Here's another surge protector that has a very low (specified) clamping voltage (135V), as compared to many other surge protectors that don't clamp until 300 volts, or even as high as 600 volts. The linked surge protector may be marketed as a refrigerator surge protector, but it could still be used for audio and video surge protection, especially since it has a very low clamping voltage.
Why whole house surge protectors are not enough
TL;DR:
One measure of a surge protector is the clamping voltage. That is, at what voltage does the surge protector actually start to work. Whole house surge protectors are limited to no less than ~ 600 Volts (instantaneous) between a leg and neutral or ground. That’s up to 1,200V if symmetrical.
The best surge protecting strips and conditioners clamp below 200 Volts.
Please keep this in mind when deciding whether or not to use surge protectors at your PC, stereo, TV, etc. in addition to a whole house unit.
I wrote more about this here:
https://inatinear.blogspot.com/2021/09/time-for-new-surge-suppression.html
No manufacturer of whole house surge protection claims that their devices alone are enough for sensitive electronics when you check the fine print.
71 responses Add your response
@erik_squires Yes, already aware, and yes, for the sake of others. One other thing (that I learned in broadcast engineering): many times a lighting strike discharge does not like to take corners. Straight wires (with the least amount of bends) are always encouraged when designing grounds that will dissipate and discharge lightning strikes quickly into the ground. Also, due to the skin effect of wire at certain frequencies, and the general frequency (spectrum) of a typical lightning strike; in the broadcast world, we almost always use 3"- 5" copper strap (very low resistance with lots of surface area) when dealing with lightning and grounding. |
I understand what you’re saying Erik. You’ve given me another idea. As of right now (and as with almost any), my outdoor A/C condenser’s earth ground goes back into the house, and attaches to the panelboard’s grounding bus bar. If we’re looking at lightning protection for a condenser (if it sustains a direct hit), one would want that strike to immediately discharge into the ground, *before* hitting the circuit breaker box, and *then* discharging into the ground via the ground rod(s) feeding the circuit breaker box's grounding bus bar. For many this may not be feasible, but in my case, my ground rod is right beside my A/C condenser. While maintaining the current condenser earth ground connection, I may install another low impedance earth ground directly from the A/C condenser to the ground rod (again, OCD). Having been a Radio Broadcast Engineer for decades, this is basically the same thing we do when grounding broadcast towers. The main ground system exists around the broadcast tower (many times incorporating a ring of ten 8’-10’ grounding rods cadwelded together), so that the strike can *immediately* discharge into the ground, *before* entering a transmitter building or studio/office building. The rest of the star ground system for the facility then feeds off of this broadcast tower base ground system. |
Interesting!! Based on what I've read about lightning striking outdoor AC units directly I really think that it's our outdoor units, not our stereos, which need a separate panel. That is, if I could redo my house wiring, I'd run a panel from the meter straight to the outdoor heat pumps, with their own breakers and surge protectors, and another line from the meter into the house. I mean of course to meet code 100%. What I'd avoid if building new is to have the electricity come inside to a service panel then back out to AC units. As it is, any lightning striking those outside units gets to come inside before meeting a surge protector. |
@erik_squires Around $250. I’ve just recently discovered these, and plan on installing one on my condenser. I also have these on my humidifier, dehumidifier, refrigerator and furnace (i.e., any device I own that has a motor or compressor), even though I rarely ever experience brownouts (you never know though when they might pop up). I like to be proactive (some may call it OCD). This also looks to have one of the lowest *specified* clamping voltages (140 V) I’ve ever seen on a surge protector. Even though I already incorporate a ton of surge protection in my house, and on my video and audio gear, I may even consider adding one of these to the audio and video (non power amp) AC feed for this gear: |
Than most people here is not setting a very high bar but even then I am not sure. They say a lot of dumb stuff. 150 vrms. They use 140v MOV probably. Not doing anything till 240 DC. A big surge is going to be over 400V. The datasheets don't give a lot of details. What's the controversy? Whole house plus a power bar for surge protection. Seems pretty obvious. MOVs don't do anything to your audio. Crazy to believe they do.
