View Full Version : Surge protection, do you have it?
nuke61
10-26-2003, 10:29 AM
You've spent a few to several thousand dollars on your home theater system, you DO have at least minimal MOV protection, but even better, Series Mode protection, right?
If you do have an MOV device, you DO know that it should be periodically replaced, right?
kevinw
10-26-2003, 12:00 PM
You seem to know, so explain this for those that don't.
Thanks
KevinW
nuke61
10-26-2003, 12:51 PM
MOV based surge protectors, the most common kind, use metal oxide varisters to reduce the impact of surges. The MOVs are sacrificial, meaning that they will be damaged or even destroyed when supressing surges. They work by shunting (diverting) the surge voltage/current to ground once they detect an overvoltage condition. Additionally, surges are cummulative in nature. Many smaller surges may have the same effect on the MOV that a fewer larger ones have. Because of these effects, MOV based surge limiters have a limited lifetime *and* a limited surge capacity.
The series mode suppressors use a large inductor and capacitor to reduce the voltage surge. The components are not sacrificial and they are passive in nature, so there is effectively a 0 detection time. The voltage that is let through is also typically much less than an MOV based suppressor.
More information can be found here:
http://www.zerosurge.com/HTML/movs.html
http://www.zerosurge.com/HTML/works.html
http://brickwall.com/oscope.htm
http://brickwall.com/nofail.htm
http://brickwall.com/howwork.htm
http://www.surgex.com/benefits.html
Ratman
10-26-2003, 02:41 PM
Good info. My question would be...
If your home is older and/or not grounded as specified by today's newer electrical codes, wouldn't a device such as this be a waste of expense? Unless of course, you pay a contractor to perform the necessary/proper work to make this device effective.
Not being sacastic (as I usually can be)! Just a question for those of us that have 'knob and tube' wiring and older type service.
nuke61
10-26-2003, 04:42 PM
Good info. My question would be...
If your home is older and/or not grounded as specified by today's newer electrical codes, wouldn't a device such as this be a waste of expense?
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Actually, I think just the opposite would be true. IOW, the MOV devices divert a voltage spike from the HOT wire to the GROUND wire. If you have an older home with poor or no ground, then the MOV device will either work poorly or *not at all*.
The series mode devices all store the excess voltage in an inductor and let it bleed to the neutral wire, and all houses [with working electricity :) ] will have a wired neutral.
Even if you've already done so, take a look here, keep your question in mind, and I think you'll come to the same conclusion that I did:
http://www.zerosurge.com/HTML/works.html
One thing I forgot to mention... NONE of these devices are designed to protect your equipment from a direct lightning stike.
DISCLAIMER: I am NOT an electrician, this is simply my opinion.
nuke61
11-09-2003, 01:42 PM
Followup... what I should have added was that if you're in an area with frequent lightning storms then you really should have a whole house surge suppressor installed at the electrical service panel. Keep the surge out of your house wiring to begin with, and use device supressors for "just in case" insurance.
FYI, LEA International ( http://www.leaintl.com ) makes these "whole-house" supressors -- MOV, and others too, I believe. I had my electrician install one in the sub-panel that was used for my theater in the basement. While this protects everything on that panel, it does not actually protect the entire house because it is not on the main breaker panel for the house (I did not have any breaker roon left for the TVSS/USPS on my outside panel, and frankly all the stuff I really care about much is on the sub-panel anyway). Seems like good technology for the money. Also does not limit current, etc.
-R.
