AC Surge/Lightning Suppressors

[eliwhitney]

TO : ALL

Many Models out there - here's one by a major mfg that has "done" very well over many samples for me these past years . . . . http://www.samsclub.com/shopping/naviga ... tem=414268

eli
p.s. -
also @ Wal-Mart, of course - but - more $$$

Sadly, used to be assembled here . . . .

[westom]

If it does fry the surge suppressor, it did its job. When MOVs conduct to failure, that failure is almost always a dead short that opens the protection in the SS and/or throws the breaker.

Protectors do not work that way for so many reasons.

Will that fuse or circuit breaker stop a surge? Surges are done in microseconds. Fuses take milliseconds to blow. Anyone who is making a recommendation should have that basic knowledge.

Will a fuse or circuit breaker block thousands of volts? Read numbers on those breakers and fused. 250 volts means a higher voltage simply keeps conducting through that fuse even after the fuse blows. It does not stop any surge.

That ground tester (that another uses) does nothing for what is discussed here. For example, does that outlet tester report an earth ground exist? Of course not. But more important is the nature of that ground connection. Thicker wire means lower resistance. Resistance is not relevant. Lower impedance is critical. That means a shorter wire is more important than a thicker wire. Essential to earthing a surge is a connection to earth as short as possible. Wall receptacles safety grounds are just too far away.

Other problems. To earth a surge means no sharp wire bends. No splices. Wire separated from other non-ground wires. Not inside metallic conduit. Just more reasons why a safety ground is not earth ground AND why power strip protectors do not even claim to provide protection in their numeric specs.

Essential to surge protection is no surge energy inside the building. A surge inside the building will seek earth ground destructively through household appliances. A surge that does not enter the building is, instead, harmlessly absorbed in earth. Where does that energy get dissipated?


Where ever surge damage must never happen, earthing is upgraded and a 'whole house' protector is installed. Does your telco use plug-in protectors? Or do they just disconnect phone service when ever a thunderstorm approaches? Neither. They earth a 'whole house' protector on every wire of every entering cable. A surge earthed before it can enter the building means protection inside every appliance is not overwhelmed.

Homeowners can install the same solution for about $1 per protected appliance. More responsible companies such as Intermatic, Leviton, Square D, Siemens, and General Electric provide these effective devices. A Cutler-Hammer 'whole house' protector sells in Lowes for less than $50. If properly earthed, then protection inside appliances is not overwhelmed. After all, what protects electronics in the dishwasher, smoke detectors, clock radios, and furnace?

What is inside the Monster Cable protector that sells for $150? Same protection circuit also found in the $7 protector sold in a grocery store. And the numeric specs for both make the same protection claims. Neither claims to protect from a destructive surge that is seeking earth ground. Earth a 'whole house' protector so that even direct lightning strikes cause no damage AND so that nobody even knows the surge exists. So that even direct lightning strikes do not damage the protector.

Money wasted on plug-in protectors is better spent upgrading the earthing. A protector is only as effective as its earthing.

[Roger Halstead]

All of these items are important for surge protection and Westom made some good points, but I think I should make some distinctions: BTW as a background in addition to over 100 credit hours in college electronics courses with a Bachelors in Computer Science, I taught every thing from introductory electricity to semiconductor circuit design and analysis to digital logic in the skilled trades program for a large multinational corporation before retiring.

First, we should not confuse surges with spikes. Surges may go high or low with durations in seconds to sometimes minutes. Spikes OTOH are just that. They are a pulse with a rapid rise and fall time. (Technically referred to as Dv/Dt, or voltage change "Dv" versus time "Dt") Surges may contain a lot of energy, while spikes are *usually* a high voltage with low energy.

