In Holland any electrical installation you can think of has to be grounded...by law. Insurance companies don't even pay if your house burns down because of an electrical failure if no proper grounding is in place.

Earthing has long been required everywhere.  However surge protection in the US required earthing that both meets and exceed post 1990 National Electrical code requirements.    A date that suggests how many homes still have woefully insufficient earthing.

 An example.  One FL couple had lightning repeatedly strike an outside bathroom wall.  They installed lightning rods.  Lightning again struck that bathroom wall.  Why?  Lightning rods were only earthed in sand with 8 foot (3 meter) ground rods.  Bathroom plumbing made a better connection to deeper limestone.   Lightning avoided ightning rods to obtain a better connection to earth.

 For surge protection, earthing also must be single point (as demonstrated why in a previous post).  Ufer grounding or equivalent is routine in FL due to poorer conductive sand and the higher frequency of surges. And then all incoming utilities are earthed short, no sharp bends, etc to that single point earth ground.  If the cable enters from the other side, then the house has been setup to have surge damage.

 Circuit breakers never stop damage.  A circuit breaker's function is to disconnect power after something has failed.  Protection of human life from fire created by already existing damage.

  Now put numbers to it.  A circuit breaker takes tens of milliseconds to respond.  A surge is done in microseconds.  300 hundred consecutive surges could exist and the circuit breaker still never trips.

 A circuit breaker would stop or block what three miles of sky could not?  Of course not.  Never happens.  That damning fact defines the difference between effective protection (ie a 'whole house' protetor or why nothing inside the church was damaged) verses a protector that magically absorbs surges.  The one factor that defines even how good a protector is – earth ground.  No earth ground means no effective protection.  A protector is only as effective as its earth ground.

 This is not popular in retail stores where such protectors (and earthing) are not sold.

After taking a look you were more or less right about reaction times, however I found a schematic (near the bottom of the page) which explains better what I meant. ... the best reaction time is 1.2 µsec

  Your citation is more commonly known as a GFCI or RCB.  If the outgoing current does not match the incoming current, then the breaker assumes a human is being shocked – and cuts off power.

  Will a switch stop a surge?  Of course not.  Surges are currents whose voltage increase, as necessary, to blow through any blocking device.  Why do surges find no problem conducting through 3 miles of the most non-conductive material – air?

  Furthermore, switches always take milliseconds.  Even fast blow fuses take milliseconds.

  To do 1.2 usec, the power must be controlled by semiconductors.  That means the blocking ability is even less.

  Appreciate what it is blocking?  A constant voltage of 240 VAC.  Surge voltages typically go to 6000 volts when something tries to stop the surge.  Your source says the electronic device must withstand 6000 to 8000 volts. That is not stop it.  That is survive a current pulse that, if stopped, could generate those voltages.  The standard solution – to not block those currents so that a massive voltage is not created.  Not block as in let the surge go where it wants to.  Don’t try to do any surge protection.

  GFCIs, et al have become standard in the industrial world since first demonstrated in the 1960s.

You can’t have it both ways. You are saying the a strike … hit a … pine tree (which has a 30-40 foot tap root), but decided to completely ignore its already being deep underground and decided to come back up through a ground rod which is on the (lengthwise) opposite end of the house … and exists for the sole purpose of directing surges downward?

Again you are making assumptions rather than read what was posted.  Did you see the phrase about earthborne charges miles away?  Apparently not.  Without understanding the principles, then you misrepresented what was posted; did not grasp what was posted.  What was posted has been understood for most of the last 100 years.  There is no contradiction.  But there is a reader who is having difficulty dismissing and forgetting the myths he once believed.

 In one location, surge protection was properly installed.  Damage occurred.  Why?  In earth were veins of graphite.  Since earth was not monolithic, protection system (earthing) needed upgrading.  They had what you have described – pockets of more conductive earth.

 Tightening grounds is nice.  And does little for better earthing.  For example, how does the 6 AWG ground wire connect to a ground rod?  Up over the foundation and down to that rod.  Sufficient to meet code.  And insufficient for surge protection.  That ground wire must go through the foundation and down; to be shorter, no sharp bends, separated from other wires, etc.  

 Meanwhile a lightning strike to the tree could have also forked off into AC electric, buried power line, etc.  Most all strikes leave no apparent indication.  With questions, we eventually discover they had no idea where lightning struck.  They assumed  - then converted assumptions into fact.  Same problem is repeated often in this thread.

 I provided only a sample of reasons why you had damage from a struck tree.   As a novice, you might finally begin to learn this stuff in highly regarded application notes from Polyphaser:
 http://www.polyphaser.com/technical_notes.aspx
Warning: this may be tough reading if too attached to many erroneous myths.  Too many make assumptions and therefore need to reread it more often.  You see contradictions only because you have not grasp some basic concept.

 From information provided, your had damage because and the solution begins with earthing.  If earth has pockets of more conductive earth (lime rock mines) or if a major pipeline passes nearby, then your earthing needs additional improvements.  If at the end of a AC distribution system approaching from the west, then frequency of damage would be even higher – more corrections required.  How to do this is more complex.  But the description of your damage is typical of bad earthing and no ‘whole house’ protection.

 Most homes are still built as if transistors do not exist.  Surge protection starts when footings are poured.  Many supplement a weak protection system with compromises.  Some foolishly think a cold water pipe entering on the other side of the basement is good earthing.  Wrong – for so many reasons posted previously.

