household ground system

Hi, I invested in a UPS system, primarily to filter surges and spikes.
However, I know for this to be useful I need a good ground. I think,
but Im not sure, that the ground for my house is a pipe at the side
stuck into the earth, and it looks a little dodgy. So I was thinking
of instlaling my own ground outside my room, in the form of 3 1.5
meter galvanised pipes in the ground. I'd then take a wire from each
and connect each wire to the ground pin of a standard plug. THen, I'd
put the 3 plugs into a 4 way power board, and plug the power board
into a wall outlet. the 4th socket would hold the plug for my UPS.

Are there any problems with multiple grounds for a house system?
POtential problems I can think of, would be

- galvanic corrosion of the ground electrodes
-ground loops
- melting of the powerboard lead iin case of a lightning strike

but I don't know enough aobut the above to come to a conclusion. COuld
anyone give me some advice please?

Thanks,
Arpit THomas

 

** A UPS generates a new AC supply - so how will there be any spikes ???

** Bits of pipe stuck in the ground may produce an electrically quieter
earth than the usual one - BUT there is no way the impedance to will be
as low.

You will be lucky if a short from a bit of pipe to the active even blows
the fuse.




............ Phil

 

You dont, actually. Thats always beena pig ignorant myth.

A decent UPS will get rid of differential mode spikes fine and
thats what the absolute vast bulk of spikes and surges are.

Yes, thats the usual way its done.

In what way ?

Pointless, wont help.

And that wont help either. The surge impedance will be much too high.

If you do want to do something about common
mode surges, you need to put that in the meter
box and that has to be done by a licensed electrician.

It makes a lot more sense to just makes sure that the
house insurance covers that sort damage instead.

Nope, it just wont achieve anything useful.

Sure, but galvanised pipe fixes that.

That wont happen in that situation.

Thats the main problem with doing it like that.

Dont bother, you're wasting your time.

 

sorry, what I bought was a SPS badged as a UPS

isn't the usual one a bit of pipe stuck in the ground? How will the
impedence of mine be higher than the original pipe?

Yep, a good system is typically 25 ohms, thats 10 amps at full line
voltage, so no fuse blowing. THe thing is , this new earth is in
addition to the old one, which is still connected to neutral at the
fuse box, so I expect the fuse will fail

 

hmm, ok. is lightning a differential mode spike? Id think not, but the
fact that neutral is connected to earth may change that? Its primarily
lighting I am concerned with, I lost a couple of hundred dollars of
equipment in the last storm.

the wire to it doesnt even have any insulation and looks tarnished,
THe join between the pipe and the wire looks crusty.

I'm not sure what exactly you mean by the surge impedance, but Im
assuming you mean the poor ability of the earth to take a large blast
of current sourced from elsewhere in the house, because of the thin
powerboard leads. Wouldnt the surge impedance be low on the actual
powerboard itself? THats really all Im concerned with.

I'll look into that, thanks

 

"Arpit" <

** Standby Power Supply ????

** It is linked to every other one in the vicinity via the common neutral
line.

Never heard of the MEN system ??

** You must be completely insane !!

What do you think that damn safety earth is for ????????????

A short from active to the safety earth MUST blow the AC supply fuse or
trip the breaker immediately or the metal case of some appliance could
become LIVE at 240 volts and stay live !!!!!!!

** Then it is quite pointless.




.......... Phil

 

Perhaps I misunderstand you but from my time 25 years
ago in the UK (and other places) doing electrical work,
earth resistance (and it's resistance not impedance)
had to be less than 0R5 (half an ohm) for a domestic
installation. IIRC certain industrial installations could
be a bit more - but not a lot and certainly nowhere
near 25R!

Mike Harding

 

No such reqirement here in OZ (for an MEN system anyway)

IIRC certain industrial installations could

Not a chance of seeing much less than 25 ohms more likely 100 plus in most
instances. (this is one of the resons MEN is used, athough i sometimes
wonder if it would be easier to have an isolated supply but lets not go into
that!)

