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Tech: Surge Protectors-must they be grounded?(US)
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Subject: Tech: Surge Protectors - must they be grounded From: Joe Offer Date: 02 Dec 06 - 04:58 PM I'm getting a widescreen TV this week, and I'm installing it in a room that has old-style two-prong electrical outlets. It's an expensive TV, so I want to protect it with a surge protector. Can I just use an ungrounded adapter for the surge protector, or will the lack of a third ground wire make it so the surge protector won't work? -Joe- |
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Subject: RE: Tech: Surge Protectors-must they be grounded?( From: number 6 Date: 02 Dec 06 - 05:02 PM Are you saying that you will cut off the ground prong on the surge protector?? In doing so, it will work ... but I if I were you I'd rewire that room. Must be an old house Joe? biLL |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: Bill D Date: 02 Dec 06 - 05:10 PM Joe...it is usually possible to put in a 3-prong receptacle and ground it to either the electrical conduit or run a ground wire to some other spot (I have one I actually drilled thru the wall and grounded to a water faucet outside). You need to find either an electrician or knowledgeable amateur to do it, so that they can check that the grounding is 'correct'. There is a simple gadget you can get at a hardware store to stuck in a socket that tells you if it's ok. But do make sure it's done before you plug in an expensive gadget. |
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Subject: RE: Tech: Surge Protectors-must they be grounded?( From: number 6 Date: 02 Dec 06 - 05:12 PM Depends on what the surge is caused by ... l wouldn't trust it being ungrounded in the event of a lightening caused surge. I may be wrong .. but looking forward to the answers posted by others. I noticed you mentioned an 'ungrounded adapter' ... far as I know they are not sold anymore in Canada. biLL |
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Subject: RE: Tech: Surge Protectors - must they be grounded From: GUEST,beachcomber Date: 02 Dec 06 - 05:13 PM Yea, a most interesting question for me too.(I have an old house also, with what, I strongly suspect, is dodgy wiring.) In my case (apologies Joe Offer, I am not hijacking your query but hoping some one can enlarge upon the answer to your question to include some info on mine) In my own house I have observed that the electric cooker has been wired so that it's Earth conductor (Coloured Green/Yellow over here)is connected directly back into the supply Neutral Cable from the Meter. There is no Earth Terminal on the Fuse Board. All other circuits have their Earth Cables connected to the Neutral Terminal in the Supply Company's "Cut-Out Box" before the Meter. Perhaps this could be a solution to Mr Offer's problem? |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: Joe Offer Date: 02 Dec 06 - 05:22 PM The house was built in the 1940's, and the wiring is two-conductor, fabric-covered, 14-gauge Romex. This is on the second floor, and the nearest ground is a long, long way away. I'm tempted to just put a three-prong outlet in the box and not run a ground wire. After all, the white wire in my house wiring IS grounded at the fuse box - it's just the black wire that's "hot." The three-prong outlet will ensure that the white wire on the surge protector is connected to the white wire on the house wiring, but is that enough. I've always questionsed the need for that third green wire in house wiring, since both the ground and the white wire get connected to the ground at the fuse box. I always wire in a ground when I do new wiring because I know that's what the code demands (and I know at least some good reasons for that ground wire) - but in this situation, I'm shooting for functionality and ignoring the code... -Joe- |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: Joe Offer Date: 02 Dec 06 - 05:38 PM Perhaps I'd better add some specifications for US house wiring, so the non-US participants understand where there's common ground (sorry for the pun) in this discussion.
