theres a lot to read here-ill have to find the time to read

what if a vcr is pluged alone ,in no protector, just to the wall, and the tv in protector?

is anyone concerned with issues like too much emf?i am -i swear since i got rid of dvd player i feel better-was it the rf modular?-how do you measure the emf?

a dvd in computer seems ok

i hate cordless phones

You are missing the entire point. The word 'vcr' also must be replaced by GFCI, dishwasher, and smoke detector. Answer remains same. Either current is earthed BEFORE it can enter the building. Or that current is inside hunting for connections to earth destructively via appliances. Protection means that current (that cannot be stopped or blocked) must connect to earth BEFORE entering a building.

EMF is another myth popular in subjective reasoning and hearsay. If EMF was destructive, then every nearby mobile phone, automobile radio, and wrist watch is destroyed by a nearby lightning strike. In one case, a direct lightning strike to a light rod was connected to earth only four feet away from a PC. The PC did not even blink. Tens of thousands of amps were flowing to earth only four feet away. Is that EMF big enough? And nobody even knew. EMF destroyed nothing.

By what path does the current get to earth. That is where attention is focused.

Hi,

I guess that when I run my welder in the shop then the PC is OK? Not! You would not use a Walmart Surge protector but a quality Line filter/Suppressor.

What about that large corn grinder? Load for the motor does vary for that and scoping the line shows noise, I bet if I used a spectrum analyzer on the line then the noise will be even worse.

I have seen noise from large refrigeration units that could cause issues with electronic equipment/instrumentation. Heck, a sub-sonic wind tunnel produced noise (electrical from the compressor unit) that was filter out for sensitive instrumentation. We had to be very careful in the LAB with sensitive electronic equipment, transducers & instrumentation. Some general instrumentation cost were $50K to $100K so isolation was very important.

We had a Laser Doppler Velocimeter/Anemometry(LDV/LDA) that cost over $300K without the laser subsystem. This unit was on a separate service and filtered power. So power line filtering and suppression depends on the environment with the equipment in use. Add to that a radio station above our labs and boy did we have to filter & suppress, both active and analytically. So do not say that EMF will not harm. It will depend on the environment and equipment sensitivity along with the units power supply design.

Lightening is another story. On my farm, We are at the end of the transmission lines. Neighbors have been hit but I get the damage. My power from the source to the farm is underground for <100 yards but the neighbors transformer hangs on a pole at the top of a hill. That pole has been hit so many times. Of course filtering & conditioning is now done on my service entrance along with arresters to protect the lines.

My electronics LAB has independent filtering/conditioning with suppression. I thought about building a UPS for the LAB but the task is way down on my list.

Better to be safe than sorry!

Craise, there is way too much information here for what you are asking. It has turned into a National Electric Code and Uniform Electrical Code deal with EMI/RFI thrown in and reactive loads.

All you need to know is this. A typical home wall jack has two outlets. Each of those are for your question the same electrical point. You don't need to care about which is which unless you have an issue where a wall switch controls power to one or the other. onebuck and I seem to stated the same things in different words.

It makes no difference as to what you connect as long as you don't overload the circuit. When it doubt move loads to another circuit. That may require you to find out how your home circuits are set. I built my home way over standards. Most newer homes are based on points. Older homes are not so well designed. Some homes are fire hazards. If you are in doubt at all pay a few bucks for a professional licensed Master Electrician to inspect your home.

For the point of this discussion, any consumer product is the same as another. A VCR is the same as a wall charger.

The rest of this discussion ought to be moved to a new post really where we can re-hash the technical issues that were asked here.

If you want you can send a PM to any member for more direct answers.

I'd like to see this on a new post as it is a good set of questions.

Would the knowledgeable contributors like to comment on (primarily in the context of lightening-induced transients):

The importance of low resistance earth (ground) paths.
The effectiveness of 1:1 ("isolating"?) transformers.
The effectiveness and desirability, within a junction box, of connecting L-N, L-E and N-E terminals with wire and cutting the wire -- with the intention of providing a normally open circuit spark gap that will be jumped by high voltage differences. EDIT: presumably an arc tube is a more evolved way to implement this.