 

I imagine that is due to the earth consistency and the very dry
ground in Oz? It was sometimes hard to achieve in the UK
but a little salt and water often helped at testing time

I think the UK has largely gone over to PME (Protective
Multiple Earth) ie. bonding of the earth to the neutral connector
at the supply connection point at the consumer premises,
these days - seems to work OK I understand but I guess a
broken neutral at the sub station transformer could cause
some issues - although it would also need a fault to occur
at that time - perhaps unlikely. ("We're sorry you died but
it was a very improbable event" .

Could well be something in what you say.

Mike Harding

 

Mike

Sounds like PME and MEN Multiple Earth/ed Neutral are one and the same
thing - The broken neutral problem you mention should not cause a rise in
the earth potential provided the three phase load on the sub is reasonably
balanced. (although depending on the 3 phase load balance, you may see a
change in the ditribution of the phase voltages.The LV mains(ie415/240) have
the neutral earthed on the supply poles as well as at each main switchboard
neutral link. I am trying to think what it would do to the level of fault
current that would flow if one phase was shorted to the now unbonded earth.
I think that there would still be a "virtual" neutral existing that would
cause the respective protection to operate. Anyone have any thoughts?

 

it only starts its inverter when the power fails

yeah, but if a lighting strikes a power pole in the same vicinity, the
neutral and the active are elevated in voltage. WHether or not thats a
concern, im unsure of.

I mean without being connected to the neutral, just the pipe in the
ground.

hmm ok. So in MEN, if i have a poor earth but my neighbour has a good
earth, we are both ok?

 

"Arpit" <

"Phil Allison"

** If lightening strikes a pole then the local GROUND voltage goes up
just as much as the A and N.

** I give up.

** It means the neutral conductor stays no more than a few volts above
the local ground potential.

Microsecond duration spikes can still exist on A, N or E since any wire a
few metres long has enough inductance to make its impedance high to such
spikes.




............ Phil

 

Those are still called a UPS. Just one type of UPS basically.

Thats called a common mode surge. Its seen much less
often that differential mode surges and spikes where its
the difference between the active and neutral that spikes.

Yes, but that extra ground wont help with that.

You need the surge protector in the meter box with those.

And those surges are so rare in most areas that they
are hard to justify spending what you need to spend
to stop those that arent too close to the house.

You're better to make sure that the insurance covers it.

Its unlikely that you do.

Its undesirable to have a poor earth, but thats
for safety reasons, not for surges and spikes.

 

Usually. Just not with very close lightning strikes.
And that extra earth spike wont help with those anyway.

Yes, basically a very close lightning strike will see
all of the active, neutral and ground all surge.

Even the actual voltage of the physical dirt will too.
Which is why you sometimes see animals killed by
the substantial voltage between their feet.

Most of the damage is caused by differential mode surges.

Adding that extra grounds the UPS like you were
proposing wont help with a close lightning strike.

And wont help with a more distant lightning induced
differential surge either. The problem there is just
the big hike in the 240V seen for a short time.

Thats fine, its copper. It doesnt need
to be insulated because its at ground.

It probably isnt electrically tho. Thats likely just the
part that isnt in electrical contact between the wire
and the pipe. And its easy enough to redo that.

Get the electrician to do that when adding the high
current outlets in the garage. Wont cost much extra.

Its the electrical impedance to the very sharp
voltage spike. Nothing like the DC impedance.

From the active and maybe the neutral too.

Its not the thickness that matters.

Nope, because you've got all the wire between
there and where the lightning struck.

Sure, but that approach wont help.

It doesnt necessarily cost a cent.

 

One largely propogated by an ignorant fool called w_tom who likes to
pontificate at length about Lightning protection but actually seems to know
very little about the subject (well certainly far less than me and I would
hardly consider myself an expert)

It is usually ends up being common mode in strikes to Power lines - in fact
it usually ends up heading for the Neutral/Earth and it is fairly uncommon
for Lightning hitting Power lines to cause damage and in the rare cases this
does happen all the surge supressors in the world would generally not
provide much protection (certainly not w_toms infamous 1KJ movs)

Tell me what equipment did you lose and did you have your modem plugged into
the phone line at the time ?

