I've read a good deal about the above. Ideally, the grounds for various (telephone, cable, power) electrical utilities should all be common; and the service entries for those sundry services should be located within
15' of each other.
If I ever build a new house, I will take that into account.
However, it's not practical at this time to realize the ideal. What I have currently is as follows:
The phone drop (two lines) comes in on one side of the house and is grounded to the water supply line which comes in the front of the house (about of 20' of wire clamped to the pipe where it comes through the foundation into the unfinished basement).
The power drop (100 amp 220v single-phase) enters at the back of the house, about 30' diagonally from the phone service. A ground wire snakes from the panel (inside a utility porch) around a couple of corners and through the floor to a ground post of unknown length/depth in the crawl space beneath the adjacent kitchen...approximately 20 feet of wire with at least two 90 degree bends.
The cable drop is around 15' feet from the power service entrance, and grounded to an adjacent outside faucet a couple of feet away (all plumbing in the house is copper).
Over the years, we've had a good deal of surge and lightning related damage to devices in the house...most recently a DSL modem.
Would I derive any advantage by driving a new ground post outside, adjacent to the power drop and to run all the various service grounds to it (around 15' for cable, 25' or so for phone)?
Alternatively, I could move the telephone ground wire to the existing power drop ground post (probably using the same 20' wire), and also extend cable ground to this point. That would give me a 'star' configuration with all utilities having around 20'-30' of wire from each drop to ground.
Moving the phone service drop at this time (the ideal) is not practical.
Could anyone explain why a US telephone cable needs a local ground? Aren't they balanced?
The UK system only used a local ground for shared local lines which went out years ago.
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hmm.. I can't say I know of many overground telephone wires in my area, except in older houses that have overhead power service, they used to string the telephone wire under the power wire, but the main phone lines are all burried.
I found out the hard way that burrying the wire doesn't help with lightning protection when I ran a cat5 ethernet wire from my house to a friends last year. That thing got zapped evey time we had a bad storm..
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No I'm not talking a small spark when you plug it in. I'm talking about lightning hitting the wire during storms. It would arc off the wire when it wasn't plugged into the arrestor.
Described by jakdedert is a building all but begging for lightning damage. For example, a cow stands in an open field when lightning strikes a nearby tree. The cow is killed. Killed by electromagnetic fields? Of course not. Killed because cow was part of a path from cloud, through tree, into earth to earth borne charges maybe miles distant. The electrically shortest path was not under the cow. It was up cow's hind legs and down fore legs. Cow was part of a direct lightning strike from cloud to distant earthborne charges.
Cow could have lived is a halo ground surrounded the cow. That buried conductor would have, instead, routed electricity around (not through) cows. The concept is called single point earthing. Cow with separated legs has multiple earthing connections - therefore dead. Cow centered in a halo ground has a single point ground.
jakdedert describes here (and previously) utilities (ie mutli-line phones) entering and earthed more like the cow. Building is even worse because earthing points are farther apart. Destructive charge can enter building on telephone line (overhead or underground line) either from its grounding connection or via utility wire (from nearby struck tree, from other struck building, or entering via ground rod). That transient crossed building, destructively through appliances, to obtain earth via AC electric.
Connecting phone line with a 20' plus ground wire or via pipes accomplishes little. Wire has impedance. That means earthing from each incoming utility to a single point earth ground MUST be less than
10 feet. Other features such as no splices, no sharp bends, no solder joints (on wire or pipe), etc also required to lower impedance. Not resistance - impedance.
A minimal single point ground is a grounding rod. That means even incoming cable TV wire must make that 'less than 10 foot' earthing connection to earthing electrode. Better earthing is a halo ground (what saved the 'dead' cow) or even better, Ufer ground.
What does a protector do? A protector only connects from AC electric or phone lines (that cannot be earthed directly) to an earthing electrode. Protector is nothing more than an connection. No earth ground means an ineffective protector - which many overpriced, plug-in protector manufacturers hope you never learn. Plug-in protectors that have no earthing connection, then, connect to what? They hope youj never ask that question.
Cable TV does not need protectors which often degrade cable modem or TV signal. Cable is earthed directly - hardwired - to earth without any protector for superior protection. Wire does better than a protector.
An electric utility demonstrates bad, good, and ugly earthing. Ugly because the earthing electrode must be 'lengthened' so that all utilities make a common earthing point:
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Water pipe typically is not good earthing. Pipes too long, too far away, too many sharp bends, solder joints, etc. A major difference between earthing for human safety verses earthing for transistor safety. A major difference between resistance and impedance means wire distance is more critical that a low resistance ground. Worse, jakdedert describes grounding to pipes or water faucets. That means ineffective and multi point earthing - that also killed the cow.
