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bud---

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Everything posted by bud---

  1. Opening the panel and connecting to the neutral/ground bar is 'connecting to the AC service'. From the National Electrical Code Handbook - published by the NFPA (which also publishes the NEC. "The requirement to supplement the metal water pipe is based on the practice of using plastic pipe for replacement when the original metal water pipe fails. This leaves the system without a grounding electrode unless a supplementary electrode is provided.” There are only 3 grounding electrodes that are always required (if present) to be used to ground a service. Water pipes (minimum 10 feet of metal in the earth) are the only electrode that are likely to be in a house. Water pipes are REQUIRED to be used as an grounding electrode, just as they have since time began. Connections currently have to be within 5 feet of where the pipe enters the house. Metal municipal water pipe systems typically have a resistance to earth of 5 ohms or less. Ground rods are only required to have a resistance to earth of 25 ohms, or you can use 2 rods and there is not requirement. Two rods were typically installed. Ground rods are a crappy electrode. For new construction with footings or foundations a "concrete encased electrode" is usually also required. It is a good electrode, and is used instead of ground rods as a "supplementary" electrode. Nonsense. BTW protecting the camera from a direct lightning strike involves far more than #12 wire. There is other particular current source from lightning for the camera mounted on wood. A dedicated ground rod for the camera, in another westom post is stupid. The earth potential the rod can be far different from the power system earthing system during a strong surge event or a very near lightning strike. Resulting high voltage can show up at the DVR between power and camera wiring. It is also a NEC violation. Excellent information on surges and surge protection is at: http://www.lightningsafety.com/nlsi_lhm/IEEE_Guide.pdf - "How to protect your house and its contents from lightning: IEEE guide for surge protection of equipment connected to AC power and communication circuits" published by the IEEE in 2005 (the IEEE is a major organization of electrical and electronic engineers). And also: http://www.eeel.nist.gov/817/pubs/spd-anthology/files/Surges%20happen!.pdf - "NIST recommended practice guide: Surges Happen!: how to protect the appliances in your home" published by the US National Institute of Standards and Technology in 2001 The IEEE surge guide is aimed at people with some technical background. When using a plug-in protector all interconnected equipment needs to be connected to the same protector. External connections also should go through the protector. I would connect camera power supplies at the DVR protector, if you are using one. But wallwart supplies tend to not be a surge problem. I would avoid other connections to grounds - during a surge event they may be at a high voltage with respect to the DVR. I agree with almost everyone that this is being overthought.
  2. bud---