The most common path for Lightning causing damage is in via Phone/Data Lines
or cable TV
The second most common path is in via TV/Radio Aerials
The third most common path is via building wiring (Alarms, Lans, Audio lines
etc) in near/direct strikes
After this lot comes Damage via Power Lines.

Well actually even worse in the event of a lightning strike extra grounds
added at semi random will increase the chance of something being fried a
good Earth (around 0.5 ohm ) will typically achieve an EPR in excess of
50,000 Volts above Earth in the event of a direct strike.

If your Earth is dodgy it is also Backed up by your neighbours earth etc but
then again maybe you should get a sparky to re-run the earth while he
installs that new 30 A circuit you want



The Earth stakes need to be bonded directly to each other with substantial
braid and at least the length of the Earth stake apart (ie 6 Feet) or is
that twice the length of the earth stake apart ? - to keep them outside of
the 'zone of influence' of each other then bond the Earth system at the
switchboard with the Neutral from the Street.
Next enclose all your equipment in a metal box (Metal room etc) bonded to
this earth system -note when this earth system is implemented properly it
will cost a few $ in fact a decent earth system as used for Radio/TV
transmitters often covers 1000 square meters or more and even then the
Transmitters still suffer Lightning damage from time to time (I noticed
channel 7 went off the air the other night due to Lightning).

Check your house insurance cover Lightning damage

Unplug your Modem from the phone line when not in use,

Log off when Lightning is brewing and Unplug the phone line (computer etc)

Never use an internal modem (Once you have brought the Lightning into the PC
chassis it is all over at least an external modem keeps the Lightning at
arms length)

Back up all important data Regularly

Ignore advice offered by w_tom . ( in fact where is the fool maybe he
received such a bollocking last time he visited aus.electronics he ignores
it now)

 

Hi there,

Sorry to hear about the problems you encountered because of the
lightening. The energy dissipated by a direct strike is HUGE. It is
pretty much financially impractical for a homeowner to install
something capable of handling this situation. The best investment is
an insurance policy that handles this type of event.

In the 70s, I worked at CNCP Telecommunications, here in Toronto
Canada, home of the worlds tallest free standing structure aka the
worlds tallest lightening rod! It gets directly struck many times a
year. I had a tour of the systems installed to handle this:

A copper alloy ground plain the size of a football field.

Huge copper buss bars connecting the antennae systems to the ground
plain (about 1 inch by 6 inches if I remember correctly).

A motor generator set installed on the equipment floor (just under the
restaurant) to isolate the power system from the grid.

All data/communication connections running vertically up the tower are
fibre optic.

There are many "rules" developed over the years about what and how
things can connect together to prevent any unwanted electrical paths.
These have been developed as a result of investigation of failures
after lightening strikes.

Here in Canada, each home owner is required to provide a ground
connection to the utility grid. Three ground rods, each 3.5 meters in
length must be pounded into the earth at least 3 meters apart from
each other. They must be connected with a minimum #8 gauge wire to the
neutral/grounding buss connection in the main power panel. In some
cities, you can use the incoming water pipe as a ground source, but
this is becoming less and less practical because the water
distribution systems are being upgraded to fibreglass/plastic pipes.

The best you can do is ensure your main panel grounding system is up
to code and install surge protected power sources to your equipment.
If you have the opportunity, shutdown and disconnect any electrical
equipment during storms.

The most important thing is to ensure your insurance premiums are
paid!

Cheers from Canada!

Bob M

 

Wrong. As always. Most of the spikes and surges
on the mains due to lightning are in fact differential.

Its only very close lightning strikes that are common
mode. And it aint economically feasible to attempt to
eliminate those in a residential situation. The only thing
that makes any sense in a residential situation is to
ensure that the insurance covers those rare events.

That doesnt necessarily even cost anything, you just
need to make sure that the insurance you buy covers it.

Not for residential housing they dont.

Thats for situations where the cost of outages is very high,
and where the risk of a direct lightning strike is high too.

Not a clue, as always. ALL transistorised equipment
that is powered from the mains has differential
protection built in, because the cost of warranty
claims would be unsustainable without that.