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Simple answer: yes, just one surge protector plugged in to just one outlet. If you don't agree, then all the science comes out to justify the simple answer.

Beyond the issue of effective surge protection, whether an outlet is switched, and whether they are on the same circuit, separate circuits, or shared neutral, and the convenience of being able to easily reach the one that is more often plugged in and unplugged, it doesn't matter which is which.

Two separate surge protectors protecting separate equipment that is never interconnected can each be plugged into separate outlets anywhere, even on a duplex.

But leave the simple answer above here, or remove the question that asked if "its best to have just one (unclear, but surge protector is implied) in an outlet so that one deuplex is empty". The point being that if you plug in TWO surge protectors separately to each of the outlets, AND make connections between equipment plugged into these separate surge protectors, the surge protection is degraded. The science supports this.

If you want you can send a PM to any member for more direct answers.

Agreed. A better question would have made the thread less complicated.

Sure. Where's the new thread?

BTW, lightning induced transients are less than half of the surges to be protected against. But they do have the widest range of possible power levels. Other sources like switching motors on an off are more frequent, but are more likely to accumulate damage. These are the ones that will conduct across the MOVs for a few microseconds or so. This brief level of conduction protects the sensitive equipment, does NOT trip the breaker, and leaves the MOVs intact to continue protecting against the next surge. Lightning just gets more attention because we become aware of it more readily due to the flash of light and the boom of thunder, and because in very rare cases it can cause spectacular damage, or set a surge protector on fire.

In accordance with UL and NEC one could install almost any number of serial surge protectors. One can not install serial GFCI's as the tend to trip but it won't be against code. There is nothing unique about a wall plug type surge protector. I dare someone to find this as a violation of NEC or UEBC.

Serial is like a wall jack, extension cord, surge protector. See how they all follow a single line. That is the normal way to connect all home devices. There is no safe way that I know of to cross connect devices as they don't even offer any choice unless you cut into wires. I know of no equipment for commercial or military use that has such a dangerous connection. (let's not get into Navy electrical as it doesn't apply)

If you are referring to an outlet device that fits into the wall box and gets covered by a plate, and includes surge protection ... those do exist. I've never taken one apart to see if they are correctly wired. I assume the ones from reputable manufacturers of such devices, such as Leviton, to be doing it right. And that would mean the duplex versions are not splittable. As a single point of protection through which the supply current for both outlets flow, it would be a valid way to surge protect devices plugged into both outlets, and allow interconnection between those.

I've never seen these in stores. But they might be around in some places, like electrical supply stores. In the catalogs I've looked at, they are in the hospital equipment section. I guess they don't want to have power strips dangling around the place.

However, I have not seen these with other kinds of connectivity for protection like phone line, coax, or CAT5/8P8C. If you don't have other connections to the protected equipment, these can be used.

If the devices being cross connected are protected on the same single surge protector from ANY and ALL wires coming from elsewhere, then this is generally safe. When I say cross connected, I'm visualizing a computer with external peripherals like a monitor and USB backup hard drive with the power for these plugged into the same surge protector ... or a TV/VCR/DVD combination with all those devices plugged into the same surge protector ... or a stereo system with everything all plugged into the same surge protector.

Extra long interconnections can be risky. I've experienced this personally. I had a stereo system with no surge protector, which I dutifully unplugged when not in use. One day it was dead. There had been a thunderstorm the evening before. The problem was determined to be the extra long speaker cables. They were 50 foot monster cables (AWG #4 finely stranded). The damage melted the coil windings of both tweeters. The midranges and the big center woofer was not damaged. All PA transistors of the amplifier were damaged. There was no visible damage, but they tested open. Once replaced, the amplifier was fine, again.

Keep interconnections short or disconnect them when not in use.

14 posts! I'm a hardware guy, pure & simple.

ups is the best surge protector around, and not tinyinductors in a 'wall wart'.
Better in any business to have a 'clean power' circuit where you can put meaningfully sized surge protection in the panel.