In a home with a good ground system and hopefully a full house suppressor at the entrance, the so called surge protection outlet strip is a good investment. It is unlikely to protect against surges, but does a good job on spikes. A good UPS, properly configured will do a good job of protecting against surges and it should have spike protection built in. BTW, MOVs have a finite life. Every time they conduct they use up a little bit of themselves until eventually they reach a point where they conduct at too low a voltage to be of any use. They can fail either open or shorted, but shorted is the usual mode.

Backing up a bit. It's not a hard and fast rule but, surges normally come in on the power mains while spikes can and do, come in on anything. If lightning is anything it is unpredictable.
What it amounts to is the best defense is a good "single point" ground system followed by whole house suppression at the entrance. Please Google "single point ground" as this can get complicated in a hurry and I don't want to use the forum for an article.

There is no absolute protection from a lightning strike. The best we can do is follow the rules which will minimize the damage a direct or nearby strike can cause.
The whole house suppression helps protect from high voltage spikes coming in on the power mains or telephone lines. Don't forget that coax from antennas and the cable company should be properly grounded before they enter the home and that ground should be tied into the whole house, single point ground.

Another thing to remember is the idea behind the single point ground is everything at any given area in the home rises and falls at the same rate and potential. (if all goes well) Also power surges and spikes do not need a physical connection to the outside world to do damage in the home. A normal lightning strike a mile away can induce as much as a 1000 volts per meter in a piece of wire. With everything properly connected to a single point ground a piece of equipment like that new HDTV can rise to several thousand volts, but as long as the coax, interconnecting cables, AC line, telephone line, and ground also rise to the same voltage at the same time there should be no damage to even sensitive solid state devices.

One more thing. Fuses. A fuse has only one primary purpose. To prevent a catastrophic failure that burns down the house. It is not there to protect the equipment. That is taught way back in beginning electricity.

Lightning and surge protection can become quite complicated and I could write far more, but I think this pretty well covers the basics.

[Richard]

Our members have shown this topic can become quite complex, intense and down right intimidating. Don

[carddinal]

Newer homes have plastic rather than metal water pipes. Cable and satellite system installers seem to be unaware of this and will run ground wires from their equipment, where it enters the home, to an external hose bib/water faucet. Were lightning to strike their equipment all you would have is a burst of steam throughout the home, exploded pipes, and water all over. Make them install a good earth ground or locate the service entrance ground and use it.

[westom]

[quote="Richard"]Our members have shown this topic can become quite complex, intense and down right intimidating. Don

[lcaillo]

A couple of things that just don't make sense. UPSs aren't recommended for A/V systems because of the ratty wave form? Who cares? Why would some one care and if they do they don't know how a UPS works. A good UPS does basically two things. It protects equipment from voltage surges both high and low as well as spikes from near by lightning strikes. You don't run your equipment off the UPS itself. During normal operation it only serves as an outlet strip with surge suppressors. The UPS only kicks in to protect the equipment in case of Low or high voltage and spikes. It's supposed to keep things running long enough to shut the equipment down properly, not support the equipment in normal operation. To repeat: In normal operation the good ones only serve as a protected outlet strip. So distortion on the output of a hi-fi set should be a non issue. Now that is the job of line conditioners, but they are normally as much as 10 times or more than the price of a good UPS because they have to protect the equipment AND produce a good sine wave output. So due to price they are not usually considered a normal way of protecting equipment.

Yes the surge suppressors and strips are a good idea IF the house has a good ground system as Icailo stated. They are also the most economical. OTOH research the net for the quality of the insurance they offer. Many have so many outs, the insurance is worthless in most cases.

The main problems that I have with UPSs are that some do not have signal line protection and that we have seen some sets that will not run on them. I suspect it has something to do with circuits like the zero crossing detect in Sony and other products, but that is just a guess. I would not assume that a UPS is protecting, you have to look at the specific specs.