OK, now that we agree on terms, we can continue the discussion. It would be interesting for somebody to post the specs for wiring in the EU, so we can see the difference. -Joe- |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: JohnInKansas Date: 02 Dec 06 - 05:40 PM I assume that Number6's comment "it will work" means the TV will work, not that the surge protector will do anything. If a voltage transient that might damage things gets to the surge protector, the protector momentarily connects the power line to the ground terminal. If there's no ground connection, the "surge" has no place to go. Most surge protectors DO NOT disconnect the hot line from the stuff connected to it, so if the ground connection can't soak up the surge it just goes right on into the connected equipment. Some - but not all - surge protectors will short the "hot" line to both the ground and neutral lines, but for typical house wiring in the era when 2-wire circuits were used the "neutral" line is much too small (too much resistance) to be effective at draining off a significant surge. Whether a shunt to neutral gives any protection at all depends largely on whether the "neutral" itself is well grounded, and unfortunately for many systems from this time period it's "iffy." Local codes vary as to whether you could add a separate ground wire to a cold water pipe, just for that receptacle. Some codes now require that a ground be "outside the foundation perimeter," but there's a lot of variation on this. (Of course, only a metal cold water pipe works, and lots of homes from the period have had plastic supply lines put in when the old stuff rotted.) Get an estimate before signing the contract for your upgrade. John |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: JohnInKansas Date: 02 Dec 06 - 05:57 PM Joe - Your last post popped in while I was writing. A GFI receptacle requires a ground, generally; but for the GFI it doesn't need to carry a lot of current, so the ground doesn't have to be able to short out a surge. For the GFI, the ground is just a voltage reference. If the difference between the currents going through the hot and neutral lines exceeds a "trip level," the GFI disconnects the hot line. Most surge protectors do include a circuit breaker that will disconnect the device(s) connected to it if the total current exceeds the breaker's rating; but if excess current comes from a high-voltage surge your device is probably "fried" before the breaker can work. In two separate "strikes" when lightning destroyed computer components, the breakers did NOT trip. (And in both cases the computers were on "properly grounded" surge protectors - indicating that my house circuit grounding1 is really sub-par.) 1 early 1950s house, 2-wire circuits except for a couple that were supposedly updated to 3-wire "by licensed electricians," during previous owner's occupation. (Previous owner not trustworthy.) John |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: Q (Frank Staplin) Date: 02 Dec 06 - 06:03 PM I hope you don't mind if I piggy-back and ask about the reverse. I have a few old radios without the third wire, a couple are collector's items. Do they need protection? I do have metal cold water pipes. |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: JohnInKansas Date: 02 Dec 06 - 06:06 PM Joe - Afterthought: One workaround that some people use is to install a UPS (uninteruptible power supply) to connect the critical device(s). A suitable UPS contains a battery, and the "house circuit" charges the battery. An inverter runs full-time and converts battery DC to AC for the connected devices. Since everything has to go through the battery in a UPS of this kind the battery is a massive surge protector. (Think how long do you have to charge a battery to get the voltage to increase?) Your sensitive component is never connected directly to the house circuit. Other kinds of UPS devices, that only turn on the inverter if the "house circuit" fails, do NOT provide this kind of protection, and it's sometimes hard to tell which type you're getting. John |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: Grab Date: 02 Dec 06 - 06:21 PM Q, if the equipment is suitably constructed then it doesn't need an earth - figure-8 cables (without an earth) are commonplace for low-power electrical kit. Usually "suitably constructed" means double-insulated. Graham. |
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Subject: RE: Tech: Surge Protectors-must they be grounded?( From: GUEST,Jon Date: 02 Dec 06 - 06:26 PM There are a few different earthing systems in the UK Joe. try here if you really want to look through them... |