Most critical component in a lightning protection system is earthing. Earthing defines uality of that protection 'system' and effectiveness of protectors. Ineffective plug-in protectors avoid all mention of earthing to sell hyped products at higher profits. Such ineffective products have no dedicated earthing connection AND avoid earthing discussions to keep customers ignorant. Bottom line: a protector is only as effective as its earth ground.
Effective protector manufacturers have names such as GE, Polyphaser, Square D, Intermatic, Siemens, Cutler-Hammer, and Leviton. Their effective products have that dedicated earthing wire.Notice that names such as APC, Tripplite, Belkin, and Monster are specifically not mentioned. The telephone company already installs an effective 'whole house' protector in their NID (premise interface) box. But again, you (the owner) define its effectiveness by providing an earthing system.
UK residents who suffer so few lightning storms also suffer frequent and unnecessary damage. This because UK incoming phone lines don't have that necessary earthing. BT does install effective earthed protectors on their end. But subscribers are expected to pay for their own protection - which is provided free in North America.
Also is a myth that underground wires are better protected. Does not matter as demonstated by the 'dead' cow. Any utility that does not first connect to single point ground before entering a building is an obvious incoming path for household electronics damage. As the 'dead' cow demonstrates, single point earthing means even a nearby lightning strike can be a direct strike into building electronics - if building's earthing is not properly installed and connected to by every incoming utility wire.
Damage could have been from voltage potential between different build> Michael Kennedy wrote:
Yes, I've had problems which I have detailed here before. Still, the above (and snipped portions) still beg the question: It's gonna be at least 20 feet of copper between the service and ground. Still better to single point? That's the 'hit' I'm getting....
Anything would be better than what we have, right? Upgrade the ground conductor? I've read (here?) that 1/8" copper tubing is superior to the (looks like) 12 ga. wire currently used in the phone and power grounds.
From the above, I'd assume that 'anything' I did to lower (and equalize?) the impedance to ground would be--even though not ideal--at least an improvement. How about multiple ground rods, one at each service drop--connected together with the aforementioned tubing?
I know that if I could get the telco to drop the lines in between the cable and power drops, the job would be significantly simplified...and yes, I have a 100'+ oak tree within 20' of the house.....
'Tree' does not mean it must be a tree. Lightning could strike a rock, a neighbor's house, a transcontinential pipe line, or even a water box to create same effect. Earthing is the one solution always required even if lightning strikes something distant or if lightning strikes street utility wires.
Did you view 'bad, good, and ugly' figures from cinergy.com? That earthing (in this case a 'right' solution) must conform to two masters. One, for earthing transients (ie lightning). Two, to meet electrical code defined in NEC Article 250 Section III (Artcile 250.50 through
250.70. Section III defines seven types of grounding electrodes and numbers that apply including wire sizes.
For example, install a ground ring terminated by rod electrodes (8+' copper clad steel rod). Since that ground ring has a ground rod where each utility enters, then each utility can make a 'less than 10 foot' connection to top of ground rod. Each rod is the same, large, single point ground.
Code demands a ground ring be 2 AWG bare copper wire buried at least
30 inches. From your perspective, this so that ground wire is below frost and remains in soil of constant humidity. Suggested is to obtain of copy those five pages from an National Electrical Code book (maybe in the library) to better appreciate what is required of each (of seven type) electrodes.
Above to meet code. However grounding wires (to attach to that single point ground) also must not have splices, no sharp bends, not inside metallic conduit, routed away from all other non-earthing wires, and must be firmly attached with proper connectors - for conditions beyond what code requires. Best that all earthing wires remain separate until all meet at the single point earth ground. Don't worry about exceeding wire diameter. Worry more about wire length. Every foot shorter than 10 feet means less electricity from lightning will seek earth ground via household electronics.
Next part of that system would connect every wire from every incoming cable to that earth ground. Telco has a protector from each (of two) wires in cable to the ground wire. AC electric has three wires - only one connects to earth directly. Therefore 'whole house' protector (see manufacturer list that includes GE, Square D, etc) in AC mains box connects other AC wires to that earthing wire.
Coax for cable TV and satellite dish use a ground block ($2 available > Yes, I've had problems which I have detailed here before. Still, the
Thank you, Tom...I think. I'll have to reread your post several times to get the gist of what you're saying. I'll also do some (more) research and get the relevant parts of the Code.
'Tree' in this case does mean a tree...a big one, the highest single point on my entire street...even though there are houses which sit considerably higher than mine. This is one big tree...probably at least part of the reason I seem to be plagued.
I'm assuming the DSL modem and computer are plugged into the same outlet . . .
It sounds like you have two unknown grounds that are far from the ideal. You don't say what the failure mode of the equipment is and how severe - I'm guessing it is probably common-mode developing between the two ground systems. If you get something like bridge rectifiers in power supplies shorting - that could indicate a differential voltage spike.
