Talk:Surge protector

h-n, h-g, and n-g
I have a surge protector and it says it protects the h-n, h-g, and n-g lines. Any idea what it is telling me? It is for 3 prong US 120 V surge protector. Jrincayc 18:07, 23 May 2004 (UTC)

That probably means it has three MOV's, one each from hot:neutral, hot:ground, and neutral:ground. A spike on any of the three will cause the MOV's to short the spike out. --ssd 03:22, 29 May 2004 (UTC)

iron poor vs. iron core
Nearly all transformers are iron core. (Some are air core.) The article should say iron poor, meaning that the core has less iron in it than necessary to transmit the full current. Please don't confuse these and change it back. --ssd 18:28, 18 December 2005 (UTC)

external links wanted
I would like to see other websites apart from howstuffworks for this article. Anyone taking the bait? I would ask StuRat but I thought it would be better to post it here. -- Kushal one 17:43, 12 April 2006 (UTC).

This article needs an authoritative reference. There are a number of misinformed statements in the article. Its a complex matter but this link provides credible references:

http://www.nist.gov/eeel/quantum/spd.cfm

The anthology is from Francois Martzloff, considered a 'father' of surge protection technology Igsaturation (talk) 18:29, 21 December 2009 (UTC).

The link to Martzloff's anthology is no longer valid. This is the updated link:

http://www.nist.gov/pml/div684/spd.cfm — Preceding unsigned comment added by 85.18.87.187 (talk) 07:53, 28 June 2012 (UTC)

MOVs do degrade
The page on MOVs (metal oxide varistors) says that they degrade over time. Also, in my personal experience and from the reports of many others, they do fail after time. The way companies get around paying up is to make it really hard to claim the insurance. For example, you need to prove that the damage was done by a power surge, which can be very hard if there are no obvious burn marks. Even the, can you prove it was the surge protector that failed? They also rely on most people not bothering to claim anyway, similar to rebate coupons.
 * Can you prove it? Because if so, it could be included in the article. 205.157.110.11 01:21, 22 February 2007 (UTC)
 * I gather that's an unintended pun :) --68.85.99.144 18:08, 4 November 2007 (UTC)

Yes, MOV do degrade, if they are used; the closer they are used to their cutoff voltage, the more they degrade. If not used, they will last indefinitely. If they do 'degrade' MOV become more sensitive, and will self destruct sooner than one that is virgin. There is no indicator to determine if a MOV has experienced a surge or not.

If a company's policy is to not honor their warranty through double talk, its best not to buy it from that maker. The top makers honor their replacement warranties.

Some MOV based SPD designs use inline fuses, and so if a sizeable current is passed, the fuse will blow, should the MOV fail as a short circuit. Igsaturation (talk) 18:34, 21 December 2009 (UTC)

Picture
The surge protector pictured is obviously not American. Where is it from and should that be noted in the caption? PrometheusX303 21:03, 5 July 2006 (UTC)
 * It's a CEE 7/4 standard plug. See the Schuko article. I don't think this needs to be mentioned; its proves the point and is possibly a more internationally recognised format than the American style. ―AdamMillerchip 05:40, 15 December 2006 (UTC)

Surge arrester
Please see the original schematic from SchneiderElectric: http://d.interbild.net/vstoykov/tmp/shemi/surge_arrester_merlin_gerin.png and my modified verion: http://d.interbild.net/vstoykov/tmp/shemi/surge_arrester_merlin_gerin_MODIFIED.png (The blue line is the mechanical connection between circuit breakers!)