Utterly mangled all over again with the ground stake.
Its just a fundamental part of the MEN system design.

In fact the modern trend is double insulated appliances
where thats practical with no earthing at all.

Not for safety.

Separate issue entirely to the ground rod.

And cant be justified for houses unless they
are in a particularly lightning prone area.

Soorree, not even possible with MEN.

You keep mindlessly rabitting on about what is
feasible when MEN isnt used and havent even
noticed that it aint even possible with MEN systems.

Just not feasible with residential housing.

Not even feasible in this country you pig ignorant fool.

Again, not economically feasible with domestic housing.

Not a fucking clue, as always.

Not a fucking clue, as always.

Not a fucking clue, as always.

Wrong. As always. Thats by far the least common cause of damage.

Not a fucking clue, as always.

None of which has any relevance to
whats practical with domestic housing.

Not even possible with the MEN system, you pig ignorant clown.

None of which are even using the MEN system, clown.

Not even possible with the MEN system, you pig ignorant clown.

Nope, because they realise that its differential mode that matters.

Which is what works with differential
mode spikes and surges, fuckwit.

Not a fucking clue, as always.

Never economically feasible with houses, fuckwit.

Not even possible with the MEN system, fuckwit.

Not even possible with the MEN system, fuckwit.

Not even possible with the MEN system, fuckwit.

Not a fucking clue, as always.

Not even possible with the MEN system, fuckwit.

Not even possible with the MEN system, fuckwit.

Not even the MEN system, cretin.

 

Ahh that is a relief then that means equipment is safe from Lightning
strikes to AC Mains!

Well actually if Lightning were differential it would damage equipment
connected to AC Mains much more often than it does in reality

well this is a load of crap to start with a single Earth stake will suffer
an EPR well in excess of 50,000V in the event of a Lightning Strike
rendering it ineffective This is actually one of the Reasons that the MEN
Earth system is so effective. But then admitting this fact would show that
most of w_toms other statements were crap also.

Unfortunately though Surge protectors are not worth a pinch of .... in a
Lightning strike. Fortunately though the MEN AC power distribution System
actually does a pretty good job of absorbing and riding out Lightning
Strikes.

One or All??? Is it common mode or differential ??? in one sentence you say
it is common mode in the next you suggest it could be either

So this surge leaves on the phone line and goes where ???? Phone lines are
not earthed !! not any bloody where - yes they connect to earth via a feed
bridge at the exchange but this usually adds 1K ohm resistance to this path
to earth and as for surges arrestors in the event they are connected to the
phone line (not all that common in Australia - and this is aus.electronics )
they typically last about 20nS in a Lightning Strike lasting in excess of
100nS (often well in excess).

w_tom as per usual is completely wrong here the most common path for
Lightning damage is :

Lightning hits phone Line (yes even underground Cables) and heads for the
nearest low impedance path to earth - this is typically a modem or fax
Machine. Lightning may pause momentarily to blow the living shite out of any
surge protection connected to the Phone line but really the best earth
available is usually that provided by the MEN Earth via your Modem.

I have seen MDF's at buildings (which did have Surge arrestors installed)
following Lightning strikes where every single Surge arrestor (on a 200 pair
cable so 200 Surge arrestors ) was blown to kingdom come and Modems and Fax
machines in the Building were still fried.

What? Does w_tom actually know the difference between a UPS and a surge
Protector ??? - yes UPS often contain spike suppression but they also often
(depending on the type of UPS) provide isolation which can and often does
provide better protection than a MOV (note that most of the cheaper UPS's do
not provide full isolation until/unless the Power Fails.

Well actually probably the single most important feature for effective
Lightning protection is installing all equipment in an Earthed Metal Box or
Rack and ensuring that all the equipment remains at the same potential.

Bullshit !!! - there really is no other single term that describes this
statement and its inaccuracy adequately - this is a load of utter, utter
Crap - but then would we expect anything else from w_tom ? long and hard
experience by Telco's, and Transmitter owners proves time and time again
that even with the best Lightning protection regimes available Transmitters
and Telco installations can and Do Suffer Damage from Direct Lightning
Strikes.

