Surge Protector Mystery resolved

By fw2004
Jun 7, 2008
  1. Hello;
    I have been using surge protection since it was invented, and I paid over $50 for a network quality 6-outlet strip by Newpoint.
    These protectors always seem to have an LED labeled "protected when lit", whether they are the run of the mill Staples brand or a more expensive APC model.

    I have one from Radio Shack with only one outlet, designed for a large appliance such as a microwave, or AC with electronic controls that can easily be destroyed by a surge.
    Recently, I noticed that the green LED that indicates "protected when lit" was not lit, but the appliance was powered and working fine.

    I have always suspected that these "protected when lit" indicators were put there for one reason, and it's not to tell you that the protection circuit is working!
    The reason they are used, at least in the model I own is so that when the LED burns out, you go out and buy a new protector.

    On my Radio Shack unit, screws were used to hold the two halves of the case together, so I took it apart, and proved my theory correct.
    The LED that is labeled "protected when lit" is wired through a 24K 1/2 watt resistor directly across the 115V fused line.
    The LED has absolutely nothing to do with the fact that the MOV's (there are 3 of them) are working or not.
    The only thing the LED could possibly indicate is that the internal fuse has not blown, and that can be found out by testing the appliance plugged into the unit.

    The LED in this unit is wired through the 24K resistor directly across the 115VAC line, without a diode. This puts the full 115V on the diode during the reverse phase of the AC cycle (when the LED is not conducting).
    In this circuit, it is only a matter of time that the LED will burn out. I am now convinced that the designer chose the LED to sustain the high reverse voltage without breaking down for several years, but no more. This insures that the owner will have to buy a new protection device, and chances are they will buy the same model they had before.

    So, to make a long story short, it may be OK to continue to use the surge protector if the "protected when lit" LED is out.
    However, it is NOT OK to use the device if the LED indicating a WIRING FAULT is lit. Wiring fault indicates a faulty ground or reversed hot and neutral on the receptacle into which the protection device is plugged. This is a serious problem, and must be repaired immediately.

    I hope this saves some of you time and money, but I am also interested to know whether anyone else has taken such a device apart and found the same thing to be true of different types and brands.

  2. kimsland

    kimsland Ex-TechSpotter Posts: 14,524

    But when not lit, this means there is a fault (either in the Led or the power itself)
    Therefore the Surge Protector would be deemed as faulty (even if it still protects)
    I believe this may also be stated in the manual

    It is not for the user to take the Surge Protector apart, to confirm that it may just be a LED fault. Therefore the Surge Protector should either be serviced or replaced.

    Note: Many users have also successfully replaced internal batteries inside the Surge Protector, but again this requires a qualified service technician (and must adhere to the manufacture warranty requirements).

    I do not recommend users to take apart their equipment, especially devices holding voltage, that could potentially be dangerous and at least, causing a warranty void issue.

    Not recommended
    But interesting fact about the fact that the light may not be the diagnostic reference.
  3. fw2004

    fw2004 TS Enthusiast Topic Starter Posts: 150


    I was not really suggesting that anyone except those qualified take apart any electrical or electronic device. I was just making a point, mainly for the sake of interest.
    IMO, the manufacturer should build a device which provides true diagnostic indicators, or none at all.
    Having the LED in the case of my device is useless, as one can easily tell whether or not the internal fuse has blown by simply switching on the connected device.
    I guess it does serve to differentiate between a blown fuse in the surge protection device and a tripped circuit breaker, or dead receptacle.

    As to whether or not the surge protection is still working remains unknown, as the indicator LED cannot make this determination, at least not in the model I own.

    I apologize for giving anyone the impression that a device like this can be repaired by the user.
    I am not a "user" so to speak, because I have worked professionally in electronics, and am proficient with electrical devices.
    I would (probably incorrectly) assume that anyone who is going to open up a device connected to line voltage (or any voltage for that matter) would disconnect it from the source before proceeding. Then again, our society (not sure where you are located, but here in the US) needs to have warnings on coffee cups to prevent frivolous law suits against McDonald's and Dunkin Donuts by people being burned when they spill the contents.