Where i may found free pictures of 1P circuit breakers and surge arresters to draw a free picture? --Valentin Stoykov, 09 October 2006

Silistor, what kind of arrestor is this?
In Japan, they commonly use a "silistor" in these kind of arresting situations, primarily in DC circuits, one leg of the silistor on the negative DC side and one leg on the actuated side, which is + DC. It does not appear that there is a polarity to the device. What is a silistor and how does it work and are they available in the US? 68.84.76.193 15:02, 8 November 2007 (UTC)


 * Apparently, a Silistor is a silicon-based PTC thermistor. It's more of a temperature-sensing device than an abrupt-cutoff protection one, so I'm not sure how it would work.  Can you clarify?  Reference: http://homepage.hik.se/staff/tkuwl/Measure_Sensors/My_Book_Temp_Whole.pdf
 * If it's simply connected across the supply lines, it could be a Silicon avalanche diode, a.k.a. transorb, under an unfamiliar name. A part number would answer the question more definitively.  71.41.210.146 (talk) 05:33, 8 March 2008 (UTC)

Joules
A "buying guide" from Tripplite is not a technical resource. Surge protection means spike protection from what would otherwise cause electrical damage. The average lightning strike is 20,000 amps and as large as 200,000 amps. Therefore a nominally sized protector is rated for 40,000 amps or higher which is about 1000 joules. Such protectors will survive about 10 average 20,000 amp lightning strikes, 400 surges of 2000 amps, or the one typically extreme surge. Protectors start at 1000 joules to survive multiple lightning surges or survive the extreme surge.

A 200 or 400 joules protector is too small to protect from one average lightning surge. The www.tripplite.com/EN/buying-guides/technology-primers/surge-suppressor-how-it-works.cfm "buying guide"  mentions lightning as a surge. But it balks at asserting protection. A 400 joules protector is too small to protect from one lightning surge. Survival, as varistor manufacturers define, means the protector is not damaged. "Buying guide" numbers are too small but are what that manufacturer markets.

When sized to survive the typical destructive surge, the protector is rated for 40,000 amps. Charts from varistor manufacturers define this as 1000 joules or larger. —Preceding unsigned comment added by 71.123.49.22 (talk) 21:19, 6 February 2009 (UTC)

The joule is a misleading parameter for gauging a SPD. The amps and voltages quoted here are possible, but they occur in microseconds to nanoseconds. A well designed SPD does not require the MOV to absorb that energy and dissipate it, any device will do so will generate heat and if too much potentially melt the casing or explode, rather it should blow gracefully, like a fuse, and sacrifice itself to protect your home or equipment. Therefore, a low joule rating is not a pejorative, but is more a feature IF the manufacture honors and provides a lifetime warranty, so you can easily replace the SPD.

A higher joule rating allows the SPD to absorb more energy without self destructing, thus the SPD is still alive. However, as mentioned before, repeated exposures degrade a MOV, so it will likely blow at lower energy level at an unknown date; futher 'containing' this energy means the potential energy will be released as kinetic energy, and more joules = violent reaction. Makers make higher joule rating SPD by putting MOVs in parallel. The problem is MOV have non-linear responses and when exposed to the same overvoltage near its threshold voltage, some individual MOV can be more sensitive that others, causing that one MOV to conduct more than others, leading to its premature failure. If an inline fuse is placed as a power-off safety feature, which good SPDs do, then it will trip, and fail your SPD even if the other MOV are still intact. Thus, multiple MOV will be useless, and placed in series with a fast acting fuse, the fuse will likely blow before the MOV. Igsaturation (talk) —Preceding undated comment added 16:07, 22 December 2009 (UTC).


 * The section on joule rating spends much of the time telling us that joule rating isn't useful. If everything else is constant, higher joule rating should be better. It is volts times amps times time, or an integral when they aren't constant. An MOV conducts to keep the voltage across itself more or less constant.  Yes a higher voltage means more power (and joules), but one should choose the appropriate MOV voltage.  The usual failure mode for MOV is to short out, that is sacrificing itself for your protection, assuming something else, such as a fuse or circuit breaker then shuts off. Otherwise, all the energy goes into heating up the MOV, which has to not melt before the surge goes away. Gah4 (talk) 23:23, 26 May 2017 (UTC)

The idea of a joule rating as a figure of merit assumes that the clamp voltage stays about the same. While this is true of MOVs, it is NOT true of spark gaps or gas discharge tubes, both of which have a much lower voltage after being tripped. This makes them much harder for the lightning to destroy. It should also be kept in mind that every surge protector has spark gap protection whether you want it or not -- a high enough voltage arcs across the wires in the wall of in the power cord. This limits how much energy a nearby lightning strike can deliver. Guy Macon 13:59, 2 June 2010 (UTC)

References to show these things actually work?
I have been trying for years to find some genuine tests of surge protectors that show they actually work as advertised. There are loads of "reviews" which consist of "they offer $$$ insurance and nothing blew up when I tested it", but no serious, scientific tests as far as I can tell. All the ratings on the units are simply safety related, i.e. "will not explode if hit by X volts".

