer and got a nice shock. I'm
trying to figure out this problem and am hoping you folks could
help me out.
I get the shock when I touch any part of the back of my computer or
wires, and also touch the metal part of the cable that comes in and
connects to my cable modem. Here's the deal:
I live in an older house that is not grounded. The ground prong on
the outlets isn't connected to ground or anything else.
|
Then get that fixed by a qualified professional before you burn
your house down or kill one of your children.
Sorry,
Rich |
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Gary Schafer
Guest
|
| Posted:
Sat Jun 11, 2005 4:44 am Post subject:
Re: Power Strip Causing Ground Loop? |
|
|
On Fri, 10 Jun 2005 21:39:09 -0000, howardkinsd@yaEXPUNGEhoo.com
(Howard Knight) wrote:
| Quote: | First, let me tell you that I'm a retard when it comes to electronic
stuff. Anyway...
I was fiddling around behind my computer and got a nice shock. I'm
trying to figure out this problem and am hoping you folks could
help me out.
I get the shock when I touch any part of the back of my computer or
wires, and also touch the metal part of the cable that comes in and
connects to my cable modem. Here's the deal:
I live in an older house that is not grounded. The ground prong on
the outlets isn't connected to ground or anything else. Also, I've
determined that the coax cable coming in to my cable modem is
grounded. Somthing seems to be making the ground prong on my outlet
hot. I've narrowed down the problem to my power strip. I've
unplugged everything from my outlet and I check the outlet for
voltage. Neutral to hot gives me 110V. Neutral to ground give me
nothing (actually, for some odd reason, there does seem to be a
slight voltage (less than 2V). Hot to ground also gives me nothing.
As one would expect.
Now, if I plug in a power strip and do the same check on one of the
outlets on the power strip, I get: neutral to hot 110V, neutral to
ground around 60V and hot to ground around 60V. Is this right?
I've checked this with two power strips and I get the same results.
What would cause this? Is the polarity on my outlet wrong? Or,
am I just a dummy and am misintepreting what is going on. This
misterious 60V is what give me the shock.
Howard
|
The doom and gloomers sure do come out of the woodwork.
There is probably nothing at all wrong with your power strips. If they
have surge protective devices in them what you are reading may be
normal. Some power strips have capacitors from hot to ground and
neutral to ground in addition to mov's. Mov's by themselves have some
capacitance and can act like a voltage divider as one poster
mentioned. The fact that you measure 60 volts would indicate that both
devices are acting in the same manor and dividing the voltage equally,
so they are probably ok. However because of the nature of the devices
it puts some voltage on your items that are tied to the ground of the
power strip.
You should run a ground wire from the ground pin on the outlet back to
the power service panel (breaker/fuse panel). The service panel should
have a ground wire going to a ground rod already.
Running your outlet ground wire to a ground of its own would be better
than nothing but the correct way to do it is to run it right to your
service panel.
Regards
Gary K4FMX |
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Rich Grise
Guest
|
| Posted:
Sat Jun 11, 2005 4:44 am Post subject:
Re: Power Strip Causing Ground Loop? |
|
|
On Fri, 10 Jun 2005 23:31:57 +0000, Howard Knight wrote:
| Quote: | Todd H. (bmiawmb@toddh.net) wrote:
: ...your outlet is heinously miswired.
Not miswired, just wired 40+ years ago with no ground. Couldn't I
just ground the outlet myself? Run a wire from the ground in the
outlet to a water pipe outside? Would that solve my problems?
Use #10 AWG solid bare copper, and if you can't afford to have it |
done by a qualified professional, at least have it inspected by
a qualified professional.
Don't murder your children.
Good Luck!
Rich |
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MetalHead
Guest
|
| Posted:
Sat Jun 11, 2005 4:44 am Post subject:
Re: Power Strip Causing Ground Loop? |
|
|
Howard Knight wrote:
| Quote: | Todd H. (bmiawmb@toddh.net) wrote:
: ...your outlet is heinously miswired.
Not miswired, just wired 40+ years ago with no ground. Couldn't I
just ground the outlet myself? Run a wire from the ground in the
outlet to a water pipe outside? Would that solve my problems?
|
Howard,
First, I think you should replace that outlet strip. They have MOV's
between the hot and ground and neutral and ground. When an MOV gets a
big surge, they start leaking current that they would have blocked
before the damage. Because your ground is floating, the leakage of the
two sets of MOV's has made a voltage divider between hot and neutral
with the ground at the midpoint. Grounding the outlet feeding your
computer is a good idea, but it may trip breakers or blow fuses if the
outlet strip is really hammered.
You might think about getting your house wiring brought up to modern
configuration, proper grounding and GFI outlets add a lot to the
electrical safety of a house. It would probably add to the resale value
as well. If you are in a rental house, good luck.
