If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#51
|
|||
|
|||
w_tom wrote:
Yes, utility switching does cause transients. But nothing that should overwhelm internal protection in household appliances. Except that it can and sometimes does. If switching transients were so destructive, then we all would be replacing RCDs, dimmer switches, and clock radios weekly. Once numbers are applied to those switching transients, then those transients become irrelevant. That's as illogical as saying if lightning strikes were so destructive we'd be replacing RCDs, dimmer switches, and clock radios every time it rained. Neither are 'destructive' till the relatively infrequent occurrence when they are. Bob Eager wrote: On Thu, 8 Jul 2004 23:41:08 UTC, w_tom wrote: The frequency of destructive surges is about once every eight years. What is that frequency in your neighborhood? Lightning isn't the only cause of surges. I've seen excessive voltage several times over the last few years. Switching transients, etc. |
#52
|
|||
|
|||
w_tom wrote: Some deja vu. You're not in the States m8. In a densely populated country like the UK, most of the risk are spikes from manmade installations, induction from heavy machinery, fuse testing, outages. A simple protector is well worth having and a once only investment. |
#53
|
|||
|
|||
In article , David Maynard
writes You mean a separate earth. I do, yes. Neutral is, of course, earthed. This is the distinction made in the wiring code between the "grounded" and the "grounding" terminal... which causes confusion all of its own No, they expect an earth ground too. I've been over this with w_tom at considerable length in the past (feel free to have a google.) Because American electrical outlets can't be guaranteed to have an earth terminal (for example, in older construction as you point out), the makers of surge protectors for the American market have to wire them to the lowest common denominator, so that a surge on phase is shunted to neutral using one MOV. In the UK and Europe, two MOVs are used - one to shunt phase to earth, and another to shunt neutral to earth. This makes surge protectors made for this market much more effective. -- A. Top posters. Q. What's the most annoying thing on Usenet? |
#54
|
|||
|
|||
In article , Graham
W writes I'm never one to jump to the defence of w_tom's American based opinions Quite wise, IMHO. but I think his 'lightning rod' = our 'earth-spike' and thus he is talking about the effective ground rather than the place where the strike enters the system. AICBW 8¬) You miss the point. If you have a lightning rod and a TV aerial on the roof of a house, the lightning rod, even if it is higher than the aerial, is not going to save your TV set from a direct strike. Your TV will blow up regardless. -- A. Top posters. Q. What's the most annoying thing on Usenet? |
#55
|
|||
|
|||
In article , w_tom
writes Wall receptacle is safety ground; not earth ground Please explain the difference. I could do with the laugh. - as explained in another post in this thread. I see no explanation elsewhere. However let's assume the plug-in protector does earth a destructive transient via wall receptacle. Which it does in the UK and Europe. Now that transient is on a wire bundled with other wires. So? The transient is shunted to earth via a low impedance path. Induced transient is now created by that plug-in protector. Induced on what? The earth wire? That's what it is there for! By earthing on safety ground wire, we have now induced transients on all other adjacent wires. Absolute crap. There are three wires - phase, neutral and earth. A transient on the phase wire is shunted to earth by the surge protector. What do you mean by "all other adjacent wires"? If you mean low voltage cabling, for example twisted-pair Ethernet cabling, any electrical installer worth his salt (i.e. not you) knows that you /do not/ run low voltage cabling in the same conduit as mains power. It's called segregation. What kind of protection is that? Ineffective. Very effective. One well-known maker of surge protectors in UK and Europe, Belkin, gives a free £10,000 warranty on equipment connected via any of its products. If the surge protector fails and the equipment is damaged, you can claim the cost of a replacement. If their products were that ineffective, do you think they'd offer the warranty? Same problem applies to the service entrance and single point earth ground. All earthing wires must be installed from each utility wire to earth ground separated from all other wires. In your American Mickey Mouse electrical installations, yes. In the UK and Europe, it's unnecessary. Too many installers want to be neat. They make clean sharp bends and nylon ty-wrap all wires together. IOW they compromise the protection 'system'. Even sharp wire bends increase wire impedance. Earthing wires