I took a surge, should I worrie?`

Discussion in 'Home Theater Projects' started by Joe Tilley, Jul 8, 2003.

  1. Joe Tilley

    Joe Tilley Supporting Actor

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    We have been having some really bad weather here & the other day I took a pretty good hit. What I have is a Monster HTS5100 for my TV, Receiver, DVD, & CD player. Than I'm using my old Monster HTS1000 for my sub. So anyway I don't know just what to call it A surge,power outage,spike, whatever, but whatever it was my power center spiked up to 165volts my sub made a huge whomp & then everything quickly went out & than right back on. But when everything else came on my line voltage was at about 92volts according to my 5100 & it took a couple minutes before it finally switched fully back on, but the power did not return to its normal 120 for at least a good hour, it was hovering between 108 & 113volts I even double checked this with my multi meter. Now everything seams to be fine & I left all my gear off the rest of that evening just to be safe, but the thing that concerns me is will the power center loose any of it protection ability after taking a hit like that?
    I just thought that once a good surge has hit a device like this it affects its ability to stop it another time around & was wondering if there was any truth to this.

    Sorry if this is the wrong place for this but I thought it would be the most fitting.
     
  2. Chu Gai

    Chu Gai Lead Actor

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    You sure have been having some bad weather over there. Talk about all that rain compared to the same time last year!

    The Monster surge protector, like most of the others, is based upon MOV's. Now MOV's can get a bit of a bad rap. We've all read how they degrade in response to surges. And some of us have seen pictures on the web that show's the death of MOV based devices when hit with a surge. That way of thinking needs to be examined a bit more carefully though. If you undersize an MOV or have a device that wasn't manufactured properly then certainly they can die and pretty spectacularly too. If the MOV is sized well for the job, and that generally means the more joules the better, then its operating lifetime rises exponentially. The ultimate lifetime of an MOV is predicated then by two things: it's size and how many surges (their magnitude is a mitigating factor) it has been exposed to. That's why, if you're hell bent on buying a surge protection device that's an MOV point of use device, your purchasing decision should be weighted strongly towards "more joules the better".
    A surge is a pretty nasty electrical event. It is not though a spike, or a glitch, or a nominal elevation in your AC voltage.
    Surges can arise from a variety of reasons such as lightning that strikes the earth or from peculiar power grid situations like someone running their car into a pole carrying a transformer or even a squirrel electrocuting itself and shorting out a substation.
    As to what happened in your situation Joe, no one really knows but we can take a reasonable guess. Guess mind you! I'll bet you've got other transistorized devices in your home. Clock radio, fridge, garage door opener, microwave, maybe some X-10's, cordless phones, etc. If any of those devices died, then there's a pretty good chance your home was hit by something bordering on the definition of a surge. However, with a very high degree of probability, the Monster device dealt with it. And it'll deal with many many others before it gives up the ghost. Devices which are manufactured today meet the specs of UL1449 2nd edition and may well meet other UL or IEEE specifications. That includes, I believe, sustained overvoltage protection, protection against bursting into flames (an inline fuse), and the proviso that if they fail, they fail open-circuited. Some people object to the last thing. Myself, I look at it as I'm the President and you're the Secret Servic Agent. Your job is to protect my life at the expense of doing your job. Do it then!
    I wouldn't worry about what happened Joe. If you've read any of my earlier posts on surges, you'll know that I advocate very strongly for surge protection devices being purchased and installed at the AC mains. If you're a DIY guy who has no issues working around electricity, you can buy a whole house surge protection device and install it yourself. Otherwise you can always check with your power company and see if they'll install one. Usually its a nominal monthly charge and may include some sort of equipment replacement warranty. It goes without saying that a comprehensive homeowners insurance policy, with a rider if need be, that gives you full replacement is a pretty good idea. Besides, your system fries...so what? You're out of sound or TV for a couple of weeks, but you get to go equipment shopping all over again and they're paying for it!
     
  3. Joe Tilley

    Joe Tilley Supporting Actor

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    Thanks for the response Chu. Like you obviously heard we have had tons of rain here, in fact there were a few houses on my street that was a foot or two under water. But with all that rain has come lots of lightning & thats when I got hit.

    I didn't think anything was wrong afterwords as everything seams to be fine, but I wonted to be sure I didn't need to worry much should another good storm come through.
    I do have one other question if anyone could help. I use a tower mounted antenna for TV. It is grounded at the cable before it comes into the house, & the tower it's self is grounded. But every time it storms I find myself unhooking it from my tv, or rather my power center as it passes through it before the tv. Is this being over cautious or is it a good idea? We get a good amount of lightning in my area so thats my main reason for doing it, I just didn't know how pron a tower is to taking a hit.
     