I have lost devices that were supposed to be protected, and there is a lot of anecdotal evidence that actually trying to claim on the compensation offers is next to impossible. Again, no hard data though. Can anyone provide any kind of reference for this sort of thing? Without it, all surge protectors amount to little more than snake oil since presumably if they actually worked the manufacturers would have had independent tests carried out. Mojo-chan (talk) 14:03, 11 March 2009 (UTC)

There is a lot of misinformation in the SPD sales literature.

Although I wrote this review regarding one brand of SPD, the background contains details on the impropriety within the industry:

http://www.epinions.com/review/APC_11_OUT_SURG_W_TEL_COA_EA_APNP11VNT3_Surge_Suppressor/content_453665328772

Some tests are made by law offices, as a malfunctioning SPD can at times lead to a fire, and hence major product liability. Here is one URL.

http://www.sfowler.com/investigations/Surge%20Protectors.htm

Igsaturation (talk) 18:44, 21 December 2009 (UTC)

The Wirecutter has done some extensive testing of the most popular models. Testing methodology is solid, includes teardowns, and has some really good straightforward independent consumer information if you read the whole article.

http://thewirecutter.com/reviews/best-surge-protector/ — Preceding unsigned comment added by 66.194.187.100 (talk) 17:36, 15 July 2016 (UTC)

Service protectors or plug-in protectors
"Surge protectors" come in 2 basic varieties - service suppressors installed where service wires enter a building - plug-in suppressors that protect equipment plugged in downstream

The article header says "a surge protector (or surge suppressor) is an appliance". That implies the article is about plug-in suppressors.

Some of the text applies to communications suppressors that are applied at the entrance to a building.

The discussion for power wiring is essentially for plug-in suppressors except "Important specifications" was hijacked some time ago to be for "surge protector for AC mains". Some of the specifications are incorrect for plug-in suppressors.

What is the intent of the article? Service suppressors Plug-in suppressors Both

Some of the header, which appears to not be editable, is not correct for plug-in suppressors.

BudKey (talk) 19:40, 8 May 2009 (UTC)

Section on degradation needed
This article needs to include a section on degradation of these devices over time. Typofixer76 (talk) 20:45, 5 December 2009 (UTC)

IEC Standards
The article could do with references to IEC standards and please remember not all of the globe is on ANSI / NEMA standards nor on 60hz —Preceding unsigned comment added by 80.195.94.134 (talk) 00:11, 29 July 2010 (UTC)

GDT and MOV in series?
One of my coworkers was recently advised by a GDT manufacturer's application engineer to connect the GDT in series with a MOV. This is a new one one me; I typically use a GDT across the line, then series inductors, then a MOV. (the inductors slow the rise time so that the MOV doesn't fire first and clamp the voltage, stopping the GDT from firing). The GDT should self-extinguish at the next zero crossing as discussed in http://www.comptronic.se/files/documents/AN-111.pdf

I am researching this, and once I get a good anwer from reliable sources, I hope to add the info to this Wikipedia article. I haven't been able to find the kind of high-quality references I need to write it up, so I am putting my preliminary research here in the hope that someone else knows of some better references.

I started this by thinking that this doesn't make any sense at all. A GDT is a slow high current device and a MOV is a fast low(er) current device. Put them in series and it seems that you would get the low current capability of the MOV and the slow turn-on of the GDT. Am I missing something here?

To start with, UL mentions it here:

http://www.ul.com/global/eng/pages/offerings/industries/hightech/consumerelectronics/pag/pag142/

Quote: "The combination of an MOV in series with a GDT provides a fast reaction time and long life for high voltage and high current transient protection applications."

