# Solved: How long will a surge protector last.



## Cpl. Chronic (Feb 15, 2008)

My father wants to replace the surge protectors on his TV and computer because someone told him surge protectors only last about 6 months. I find that to be a little questionable. Now cheap ones (like what he usually buys) I can understand going bad if you have dirty voltage coming into the house. But does anyone now of any detailed information on this matter. Personaly I try to drop at least 30 to 40 bucks on a decent surge protector and not the 9.99 blue light special. Does anyone have any suggestions?
And thanks,


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## Elvandil (Aug 1, 2003)

They will last indefinitely unless there is a surge. Then, they are toast. Most are good for one use. Others are questionable after being used for suppression. They usually have some sort of indicator for when they have been compromized.


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## JohnWill (Oct 19, 2002)

Actually, it's a good idea to replace MOV based surge protectors every three or four years if you really want continued protection. There are continuous surges on your power line as a rule.

[WEBQUOTE="http://www.answers.com/topic/surge-protector"]*Metal Oxide Varistor *- The metal oxide varistor (MOV) is a device containing a material that conducts current (shorts) when presented with a voltage above its rated voltage. MOVs can prevent high voltages from continuing at full levels to the susecptable circuits. MOVs typically limit voltages to about 3 to 4 times the normal voltage in the circuit. MOVs have finite lifetime, and will "wear out" when exposed to a few very large transients, or many more smaller transients. MOVs are used in parallel to increase current capabilty and lifetime. The normal failure mode is a short circuit, so MOVs usually are fused or otherwise protected when used in an ac power application.[/WEBQUOTE]

If you really want the details of MOV MTBF testing and calculation, here's another site: http://www.iaei.org/subscriber/magazine/04_b/04_b_brown.htm


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## Elvandil (Aug 1, 2003)

JohnWill said:


> Actually, it's a good idea to replace MOV based surge protectors every three or four years if you really want continued protection. There are continuous surges on your power line as a rule.
> 
> [WEBQUOTE="http://www.answers.com/topic/surge-protector"]*Metal Oxide Varistor *- The metal oxide varistor (MOV) is a device containing a material that conducts current (shorts) when presented with a voltage above its rated voltage. MOVs can prevent high voltages from continuing at full levels to the susecptable circuits. MOVs typically limit voltages to about 3 to 4 times the normal voltage in the circuit. MOVs have finite lifetime, and will "wear out" when exposed to a few very large transients, or many more smaller transients. MOVs are used in parallel to increase current capabilty and lifetime. The normal failure mode is a short circuit, so MOVs usually are fused or otherwise protected when used in an ac power application.[/WEBQUOTE]
> 
> If you really want the details of MOV MTBF testing and calculation, here's another site: http://www.iaei.org/subscriber/magazine/04_b/04_b_brown.htm


Thanks, John. I knew that 6 months was a too short time, but was concerned that there should be some other upper limit. And though, as you say, small surges are present all the time and should be handled well by protectors, a lightning surge, even sympathetic, could be a different story and inactivate them.


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## JohnWill (Oct 19, 2002)

I used to have some pictures of what a floating neutral will do to a whole house Leviton unit, it wasn't pretty!  The poor guy was freaked out when he was near it and the box blew. He said that flame shot out all four sides of the cover, there were little pieces of MOV's all over the place inside.


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## Cpl. Chronic (Feb 15, 2008)

I never really thought much of them going bad. Only if they got hit by a big surge. (ok the "y" key is sticking on my keyboard) great, now something else to clean. Anyway, I know his are at least 6 years old and mine are 8, but the lights are still green. I know dirty voltage can cause problems, just didn't think about my surge suppressors. They're one of those things you don't think about till you stretch your legs under the desk and click the switch off. ! LOL. So, how many different types do you know of and do they last longer or shorter than "MOV" type suppressors? Something under $60. The 2 I have are Belkin and CyberPower.

I saw the aftermath of a 35kW Diesel Generator with Neurtal and Hot reversed. That was a pretty picture, it blew the cover off the breaker panel and melted 4 $300 dollar suppression modules. 

And thanks for your help.


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## JohnWill (Oct 19, 2002)

Most inexpensive surge suppressors are based on MOV technology. I'd be really surprised if you find anything under $60 using anything else.

If you step up in price, you can have series protection, which normally uses LC filters to damp the surges and doesn't resort to shorting the surge to ground. This don't require periodic replacement, since they don't have consumable components involved. One product like this is: http://www.surgex.com/prod_stn_alone.html

Here's a pretty good page on the different types of surge protection and how they function: http://computer.howstuffworks.com/surge-protector.htm

Truthfully, for the best surge supression, you need an on-line UPS. This is a UPS that continuously runs and converts the incoming power all the time, so you're always behind the UPS. Most inexpensive UPS models are off-line models that power up only when a power loss is sensed. Slightly more expensive models monitor the voltage and will actually adjust to under and over voltage conditions as well.

Here's a page on UPS systems: http://en.wikipedia.org/wiki/Uninterruptible_power_supply


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## Cpl. Chronic (Feb 15, 2008)

Thanks for the info.


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