must be shorter (less than 3 meters) Why less than 3 metres? This is another of the claims you frequently make without a shred of evidence to back it up. And remember, we are discussing this in relation to UK and European wiring practice. I sincerely doubt you have ever worked on an electrical installation outside the US (thank god for that too.) Just more reasons why plug-in protectors are so ineffective. What reasons? Where? I see only more hand-waving from you. I've come to the conclusion that you must work for a maker of these "whole house" surge protectors that you constantly advocate. Your opinion is therefore biased, not objective, and worth **** all. HTH. HAND. FOAD. -- A. Top posters. Q. What's the most annoying thing on Usenet? |
#56
|
|||
|
|||
On Fri, 9 Jul 2004 16:39:26 UTC, Mike Tomlinson
wrote: In the UK and Europe, two MOVs are used - one to shunt phase to earth, and another to shunt neutral to earth. This makes surge protectors made for this market much more effective. Indeed. I think (can anyone confirm?) that sometimes three MOVs are used, with one between phase and neutral... -- Bob Eager begin a new life...dump Windows! |
#57
|
|||
|
|||
"Bernard Peek" wrote in message ... In message , w_tom writes Concepts such as 'whole house' protectors and lightning rods are long ago proven to be superior protection. Why? They (unlike the ineffective plug-in protector) make a superior connection to earth ground so that lightning does not find earthing via TVs or computer. That's not how lightning protectors work. They create a corona discharge around the building, dissipating charge buildup immediately around the site. That means that a strike is more likely to happen elsewhere. The copper strap has a cross section of less than an inch, nowhere near enough to safely shunt a real strike to earth. If the building does get hit the strike will still do nearly as much damage as if it was not there. -- Bernard Peek London, UK. DBA, Manager, Trainer & Author. Will work for money. I know a Russian who was killed while rewiring his house, his name was Sergi |
#58
|
|||
|
|||
"w_tom" wrote in message ... Assumed is that lightning confronted everything inside the house equally. Just not true. Based upon your description, the circuit from cloud to earth borne charges found a good path via those TVs. Therefore only TVs suffered a direct lightning strike incoming and outgoing. Incoming and outgoing are essential requirements for surge damage. If the computer only had an incoming path and no outgoing path, then lightning currents did not pass through nor damage computers. That complete electrical path to earth ground is the essential requirement for surge damage. Clearly other household appliances did not make that same "complete electrical circuit" connection; therefore were not damaged. I don't really care about the Physics........all I know is that I wont take the chance anymore |
#59
|
|||
|
|||
Mike Tomlinson wrote: [...] I've come to the conclusion that you must work for a maker of these "whole house" surge protectors that you constantly advocate. Your opinion is therefore biased, not objective, and worth **** all. This explains w_tom's surge of mains FUD surge protector posts... |
#60
|
|||
|
|||
"Mike Tomlinson" wrote in message ... In article , Graham W writes I'm never one to jump to the defence of w_tom's American based opinions Quite wise, IMHO. but I think his 'lightning rod' = our 'earth-spike' and thus he is talking about the effective ground rather than the place where the strike enters the system. AICBW 8¬) You miss the point. If you have a lightning rod and a TV aerial on the roof of a house, the lightning rod, even if it is higher than the aerial, is not going to save your TV set from a direct strike. Your TV will blow up regardless. No, I haven't missed the point - what you say is right. It is just that his faltering English is difficult to read and it makes more sense if referred to the earth spike than a lightning conductor over the roof. But he seems to mean the latter in what he has subsequently said. I'll go away now! 8¬) -- Graham W http://www.gcw.org.uk/ PGM-FI page updated, Graphics Tutorial WIMBORNE http://www.wessex-astro-society.freeserve.co.uk/ Wessex Dorset UK Astro Society's Web pages, Info, Meeting Dates, Sites & Maps Change 'news' to 'sewn' in my Reply address to avoid my spam filter. |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
power supply | Not so quick | General | 27 | January 22nd 04 12:21 AM |
Effective surge and spike protection for computers? | SQLit | General | 12 | December 6th 03 05:58 AM |
Dial up modem problem | Richard Freeman | General | 21 | September 22nd 03 05:50 AM |
Power Surge | David LeBrun | General | 44 | September 12th 03 02:35 AM |
Surge protectors with full warranty? | S.Heenan | General | 5 | August 14th 03 09:39 PM |