Yes well I guess this sums up w_toms ideas on Lightning protection ...
Unfortunately though contrary to w_toms wild ideas Lightning follows fairly
simple rules of Physics - and therefore it is not a black art .

Engineers?? when you skim through the list they seem to be mostly Farmers
and even then there are a few who point out that the best (in fact the only)
sure protection is to unplug during a Thunderstorm. But then again that is
probably why w_tom holds these postings up as 'proof' of his fantasies -
there are no engineers on that N.G to argue with him and point out that he -
w_tom speaks utter crap.

In point of fact Rural Power can be quite a different Beastie to
Metropolitan Power with such things as earth return Power feeds and limited
numbers of Houses/Premises being feed by a single transformer (and hence
maybe only 1 or 2 Neutral- Earth connections)



Regards
Joe Van (you work it out ;-)

 

In a desperate attempt to misquote a post he is responding too "w_tom"

hmm it is not immediatley clear what w_tom is misquoting here I suspect it
was :"Fortunately though the MEN AC power distribution System
actually does a pretty good job of absorbing and riding out Lightning
Strikes. "

Unfortunately for w_tom I did not say that all the wires were earthed merely
that MEN does a pretty good job of :
Absorbing Lightning strikes - well this is self apparent if you have a well
earthed Power distribution System (ie MEN) then Lightning is going to most
likely head for the Earth (Neutral) Wire or through all the (cumulatively)
low impedance paths (including the secondary winding in the distribution
Transformer) to MEN Earth

where / how do these cause damage ?? as per usual with all of your claims
you are wrong !! explain using basic electrical Theory and physics how
common mode transients cause damage. But anyway it seems you do not
understand the MEN system - dont feel alarmed at your ignorance you show it
in regards to almost everything you choose to pontificate about - The
Queensland goverment have a good little series on MEN at :
http://www.eso.qld.gov.au/publicat/men/

Like many of your claims this contains a thread of truth but in the
application you have presented it is fundamentally flawed and in fact wrong
!! the earth stake is at 50,000Volts however unless the House is made
completely of metal then the house is Not ! neccasarily at 50,000V so that
the poor sod at the sink putting on a Kettle of water suddenly provides a
good path from the AC Mains Earth through to the water pipe connected to the
sink, connected to the

I see you must have a wee bit of trouble with basic Physics lets see now
.....
Yes you are right Current is a dominant Factor as is hmmm ..... thats It !
Earth Resistance ! ummm lets see now -
Typical Lightning Strike Current > 100,000 Amps
Good Earth stake = 0.5 Ohms
Now whats the name of that law Thingy well known by all first year
electrical/electronics Students .... hmmm that one that is so well known
that even Sparkies often know it ..... Something to do with Ohm Thingys
wasent it ??? ..... Ahh yes OHMS LAW !!!

E=IR
E=100,000*0.5
E=50,000 Volts !!!!

I knew I figured that one out somehow ;-) I guess w_tom doesnt know :
1) Facts about Lightning
2) Basic Physics
3) Basic electrical Theory

Remind me again when was your beloved MOV developed ???

where are your esponsible citations talking about protection of domestic
premises ??
Your Main problem is that you have so little understanding of Lightning
protection, Physics and basic electrical Theory that you take examples of
Protection systems that do enjoy some (but not complete as you claim)
success against Lightning then assume that implementing half the system in
for e.g. a domestic premises is going to afford better protection than
offered by the system when fully implemented.

It is actually a system employed by Electricity authorities around the world
Because it offers the best inherent protection and Safety of any
Distribution System. This information btw is available in most primers on
power distribution systems.