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Did I miss the response to what we think about "Envionmental Potentials" as a protective technolgy? VH Audio has always seemed to be edgy, but grounded in things that work, and they carry their products. I would really love to have more protection for my system than the whole house Leviton I have and several Shunyata Defenders plugged into my amps dedicated lines. |
This Belkin surge protector in front of your gear rack is all you need. Less than $45. |
Great, so which of their gear has been UL or ETL tested? Do they promote any of it as surge protectors?
That is interesting if true. Are you sure that isn't how it clamps after activation? |
Caelin Gabriel and Shunyata make suppressors for medical gear so I think they're a lot more knowledgeable than most people here. I spoke with Tim from Transient Protection Design who said that their whole home unit has MOVs that turn on at 150v. I encouraged him to have his engineer write something more detailed that I could share. They also recommend a defense on depth approach for sensitive electronics, and have detailed pdf showing how a home filled with electronics might be protected. |
If you asked me that 15-20 years ago maybe I would have known the answer. I doubt UL or NEC would ever say the capacitor can only be this big. They will write a bunch of paragraphs that will have the same effect. 5 minutes on Google and I found maximum of 34V after 1 second. |
@erik_squires Why thank you. Thank you very much. |
@britamerican Isn’t there an NEC or UL limit to the amount of capacitance you can put on the AC line, before any primary windings?? |
I was only half joking when I wrote "safety be damned".
Then I came across this for a different product that has their PFC function on whatsbestforum.
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@vinylshadow Given your series of posts I find your choice of words really funny. |
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That should tell you all you need to know about these two. They don’t know what they are talking about and are giving bad if not financially dangerous advice. I would say the same thing about the person who wrote this. They either don't know what they are doing or are lying. I get the impression the UberBUSS is like the BlueCircle and TLP products. Stack as much capacitance across the line as possible, safety be damned!
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When used in series, possibly, but that’s now how RG’s chokes worked. They are in parallel. PS - You should open up your Uber Buss. I’m sure you are going to find a whole bunch of chokes and coils if it does anything at all. 😁
Facts, the National Electric Code requires whole house surge protectors since 2020 AND recommends point of use surge protection devices for sensitive equipment. The first post explains why they recommend both. While the NEC requires whole house surge protection, it does not force you to use a surge protector for your stereo or TV. That part is up to you, but I’ve explained why the two are complementary as opposed to exclusive. Also, anyone who says that a whole house protector could cause RF noise is full of it. |
Sorry, current. My Gray was an old model from 2008. The Gray had chokes. Chokes compress dynamics I've been told. I have a 30A dedicated line connected to my Uber Buss power conditioner with a 30A Neutrik connector. My UBER Buss does a better job with noise than the Gray. Power Factor Correction of 1 if memory serves me.