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Subject: RE: Tech: Surge Protectors-must they be grounded?( From: Greg F. Date: 02 Dec 06 - 06:30 PM I'm tempted to just put a three-prong outlet in the box and not run a ground wire. Joe- Aside from not shunting the high voltage transient to ground properly, that'll probably void your homeowners insurance very nicely. Best, Greg |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: JohnInKansas Date: 02 Dec 06 - 06:36 PM Q - Your old time radios probably are much less susceptible to surges on the power line than a lot of more modern stuff, simply because everything goes through a relatively "massive" power transformer that can soak up abuse and "levels" the transformer output to some extent. The HUGE power supply capacitors also help some. An exception to the lesser sensitivity is a few old sets that had "fast warmup" devices. This was usually a diode across the power switch that conducts during one half-cycle and not during the other half-cycle, giving "quarter power" to the filaments so they stay warm. Many of these used solid state diodes that are easily punctured (and usually will short-circuit on failure so you can't turn the device off). Popular in the 60s - 80s(?), especially for TVs. If your old radios have solid state devices (transistors/diodes) in the power sections, they're about as tender as more modern stuff. The thing that's more likely sensitive, and often neglected, is the antenna connection, assuming that any of them have external antennas, especially out door ones. One can get "antenna protectors" that are just a small plastic blob with a neon lamp (now probably a varistor) between the antenna line and a ground post. You can connect the ground to an outdoor water faucet, and it must be connected and grounded outside the house. I had one connected when lighting hit a rooftop TV antenna. It simply "removed" all the twin-lead and deposited it in the front yard. (There was NO METAL left inside the twin-lead.) The TV was undamaged. Using a surge protector would be recommended practice just on principle, but it depends on the specific kinds of radios, how much it would hurt you if you lost one of your pets, what kind of weather you get, and on how good/bad your mains supply is. You can get good ones for a few bucks. John |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: Lonesome EJ Date: 02 Dec 06 - 06:39 PM My understanding is that most surge protectors have what might be called a fusible link : In effect a hard-wired fuse that will blow in the event of a system overload, or surge. This has nothing to do with a ground, and is meant to handle line spikes, ie fluctuations from the power company's supply, or surges involved with power outage interruptions and the spikes that take place when the power comes back up. Lightning is another issue. Lightning can deliver hundreds of thousands of volts, jump 50 feet from tree to tree, and no surge protector will stop that. The best it can do is prevent ambient surges from nearby strikes by blowing its fusible link. |
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Subject: RE: Tech: Surge Protectors-must they be grounded?( From: GUEST,Jon Date: 02 Dec 06 - 06:46 PM I'll go by this page for standard surge protectors. As for bodging earth connections. It's not something I'd do. I (UK) think getting an earth for the property is something that must be done by a qualified electrician with proper test equipment. |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: JohnInKansas Date: 02 Dec 06 - 06:48 PM Joe - In line with the antenna comments for Q, don't forget that anything connected to your fancy device can feed surges into it. The signal lines probably are even more likely to cause surge damage to your monitor than the power lines. Every device that connects to the component you want to protect must be on a surge-protected circuit, preferably all with the same ground point. Your TV converter/antenna/cable entry is probably more dangerous, if not properly protected, than the monitor power input. One of the two computer zaps mentioned above was from a surge on the phone line - (which was run through phone-line surge protectors). John |
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Subject: RE: Tech: Surge Protectors-must they be grounded?( From: GUEST,Jon Date: 02 Dec 06 - 06:55 PM Also, LEJ, I would think that by the time the fuseable link goes, your equipment is likely to be fried. I agree about the lightening being capable of providing far more energy than a surge protector can handle though. And Like John, I have had a surge protected PC blow up during a storm. |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: JohnInKansas Date: 02 Dec 06 - 07:18 PM The "immense power" in a lightning strike seldom gets into your computer. A strike on a power line usually doesn't "decide to go hit just Joe." The line itself should have surge protection, so a lot of it gets shunted to the ground (so don't stand close to a pole in a thunderstorm). The total "system capacitance" absorbs a lot of it before it gets to your pole. In the US, most above-ground transmission systems have a "ground wire" above the power lines, and it's usually this wire that gets the strike. It's the currents induced in the power lines by the surge of current in the ground line that get to you. The surge can still be very large, and can exceed the capacity of almost any surge protection you install; but it's a lot less than the direct hit that produced it. The "fusible link" in most surge protectors has been supplanted by "electronic circuit breakers" in many devices, since you can reset