What are you protecting against? Noise - that's sort of doable, but ups (power recreation) is best.
Lightning (50Kv 5k/50k amps) - not really doable - the numbers are too big. You can choose what blows first, but it selects what blows last.

Miswiring of mains? not really doable except by ups. I'm on 220Vac here, 380Vac phase to phase. Some twit in a substation put a phase on the neutral and fried the electronics of a street a few years back(putting 380V on a 220V line). I shouldn't complain - I made a few €€ from it.

Hi there,

I'm surprised - to my knowledge, Europe has been striving for a homogeneous electricity network for many years, one of the goals being the same nominal mains voltage in all countries. Thus, Germany raised the nominal voltage from 220/380 to 230/400V (which was supposed to be the consensus) in the 1980's, while for instance the UK lowered the nominal voltage from 240 to 230V in the 1990's, IIRC.
Did Ireland choose not to join that consensus?

[X] Doc CPU

Telephone COs, connected to buildings all over town, suffer about 100 surges with each thunderstorm. Therefore a telco turns off telephone service with each approaching storm? They don't? Then your town must be without phones for four days after every thunderstorm. After every storm, your telco replaces their $multi-million computer? Never. Because protection from direct lightning strikes has been routine even when telephones were operators with headsets.

A typical UPS does not protect hardware. That UPS connects hardware directly to AC mains - no protection. That UPS does not even provide spec numbers for hardware protection. A valid recommendation will provide hard facts with numbers. But a UPS manufacture does not provide them. We know a typical UPS does no hardware protection also for so many reasons cited above.

By what path does current get to earth? Anomalies, that can overwhelm protection already in appliances, mean connecting that current harmlessly to earth. Where is even one plug-in UPS that claims to protect from such anomalies? No spec numbers will be quoted because even the manufacturer does not claim that protection. UPS manufacturer numbers make it obvious. A UPS does near zero protection.

Subjective claims are best ignored. Some hardware techs make UPS recommendations only from hearsay. Protection even from direct lightning strikes is routine when well proven solutions are learned and implemented. That means a direct connections or protector connected to earth ground. Because that was how it was done even 100 years ago. Protection from lightning has been that routine for that long.

This is kind of wrong. There is no cross connection in regards to the electric code.

"If the devices being cross connected are protected on the same single surge protector from ANY and ALL wires coming from elsewhere, then this is generally safe. When I say cross connected, I'm visualizing a computer with external peripherals like a monitor and USB backup hard drive with the power for these plugged into the same surge protector ... or a TV/VCR/DVD combination with all those devices plugged into the same surge protector ... or a stereo system with everything all plugged into the same surge protector."


What would need to happen and it may in some rare cases is that such non-line voltage connections between devices would have to suffer both a design error and a catastrophic failure to pose a risk. By design and in accordance with testing labs the devices would have to be so totally poorly designed as to allow this to happen even in worse case.

The topic of lightning can not be considered in any of this since it is static electricity and at such HUGE voltages doesn't follow any typical line. Lightning can follow dirt on walls and jump to wires and back to air and back to carpet tack strips. Lightening almost never runs in wires, it runs on the outside of wiring, if it follows wires it does so on the outermost layer of copper or causes the insulation to fail and follows that.

One can protect systems to a degree but as you read rated protection numbers on these devices they make a very small assumption that is way less than even the smallest strike.

Surge protectors protect against secondary changes in voltage or distributed issues in power generation and can never offer true protection against lightning.

/Note to self: Unsubscribe from this thread. I don't want an argument. Sorry, OP, I was trying to help.

Telcos have used my company to repair their lightning blown equipment, and to provide technical reports on it. Simple stuff can be made to survive - fancy digital stuff does not take a direct strike.Period. The periphery blows (usually 1st board in.


Agreed - the cheap computer shop ups does not greatly protect.
If you read my post you will note that I specified power recreation

AC-->DC-->New Sinewave. These protect. Goodbye.