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Not even a little bit true. You are confusing current with voltage. An MOV activates when the (for instance) voltage between neutral and hot exceeds a limit, like 300V. Each MOV sits across a pair of wires and does nothing most of the time. There’s no current, no noise, nothing. It just sits there until a high voltage happens and then it turns into a closed switch. A huge amplifier, playing at maximum output might cause the voltage to DROP below 120V. We call this sagging. The MOV would be even less inclined to activate with a big amp like that. By the way, Richard Gray’s devices famously use a resonant tank to stabilize the AC voltage and eliminate noise and are parallel devices. If you don’t want it in line you can plug it into the other AC socket and it will still work. They do an excellent job of eliminating noise and keeping the voltage stable even when your amp is causing the voltage to sag. Having said all of that, I encourage you to use Furman with SMP. It uses series mode protection instead of MOVs, though they do have an edge case that uses an MOV. It may help you to understand that having a high voltage at your speaker requires more CURRENT (amps) from the wall which will probably lower the Volts at the wall socket. If an amp played music loud AND raised the voltage at the wall you’d have an infinite power device and not even Elon Musk can do that. The plethora of things audiophiles do, like run dedicated lines with extra thick wires, use power regenerators and voltage regulators is all to keep the voltage at the AC outlet from sagging. |
Isn't it so that depending on their specs, MOV's can "clip" those occasional transient peaks of current to your amps so your speakers can not express those flash cymbal crashes for example. That's the reason that I pulled my Richard Gray MOV power conditioner out from my system and placed a Seimens Pro 140 at the circuit breakers. I'm in S Florida so it's a risk but I don't want any MOV's by my equipment. I think the Shunyata designer feels the same. I have a tricked out PI Audio UBER Buss power conditioner though. |
So, MOVs are not perfect, or instant. They live in two states, denial and confusion. Hah! I mean, on and off. When off, they conduct no current at all. However when they DO turn on they are not perfect, which is what is meant by Maximum Limited Voltage. Essentially this is Ohms law:
V = A * R In other words, the voltage that remains at the MOV is proportional to the current it's shunting AND the MOV's resistance. In a perfect world, R would be 0 and therefore V would be zero. A perfect switch, and no voltage across it, but since MOVs are not perfect, even when they've fully activated and are conducting they will have some voltage across them. |
@nagel I don't know of any SPDs in panel that activate below 600V due to reliability/safety issues. That is, they can't use MOV's with lower voltages because they could activate too often. For this reason almost all SPD makers for panels have about the same clamping voltage. I think the Maximum Limited voltage is AFTER the MOV has activated. It goes up with more circuit resistance to ground. In other words, you could see a 600 V or higher at the AC line before the MOV kicks in. This is why downstream strips which can safely clamp ~ 200V can be so helpful. Not to mention, any series filtering will slow the pulse down so the protector can activate. |
Erik, thanks for this thread! This brand was recommended as the very best by an electrician recommended from a reputable audio dealer: Any comments on this brand? They are pricey at $1400 but have lifetime warranty and made in US. They have a few pdfs showing complex protection for the home. By putting it in the panel and behind a pair of 30A breakers, I assume that the idea is that the MOVs will be just slightly removed from the signal path and so interfere with that wave less during normal operation and have less detriment to sound quality. How are we to understand Maximum Limited Voltage in this context? I'm looking at model TK-TTLP-1S240-FL with MLV ratings as follows: 2kV,67A - 36V, 6kV; 3kA - 590V; and 20kV, 10kA - 970V. I think this means for an impulse of less than 2kV and 67A, the clamping voltage will be about 120+36=156V. I agree that a panel installed protector does nothing for induced EMF from a nearby strike, but I had a strike 20 years ago that took out the speaker and amp channel that were closest to it but not the other channel. I assume that was due to induced EMF in the speaker wire or even voice coils. Point is, if lightning strikes really close, all kinds of problems may occur including on the ground leg. Does anyone have an opinion on these? https://ep2000.com/products/home-protection-products/premium-surge-protection-filter/?v=e75edac1b83f |
From an important textbook:
"Art of Electronics 3rd Edition", Horowitz and Hill, page 38. |
@carlsbad2 Sorry I didn’t really answer your question. As I understand it, the most common cause of a surge inside the home is when a large inductive load (motor) is turned off. The magnetic field has inertia and until it collapses is present and the motor tries to feed that energy back into the system. This is the best description I've found:
https://forums.mikeholt.com/threads/can-a-vacuum-cleaner-cause-a-surge.60537/ |
Awww, thanks @terry9 |