Bob |
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Jim Adney
Guest
|
| Posted:
Sat Jun 11, 2005 9:51 am Post subject:
Re: Power Strip Causing Ground Loop? |
|
|
On Fri, 10 Jun 2005 21:21:55 -0400 Gary Schafer
<gaschafer@comcast.net> wrote:
| Quote: | The doom and gloomers sure do come out of the woodwork.
|
Yep, I completely agree. It's rather clear that no one before Gary had
much of a clue as to what was really going on here.
What you are seeing is the completely normal result of having a home
system with no ground, a power strip with surge protection, and a
voltmeter with a high imput impedance.
You can leave things just the way they are, but the best thing would
be to update the house wiring and give yourself some good grounds. In
the meantime, your surge protector only gives your computer limited
protection.
A proper ground is applied at the service entrance (where the AC power
enters the house) and follows the wiring out to each outlet from
there. An alternate ground can still protect you from electrical shock
if it is well done, but it may cause other problems and may not allow
your surge limiters to protect your equipment as well.
-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
----------------------------------------------- |
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w_tom
Guest
|
| Posted:
Sat Jun 11, 2005 11:43 am Post subject:
Re: Power Strip Causing Ground Loop? |
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|
Rather scary that so many know so much as to reply ...
without first learning electrical basics.
The wall receptacle safety ground must have a dedicated wire
connection to breaker box safety ground. Not to earth; to
safety ground. And definitely not a connection to pipes.
Wire connection to pipes must be to remove electricity from
that pipe. Never make a connection intended to dump
electricity into pipes. A worst case scenario, a pipe
connection might only electrify a wet human in a shower or
bath. Wet is the worst time to touch electricity.
Connection to earth ground also does nothing useful. The
important connection to earth must be from breaker box only.
A receptacle safety ground must connect to breaker box so that
a wiring fault does trip the circuit breaker. No way around
that grounding (bonding) requirement.
The wall receptacle, power strip, or computer need not be
miswired to obtain leakage voltage. Without a safety ground,
then leakage currents might cause the chassis to 'feel'
electrically hot. Not a danger to a dry human. However
leakage can cause damage to interconnected computer components
and cause other irritating problems.
Easiest solution is to have an electrician route a properly
earthed wire to that receptacle. Electricians have fancy toys
that make 'impossible to route' wires simple.
If a receptacle is not safety grounded, then the circuit
should be GFCIed. GFCI is a minimum necessary correction.
Better power strip is typically about $3+, no nonsense surge
protector or filter components inside, AND the power strip
must include a 15 amp circuit breaker. The breaker being
important for human safety - for reasons not discussed here.
Howard Knight wrote:
| Quote: | Todd H. (bmiawmb@toddh.net) wrote:
: ...your outlet is heinously miswired.
Not miswired, just wired 40+ years ago with no ground. Couldn't I
just ground the outlet myself? Run a wire from the ground in the
outlet to a water pipe outside? Would that solve my problems?
Howard |
|
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Dimitrios Tzortzakakis
Guest
|
| Posted:
Sat Jun 11, 2005 5:12 pm Post subject:
Re: Power Strip Causing Ground Loop? |
|
|
--
Tzortzakakis Dimitrios
major in electrical engineering, freelance electrician
FH von Iraklion-Kreta, freiberuflicher Elektriker
dimtzort AT otenet DOT gr
? "Todd H." <bmiawmb@toddh.net> ?????? ??? ??????
news:8464wm7wn5.fsf@ripco.com...
| Quote: | howardkinsd@yaEXPUNGEhoo.com (Howard Knight) writes:
I get the shock when I touch any part of the back of my computer or
wires, and also touch the metal part of the cable that comes in and
connects to my cable modem. Here's the deal:
I live in an older house that is not grounded. The ground prong on
the outlets isn't connected to ground or anything else.
Red flag. This is problem #1. This isn't a ground loop. This is an
absence of ground. The former is an inconvenience, the latter can
kill ya.
Is this legal in USA?Here, there are people who put shucko-plugs in old |
fashioned three-prong receptacles, with the result, abcence of ground (the
appliance works, but is not grounded).Modern computers that work in the GHz
range need very good grounding, because their case becomes hot otherwise
from induced high-frequency currents.
| Quote: | Also, I've determined that the coax cable coming in to my cable
modem is grounded.
Typically staked at the junction box by the cable company.
Somthing seems to be making the ground prong on my outlet hot. I've
narrowed down the problem to my power strip. I've unplugged
everything from my outlet and I check the outlet for voltage.
Neutral to hot gives me 110V. Neutral to ground give me nothing
(actually, for some odd reason, there does seem to be a slight
voltage (less than 2V).
The odd reason is that if we believe what you're telling us (i.e. that
your ground on your outlet is completely floating) I'd believe any
voltage you'd tell me between ground and the neutral of the outlet.
In my house:hot to neutral and hot to ground 225 volts (3:10 pm)and, of |
course, neutral to ground 0 volts.I have checked every inch of the
installation myself, because I think that electricity is quite a good
friend,but canbecome dangerous sometimes.
| Quote: | Hot to ground also gives me nothing. As one would expect.