    As for changing the batteries in (I am assuming you are referring to) UPS units, I have done this a number of times, and never found it a problem.
    That said, I can understand that it should not be done by just anyone due to the high current capacity of the battery, and possibility of injury, just as I would not recommend everyone replace his own car battery.

    Given all the law suits, aren't you a bit surprised that we are still able to buy such things as high current batteries, home wiring devices, etc that can cause severe injury or death if installed incorrectly?

    Home Depot will sell anything to anyone. I wonder whether they have ever been named in a lawsuit where someone was injured while working with a product purchased there.

  4. kimsland

    kimsland Ex-TechSpotter Posts: 14,524

    Oh yeah that's UPS for batteries, totally unrelated, sorry about that.

    Anyway yes I'm a qualified Electrician and Electronics certified (well certificate there) and later (about 15+ years ago) decided that computers are more fun

    This line:
    Is why I replied, but you've now cleared that up.
    So red tag it ! And have it serviced by a qualified technician is the answer.

    I think this is your main point of the entire post
    You know I'm not sure, because when the light was out, I've probably replaced the entire unit in the past (at users cost) Better to be safe than sorry.
  5. Tedster

    Tedster Techspot old timer..... Posts: 6,000   +15

    While using a surge strip with a burned out led will always be questionable, that's the risk you take. Without physically opening up the strip and examining the wiring or circuitry, you have no real way of knowing if your protection is still valid or not. I think 99% of most consumers will either take the risk, or go out and by another one rather then open up the strip to check - it's just not cost or time effective. Plus I would imagine, most wouldn't know how to check.

    I think in general, it is better just to get an UPS.
  6. fw2004

    fw2004 TS Enthusiast Topic Starter Posts: 150

    Most of the strips are "plastic welded", so there's no way to open them up anyway. I wouldn't have opened up mine except that I was curious.

    UPS is really nice. We have those occasional glitches that would cause a reboot, and the UPS keeps the system running.
    Another nice thing is that if you have other stuff, like a cable modem that also handles your phone (Optimum Voice), it's nice not to be cut off when there is a brief outage.
    Only problem there is that when local power goes out, it is likely that the cable amp on the pole will go out, so you will lose phone, Internet, and TV.

    Saturday morning I had to shut off the whole house to install a couple new breakers in the panel, and was happy to find that I didn't need to reset the clock in the answering device after I was done. It was connected to the UPS.

  7. jobeard

    jobeard TS Ambassador Posts: 9,156   +598

    IMO, a surge protector is a throwaway component. I use a UPS for everything.
    Why take a chance using a $1.95 device (hint: disparaging comment, not a pricing comment) when the equipment attached to it is worth 50-100x that amount?

    Yea, I did shortwave radio too, but it's not worth the time and effort to save so little and take such a chance.
  8. westom

    westom TS Rookie Posts: 18

    View the spec numbers. Protection in a UPS is even smaller than in a power strip. UPS connects electronics directly to AC mains when not in battery backup mode. Where is the better protection? Again, view the specs. Even the manufacturer will not make those claims.

    Put so little protection inside as to be near zero. But it is not zero. So the UPS manufacturer can subjectively *claim* surge protection. That is enough for myth purveyors to hype it into superior protection. Don't take my word for it. The protection numbers in power strips are superior to those in a typical UPS. Only urban myths say otherwise.
  9. westom

    westom TS Rookie Posts: 18

    Surge protection has existing for over 100 years. But the protection that has worked for over 100 years is not same as the protector you are promoting. Take a $3 power strip. Add some $0.10 parts. Sell that protector either for $7 in the grocery store, $50 to others who know without learning manufacturer spec numbers, or $150 to customers in Best Buy. After all, if it is more expensive, the same circuit must be better?

    MOVs inside protector have acceptable failure modes and completely unacceptable failures. MOV manufacturer datasheets are blunt about this. MOVs must only degrade. Their voltage changes by 10%. Still functional, but degraded.