OK. There seems to be a serious problem with understanding the underlying concepts. These concepts were first demonstrated by Franklin in 1752.

Lightning seeks a connection to earth. If finds a more conductive path in a wooden church steeple. But wood is not a best conductor. So 20,000 amps connected to earth via wood creates a high voltage. 20,000 amps times a high voltage is high energy. The church steeple destroyed.

Franklin installed a lightning rod. But a lightning rod does not do protection. It simply makes a more conductive connection to earth. So 20,000 amps connected via that wire creates a near zero voltage. 20,000 amps times a near zero voltage is near zero energy. Nothing destroyed.

Some have so little grasp as to even argue about pointed verses blunt rods. Because it is not seen, most will completely forget what does protection – earth.

Appliance protection is same. Either a surge makes a low impedance connection to earth so that near zero voltage exists inside. Or someone foolishly tries to stop a surge that is now inside and creating a high and destructive voltage.

Again. Protection is always about where energy dissipates. An honest recommendation will always say where hundreds of thousands of joules dissipate. As Franklin demonstrated, either destructively in a steeple or harmlessly in earth. Protection is always defined by what does that protection. Where energy is absorbed. Not inside any protector. In earth ground. A protector, like a lightning rod, is only as effective as its earth ground.

We earth a 'whole house' protector so that lightning damages nothing inside the house. Even the protector remains functional.

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Actually lightning rods do not make a connection to earth as pointed out. They have proven that they allow a small bolt to actually move up from the ground line to the rod. At the instant the strike happens it now happens a few inches to a few feet away from the building. This is why buildings are protected. It is the arc blast that damages buildings. This protection does not impart protection to the other forces that can affect electromotive force. The strike affects the nearby electrical grid and affects transformers and induces current into any conductive material both electrically and conductive to static electricity.
Lightning rods are for building protection only.

However in the instances where proper lightning protection systems are not installed then any number of cases can occur. There is no device made that can handle a strike.

Surge protectors are NOT lightning protection. The boxes sell them with images of lightning in the background but they will never work to save electronic devices. They simply can not handle the voltages and current.

Lightning never follows a predictable path to earth. Many insurance claim examples show that lightning will simply jump to some point even if a very good conductor was near and should have been followed. Children draw lightning as a wiggled line and not a straight line don't they?

The OP was only interested in surge protector and how to use them.

Someone took you if you believe your home is protected against lighting by some device. The claim, if you carefully read it, on the device will only state some small value and under some conditions and not anything about static electricity. In the event that you attempt to make a claim and they are forced to pay their limit is some figure that you may never get paid. Some of the "insurance" backing are completely based on in an offshore company that will fold before they pay.

Pictures show this upward connection. Did that picture capture what happens in microseconds - the surge current? Of course not. That picture shows how an electrical path is constructed. You have confused construction (that takes milliseconds) with a surge current that flows in microseconds.

A lightning rod connects a typically 20,000 amp current harmlessly to earth.

Same applies to surge protection. Anyone can go to Lowes, Home Depot, any electrical supply house, etc to read numbers on the proven solutions. Solutions from more responsible companies such as General Electric, Siemens, ABB, Leviton, Square D, Cutler-Hammer, Intermatic, etc. These devices even state how many amps that protector will connect to earth without failing. A minimally sized 'whole house' protector is 50,000 amps. Then a 20,000 amp direct lightning strike does not even harm the protector. Then the massive current need to find earth ground destructively via appliances inside a building. Then lightning does not create a massive voltage.

Franklin demonstrated protection of a building. 'Whole house' protectors do protection of appliances inside that building. In each case, neither lightning rods nor protectors do the protection. Protection is always about quality of and connection to earth ground. Effective protection is about where that hundreds of thousands of joules dissipate. Stated again because it is fundamental to protection. And why direct lightning strikes are routinely made irrelevant. As proven by over 100 years of science and experience.

If challenging this, then explain where hundreds of thousands of joules are absorbed. Surge protection is always about where energy dissipates.