them. They also can respond faster than thermal fuses if designed to do so. These links do not participate in surge suppression. They're there only to protect the surge suppressor if you plug too much stuff into one. You can consider them as "fire protection" but if the fuse blows due to a surge, the surge has already destroyed your equipment. John |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: Q (Frank Staplin) Date: 02 Dec 06 - 07:24 PM Thanks, John. The radios all have 10-ton transformers and tubes, circa 1930's. I do have a 13-tube National HRO from the 1940's, ex-air force, but it, too, has a heavyweight transformer. The antenna is stretched in the attic crawl space and it is grounded to an outside water pipe. |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: The Fooles Troupe Date: 02 Dec 06 - 07:30 PM Don't Monkey with Electricity! From a sign I saw in my childhood outside an electrician's place in the 60s in Bundaberg. In one hand was an iron, in the other hand a screwdriver, and 'lightning zap symbols' surrounded the monkey. |
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Subject: RE: Tech: Surge Protectors-must they be grounded?( From: GUEST,Jon Date: 02 Dec 06 - 07:33 PM John, the strike (or srikes) in the storm that zapped me zapped dozens of PCs in the area. |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: Cluin Date: 02 Dec 06 - 07:40 PM Lightning strikes are less of a problem for computers and other electronic devices than spikes and power surges from your power company. Had a surge protector save my computer a couple of years ago. Unfortunately my TV and VCR and stereo weren't on surge protectors then, damnit. They are now. Once burned... |
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Subject: RE: Tech: Surge Protectors-must they be grounded?( From: number 6 Date: 02 Dec 06 - 09:07 PM I guess the bottom line is ... how much is that TV worth to you Joe ... take the chance and not have the room wired to spec (spec is the proper, safest route) or .. leave it as it is and in all probability nothing will happen .. but then again .... biLL |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: JohnInKansas Date: 02 Dec 06 - 10:19 PM Yeah Joe: You may actually want to cut a few corners on the protection for your new "puny" monitor. You'll probably need an excuse for the next one: Analyst: 70-Inch LCDs 'The Right Size' In 2009 ""We decided to investigate the optimal screen size for high definition viewing," wrote analyst Jeff Evenson … … . "We conclude that 65 inch to 75 inch is the right size for a 10 foot viewing distance." "Affordability of large screens has and should continue to improve," Evenson wrote. "Our analysis indicates that 70 inch - 80 inch screens could cost around $3,000 in 2010." You will NEED one of these - in a couple of years. No sense babying your present one. Or did you get the 72" model now? John |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: Bill D Date: 03 Dec 06 - 10:52 AM You mean the cable-ready 6" TV I recently bought for $99 is NOT the cutting edge? Why, it even runs on 10 D cells for emergency use, when I'm recovering from the latest lightning strike! |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: GUEST,HughM Date: 03 Dec 06 - 11:28 AM In the UK the domestic electrical system is fed from one phase and the neutral of the 230V supply. In modern houses, rightly or wronly, the earth connections of the three-pin sockets are connected to the neutral at the consumer unit (the junction box where the supply enters the house). In other words, the system is similar to what you have in the US except for the voltage being different and there being only one phase supplied to each house. If the power line or the antenna is struck directly by lightning there is little chance of the TV surviving. However, most surges are induced in the supply by nearby lightning strikes. In the EU, industrial equipment running from a 24v d.c. supply has to withstand surges of 1kV between the lines and 2kV from either of the lines to ground. If I remember rightly the requirements are 2kV and 4kV for 240V supplies but I'm not sure. I don't know whether equipment in the US is subject to similar requirements. If so, you probably have nothing to worry about. If not, you will still benefit from an ungrounded surge protector. The isolation provided between the supply and other connections (antenna, speakers etc.) to meet safety requirements will probably be so good that it will take an unusually large surge (line to ground)to do any damage. |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: Stilly River Sage Date: 03 Dec 06 - 11:32 AM Joe Offer, it is a huge expense to have the electrical system upgraded, but if it needs to be done then you should consider planning for it and bite that bullet. When you ever get around to selling your house the old system will count against you in the sales price, so the cost of the work might equalize out. I did a big remodel here when I moved in almost 5 years ago. The moment electricians were called to wire the new part of the house I was obligated by the village to upgrade my electrical system (adding about $3000 to the job). The old system (built in 1976) already had circuit breakers, but it had to go from 150 amp to 225 amp to be up to code. I have plugs all over the place and can use them without often having to use those little adapters to extend the number of plugs at each wall plate. My point is, it's expensive but it's important and in this day and age I'd be scared of using old fashioned fuse boxes. I think your best bet, if you don't upgrade, is to follow John in Kansas' advice to get the APC battery backup box for the new television. They're heavy and expensive but they're a lot cheaper than rewiring. SRS |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: Q (Frank Staplin) Date: 03 Dec 06 - 01:52 PM Omigod! 