    A completely unacceptable operation is MOV vaporizing. This is also a fire threat seen by most every fire department. Undersizing the MOV get the naive to promote it. And when that unacceptable failure occurs, the LED will change.

    LED can only report the completely unacceptable failure mode. It cannot report degrading. But that catastrophic failure gets the naive to promote the ineffective protector.

    Surge protection means nobody even knew the surge existed. Routine is to have a direct lightning strike without the protector failing. But that does not get the naive to recommend it.

    Well, you have demonstrates that even some protectors will even scam what the protector light reports. But then where does that power strip protector define protection from each type of surge in numeric specs? It does not. It claims to protect from a type of surge that does not typically cause damage. A surge made irrelevant by protection already inside every appliance. Does not matter whether the protection is relevant. It protection from something that is not destructive - therefore if can be called a surge protector.

    Let's take apart a surge protector. Notice they removed all MOVs and the protector light said it is still OK:
    Triple w dot

    But then undersized protectors also create other problems seen by most fire departments:
    Triple w dot
    (Numerous links to fires created by surge protectors that the system needs to protect you from).

    A protector is only as effective as its earth ground. As is common knowledge even in Ham radio, the protection means the surge is earthed AND does not even enter the building. To make the protector effective, it must connect short (ie less than 10 feet) to single point earth ground. To make it even better, telco COs prefer the protector up to 50 meters separated from electronics. That separation and short distance to earth is critical due to wire impedance.

    Other earthing connections necessary to make a protector effective - no sharp wire bends, no splices, wire separated from all non-grounding wires, not inside metallic conduit, etc. To better appreciate why earthed protectors are effective and why power strip protectors do not even claim that protection, read the highly regarded application notes from Polyphaser:
    (The application notes that most every ARRL member knows but is too revolutionary for the system to grasp - so the system banned the URL.)

    If MOV failure causes an indication on that LED, then the protector was so grossly undersized as to violate parameters defined on the very first page of every MOV datasheet. Only grossly undersized (ineffective) protectors fail so catastrophically as to be reported by that light.
  10. jobeard

    jobeard TS Ambassador Posts: 9,156   +598

  11. westom

    westom TS Rookie Posts: 18

    View what you have just posted. From your second citation:
    > Surge protectors act like an electrical sponge, absorbing dangerous excess
    > voltage ... Like a sponge, surge protectors have a limited capacity to absorb.
    > Once the capacity is reached, the unit is no longer protecting your equipment
    > and it should be replaced.

    Your protector is 890 joules. That means only 300 joules and never more than 600 joules absorb surges. You said 300 or 600 joules can absorb how many joules like sponge?

    It claims to conduct up to 36,000 amps. Lets assume that surge creates a trivial voltage - only 6000 volts (static electricity discharges can exceed 18,000 volts). 36,000 amps times 6000 volts times 20 microseconds is how many joules? 4300 joules. Even if your protector used all its joules (which it does not), how does an 890 joules protector absorb 4300 joules like a sponge? Did you forget to do simple arithmetic? Where does all that extra energy (not absorbed by the sponge)go? Cause electronics damage where? Maybe create a house fire?

    What happens if a surge is even slightly more robust - 10,000 volts? Well it claimed to provide surge protection. It said so without numbers. So it must?

    A protector failed even on a surge so small as to not harm the computer - and how many other devices in the house? The naive will recommend it? Of course. Once you believe it is a protector, then damage will get you to recommend it to others. You told everyone it "is better than many in-line surge protecting power strips". Your own numbers say failure. Which will you believe? The numbers, or what a retail salesman said? How curious - the sales brochure also do not list numbers. Why would they only claim subjective (near zero) protection?

    Cyberpower does not list each type of surge and protection from that surge. No wonder facilities that can never suffer damage do not use your protector. Instead, 'whole house' protectors are used that actually do provide protection. Effective device that costs only $1 per protector uses all its joules to earth direct lightning strikes harmlessly and repeatedly to earth. Less money for a protector that remains functional even after direct lightning strikes.
  12. jobeard

    jobeard TS Ambassador Posts: 9,156   +598

    the comment re sponge was an analogy in the cited article and has nothing to do with the implementation.