  4. Chu Gai

    Chu Gai Lead Actor

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    Joe, I'd probably be doing the same thing as you. As to how your tower is specifically grounded you haven't made clear. If it's via an earth ground (grounding rod) and the connection from the tower is no more than say 10 feet or less then you've probably got a good ground. While grounding your incoming cable is a good approach to minimize or eliminate ground loops, it does nothing to protect you against surges. You're relying upon your Monster unit and given that your antenna is outside and elevated that can only increase the probability of a strike.

    You can purchase a separate product specifically for the cable like this one from Northern Tech: http://www.northern-tech.com/TVSS_Products/coax.htm The cost of this particular product is somewhere under $100 but I'm sure there are similar units doing the same thing for less. That estimated price is a direct buy from them but keep in mind that they also OEM their stuff and you might even be able to get something very similar locally. What I like about it is that it incorporates 2 technologies. The Silicons are incredibly rapid and will deal with spikes. The GasTube can take one mother f****er of a hit. You're protected two ways there. It'd be installed so that the ground from the device is within 10 feet of earth ground. I can't stress enough how the effectiveness of a surge protector depends upon two conditions that must be met.
    1) a good earth ground
    2) less than 10 feet from that ground.
    Any such product that you buy you should confirm by calling the manufacturer that it's suitable for the bandwidth for the signal the cable is carrying. They'll also tell you what the insertion loss of such a product is. In other words, how many dB of signal loss you can expect. Usually its very much under 1 dB...maybe even 0.1 dB. That's a small price to pay for not providing a conduit of electrical destruction.

    I'm not the biggest fan of audiophile type products to serve as the primary means of protecting oneself. As a means of redundancy and acting as a secondary source, I guess they're OK, just way overpriced. I'm not interested in companies selling electrical protection also selling me hi-fi equipment. Really, what the hell do they know? Extend the logic and you'll understand where I'm coming from.
     
  5. Joe Tilley

    Joe Tilley Supporting Actor

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    Sorry I didn't think to specify just how the tower is grounded. I'm using a 4' grounding rod that the tower & coax are both tied to. The lead coming off the coax is 8awg & about 14' in length since the coax enters through my attic, & the tower is grounded at the base with about a 2' section of the same 8awg tyeing it to the ground rod.
    I will definitely look into the coax protection you mentioned. And with the way the weather is going here I think I will be looking into a better approach to ground the tower as well. I always questioned whether the ground at the tower is good enough, & had thought about getting a larger 6' to 8' ground rod & using a 2 or 4awg ground wire for just the tower its self.

    Ps It may not be as effective as the surge protector you mentioned but would the in line coaxial surge protector that PE sells offer much protection? Part # 180-190 The only reason I ask is they are pretty cheep at about 4 bucks compared to the possible 100 you spoke of.
     
  6. Chu Gai

    Chu Gai Lead Actor

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    Your local building department can tell you what code for a grounding rod and the wire is (insofar as the NEC is concerned). I just don't remember. I do know that you want to keep that distance as short as possible and yes 5 feet is better than 10 feet. And thicker wire is better than thinner. Also that wire should be a straight run, no kinks!!
    In my opinion, it's a good thing to go beyond NEC code because your looking to protect transistorized devices and realistically NEC is concerned with human safety. You're concerned with that and protecting your electronics.

    You're right that's a lot cheaper but it's different. For starters it is probably designed to absorb a charge and I'm guessing that it's a gas tube. If you compare that to what I suggested you'll see that my suggestion has a ground wire that's designed to shunt or divert the incoming spikes. Look at it in terms of a dam vs a dike. Dam's can get overwhelmed, dikes divert. Also we've no idea what the insertion loss is (probably small, but we still don't know) nor do we know for what bandwidth it's designed. You certainly want one that's designed for the frequencies you're going to be passing otherwise you'll be cutting off stations.

    Why not print out the web page and the manual that's on there and go to a few places to see if they've got something similar? You might try a well stocked electrical supply house, a place that deals in cable or satellite installations, maybe even your local cable company. If you know anything about my suggestions Joe is that I really hate spending other people's money and I try to come up with approaches that make sense and then try to find the most cost effective approach.

    On a side note, if your soil is sandy and dry then one might need a more vigorous approach to ensure a low impedance ground. They have these devices called electrolytic grounds that are enormously effective even in deserts. Also there's a real old approach that's also effective in deserts but rarely used today. It's called the Ufer ground. If you've seen foundations poured, typically they're reinforced with rebar. That forms the basis for this system. This link http://www.scott-inc.com/html/ufer.htm has more info on it and a google search will turn up more. Just think, people who are building their own homes have access to a spectacular grounding scheme and don't even know it.

    I'll poke around and see if I can find a more cost effective source. What I'm looking for is a device with a small 'let-through' voltage and uses those silicon diodes. Gas tubes are kinda slow in responding and have let throughs of a few hundred volts. The actual let through is very manufacturer specific.
     

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