72-inch at ten feet? I would be swinging my head like I was at a tennis match. A 26-inch screen at about ten feet is just dandy. A neighbor has one of those wall-fillers and it gave me a headache and watery eyes after watching for a bit. But I do agree that modern wiring is both safer and more convenient. Here in Alberta, one can home-wire, but it must be inspected, and the inspectors are strict (no insurance valid unless wiring has passed inspection). |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: JohnInKansas Date: 03 Dec 06 - 04:11 PM Much of the discussion here has been about lightning surges. A good surge suppressor may help with line transients during storms, but can't generally be made massive enough to protect against all possible storm transients. A surge suppressor will help for "distant distrubances" and some "induced transients," but can't block direct near strikes. An insurance policy, possibly as a "rider" on your house policy, is better protection there. Note that many extended warranty and/or service contracts exclude so many things that they're of questionable value for damage due to external effects, so one must ask the questions before paying the money. The real purpose and need for surge protection for susceptible items comes from the smaller and much more common spikes and surges one gets from things like the refrigerator or air conditioner turning on and off, the industrial strength arc welder in your neighbor's garage, or your kid,s nuclear reactor experiments in the basement. Most house circuits are, by electronic component standards, incredibly "dirty." While turning on a moderately sized motor obviously will pull the voltage on that line down, and turning one off can produce substantial spikes, even flipping the switch on a 60W incandescant lamp can produce a significant "surge." A cold 60W bulb typically has a filament resistance of about 12 Ohms, so the initital surge current, at 120 V is about 10 amps, dropping to the running current of ~0.5 amp in a few milliseconds as the filament heats up. Fluorescent light starters can be equally noisy, or worse. Little things like light dimmers sometimes are quite noisy. The cumulative effect of many small transients can be damaging to sensitive components, and a good surge suppressor can be effective in eliminating many of them. An additional benefit of using a suppressor is that it gives one a single point for connecting all the components of a system. Although safe house wiring is all "grounded," at least to a neutral line, where there's current there's voltage drop, so the "ground" at the end point where you plug in may not be the same as the "ground" at the next hole in the wall. Differences between several floating grounds can cause "noise" in your equipment, and stress on the components that can affect component life. Quite a lot of "computerish" equipment now doesn't actually have an on/off mechanical switch. When you hit the BRS on recent computers, a signal is sent to a controller that you want to shut down, but the computer decides when it's ready. The power cord, and the feed-through to the controller logic level solid state devices that actually turn things on and off, remains connected to the innards of the computer. (If it actually disconnected, you couldn't send the logic level signal to the computer to turn it back on.) There is no physical disconnect, and line surges can still feed through, even if component line power is turned off. If there's a storm, or another "risk" condition, if all your stuff is plugged into a single point, as with a surge suppressor, you can unplug it all at one place. Removing the plug from the wall socket is the only safe way to "shut down" for a thunderstorm, and disconnecting cable and phone feeds from the wall sockets is part of "pulling the plug." John |