    I can do the math too and have years of experience building radio and mobile transmitters + power supplies and while you seem to need to rant on this subject, I'll concede without agreeing -- I hate to see someone so upset.

    I've suffered several 'brown-outs' (ie loss of power to the home) and never lost any equipment -- thank UPS. As there is very little lightening in S. Calif., the house or a/c line service have never taken a hit and the a/c line has been well regulated thanks to S. Calif Edison.

    as that's my opinion -- you're welcome to yours.
  13. westom

    westom TS Rookie Posts: 18

    That 'sponge' is a popular myth to sell ineffective and highly profitable products. Best protectors absorb no energy. Mythical protectors absorb energy like a sponge. That sponge analogy is how obscenely profitable and ineffective protectors get sold to the naive.

    Another myth: brownouts harm electronics. I will always confront myths promoted due to insufficient technical knowledge. I don't like retail store myths and those who blindly promote them. How do we design electronics to last longer? A circuit is installed to create a brownout. Brownout created because it is not harmful to electronics. Brownouts only cause electrnics damage in myths.

    Brownouts are harmful to motorized appliances. Brownouts are not harmful to electronics.

    Industry standards have long required brownouts to be non-destructive. A chart for one 1970 standard even includes this phrase in the brownout section: "No Damage Region". Why no damage? During power up or during normal operation, brownouts only cause damage when speculation replaces technical knowledge.

    That "sponge" is how ineffective protectors are promoted for obscene profit. Effective protectors never act as a sponge. Your protector recommendation is a classic example of how they promote a scam. I’m sure you did not do it intentionally. But you did not even know that brownouts must never be destructive to electronics.
  14. jobeard

    jobeard TS Ambassador Posts: 9,156   +598

    fluctuating voltages are disastrous good buddy;
    • start a write to disk
    • move the arm
    • wait for the correct sector at that cylinder/head
    • enable write and before the operation completes
    • voltages fluctuate/decay
    if the decay is rapid, the circuit is still enabled and while the arm is retracting, it scrambles sectors all the way.

    go ahead and never use a UPS; that's your choice. As I've not lost a system in 30 years, I think I'll continue with my choice.

    enough; I'm unsubscribed to the thread
  15. westom

    westom TS Rookie Posts: 18

    Your post discusses data protection - not hardware protection. A poor example because that earlier post recommended a UPS for hardware protection. As stated - a UPS is for protecting from data loss; is not for hardware protection.

    Moving on: your post works in theory if knowledge of disk drives operation is unknown. Back in the early 1970s, working on disk drives at the semiconductor level, that problem never existed. And still does not exist today for long list of reasons - some provided here:

    1) What is the job of a power supply? To provide either steady voltage or remove voltage. There is no fluctuating voltage when the power supply meets standards from even 40 years ago. Either voltage is constant, or power is cut off.

    2) When does a disk drive respond to power off? Only after power starts to disappear. Notice how routine and unexpected power off does not destroy data - because the same circuit makes data damage impossible. Even 40 years ago, a drive did not erase data as you have speculated. Drives did not even learn about power off until after power was turned off. Could never do what you have posted.

    3) We once saw a disk destroy data due to a power failure. Rare and completely unacceptable even 35 years ago. That one drive was an Interdata 8 inch floppy. So I analyzed it design (back then, we were provided with schematics). The relationship between 5 volts and 12 volts was improperly controlled by the drive. Therefore heads would destroy data - often the directory index. Did your 8 inch floppies suffer data loss? Mine used on Date General and Dec machines did not.

    This may be too technical. However it does say how deep my knowledge and experience when I again note: brownouts are not destructive to hardware. Your example of data destroyed by power cycling is a myth promoted when basic hardware knowledge gets replaced by speculation. And your example does not demonstrate brownouts destructive to hardware.

    Bottom line: brownouts are not destructive to electronic hardware. UPS is to protect data; not for hardware protection.
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