As one would expect in Danger World where ground is left completely
floating. :-)
In the Safe World, neutral and ground should be the same potential
with 0V, and hot to ground should measure in the 110-120V range.
Notice however that neutral even having a potential of 0 volts is run by |
large enough currents to cause problems in bad installations (neutral bars
in distribution panels and neutrals in electric ranges e.g. tend to burn to
be charcoaled completely).
| Quote: | Now, if I plug in a power strip and do the same check on one of the
outlets on the power strip, I get: neutral to hot 110V,
Good.
Neutral to ground around 60V
Wee! This is a Big Problem.
and hot to ground around 60V. Is this right?
Oy. No.
You gotta remember here, your ground in your outlets is completely
floating, and someone should tell you this is Very Bad.
I've checked this with two power strips and I get the same results.
What would cause this? Is the polarity on my outlet wrong? Or, am
I just a dummy and am misintepreting what is going on. This
misterious 60V is what give me the shock.
Call an electrician. Today. You've got potentially lethal problems
with your home's electric wiring. You may also have some power
strips in need of replacement.
60V on your third wire ground is Not Good (tm). Since your computer
is a metal enclosed 3-wire appliance, it's presenting allcomers with
60V ready to shock the crap out of em.
Most aren't aware that surge suppressing power strips do nothing
without a real third wire ground, and it appears that they might also
be creating a rather hazardous situation. I suspect that these may be
surge suppressing power strips with some circuitry that is potentially
faulty (burned out MOV's for instance) and is therefore creating a
more hazardous situation than you have at your outlet to begin with
because your outlet is heinously miswired.
Don't take offense, but do call an electrician.
Best Regards,
--
/"\ ASCII Ribbon Campaign | Todd H
\ / | http://www.toddh.net/
X Promoting good netiquette | http://triplethreatband.com/
/ \ http://www.toddh.net/netiquette/ | "4 lines suffice." |
|
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Vidar Løkken
Guest
|
| Posted:
Sat Jun 11, 2005 5:29 pm Post subject:
Re: Power Strip Causing Ground Loop? |
|
|
Dimitrios Tzortzakakis wrote:
| Quote: | Is this legal in USA?Here, there are people who put shucko-plugs in old
fashioned three-prong receptacles, with the result, abcence of ground (the
appliance works, but is not grounded).Modern computers that work in the GHz
range need very good grounding, because their case becomes hot otherwise
from induced high-frequency currents.
|
Bullshit. The potential at the case is power leaked in the psu, not
_any_ other parts in the computer. The psu has a filter on the input,
which leaks tiny currents to ground/chassis. This has nothing to do with
the cpu or any other thing. It has nothing to do with induction afaik.
--
MVH,
Vidar
www.bitsex.net |
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colin
Guest
|
| Posted:
Sat Jun 11, 2005 6:03 pm Post subject:
Re: Power Strip Causing Ground Loop? |
|
|
"Howard Knight" <howardkinsd@yaEXPUNGEhoo.com> wrote in message
news:11ak23tensjvm95@corp.supernews.com...
| Quote: | I live in an older house that is not grounded. The ground prong on
the outlets isn't connected to ground or anything else.
|
if you want to carry on living i sugest you get this problem rectified
imediatly. if you were living in the UK the wiring would be condemed by the
power company as soon as they were aware of it.
Colin. |
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CJT
Guest
|
| Posted:
Sat Jun 11, 2005 8:09 pm Post subject:
Re: Power Strip Causing Ground Loop? |
|
|
Jim Adney wrote:
| Quote: | On Fri, 10 Jun 2005 21:21:55 -0400 Gary Schafer
gaschafer@comcast.net> wrote:
The doom and gloomers sure do come out of the woodwork.
Yep, I completely agree. It's rather clear that no one before Gary had
much of a clue as to what was really going on here.
What you are seeing is the completely normal result of having a home
system with no ground, a power strip with surge protection, and a
voltmeter with a high imput impedance.
|
But ... that combination can be deadly. If you don't believe me,
google "guitar amp death caps."
| Quote: |
You can leave things just the way they are, but the best thing would
be to update the house wiring and give yourself some good grounds. In
the meantime, your surge protector only gives your computer limited
protection.
A proper ground is applied at the service entrance (where the AC power
enters the house) and follows the wiring out to each outlet from
there. An alternate ground can still protect you from electrical shock
if it is well done, but it may cause other problems and may not allow
your surge limiters to protect your equipment as well.
-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------
|
--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form che...@prodigy.net. |
|
| Back to top |
|
|
ric
Guest
|
| Posted:
Sat Jun 11, 2005 11:13 pm Post subject:
Re: Power Strip Causing Ground Loop? |
|
|
w_tom wrote:
| Quote: | Rather scary that so many know so much as to reply ...
without first learning electrical basics.
|
Oh, gawd. He's invaded yet another group. |
|
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