 Bottom line in any facility: if damage results, then corrections start with a study of earthing.

@bob99 - We're on the same page man, just different paragraphs... You're talking about a proper surge device that actually has power conditioning circuitry. I'm talking about one of those Cheap-O power strips (that most end users seem to end up with) that only has a breaker in it.

Almost all 'cheap-o' surge suppressors I've seen, (or have), use MOVs because they're cheaper than circuit-breakers.

A typical cheap surge suppressor circuit is, (taken straight off one I just pulled apart):



If a sufficiently large surge gives the MOV a hard time, it will, generally, go short-circuit thereby turning on the LED and thus giving a failure indication.

If your strip has a circuit-breaker then I'd take a pretty fair guess that the circuit-breaker is there for output current overload protection.  A thermal circuit-breaker is just too slow for surge suppression use.

If you open it up I'm sure you'll find a MOV is across the line to do the actual suppression.

In Australia, I believe it was regulated that all power-boards, (power-strips), have a circuit-breaker to guard against output current overload.  Previously they didn't and there were some reports of fires starting by people plugging too many things into power-boards, IIRC.  I'd be surprised if America didn't have a similar regulation.

Enough is enough, Judging by your joined on date & first post you joined this board for the sole purpose of launching a rather highhanded & condescending attack on me. For the “crime” of sharing the events of my day with fellow members. Your imperialistic attempts at making me look stupid have only succeeded in impressing me with your arrogance.

Feel free to enjoy your “win”, as I will not be returning to this thread.

Your reply to westom came in while I was typing away at this and I was then in two minds as to whether to continue or not.  As it is, maybe someone will find my post relevant - so here it is.

EDIT: Stupid me, I got my circuit round the wrong way 

Almost all 'cheap-o' surge suppressors I've seen, (or have), use MOVs because they're cheaper than circuit-breakers. A typical cheap surge suppressor circuit is, (taken straight off one I just pulled apart):

That circuit is incorrect.  View MOV datasheets.  Leakage currents are well below 1 ma.  An LED requires at least 10 ma.  Furthermore, 1 milliamp through an MOV is a test current for its threshold voltage - a voltage well above what should be on AC mains.

  Circuit breaker does nothing for surge protection for so many reasons.  CB is a device required for every power strip – with or without protector circuits. Installed only for human safety.

Thermal fuse is required so that a failing (grossly undersized) MOV does not create fire.  Thermal fuse disconnects MOVs long before an MOV conducts anywhere near what might be its maximum protection.  Sometimes the fuse does not work which is why most fire departments have been called for protector fires.  Problems detailed in so many previous examples and in Norma’s quoted experience.

  MOV is effective if it has something to divert surge energy into.  That means a low impedance (ie ‘less than 3 meter’) connection to single point earth ground.  No earth ground means no effective protection.  No earth ground means a protector may divert that surge destructively inside the building – maybe destructively though some appliances.

  Meanwhile your circuit is incorrect – is missing other critical connections.  Your assumption is that the MOV can fail catastrophically.  As repeatedly noted, that is not an acceptable failure mode.  Again, read page one of every MOV datasheet.

  How is the light connected?  See the picture where all MOVs are removed – and the light says that protector is still good:
  http://www.zerosurge.com/HTML/movs.html

Quote from: 4wd on June 08, 2009, 03:20 AM

Almost all 'cheap-o' surge suppressors I've seen, (or have), use MOVs because they're cheaper than circuit-breakers. A typical cheap surge suppressor circuit is, (taken straight off one I just pulled apart):

That circuit is incorrect.  View MOV datasheets.  Leakage currents are well below 1 ma.  An LED requires at least 10 ma.  Furthermore, 1 milliamp through an MOV is a test current for its threshold voltage - a voltage well above what should be on AC mains.

Aaargh!  You're right, next time I'll grab some glasses - corrected circuit:

Circuit breaker does nothing for surge protection for so many reasons.  CB is a device required for every power strip – with or without protector circuits. Installed only for human safety.

ummm, yes - as I stated.

Your assumption is that the MOV can fail catastrophically.  As repeatedly noted, that is not an acceptable failure mode.

No offence but while it may not be an acceptable failure mode, it is a fact of life.  Everything is subject to catastrophic failure no matter how well engineered or designed it is.  The fact that something hasn't failed catastrophically is simply due to not having the right circumstances in place for it to occur.

EDIT: And as a side note, it shows you how cheap they make these things because that really isn't a good way to power an LED from 240V - the resistor dissipates for more power than is necessary all because they don't want the added expense of a mains-rated capacitor.

Truly interesting discussion. Thanks, everyone!

I've been using a Cyberpower CP1500 with the LCD screen for the home office machines, and an APC BR1500 for the server. Both have been running without problems for the last couple of years. I keep an older APC 850 to use with a machine dedicated to audio work; there's seldom any load on it. I've had battery backups since I built my first 486 machine, and yes, surge protectors as well.

Lightning isn't the issue here in Los Angeles; I'm more concerned with having equipment bolted down when the ground shakes!

  Let's see, my electric goes through three fuse boxes, my computer system is on a battery backup plugged into a voltage regulator to prevent the battery backup from constantly switching from online to offline while on generator power.  I think I'm pretty well protected... 

  You may be protected.  But your electronics are not.  Fuses do  not protect electronics or appliances.  Fuses only stop fires from happening after the damage has been done.  Fuses, circuit breakers, etc are only for protecting human.  Even the UPS does not provide and does not claim to provide appliance protection.