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Subject: RE: Tech: Surge Protectors-must they be grounded?( From: Rapparee Date: 03 Dec 06 - 06:23 PM Joe, I'd go with a good UPS as a stopgap measure and do some serious saving for rewiring. Personally, I prefer Liebert UPSes to APC -- I feel that they cost a trifle more (and just a trifle) but that the engineering is better (better line conditioning, etc.). Also, the batteries are replaceable. When we moved in we had the house rewired -- and in doing so (among other things) eliminated a home-owner installed circuit breaker that was JUMPERED to the mains! We also had the house re-grounded. Why someone would un-ground a house I don't know, but we've found lots of stuff previous owners did that raise HUGE questions in our minds as we correct them or have them corrected. My father-in-law was working on some wiring when there was a ZAP! and the lights went out. My mother-in-law turned to my wife and calmly said, "Go see if you're father's dead." Electrical work is NOT, by and large, a DIY thing. |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: Joe Offer Date: 03 Dec 06 - 07:04 PM Well, for now, I'm going to use a UPS, and put in a three-prong outlet with no ground wire. I'll get to hooking up a ground sooner or later, but it's a real hassle to get where I have to go to hook up the ground. My house is what they call a tear-down in this area. It's on a ridge, 3-1/2 acres of land with a spectacular view. The house is an old farm house, built by the owner in the 1940's. The house has a lot of "issues," and I'm trying to convince my wife that we really need a house with a thermostat to turn the heat on. We have friends who are building a house, and their building nightmare has set my new house plans back five years..... -Joe- |
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Subject: RE: Tech: Surge Protectors-must they be grounded?( From: Rapparee Date: 03 Dec 06 - 07:12 PM Joe, I've see 3-prong outlets put in with the green ground wire attached to one of the screw that holds the outlet cover one. The screw in the middle of the outlet. Probably not good electrical work, grounding the outlet to itself. I'm just sayin', ya know.... |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: JohnInKansas Date: 03 Dec 06 - 10:24 PM Rapaire - The little green tab that you can put the screw through is connected to the ground pin of the adapter, and is supposed to be used to ground the adapter. Since they started using plastic boxes for receptacles long before they quit using 2-wire hookup, and since they almost never used conduit for in-wall wiring in residential construction, the box you screw it into probably isn't even a conductor, and almost certainly isn't grounded (in US residential wiring from the 40s - early 60s). The screw is effective though for holding the adaptor in place in the wall receptacle, which is necessary since with the receptacle and a power plug all stuck into the (two-hole) receptacle the whole gob would probably be on the floor most of the time if not nailed in place. But it's unlikely to provide a ground. John |
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Subject: RE: Tech: Surge Protectors-must they be grounded?( From: Bev and Jerry Date: 04 Dec 06 - 12:09 AM Joe: Here is a good site to explain to you how surge protectors work. Good surge protectors not only protect against surges between the black and white wires but also protect against surges between either of these wires and ground. So, no ground, no protection against these surges. See you in a few weeks. Bev and Jerry |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: Joe Offer Date: 04 Dec 06 - 12:09 AM For a time, the standard in many places in the U.S. was BX, a cable shielded with flexible coiled steel. It seemed much safer than plastic or fabric-covered Romex, since it had that (grounded) metal shield. My friend Fred the Electrician said that many homeowners found that if the cable was crushed, it could pierce the insulation of the "hot" fire inside and short out. The steel was not a good conductor because it had a lot of resistance. Instead of blowing a fuse, the steel formed a heater element, and caused a number of fires. that was the end of BX cable. There is still a flexible steel conduit that can be used in certain situations. The standard here in California is three-wire, plastic-covered Romex - but it's not allowed in open areas. -Joe- |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: Stilly River Sage Date: 04 Dec 06 - 12:09 AM Rapaire beat me to it--you can get those three-prong adapters that use the middle screw as the ground. That and the battery pack, whatever brand, and you're going to feel better about the investment for the television. A agree with Q about the tennis match quality of that large screen when viewed up close. But I've been watching the prices of some of these really good projectors coming down, and my plan is to put in one of those one of these days. I have gorgeous panelling in a large living room with a picture rail around the top, and I'd like to get a streamlined roll-up daylight screen to use with a projector. Pull down the screen when I want to watch a movie, and the rest of the time it's out of sight. I don't want the television or the screen or whatever else appliance being the center of the room. SRS |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: JohnInKansas Date: 04 Dec 06 - 01:09 AM SRS - But you missed the note after Rapaire's comment, that putting a screw through that little tab NEVER produces a ground, unless you replace the plastic box (if that's what you've got) with a metal one AND GROUND THE METAL BOX. In a 2-wire circuit the receptacle box won't be grounded unless you do it on purpose in the majority of cases, and connecting to it without making the connection to ground just gives you a bigger place to get zapped in the event of a ground fault in the circuit. (Like an incandescent light bulb, a person being well-zapped produces a significant transient that can damage your TV.) John |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: Bert Date: 04 Dec 06 - 01:14 AM I would say that if the plug has three prongs then it needs a ground. But it may depend on the design of the UPS. Ask the manufacturer. |