    lightning protection both ends of cable

    When lightning strikes it typically has multiple paths to earth. As I wrote in a previous post the maximum surge current that has any reasonable probability of occurring is 10,000A per hot service wire. That is based on a 100,000A lightning strike to an adjacent utility pole in typical overhead distribution. There is a reference to the 10,000A figure in the IEEE surge guide. Note this is worst case, not "typical". In US systems, at about 6,000V there is arc-over from service panel bussbars to the enclosure. When the arc stabilizes the voltage is hundreds of volts. Since the enclosure is connected to the earthing system that dumps most of the surge energy to earth. The same should happen in other systems, with different arc-over voltage. You simply can't have anything like a 10,000A surge current past the service panel (unless you have a direct strike to the building). By which westom is saying that plug-in protectors can not possibly work. But the IEEE surge guide explains how they work. It is not primarily by earthing the surge. Nonsense. Protectors are rated in current because that is the maximum single event current that puts the protection elements at defined "end of life". A surge current rating is exactly equivalent to a joule rating. (The 100,000 rating from HeadsUp would be amps, not volts.) For an effective protector the surge current rating will be far above any surge current that it will get in a single event (just like the joule rating will be far above what the protector gets in a single event). Plug-in protectors, obviously, protect what is connected downstream from them. The NIST surge guide suggests that most equipment damage is caused by high voltage between power and signal (phone, cable, ...) wires. Plug-in protectors are commonly used on high value equipment with connections to both power and phone or cable, like TVs. Westom pays $290 because he buys from Monster. Since westom believes plug-in protectors don't do anything there must be protection inside "every" appliance (nonsense). The NIST guide says: "Intruder alarm systems using wires between sensors and their central control unit can be disturbed - and damaged in severe cases - by lightning striking close to the house. The wires necessary for this type of installation extend to all points of the house and act as an antenna system that collects energy from the field generated by the lightning strike, and protection should be included in the design of the system, rather than added later by the owner." Near lightning strikes can directly induce voltages with wires acting as "long wire" or "loop" antennas. A loop could be phone wires and power wires. This is a very minor source of damage. =========================== In protecting a device with both power and signal wires (like the DVR or camera) you want to limit the voltage between power and signal wires and the device ground. That is what a plug-in protector does, as explained by the IEEE surge guide starting page 30. That requires all wires, power and signal, to go through the protector. If you are using separate protection devices for the same piece of equipment you run the risk of creating a damaging voltage between power and signal wires that may not otherwise exist. Carefully evaluate the effects of what you are doing. If you are running twisted pair ethernet thorough separate ports on the BNC protector the transmission speed will be impaired. I have never looked but I would think twisted pair ethernet protectors are available. Like a telephone protector, the voltage on all wires to a "ground" connection is limited. Ethernet is trickier because the frequencies are higher. If the DVR has a plug-in protector the BNC protector ground wire could be kludged to the plug-in protector ground (not a great idea but it should work). Ethernet has a relatively high isolation voltage, if the standard is implemented. Only 2 pair are used for 10baseT (don't know which you are using).
  3. bud---

    lightning protection both ends of cable

    The OP did not have different buildings. He had a camera at a distant point on the same building. Treating them as separate structures is not practical. You want an added earthing system at the camera location? How are you bonding it to the main building earthing system? And in westom's opinion plug-in protectors do nothing. Complete nonsense. Plug-in (and service panel) protectors do not work by absorbing a surge. And as I wrote in a previous post the amount of energy absorbed in the process of protecting is very small - even with a very near very strong lightning strike. Gee - why wouldn't a telco use a plug-in protector to protect a hard wired high amp switch with thousands of phone circuits that would have to go through the protector? The point being that plug-in protectors, which are not well earthed, can not possibly work. Unfortunately for westom the IEEE surge guide explains plug-in protectors work primarily by limiting the voltage between all wires (power and signal) and the ground at the protector. For real science read the IEEE and NIST surge guides - excellent information on surge protection. And both say plug-in protectors are effective.
  4. bud---

    lightning protection both ends of cable

    Westom has a religious belief (immune from challenge) that surge protection must directly use earthing. Thus in his view plug-in protectors (which are not well earthed) can not possibly work. The IEEE guide explains (starting page 30) that plug-in protectors do not work primarily by earthing. They work by limiting the voltage on all wires (power and signal) to the common ground at the protector. The guide explains earthing occurs elsewhere. Westom ignores the explanation (and everything else that does not fit his belief in earthing). They don't discuss earthing because plug-in protectors do not work primarily by earthing. Nonsense. It is only magic for westom. And plug-in protectors do not work by absorbing surges (but they absorb some energy). The author of the NIST surge guide looked at the amount of energy that might be absorbed in a plug-in protector. He used branch circuits 10 m and longer. The power service surge was up to 10,000A. (That is the maximum that has any reasonable probability of occurring - based on a 100,000A strike to a utility pole adjacent to the house with typical urban overhead distribution). The maximum energy absorbed was a surprisingly small 35 joules. In 13 of 15 cases it was 1 joule or less. A plug-in protector with high ratings (like 1400 joules) and wired correctly is likely to protect from even a very close, very strong lightning strike. Wired correctly means all wires leaving a set of protected equipment (power, phone, cable, camera) go through the plug-in protector. There are a couple reasons the energy was so small if anyone is interested. Two of westom's favorite lies. Westom's religious mantra protects him from confusing thoughts (aka reality). Like - the IEEE surge guide explains plug-in protectors do not work primarily by earthing. Like - both the IEEE and NIST surge guides say plug-in protectors. are effective.
  5. bud---