@carlsbad2 Depends on how you classify them. Some statistics say 80% or more come from inside, especially whenever inductive loads (i.e. big motors) start or stop. Of course, this includes very small surges we might expect equipment to shrug off. They tend to be small, but may accumulate. Anyone who has ever heard a thump through their stereo when a vacuum, ceiling fan, AC or hair dryer has turned on or off has literally heard a surge. |
@terry9 Isolation transformers have a lot of inductance, they act a little like series mode protectors. :) |
@erik_squires Thanks for your thoughtful and detailed response. If I lived where there was lightning, I'd be full in on the best surge protection available for everything excep my audio system....I'd probably just unplug my Regenerator before each storm....I know, PITA but as you know, I don't even like the degradation caused by fuses. I'd probably come up with some inexpensive equipment to use when lightning is in the area. Difficult problem you have and I feel for you. thanks, Jerry |
Mfinch - You may be right that it is hard to get the utility to pay for a new WHSP box, but my goal is to protect my audio equipment investment, and if I can just replace a couple of hundred bucks worth of surge protection and still have my sound system, I call that a win! Trouble is, not many folks rig up their WHSP box with full temporary isolation so they can take it out of circuit and test it to see if it still works after you think it has taken a hit. I'm "old school" and although in-circuit testing can be done, I feel more comfortable when testing just the device, unaffected by anything else. In general, the components that provide the surge protection DO degrade over time from the many small hits they will inevitably receive, and so should be tested or replaced once or twice a decade, or more often if your area might indicate it is needed (Florida or similar?). |
Erik - I totally agree. I speak from the hard experience where the contractor originally building my home ran out of positions in the SE panel and rather than put in breakers with two circuits per box position or add a secondary panel, they just put the last 4 rooms on the same circuit. Running the toaster and the garage door opener at the same time always popped the breaker. When I redesigned the home, I put in a new main SE panel that was the max allowed by the local utility and then added several subpanels throughout the house. With well-marked and dedicated circuits available, it becomes very easy to isolate my gear when desirable. If the stud walls are still open, it is trivial to run separate circuits for your power amp and your lower-power devices. I also got a deal on some cable so I ran 1/0 aluminum from the main panel to the subs, so there was minimal drop to each of the 60A panels. By running some #8 cable for the power amp back to the subpanel, that gives a fairly stiff source for the amp to draw from, and compared to the cost of the designer cables used between the wall socket and the devices, the extra in-wall cable cost was almost trivial. #8 has twice the max allowable ampacity of the #12 that is almost universally used for residential outlet circuits, so when the amps ask for power, the in-wall wiring can provide it, potentially adding some punch to your music. You just have to be careful to get #8 copper, not aluminum to get the full benefit because aluminum is used for the larger wire sizes because it becomes much cheaper, but the conductivity is somewhat less. When you get up to sizes like the 1/0, those are almost always aluminum, and at that ampacity, the droop caused by the draw of your amp is minimal.
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It's true that with wire distance the ability to snub a surge via a short to ground or neutral decreases, but the function does occur. The further the surge occured and the closer it was to say your TV the less effective a panel protector can be, but there are many branch circuits in the modern home, so having a panel unit to prevent a surge on circuit 1 from making it to circuits 2 through 30 is a good thing. |
And I do but honestly I can’t be here or be aware of all of them in advance.
The fine print in the warranty make filing a claim very difficult unless there is visible proof of a surge, which there often is not, or at least not one most of us could detect. Honestly I never really think of the claimed damage coverage when I buy new units. I focus on the technology and what I’m protecting. If they sold the WHSP as protecting the TV then yeah, those things wouldn't work. True, some devices work much better than others, so caveat emptor! |
I need a new refrigerator and a lightning strike would be a great way to get rid of it and an excuse to buy a new one. I like the idea about a surge suppressor at the electric panel, don’t know at what point it triggers but it seems somewhat helpful. quality Power switches with surge protection are a real smart thing to do for miscellaneous electrical av Devices. A better power conditioner to manage noise may have some value too If you have a large electrical storm rolling through, probably a good idea to unplug your amplifiers and components. I guess having them turned off while being plugged in still doesn’t protect them. Happily the refrigerator will remain on waiting for lightning to destroy it and then I get a new one. Yeah. |