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Subject: RE: Tech: Surge Protectors-must they be grounded?( From: GUEST,Jon Date: 04 Dec 06 - 01:47 AM I wouldn't know in the US but that does not hold true in the UK where our standard 13A plug has 3 pins. These days, you see a number of plugs where the earth pin is made of plastic but the presence of a metal pin does not mean an appliance carries an earth wire. The earth pin has another purpose btw. Live and neutral are usualy covered in the socket and the earth pin entering the socket opens the way for the other pins. Coming back to distribution and Hughes comments, as far as I understand it, in the UK, we take one phase from a 3 phase system. A US domestic property takes just one phase too but it is "split". Is this correct? Oh and earthing, our house as far as I know is TT |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: Barry Finn Date: 04 Dec 06 - 02:24 AM Joe it's not all that chancy to do a good bit of the rewiring yourself (inspectors don't approve of this though) & have a licensed electrican do just the connections to the box & to do the grounding. During my additions & renovatons I've pulled all the old wiring, new lines & boxs, installed GFI's & grounded outlets, switches, upgraded to 20 amps where needed, used dedicated direct lines for the computer, the fridge & a couple other items. Running all the wires myself up to the panel (but not into the panel) & removing the old (not from the panel though). Saves alot of the costs. Then I have the electrician hook the lines to the box. Had the box upgraded recently too. I found that the higher costs involved the DIY work rather than the other way around. If you handy install new boxes at the same time & fix any wall or floor holes yourself. Barry |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: GUEST,HughM Date: 04 Dec 06 - 05:36 AM Sorry! Contrary to what I wrote before, the EU surge immunity requirements for a.c. supplies are 1kV between the leads and 2kV between either lead and ground, the same as for industrial d.c supplies. Unless your location is known to be particularly bad for surges (or maybe a location supplied by overhead rather than underground lines)I wouldn't worry unduly. Even before we had these requirements in the EU, TV sets used to last for years without being damaged by surges. One of ours is 21 years old at least (saved from the garbage skip when Tatung's Bradford laboratory closed in 1985). I would imagine that US manufacturers will be sufficiently concerned about their reputations to have ensured similar reliability. You could write to the maker's customer relations department and get their recommendations in writing. Then if you complied with their recommendations they could hardly refuse to honour the guarantee. |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: The Fooles Troupe Date: 04 Dec 06 - 06:10 AM I just recently read (Dec Silicon Chip) about a B&W Aussie tv set that is 50 years old - of course, it has a replaced tube, and all the vacuum tunes have been replaced a few times, and all the resistors and electrolytics have been replaced... but it still works as good as new! |
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Subject: RE: Tech: Surge Protectors-must they be grounded?( From: Rapparee Date: 04 Dec 06 - 08:34 AM I wasn't recommending anything except as I noted earlier -- use a UPS and save to have the house rewired. Having seen what "Joe Homeowner" did to this house before we had it rewired (which was before we moved it) I'm not at all in favor of DIYing it UNLESS you know what you're doing. Snaking romex, installing boxes -- fine. But I'd let the pros do the hookups. Electrocution ain't exactly my bag, ya know? |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: Donuel Date: 04 Dec 06 - 10:12 AM Our 2 prong plugs are housed in the typical metal box that is grounded. My surge protector on a 2 prong outlet worked fine for last summer's lightning strike. What surge protectors didn't prevent was the large EM field in the air from destroying receiver components. For example the computer was fine but the wireless router fried, the stereo was fine but its radio reciever was fried, the TV's were fine but one did have to reset itself. |
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Subject: RE: Tech: Surge Protectors-must they be grounded?( From: Bill D Date: 04 Dec 06 - 10:31 AM Just as a fascinating matter of interest, here are comparisons from around the world....it's worse than language & politics! World standards for electricity Plugs & mains design |