As for westom's suggestions, they are basically sound, other than his claims that system local surge suppression does not work, and that signal lines do not need protection. I have seen the results of using and not using them many times in the field. I fix sets all the time with lightning damage in homes that have whole house protection with no signal line protection and/or no plug in surge suppressors. I never see damage on systems with them where all the lines are protected. His emphasis on grounding is very much correct, but there is more to the story. His vehement arguments against plug in surge suppressors and signal line protection have been debunked in other online discussions by a number of people.

The bottom line is that grounding is of primary importance, whole house protection is good, but don't forget about protecting the signal lines and system level protectors can be found very inexpensively that can be very effective. Forget about connected equipment warranties, as they are likely impossible to collect on, but make use of lifetime warranties on the surge protectors themselves. The better companies will generally honor them with few questions.

[westom]

As for westom's suggestions, they are basically sound, other than his claims that system local surge suppression does not work, and that signal lines do not need protection. .

That misrepresents what was posted. I never said a plug-in protector does not work. It is not effective; a significant difference. It protects from a surge that is typically not destructive; made mostly irrelevant by protection that already exists inside appliances. Worse, even the manufacturer does not claim protection. If the manufacturer claimed that protection, then numbers could have been posted here.

Signal wires also need protection. Which is why interface chips are designed to withstand 2000 and 15000 volts. Signal protection is required and exists inside electronics.

[lcaillo]

It simply makes no sense not to use inexpensive protection that is readily available and can be installed by a user. Grounding is easy and cheap, and decent surge suppressors are also cheap. Every MOV added to a system increases the energy that can be dissipated. Contrary to what Tom says, they are not ineffective when grounding is compromised. They are less effective. They still clamp the voltage across their terminals and dissipate energy as heat.

Also, the refrain from Tom that most products contain surge suppression is simply incorrect. Most current consumer electronics products do not. Some do, but they are significantly less robust than the devices found in inexpensive surge suppressors. When they are present they are not connected to ground at all but across the hot and neutral within the device. Modern electronics ARE very insensitive to line noise, due to the conversion in the SMPS that most use. They are rather sensitive to large surges, however. I fix units damaged by them frequently. Two today, in fact.

I will say once again, grounding is the first priority, but adding surge protection that is inexpensive that covers both signal and power lines should be a consideration for anyone in an area that has significant lightning. I have seen many systems protected with no damage while nearby components with no protection were blown apart. It just makes sense to use system local suppressors that protect all lines into a system. Whole house devices are also useful, but not as effective as some suggest. It is also rare that whole house systems protect signal lines, or to have surge protection on telephone lines at the home installed by the phone company. In fact, modems are one of the most common devices damaged when lightning strikes. It is not expensive nor complicated to protect a system.

[westom]

Contrary to what Tom says, they [MOVs] are not ineffective when grounding is compromised. They are less effective. They still clamp the voltage across their terminals and dissipate energy as heat.

Also, the refrain from Tom that most products contain surge suppression is simply incorrect. Most current consumer electronics products do not.

Learn from datasheets how an MOV works. Increased joules means an MOV absorbs even *less* energy. MOVs do not provide protection by absorbing surges. MOVs work by *diverting* surge energy elsewhere. Diverting is the word specifically from the NIST. If not diverted, then ineffective protection exists. From the NIST (US government research organization):
> A very important point to keep in mind is that your surge protector will
> work by diverting the surges to ground. The best surge protection in
> the world can be useless if grounding is not done properly.

Could they be blunter? Best protection in the world is useless when? MOVs do not work by absorbing surges. MOV is only as effective as the component it connect a surge to - earth ground. An MOV with more joules means that MOV absorbs even *less* energy. That is how they work. Absorb little energy; divert lots of energy harmlessly into earth.

All electronics contain protection. Some don't see an MOV. Then 'assume' no protection. For example, a 1970 standard for 120 volt electronics required protection up to 600 volts. Telephone equipment has always had a 300+ volt requirement. Intel specs require internal protection to be some of the best in a house at thousands of volts. Even dimmer switches and bathroom GFCIs contain significant internal protection. Protection defined even with numbers