On Jul 20, 9:06 am, westom <[email protected]> wrote: > On Jul 19, 2:45 pm, Doug Brown <[email protected]> wrote: > > >. We've lost 3 computers in the last 4 years tolightningand around > > 5 dsl filters have been fried outside of that. One of them actually blew > > up and plastic shrapnel hit me in the head.
The best information on surges and surge protection I have seen is at: <http://www.mikeholt.com/files/PDF/ LightningGuide_FINALpublishedversion_May051.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 the major organization of electrical and electronic engineers in the US). 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 unwashed masses. The phone line should be protected by the phone company at the point of entry to the building. The voltage on each phone wire is clamped (limited) to a ground terminal. There shouldn't be damaging voltage between the phone wires past the entrance protector. If you are losing filters, I would question whether this protection, furnished by the phone company, is effective. I would ask them to replace it. There is a ground wire from this entrance protector to the earthing system. For good protection, the entrance protector should be near the power service and there should be a *short* ground wire to the earthing at the power service. The NIST guide, using US insurance information, suggests that most equipment damage is from high voltage between power and phone/cable wires. A short ground wire minimizes the voltage between power and phone wires. The IEEE surge guide has an illustration of a wire that is too long starting pdf page 40. If you unplug power wires you also need to unplug phone wires to the same equipment. > For over 100 years, buildings that can never suffer > damage have been using the 'whole house' protector. So that direct > lightning strikes do not 'explode' anything inside the house. Service panel suppressors are a good idea. But from the NIST guide: "Q - Will a surge protector installed at the service entrance be sufficient for the whole house? A - There are two answers to than question: Yes for one-link appliances [electronic equipment], No for two-link appliances [equipment connected to power AND phone or cable or....]. Since most homes today have some kind of two-link appliances, the prudent answer to the question would be NO - but that does not mean that a surge protector installed at the service entrance is useless." That is because service panel suppressors do not prevent high voltages from developing between power and phone (cable, ...) wires. If surges are coming in on the phone wires, a service panel suppressor won't help (but it is definitely good for surges coming in on power wires). > Cable TV is earthed directly - only by a wire. > A wire that connects short (ie 'less than10 feet') to earth. A ground block should be installed at the entrance of the cable to the building and, like phone, there should be a short ground wire from the ground block to the earthing at the power service. The ground block earths the cable shield. But the IEEE guide notes that the voltage between cable center conductor and shield is limited by the breakdown of F-connectors which is typically 2-4,000V. The guide notes that connected equipment can be damaged at those voltages. (Plug-in suppressors are likely to clamp the voltage to a reasonable level.) > > Either you earth every incoming AC wire - either directly or via a > 'whole house' protector. Or you have no surge protection. No > protection even if you have 1000 plug-in protectors inside. > > More responsible manufacturers sell effective solutions. Companies > such as General Electric, Leviton, Square D, Keison, Intermatic, > Siemens, Polyphaser, ABB, etc. All of these "responsible" manufacturers except Square D and Polyphaser also sell plug-in suppressors (which westom claims don't work). Square D for its ‘best’ service panel suppressor says "electronic equipment may need additional protection by installing plug-in [surge suppressor] devices at the point of use." > All grounds remains separate until all meet > at the single point earthing electrode. If you have strong surge current to earth, the "ground" at the house can rise thousands of volts above "absolute" earth potential. Much of the protection is that power and phone and cable wires rise together. To do that you need short ground wires from the phone and cable entrance protectors to the earthing system *at* the power service. If you are using plug-in suppressors, all interconnected equipment needs to be connected to the same plug-in suppressor, or interconnecting wires need to go through the suppressor. External connections, like phone, also need to go through the suppressor. Connecting all wiring through the suppressor prevents damaging voltages between power and signal wires. The IEEE surge guide has 2 examples of this at the end. If correctly connected, a plug-in suppressor with high ratings should protect what is connected downstream. Service panel and plug-in suppressors should have a UL1449 listing. So should UPSs that you depend on for surge protection. -- bud-- -- You received this message because you are subscribed to the Google Groups "The Unique Geek" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/theuniquegeek?hl=en.