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Subject: RE: Tech: Surge Protectors-must they be grounded?( From: GUEST,Jon Date: 04 Dec 06 - 11:15 AM Thanks Bill. |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: Stilly River Sage Date: 04 Dec 06 - 11:17 AM Geez! What a mix of plugs and power levels. No wonder they have such complex converters for travelers. I've exhausted my knowledge of electricity, and I did apparently miss a remark about plastic vs metal boxes. I skimmed back through again and still missed it. But I agree, metal box vs plastic if you're using the middle screw for a ground makes sense. I know I have plastic receptacle boxes in the new part of the house. I think they're metal in the rest of the house. But the new part (and the entire rest of) the house has grounded plugs, so it isn't a concern. SRS |
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Subject: RE: Tech: Surge Protectors-must they be grounded?( From: Rapparee Date: 04 Dec 06 - 11:21 AM If you want to protect your stuff from EMF, whether lightning or nuclear-warhead generated, you'll need a Faraday cage. |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: Donuel Date: 04 Dec 06 - 11:28 AM The origin of the tin foil hat. |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: EBarnacle Date: 04 Dec 06 - 02:14 PM Joe, Is the wiring in the house in metal wrapped wire or in metal conduit? If conduit, and the outlet box is metal, you have a grounding system is in place already--the conduit and box. Just hook the outlet to a ground wire in the outlet box. Make sure that you have the circuit turned off while you are working. This may mean using an extension cord so you can see what you are doing as you work. Remember that separate outlets do not necessarily live on separate circuits. |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: EBarnacle Date: 04 Dec 06 - 02:17 PM By the way, each circuit should have a ground fault circuit interrupter in line. It avoids that monkey with a screwdriver feeling. |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: JohnInKansas Date: 04 Dec 06 - 07:30 PM Bill D Your link to "World Standards" is a handy one, but it only shows about half the "what a mess" the situation deserves - with respect to the US, at least. It doesn't mention a half-dozen US standard plugs/receptacles that are in fairly common use here, although it gets the couple that show up in most homes. Travelers in some hotels may encounter 20A, 30A, or 50A sockets that don't appear. The 20A and 30A are 110 V, but the 50 A is 220 V, so travellers shouldn't try to plug in an adapter. Most RV (campsite) connections use these higher capacity receptacles almost exclusively, and I've seen them in lots of other places where someone might be "tempted to try." There's also a fairly common 100 A (220 V) socket found in larger camping areas, but you often have to pay extra to see one of them. On the other end of the RV cable, "Twistlock" connections are nearly universal, with separate sizes and configurations for various capacities. Add at least a dozen fairly common US plugs/receptacles not shown. The link shows what casual travelers are likely to need, but isn't really complete enough for ordering improvements from tradespersons. John |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: Joe Offer Date: 07 Dec 06 - 04:13 PM Well, I knew what I ought to do and how to do it, before I ever started this thread. I just didn't want to do it, since running a ground wire involved crawling through fiberglass insulation and dust in a very narrow space, and perhaps encountering little beasties without my having a quick path of escape. So, I was looking for an easy way out that would give me a fair level of protection. But in the end, thanks to your advice and encouragement, I did it the right way and ran the ground wire to the fuse box and hooked it to the grounded terminal. I choked a bit on the dust and itched a bit from the fiberglass, but now I feel good about having done it right. And the Sony 40-inch widescreen LCD TV works like a charm. We get almost 40 digital channels with an indoor antenna (as opposed to very fuzzy analog reception), and the HDTV channels are remarkable. The public television station in San Francisco has 4 channels of high-quality programming - I got hooked on a wonderful Vienna travelogue this morning. DVD's are remarkable on this setup - we christened the TV by playing Respighi's Pines of Rome from Disney's Fantasia 2000, and followed that with Stravinsky's Firebird. Those two pieces are the most beautiful things I have ever seen on a screen. Thanks for your advice and encouragement. -Joe- |
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Subject: RE: Tech: Surge Protectors-must they be grounded?(US) From: EBarnacle Date: 07 Dec 06 - 04:30 PM Now that you are properly grounded, you may as well do the rest of the house--or at least the rooms where there is electrical equipment. You should certainly do the bathroom and put a Ground Fault Circuit Interrupter [GFCI at the hardware store] in, even if you shave with a blade. |
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