Next, United States Patent 5388021 (Voltage surge suppression power circuits) says this:

"To clip the surge remnant, a common practice is to insert an L-section suppression circuit in the line following the gas tube. This circuit consists of a series impedance and a voltage clamping device, such as a MOV or a silicon avalanche suppressor, connected across the power line. The series impedance is connected between the gas tube and the clamp and can simply be a resistor or an inductor, or both; a resistor being suitable only for low voltage, low current applications. The impedance must be high enough in value to guarantee gas tube breakover so that the clamp only clips and diverts the energy in the remnant, not the energy in the entire surge. A major problem associated with gas tubes is "follow-on" current, the current from the power source which continues flowing through the gas tube after the surge current terminates. In ac circuits, the follow-on current clears when the line current goes through zero but the gas tube could be re-ignited on the next cycle. A typical gas tube is rated to handle a 60 Hz, one-half cycle peak current of only 20 amperes, hence, if the power source can deliver much higher currents, i.e., a 460 V ac power line, the gas tube could be destroyed, particularly if it breaks over at the beginning of a cycle. In dc applications, a separate means for extinguishing the arc must be included in the circuit. Frequently, the follow-on current is limited to a safe value by connecting a low value resistor or a clamp such as a MOV in series with the gas tube. This technique, however, can significantly raise the clamping voltage if the surge current level is high."

The first part sounds like the GDT/Inductor/MOV circuit that I have been using for years, but note the bit at the end about the MOV in series with the GDT.

United States Patent 3973224 also mentions my usual circuit, but without any reference to a series GDT/MOV.

United States Patent 4677518 ( http://www.freepatentsonline.com/4677518.pdf ) has a good explanation in the "detailed description of the preferred embodiment" section:

"Referring now to the drawing, with particular attention to FIG. 1, a transient surge suppressor according to the invention utilizes a breakdown device, for example, a gas discharge tube 12 connected in series with a non-linear resistance element, such as, for example, a varistor 14. The series-connected elements 12 and 14 are connected across a pair of lines to be protected, such as a power main 16."

"Assuming that the power main 16 is a 120 volt RMS AC 60-cycle power main, the peak voltage applied across the series combination of the gas discharge tube 12 and the varistor 14 is 120 volts times the square root of two, or approximately 170 volts. Thus, the component values of the gas tube 12 and the varistor 14 should be chosen such that the gas tube 14 is not triggered by the peaks of the line voltage. Thus, if a gas discharge tube having a trigger voltage of 145 volts is selected as the gas discharge tube 12, and a varistor having a nominal voltage of 100 volts, such as for example, the ERZ-C20DK101 manufactured by Panasonic, is used as the varistor 14, the series combination will not be triggered by the 170 volt peaks of the alternating current wave. However, if a transient appears on the line 16, such as a transient illustrated by the line 20 (FIG. 2), the gas discharge tube 12 will trigger when the voltage across its terminals exceeds 145 volts, which corresponds to approximately 245 volts across the series combination of the tube 12 and varistor 14, as is illustrated by the point 22 of FIG. 2. When the gas discharge tube 12 triggers, the gas in the tube ionizes, the negative resistance phenomenon occurs and the voltage across the tube drops to the glow voltage, nominally about 60 to 75 volts. This reduces the voltage across the series combination to about 160 volts, as illustrated by the plateau 24 in the graph of FIG. 2."

"As the current through the discharge tube 12 increases further, the tube is driven into its arc mode wherein the voltage across its terminals drops further. Typically, the arc mode voltage or arc voltage of a gas discharge tube is nominally 15 volts, and the voltage across the series combination is then reduced to approximately 115 volts as is illustrated by the point 26 of FIG. 2."

"As the transient continues and the current through the gas discharge tube 12 and the varistor 14 increases due to its dynamic resistance, the voltage across the varistor 14 will increase, first at a fairly gradual rate, and then more rapidly as the current through the varistor 14 increases. This results in a gradual increase in the voltage across the combination, as is illustrated by the curve 28 of FIG. 2. This voltage will continue to rise to a maximum point 30 which is determined by the maximum current produced by the transient. Once the transient energy has been dissipated, the current through the gas discharge tube produced by the power line voltage will drop below the level necessary to sustain ionization. Also, since a substantial portion of the power line voltage will appear across the non-linear resistance device, the voltage present across the gas discharge tube will be below the voltage needed to sustain conduction. Thus, the discharge tube will switch to its nonconductive state; and because the values of the voltages of the discharge tube and the varistor have been chosen such that the peak of the line voltage will not cause the discharge tube to be triggered, the tube will remain nonconductive until the next transient occurs."

