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Battery Backup - Get One
westom:
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. -Shades (June 07, 2009, 03:19 PM)
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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.
Shades:
@westom:
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 page I link to is translated by Google, the original is in Dutch.
If you don't want to read, the best reaction time is 1.2 µsec, which is a lot faster than the values you suggest. Then again, in that region of Holland there were only two ways you were without electrical power:
1 - because of your own stupidity (creating a short)
2 - failing/forget to pay the bill
The electrical grid over there is great and is one I sure miss here in Paraguay (where the grid still uses 110 volt and people stare at you sheepishly when talking about grounding and 'noise-free' power without fluctuations).
westom:
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 -Shades (June 07, 2009, 04:28 PM)
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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.
Stoic Joker:
A nearby utility pole strike is discharged through all routes to ground (e.g. houses on the block). Being spread out lessens its impact on any one individual dwelling. … If however the strike hits (a tree towards the back of the house (opposite the service entry point) the system is effectively back fed which puts a rather different spin on the proverbial ball.-Stoic Joker (June 07, 2009, 01:50 PM)
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Exactly. Slowly we are working towards reality. Apparently you don’t realize the ground rod must be the single point earth ground. Again, you are too quick to challenge rather than learn the significance of what you have just posted. Failure to install the single point earthing means a struck tree is also a direct connection to household appliances if the building earthing is performed incorrectly.
So why would you have damage? Follow the current from cloud to earth. Down to the tree, through earth, up the ground rod, into the building through appliances, out the other side of the building via improper earthing, then miles to those distant charges. That is why homes are routinely built or upgraded with Ufer grounds or equivalent.-westom (June 07, 2009, 03:29 PM)
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You can’t have it both ways… You are saying the a strike (which in your world is a single focused point) hit a (soaking wet) 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 (next to the supply line) … and exists for the sole purpose of directing surges downward?
You insist on assuming I’m sitting on a sandy “bad ground” but given the prevalence of lime rock mines in the area that’s not actually so much the case. Not to mention that being a fan of Power-Line networking, which is dependent on a good system ground I’ve taken the time to go over (e.g. reseat & tighten) all of the grounds in the panel for the purpose of creating a good performance baseline when testing equipment (which is part of my job). And no (before you go off on a tangent) I was not using any of that type of equipment at the time.
Moving on, you are confusing big with effective. All that AC mains conditioning equipment has little involvement with surges. It mostly addresses other problems including harmonics, brownouts, blackouts, and noise.
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Hm… Strangely, that’s not what the engineer giving the tour said … but hay it’s your story.
You I gather work with antennas & communications equipment (given the nature of most of your links). In that environment any hit is always direct because you’re dealing with a 100’ tall metal stick poking out of the ground which makes for a single point of contention. Residential areas aren’t quite that neat. It’s generally more of a ground swell that culminates in two cones (one point up, one point down) meeting in the sky. Who gets how much of what becomes rather random at that point.
Once again I’ll refer to my airbag analogy in simply stating that a UPS can help.
westom:
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?-Stoic Joker (June 07, 2009, 05:39 PM)
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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.
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