Or, better yet, start at the beginning . . .Check the power transformer. There should be a lightning arrestor for the transformer
- a kind of insulator that sits off to the side of the can that is clamped to the can and has a small 1/2"-1" air gap between it and the HV terminal. (designs vary quite a bit but it should be there in some form - a collection of broken porcelain around the base of the pole and some carbon blocks means it is done its job once too often)
The transformer pole and transformer must be grounded. There should be a thick soft copper wire running from the transformer down the length of the pole and into the ground. Usually the wire is wrapped in a spiral and nailed to the bottom of the pole.
Without the transformer grounded - anything you do may be wasted effort. I had no problem getting a neighbor's lightening arrestor replaced with just a call to the power company and, in another instance, a pole ground wire replaced - they are subject to being stolen by people trying to salvage the copper. Two different power companies and no arguments - they just went out and fixed it.
Your best option is probably to get the grounds on the same circuit. I'd sink a ground and wire to it, so I knew what its condition is like. (ten foot length of half inch dia copper water pipe washed into the soil is better than anything you're likely to drive into the ground) Braze or solder the heavy wire on. Put it at the power entrance as directly under the power meter as you can with no bends in the heavy wire. Five or six feet to ground if you can manage it with no bends. Use a large radius bend if you go around an obstacle. It may not be practical, but do the best that the conditions allow.
What to do about the telephone line and power line separation? Sink a separate ground for the phone line and just use it for the lightening arrestor on the line and make sure it is bonded to the main power ground. There was some good stuff in an ARRL article some years ago that mentioned a similar problem. He solved it by adding a ground for the phone line directly under the phone's entrance box to the company supplied arrester then added a set of gas filled spark gaps in addition to the arrester.
Cold water pipes are iffy - they can be excellent grounds or very poor grounds. Too many variables - you'd have to know the material and condition of the pipe, how straight the run to ground is, and what the joints are like electrically. Some old systems used cast iron pipe and the joints are not connected electrically. Some really old cities still pull up a wooden water main from time to time . . . Galvanized threaded joints are usually pretty good if the pipe was clean when the pipes where joined and someone didn't get carried away with Teflon tape.
Beyond that you can still get fancy with isolation transformers or optical links.
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An excellent paper from the IEEE on surge and lightning protection (which came from a w_tom post) is at;
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Contrary to what w_tom says plug-in point-of-use surge protectors do provide protection and are recommended in the paper above. All the electrically interconnected apparatus, like tuner, amp, has to be connected to the same surge protector. If there are external lines, like cable TV, the apparatus can still be protected using a multiport plug-in surge protector that, in addition to the power protection, has through ports for the cable connection (and/or phone line, LAN connected to devices not on the same surge protector, ...). Multiport surge protectors, and how they protect, are described in the IEEE paper.
Another paper is from the NIST
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It also recommends point-of-use plug-in surge protectors.
I agree with w_tom that single point grounding for wires entering a building (also dish antenna) is a very good idea.
(A multiport surge protector provides a local single point ground at protected equipment.(
Why don't you get objectionable drop through the ground ring? (Not to say that the ring isn't a good idea.)
When you talk about a "halo ground", as for your cow, I presume you are talking about a ground ring. The only use of "halo ground" I have seen is as in PolyPhaser papers - a conductive ring around a room ceiling-wall edge, that may or may not be earthed, to counter the field effects from the down current from a lightning strike on an adjacent antenna tower.
If cable and power entrance points are separated, it would seem like the cable could be wired from the its entrance ground block to a 2nd ground block adjacent to the power service entrance, with a short connection from the 2nd ground block to the power service grounding electrode conductor. Cable distribution to the building from the 2nd ground block. Similarly a secondary phone protector block could be installed adjacent to the power service. I have never seen this suggested but it seems like a practical way to get a single point ground.
We had been through this before in alt.engineering.electrical. Those who once strongly advocated 'point of use' protectors (ie ex-GE employees) have backed off that recommendation. One example is an IEEE paper by them about an "Upside Down House". Francois Martzloff and Thomas Key in 1994 wrote in "Surging the Upside-Down House: Looking into Upsetting Reference Voltages" :
Why do those who once always advocated only 'point of use' protectors now change their tune?
Effective protection at the appliance is already inside appliance. If components inside 'point of use' or plug-in protectors were so effective, then those $0.05 parts would already be inside each appliance. Once they were installed. But since those parts (currently inside plug-in protectors) were not effective inside appliances, then appliance manufactures use only other well proven techniques internally.