Looking at the above, the question arises of how this is better than a MOV alone. If I am understanding the above correctly, the primary advantage is the ability to select a MOV with a much lower clamping voltage, which lowers the energy that the MOV must dissipate. Guy Macon 15:08, 16 August 2010 (UTC)

The reason for the GDT+MOV combination has nothing to with improving the electrical performance, your suspicions are correct it will degrade performance. It is for safety reasons. Standards like IEC 60950, IEC 6236 and probably others prohibit the use of a just MOV between a primary circuit (line OR neutral) and earth, except under very restrictive situations. The reason for this MOVs are not good insulators (sort of by design!) hence will leak small current under normal conditions and certainly lots under transients. this leakage can increase over time. If the earth wire of the product in question failed open the chassis would then be live. The reason the GDT+MOV is for primary to line/neutral to earth is acceptable is the GDT will not have any leakage current below its breakdown voltage. Latter versions of the standard require the GDT pass the withstand voltage test (2.5kV for typical 220-240V products). This means you'd need a GDT with a DC break down higher than this maybe 2.7kV to 3kV allowing for tolerance. So it would barely activate at 4kV under actual fast rise time conditions. So very questionable if its worth the hassle.

Between Line and Neutral this safety aspect is not applicable so just a MOV is suitable for safety and best for performance. A bit of leakage here wont result in a shock but does have fire risks so other rules apply like fuses, flammability of nearby parts etc. -- ~59.167.102.209 (talk) 00:32, 19 February 2019 (UTC)

Extensive cleanup done, but much work remains
I tried to rebalance the article away from a "MOV-centric" point of view, by placing alternative technologies in a better context while still acknowledging that MOVs are the dominant tech in simple low-cost equipment. More info should be added on the relative costs and tradeoffs among various surge suppression methods. Also, I tried to clarify the distinction between protective devices that shunt spikes and those that try to block them in series. Lastly, I did a lot of copyediting to clean up awkward, confusing, or erroneous wording.

I think Guy_Macon's analysis above is relevant and cogent, and his preferred GDT/inductors/MOV configuration (mentioned at the beginning of his writeup) is a good basic setup to combine the best features of the 3 technologies in a synergistic manner. The "negative resistance" characteristic of GDTs and the suppression of "follow-on" current is an important consideration in using GDTs, and should at least be mentioned in the article. I encourage Guy to contribute his practical wisdom to this article.

As mentioned earlier by BudKey, a distinction should be made between "service panel protectors" and "plug-in protectors" right at the beginning of the article. This article appears to be focussed mostly on consumer-level plug-in protectors. More coverage on industrial and power utility protectors could be added, or pointed to elsewhere. This article should at least acknowledge these related fields of knowledge, even if not covered here.

A lot more work is needed, especially in the section regarding specifications and testing. A neutral, unbiased specialist in surge protection is badly needed there. Reify-tech (talk) 05:17, 19 March 2011 (UTC)


 * I've done a lot of the work I proposed earlier, and I think the article is now much clearer and less ambiguous. But I may have inadvertently made some errors clearer, too.  Please review the article for technical correctness.


 * I think it would be useful to have a simple table comparing the relative tradeoffs among the different surge suppression technologies. It would have columns to compare relative cost, speed, capacitive loading, energy dissipation capacity, ease of installation, expected lifetime, failure modes, etc.  Has anybody seen such a comparison table anywhere?Reify-tech (talk) 22:42, 28 March 2011 (UTC)


 * Hello all, this page indeed does look good! I would agree, the addition of industrial scale SPDs would be a good inclusion here.  If this page were expanded to do such, also with inclusion of the Lightning arrester page, it would do much to expand the knowledge of the general category of Lightning Protection Systems.   Borealdreams (talk) 14:52, 12 March 2012 (UTC)

Relocated 2011 comments
Everyone who participated in upgrading this topic since I was last here in 2009 needs congratulations. Its far better. Best to you all Igsaturation (talk) 20:42, 9 June 2011 (UTC).

