@dpop That is an excellent idea. As you know, for the sake of others who may read this, you may not have separate grounds, but so long as you bond everything at the same ground potential you may run multiple ground conductors to the same grounding rod(s), which probably should be plural.
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.
Showing 26 responses by erik_squires
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. |
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? |
@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?? |
@vinylshadow Given your series of posts I find your choice of words really funny. |
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. |
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. |
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. |
@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. :) |
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! |
@zlone Furman makes dozens of models for the pro and home use, from actual strips, rack mount and the Elite like home equipment like units. The features I know are important for noise and surge are LiFT (linear filtering), SMP (series mode surge protection) and EVS (extreme voltage shutdown). The latter will protect you from long term over voltages which are not necessarily surges. Like 90V or 140V AC. The unit will shutdown until corrected. In SC I’ve had this trigger at least 2x. Apparently they go in and out of stock from Amazon and Sweetwater so it's worth checking in repeatedly if there's a particular model you have in mind. The cheapest is the strip, which has LiFT and SMP but not EVS. The rest are convenience features. I don’t think power factor matters that much, but the Elite units have add-ons like switched outlets which are great if you use a HT processor or preamp with a trigger but your amp doesn’t have one. I use an Elite after a unit with VR (voltage regulation). Not that I need the VR feature here like I did in California (more PG&E problems) but I have it so I might as well use it. |
Furman with LiFT and SMP has never let me down. Also provides exellent noise filtering.
I’d go the other way. I’ve never had anything but positive listening effects from using a Furman, therefore I always use them. I personally don’t think the idea that all surge protectors/conditioners are current limiting and your amp is better directly to the wall. I can see this being true for many though. As others have pointed out though, this really depends on where you live. If you are in Florida with gear you don’t want to replace, always surge protect it. I know some people who have never lost gear due to power problems. OTOH, I have and when I moved in here there was a surge protector still attached to the wall which had obvious scorch marks. Clearly this is an area prone to lightning strikes. It's not all about lightning either. When I worked in an area covered by PG&E we lost several PC power supplies over the course of a couple of days. Each time we could smell the MOV. In another job we lost two floors worth of surge strips over a week due to PG&E switching problems. |
Your math isn’t wrong, but I was referring to surge strips (not necessarily a strip, but not a whole house unit). We don’t need joules for series mode protection. It’s a parallel mode thing which I don’t recommend in a strip. For in-panel protectors, which are parallel (and the only one’s available), they publish surge current instead of joules but the effect is the same. Repeated surge current wears those MOVs down. Of course, surge protectors are a lot like air bags. No guarantee you’ll survive, no guarantee they’ll ever even be needed but still the math says cars with air bags are statistically safer than cars without them.
I’m not sure this is completely true. As I understand it, the limiting factors are the clamping voltage of the WHSP, as well as the inductance in the line in between the surge source and the WHSP. It IS true that the best surge strips (again not necessarily a strip, could be a rackable device) like Furman and Tripp Lite have lower clamping voltage and can reduce the surge effect at the TV, for instance, especially if the vacuum and the TV are on the same line.
PS - Given that all panel mounted surge protectors have about the same clamping voltage, I prefer the ones that mount as breakers. This minimizes the wiring and I hope minimizes the impedance, helping the surge protector to lower the surge voltage. Plus I think they are easier to install/remove. Right now I’m using a Siemens BoltShield, but previously had a Square-D panel and did the same. |
@audioman58 I have the same brand, but mine stop blinking and an audible alarm goes off. Even so, their high clamping voltage is why I supplement those with point of use surge protectors. |
Do whatever you’d like so long as you remain informed. :) Personally, I don’t even want to LIFT the equipment off my rack, much less deal with insurance or replacements. :) Also, I run some nice PC’s here and don’t want them to fry with my data on them, same for my music collection. Here on the SC coast I have underground power in my neighborhood but that doesn’t stop the power from glitching due to transformer and other power issues elsewhere. My surge protectors or UPS has to intervene about 3x a year even without lightning or known vehicular assaults on my gear. :) As for the rest of the home, I have a lot of permanently attached devices besides major appliances such as automated lights, fire alarms and GFCI outlets. I met a man a month ago or so whose home was struck and he lost his entire outdoor AC units. No idea if a WHSP would have saved him, but just evidence that we are prone to that kind of damage here. |
I want to point out that lightning entering the Ethernet system without actually coming through the cable provider’s wiring is an edge case, but exactly the sort of problem I’m worried about. That is, my guess is that 90% of home network surges happen from the copper that goes from outside to inside of the home, and the remaining are from induced (EM pulse) currents from INSIDE the home Ethernet wiring. The longer a run of Ethernet the better it may pick up a lightning surge. From what I’ve read this danger starts around 30’ long runs. Once the wiring is involved the next question is how will it find a path to ground? That path is often through a power supply somewhere. Once that gap is broken through everything in the way will fry as the surge arcs over. In these cases shorting (MOV) based surge protectors become co-conspirators by offering a low-volrage gap to ground. Network isolators work by increasing the necessary arc-over voltage by 4kV at a time. This forces the surge current to look for a path with less resistance to ground which hopefully involves fewer devices. And this is the thinking I've read lately. You may not stop the surge current, but you can reduce the total number of connected devices involved. If you fry a cheap switch instead of your switch, TV, streamer, PC, etc. it's a good thing. |
@upshift Sorry to hear that but really interesting.
I want to warn you not to use grounding Ethernet arrestors inside your home. Use those, if any, outside or as close to that edge. Inside stick to isolators. The most recent thinking I’ve seen is that grounding Ethernet cables during a surge just allows a high current surge to form through MORE devices when otherwise you wouldn’t have one. Better to isolate the gear and let lightning find a path through a single device and it’s power cable than to form a long circuit and let it take out even more devices downstream. So far during the worst of the lightning I’ve only lost a cable modem, which wasn’t mine anyway. 😁 Alternatively, use fiber converters to air-gap your gear. After installing my whole-house suppressor lightning took out a laptop. It was the only PC in my home that was plugged in but NOT on a surge strip. The same way audiophiles are kind of ridiculous with having too much gear to play music, we also have a lot more Ethernet devices hooked up than the average person, though hard core gamers are close. For many Americans who have Internet access Wifi is the only connection they use and lightning is not the same problem than for someone like me who has a dozen items hooked up via copper networking cables. |