....Oh sorry the 'Protection Industry' arent interested in publishing the
fact that the millions of Surge arrestors etc in fact offer no extra
protection than that already offered by the MEN distribution System I wonder
why that would be ??? can you spell Vested Self Interest or hysteria ? The
fact is that Lightning damage from AC Mains on the MEN system is very
uncommon and in the cases where it has occoured most common Surge protection
(including a 1KJ mov in the switchboard) would have offered no further
protection anyway. The rael Dirty little secret is that AC mains surge
protection offer little if any extra protection than that offered by :
protection already provided by the equipment itself or Protection already
provided inherently by the MEN distribution system

how does MEN work ? simple, Basic physics and simple electrical Theory. It
is well known that a single Earth stake often has a resistance to earth in
excess of 1/2 an ohm - multiple earth stakes connected together by
relatively low impedance wiring offers a far better earth than a single
earth stake. In addition it offers redundancy of the Earth/Neutral return. a
win win situation all round.

But any way now I have answered your question you still have a number of
outsanding questions you have not answered starting with the ones you
squirmed out of answering in my last post by your usual habit of top posting
:

First in response to :

I asked :
* One or All??? Is it common mode or differential ??? in one sentence you
say
* it is common mode in the next you suggest it could be either

which really helped Highlight w_toms ignorance of simple electrical
terminology as he seems to have trouble understanding what 'common mode'
actually means

then in response to :

I asked:

* So this surge leaves on the phone line and goes where ???? Phone lines are
* not earthed !! not any bloody where - yes they connect to earth via a feed
* bridge at the exchange but this usually adds 1K ohm resistance to this
path
* to earth and as for surges arrestors in the event they are connected to
the
* phone line (not all that common in Australia - and this is
aus.electronics )
* they typically last about 20nS in a Lightning Strike lasting in excess of
* 100nS (often well in excess).

then w_tom stated:

to which I asked :

What? Does w_tom actually know the difference between a UPS and a surge
Protector ???

and then there are questions from the past that w_tom is still yet to answer
:


Have you found out what a thermal Fuse is ?

Tell me how Lightning is a low energy event.

where and what is the direct connection between AC Mains and the Integrated
Circuits in a modern modem ?

explain how 0.28mm^2 copper wire (phone line) povides a much lower impedance
path than 2.5mm^2 copper wire (Power cable) and hence a better path to a
nonexistant earth.

Tell me how long your much loved 1KJ mov lasts in a Direct Lightning strike
?

how long does a surge last ? - what is the definition of a surge ?

what do you do or did you do for a living w_tom ?


I am sure w_tom will squirm out by top posting in answer to this posting so
he can avoid answering the points raised but then that always was his style

Regards
Joe Van (Guess its still Me ;-) )

 

Dont worry Joe that is a Classic w_tom Tactic he/It ( the moron incarnate )
will carefully avoid answering or quoting you directly that way he/it can
carefully misrepresent what you said and Lie blatently about you ( joke here
Q) how do you know when w_tom is writing crap ?
A) he is writing about anything to do with Lightning on a Newsgroup)

w_tom seems to use Google groups to find references to Lightning protection
so he can rush in and speak crap about Subjects he knows Little about ie
Lightning protection, Basic electrical theory and basic physics

Well actually joe you are being conservative here 1/2 ohm to earth is a good
Earth stake - a damn good earth stake I am willing to bet they are not often
that good and 100,000 Amps is a smaller ground strike

I personally am astounded that w_tom is intelligent enough to know how to
breath without written instructions..

Late 50,s early 60s I guess WWII was running late

I will let you into w_toms dirty little Secret - he actually knows
absolutely nothing about Electricity, Electronics or Lightning protection

posting

well actually you forgot the fundamental question which gives the whole game
away : Why is the AC mains distribution system Earthed ? what does Earthing
it accomplish ? - if you followed the sort of logic w_tom uses floating the
AC Mains actually makes it safer - think about it you could hang on to an
Active quite safely and since you are not completing the circuit you should
be O.K - the real question is why is this untrue ?

Ahh you found my list on Google - w_tom must have me killfiled as he never
answered my posts asking these questions - I think he realised I knew a heck
of a lot more about Lightning damage and protection than he/it did. as he
stopped responding to my posts pointing out what a complete moron he/it was.
In fact you have kicked him/it so thouroghly in the goolies in this post he
has probably just added you to his Kill file too, Like me and probably Rod
speed. He he he he he

Good luck getting through to the Moron w_tom you will need it

Best Regards
Maintain the Rage
Richard Freeman