I'd like to use a 120 volt surge protector (purchased in the United States) in a 220 volt European style outlet with an adapter. The appliances plugged into the surge protector would be 220 volt capable. Will the surge protector be able to withstand 220 volts? — Preceding unsigned comment added by Emilclu (talk • contribs) 22:49, 26 March 2011 (UTC)

120V USA surge protectors shouldn't be used in 220V. Surge protectors have a cutoff voltage < 330VAC peak which is very close to the operating voltage peak of 220V, 311VAC peak, so it may survive being plugged in, but depending on the type of MOVs installed its inevitable it will blow. Better surge protectors use much lower clamping voltages, far below 330V. Igsaturation (talk) 20:42, 9 June 2011 (UTC)

Merge Spike buster with Surge Protector?
There seems to be no difference between the two, from what i can tell. Furthermore that article is an orphan that cites no references. — Preceding unsigned comment added by Sckolar (talk • contribs) 12:03, 31 July 2013 (UTC)


 * Support - First of all, the Talk pointer on the Merge notice at Spike buster did not point anywhere; I have pointed it here. Secondly, thanks for pointing out the orphan article; I was unaware of its existence, and never would have though of searching under that slang term.  What little content the stub article contains should be merged in here.


 * Note that proper WP:MERGE protocol calls for a merge notice at the target article as well as the source article. You seem to be new at this, so I encourage you to read the guidelines and follow them. If you are unable to do so, I or some other editor will eventually  clean this up, but I encourage you to finish the job if you can. Also, please sign your articles with four tildes (~).  Reify-tech (talk) 17:25, 31 July 2013 (UTC)


 * Support and redirect created. There was nothing accurate or useful out of this to merge to Surge protector. --Wtshymanski (talk) 18:58, 12 May 2014 (UTC)


 * Once again you have merged two articles and not followed the correct procedure (at WP:MERGE) as recently drawn to your attention via an ANI. However: on this occasion, I am going to let it go.  This is because, as noted, there was nothing salvegeable from the source article and none of it has, in fact, been merged.  There is thus no edit history to preserve.  85.255.234.139 (talk) 07:29, 13 May 2014 (UTC)

} I'm beginning to wonder if you even know what an "edit history" is in the context of Wikipedia. --Wtshymanski (talk) 13:57, 13 May 2014 (UTC)

Ratings
I have encountered several discrepancies with this article and other sources of information around the various ratings for a surge protector, including, but not limited to, a buying guide published by Home Depot, an article on Lifehacker, How Stuff Works, and numerous other articles. I recommend that this article should clarify why there is a discrepancy, if it is justified, or an expert be brought in to resolve the problem. 161.31.231.60 (talk) 19:09, 20 March 2014 (UTC)

Radioactive GDTs
The paragraph that mentions gas-discharge tubes "formerly produced by C P Clare" uses the word "radioactive." Is the word used in the usual sense of ionizing radiation emitted by the gas, or is it a mistaken attempt (by a non-native English speaker?) to derive a word for the light sensitivity? If the former, should the information be moved elsewhere in the article? --SoledadKabocha (talk) 04:03, 11 January 2015 (UTC)
 * Apparently some do contain radioactive materials, mostly to help initiate ionization and therefore a quicker strike.. Some data sheets  explicitly guarantee the tube to be radioactive-free for this reason. SpinningSpark 18:03, 11 January 2015 (UTC)
 * Okay; sorry for being too lazy to find/check the sources myself. Perhaps it might help just to insert a paragraph break before the sentence in question. --SoledadKabocha (talk) 18:28, 11 January 2015 (UTC)

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Broken & incorrect reference links
I don't really know the subject matter, so, beyond "uhh... link no worky!", most of my comments below are based on the notoriously unreliable combination of cursory web searches and common sense, and should not, under any circumstances, be mistaken for informed, knowledgeable, or even particularly useful advice. I'll leave the corrections to someone with a better grasp on the material and/or wiki citation formatting.