    lightning protection both ends of cable

    I responded to westom - he said: "Earth ground is the only component that must always exist in any protection solution." Since flying airplanes do not have an earth ground connection according to westom they can not be protected from lightning. I have no problem understanding how airplanes are protected. If westom had valid technical arguments he wouldn't have to lie about others., I have never had any association with the surge protection industry except I use some surge protectors. One of the plug-in protectors I am using has a MOV with a rating of 1475 joules (plus 2 other MOVs). Provide a source for that MOV for ten cents. I have posted specs. Others have posted specs. They are always ignored. A 10 year old could find specs. But not, apparently, westom. Still never explained - how do you protect a flying airplane. It does not have westom's required less than 10 foot connection to earth. (Protection is somewhat like a plug-in protector.) It is not my claim. It is what the IEEE surge guide says. Read the source, starting page 30. Westom says the IEEE is wrong. Everyone is in favor of earthing. What does the NIST surge guide really say about plug-in protectors? They are "the easiest solution". And "one effective solution is to have the consumer install" a multiport plug-in suppressor. The IEEE Emerald book ("IEEE Recommended Practice for Powering and Grounding Sensitive Electronic Equipment") recognizes plug-in suppressors as an effective protection device. This book is about protecting electronics. The best solution is likely plug-in protectors, which the IEEE surge guide says are effective. The only 2 examples of surge protection in the guide use plug-in protectors. Both the IEEE and NIST surge guides say plug-in protectors are effective. Read the sources. (They contain a lot of other good information.) Then read the sources that agree with westom that plug-in protectors are NOT effective. There are none.
  6. bud---

    lightning protection both ends of cable

    The best information on surges and surge protection I have seen is at: http://www.lightningsafety.com/nlsi_lhm/IEEE_Guide.pdf - How to protect your house and its contents from lightning: IEEE guide for surge protection of equipment connected to AC power and communication circuits published by the IEEE in 2005 . And also: http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf - NIST recommended practice guide: Surges Happen!: how to protect the appliances in your home published by the US National Institute of Standards and Technology in 2001 The IEEE guide is aimed at those with some technical background. The NIST guide is aimed at the general public. Protectors do not work by "stopping". It is popular with westom. Protectors do not work by "blocking". Westom believes that surge protection must directly use earthing. The IEEE surge guide explains (starting page 30) that plug-in protectors do not work primarily by earthing. They work by limiting the voltage on all conductors (power and signal) to the ground at the protector. The voltage between wires to the protected equipment is safe for the protected equipment. The NIST surge guide suggests that most equipment damage is caused by high voltage between power and signal (phone, cable, ...) wires. When using a plug-in protector all interconnected equipment needs to be connected to the same plug-in protector. External connections, like phone wires (and camera wires), also need to go through the protector. Connecting all wiring through the protector prevents damaging voltages between power and signal wires. If using a plug-in protector at the DVR all external wires, including the wire to the camera, need to go through the plug-in protector. That is one end in the OP's question. I would also use a surge protector at the camera end. (Power supplied from a wall wart is generally more immune to surges that integrated power supplies.) I would want the ground at the protector to contact the window frame. Can you use surge protectors at both the DVR and camera? Yes. What I have read from people actually involved in surge protection is that a plug-in protector with high ratings and properly connected (as above) is likely to protect from a very strong, very close lightning strike (but not a direct strike to the building, which requires lightning rods). Flying planes are crashing every day when they are regularly hit by lightning. Or do they drag an earthing chain? Is it only 10 ft long?
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