This internal appliance protection assumes a transient will be earthed before entering a building. That being the purpose of a 'whole house' protector that also costs tens of times less money per protected appliance. If not earthed, then a transient can overwhelm protection inside appliances. As Martzloff, et al noted, excessive voltage can occur even "perhaps because, surge protective devices are present at the point of connection of appliances". Martzloff was once a major promoter of 'point of use' protectors.
Do we spend $20 to protect every appliance - or do we spend far less money to enhance earthing? Per dollar, earthing provides major appliance protection. Point of use protectors - if for no other reason
- cost massive dollars and provides little benefit. Again, if it were effective, then those same parts costing so little (and selling at exaggerated profits) would already be inside appliances. Shunt mode protectors are only as effective as their earth ground. Plug-in protectors have what for earthing? So instead, plug-in manufacturers forget to mention earthing (since earthing is not provided by plug-in protectors) AND forget to mention protection already inside appliances. Profits are just too large to be fully honest. Protection is earthing.... the most critical component in every protection 'system'.
How does a shunt mode protector do anything effective when it does not shunt to earth? Manufacturer hopes we don't ask that question. Plug-in protector manufacturers, instead, cite protection from transients that don't typically cause damage - and hope you don't notice. They hope you never learn why earthing is so critical - profits being too outrageously high to be fully honest. Even those who once only recommended 'point of use' protectors are now changing their tune in IEEE papers - citing advantages of 'whole house' protectors - that also cost tens of times less money per protected appliance.
Why would an objecti> An excellent paper from the IEEE on surge and lightning protection
This is exactly what a multiport plug-in point-of-use surge protective device protects against. These are called Surge Reference Equalizers by the IEEE. Another paper specifically about SREs is
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pdf This paper is currently available from the NIST in a collection with a forward by your good buddy François Martzloff (who was an author of this paper).
I have provided links to an IEEE paper and and 2 NIST papers, all current, that recommend plug in surge protectors. In previous threads (and this one) I have not seen any links supporting your view. Its you against the IEEE and NIST (and a lot of other people).
Default makes an important point. Defined for a house is a 'whole house' protection system - also called secondary protection. Primary protection is provided by the utility, as default has described. Pictures that demonstrate inspection of a Primary protection system:
In Bud's cited 1993 paper on 'surge reference equalizer' or 'multiport protector', Martzloff, et al defines a problem common in most residences where traditional plug-in (point of use) protectors are used:
IOW power strip protector simply creates one of many defined transient problems that contribute to electronics damage:
Suggested by that 1993 paper is a multi-port protector - surge reference equalizer- that only uses a principle called equipotential. First, $20+ to protect only one appliance; without conductivity to earth?
Second, defined are six ports that must be part of equipotential. A multiport protector must provide equipotential for all ports at a point inside the room. But as posted back in April - it does not provide equipotential because some ports are not part of that equalization technique. Where is concrete floor or linoleum tile included as part of multiport protection? Where are baseboard heat, air ducts, wall paint, or furniture included? That paper calls them 'enclosure ports'. Any one port not part of a multiport equalizer means equipotential is compromised.
To have equipotential inside a room means the entire room must be constructed to provide equipotential. Therefore we locate equipotential where equipotential is easy to achieve.
And third, protection must provide both equipotential and a conductive path to earth. Since neither equipotential nor conductivity alone is sufficient, then a protection 'system' must do both. That 'point of use' protector provides all but no conductivity - no effective earthing.
Not only is equipotential compromised in a room not constructed to provide equipotential. Also the 'system' does not provide necessary conductivity to earth. All this and $20 or $80 to ineffectively protect one appliance? How is that effective?
Meanwhile his 1993 paper then moves on to describe another protective solution:
Described is a 'whole house' protector. Note how it is described:
'Best' protector recommended by Bud's 1993 paper costs about $1 per protected electronics. It does provide equipotential to every room (by making the equipotential point beneath the entire house rather than a point inside one room). And it provides a best conductivity to earth. Both requirements - equipotential and conductivity - are necessary for a 'best' solution. Surge reference equalizer ... AND more ... that is provided for a whole building rather than just for one appliance is called 'whole house' protection. As that 1993 paper notes, part of that 'whole house' system is already in telephone NID.
The same author later states in a 1994 paper:
Curiously, this interest in a 'whole house' solution coincided with post 1990 National Electrical Code changes that require earthing an AC mains breaker box and all other incoming utilities to a common point. A common earthing point that must be adjacent - a short distance. Although code is only for human safety, still, those changes make 'whole house' protection more effective and simpler to install. To provide surge reference equalization - AND more.
What does not change? A protector - the protection 'system' - is only as effective as its earth ground. A fundamental demonstrated by IEEE papers cited in that previous April discussion.
The > This is exactly what a multiport plug-in point-of-use surge protective
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