 * Reference #24 gives a 404. The old 'About NFPA' page is archived at http://web.archive.org/web/20130401015326/http://www.nfpa.org:80/categoryList.asp?categoryID=143&URL=About%20NFPA, and their current About page is at https://www.nfpa.org/About-NFPA . I'm not sure which would be more appropriate, since (possibly due to some missing words or grammatical issues) I'm not sure what the text with the citation is actually trying to say. It states "A failing MOV is a fire risk, which is a reason for the National Fire Protection Association's (NFPA)[24] UL1449 in 1986...", but UL1449 is, as far as I know, published by UL, and not NFPA )unless it was meant to refer, not to UL1449, but to NFPA 70, the National Electric Code, which "compliments UL1449".


 * Reference #25 also gives a 404 (to http://downloads.eatoncanada.ca/downloads/Transient%20Voltage%20Surge%20Supp/Tech%20Data/TVSS%20UL%20spec%201449.pdf ), and doesn't appear to be archived. At first I thought that #4 could be substituted, as both links looked like they were pointing to copies of the UL 1449 standard, but I'm not certain what #25 actually used to be, and #4 isn't what the footnote makes it sound like (see below).


 * Reference #4 is all sorts of confusing (or else I'm just easily confused), and makes me wonder whether it's some sort of accidental conflation of a couple unrelated citations. It reads Rosch, Winn (May 2008). "UL® 1449 3rd Edition" (PDF). Eaton Corporation. Eaton Corporation. I'll take the problems with this one at a time:


 * Winn L. Rosch appears to be a PC hardware writer, and the only place on the net that I can find his name even mentioned on the same page as UL1449 (aside from this reference on this page or obvious copies/derivatives thereof) is the Wikipedia Varistor page (where #16 simply cites his Hardware Bible regarding MOVs - no clear connection there, although the neighboring #11 does cite another - otherwise unrelated - page on UL1449). Similarly, I can't find any indication that he ever worked or wrote anything for Eaton (although some of his patents are cited in one of theirs), and neither his name nor any other author is credited anywhere in the PDF (the document properties lists "Author: Zoltun", which appears to be their graphic design firm).
 * The listed title is "UL® 1449 3rd Edition", while the actual PDF is, rather than the standard itself, the significantly different "UL® 1449 3rd Edition — Key Changes".
 * The document is only a page and a half leaflet, and doesn't actually contain any of the information discussed at 4a, 4c, or 4d (although 4b could possibly be inferred, if you cross your eyes and stare at it from the right angle for long enough).

--71.234.116.22 (talk) 23:04, 1 February 2018 (UTC)

RMS
Seems to me that it would be useful to mention that AC voltages given are RMS, and that the peak is sqrt(2) times larger. For example, in the sentence mentioning the 330V clipping value for 120 VAC systems. Gah4 (talk) 12:37, 9 April 2018 (UTC)

Inductance
In some places, it could be useful to mention the effect of inductance. For example, in the case of parallel MOVs, even the small inductance of the lead wires, at high enough dI/dt, it will slow down the current rise through the first one to conduct, giving the second one just a little more time. There is some mention of series inductance later, but not of LC filters which are also used along with other devices. Gah4 (talk) 12:51, 9 April 2018 (UTC)

Power Strip
Would it be appropriate to add a link to power strip in the "See Also" section? I think these are related and often confused. Aenet1405 (talk) 21:39, 8 November 2020 (UTC)
 * , power strip is already linked in the body of the article so a See also link is not required. See MOS:NOTSEEALSO. ~Kvng (talk) 12:34, 11 November 2020 (UTC)

Merge from Surge arrester and Transient voltage suppressor
These are overlapping topics and we either need to work to reduce the overlap (perhaps by using WP:SUMMARY) or merge it together. ~Kvng (talk) 21:57, 22 December 2021 (UTC)
 * ✅ Klbrain (talk) 12:42, 23 September 2022 (UTC)