Surge Protection

Discussion in 'Electrical Forum discussion & Blog' started by Jed54, Jan 21, 2008.

  1. Jed54

    Jed54 New Member

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    Have a relative adding a new entertainment upgrade. One of which is an LCD TV. All outlets are two prong not three. To get the benefit from a good surge protector doesn't the outlet have to be three prong? I'm trying to remember if some tv manufacturers stress a three pronged outlet..... Thanks
  2. Lakee911

    Lakee911 I&C Engineer (mostly WWTP)

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    Yes, you'll want to have a ground for the system. In addition a good double conversion UPS for the TV and Audio/Video equipment would be wise.

    Jason
  3. Chris75

    Chris75 Electrician

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    I dont believe a surge protector shunts the surge to ground, so I see little benefit in that respect, and since most residential appliances do not use a ground either, again I dont see a problem... If you wanted a 3 prong receptacle without rewiring your current receptacle a GFCI is legal to install in place of the 2 wire receptacle.


    You have to remember that the ground is for clearing ground faults... in other words, its there to connect the non-current carrying metal parts of equipment to the system grounded conductor at the service equipment.
    Last edited: Jan 21, 2008
  4. Jed54

    Jed54 New Member

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    I thought the GFI basically was to disconnect power from appliance out to source.. So your saying the GFI receptacle will protect a voltage surge coming in also?
  5. Bob NH

    Bob NH In the Trades

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    No, it will not.

    A GFI receptacle measures the difference between the current (amps) going out on the hot wire and the amps returning on the neutral. If the current in the hot wire is more than that returning on the neutral by more than 0.006 Amp, then it shuts off the hot wire.

    A surge can be a voltage spike (say 200 or 1000 Volts when it should be 120 Volts), or it can be a general increase in voltage (say 140 Volts when it should be 120 Volts). Neither of those will trip a GFCI unless they cause a current to GROUND which results in a difference between hot and neutral.

    A surge protector responds to a difference in VOLTAGE between two conductors and uses a special device within the surge protector to limit that voltage difference by dumping the energy of that voltage difference to the other conductor of the pair being protected by the surge protector.

    The surge protector may have several different pairs that it is protecting. For example, a protector for a 240 Volt circuit such as a "whole-house" protector would protect between the two hot lines, and between each hot and neutral. Some might also protect between the lines and ground but the neutral is usually connected to ground at the service panel.

    Surge protectors are often destroyed by the surge and must be replaced.
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    The best protection would be a double-conversion UPS, but for most things, that's overkill. If you look at some of the surge suppressors designed especially for entertainment systems, most of them have significant guarantees on connected equipment - up to $250K or more on some of them. If the surge suppressor sacrifices itself, and your connected equipment is unharmed, though, many won't warranty the device; but, if it dies AND you equipment dies, they'll pay to replace it all, up to the warranty.

    The surge suppressor itself needs to be plugged into a grounded outlet, but the devices coming in do not. Depending on how much protection you want to have, a decent one costs at least $100, and you can spend significantly more. The better ones not only do surge suppression, but also filter noise up on the powerline - including noise that may be injected from one device to another. The magic numbers to look at are how many joules it can absorb and how fast it can respond.
  7. Jed54

    Jed54 New Member

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    I have an RCA 1500 Joules six tap surge protector which I haven't used for any reason. Would this be adequate for this? In place of adding another line/circuit. Or should it still be wired correctly?
  8. Bill Arden

    Bill Arden Computer Programmer

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    I would look into an "island" concept.

    Normal surge protection shunts the surge to ground with the idea that all the grounds are the same.

    In your case you want all the wires going to the TV to be protected to each other and make sure the TV does not have a separate ground path like threw a bracket into a stud.

    Like a lot of things it's not the voltage, but the flow of current that will kill the TV. Most outlets start to arc over around 2500Volts and electric meters generally have spark gaps that limit the voltage to 5000volts.

    So here's what I would recommend
    1. Use a power strip with Coax and Phone surge protection.
    2. Tie the protector's ground to anything that the TV is touching like mounting brackets or a stand.
    3. Use a whole house protector at the main panel and TV or CATV protector where the coax enters the house.
  9. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    1500 joules is better than some, but the one I have is nearly 3x that (and has a great warranty for attached items). Say you spend $2-3K or more for a nice TV, DVR, sound system...spend another $100 or so and help protect it. As noted, it is not only the amount of energy it can absorb, but the speed with which it can clamp the surge. The better ones have nanosecond response rates.
  10. Jed54

    Jed54 New Member

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    Thanks everyone for the info on this.... Seen an article on Arc Fault Circuit Interrupters that analyzes the signature of a spark... I would imagine the power has to be disconnect from meter or source for installation, but I'm guessing it does. I would think it might be easier, and would protect the entire home......?
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Arc fault cb detect loose connections which can cause sparks - sparks can cause fires. I doubt they would do much of anything to protect your electronic equipment from surges.
  12. Lakee911

    Lakee911 I&C Engineer (mostly WWTP)

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    It's nearly impossible to make a claim and have it paid on those warranties. Better warranties do indicate better equipment and so does prices.

    Jason
  13. alternety

    alternety Like an engineer

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    Jason is right about the warranty. I just bought some crap ones from Costco (they were out of the ones I wanted, and I needed plug space). If you read the warranty it essentially says that if this or anything attached to it breaks it is not covered under warranty. Others are more appropriately worded, but in practice it seems warranties are not paid a whole lot. Based on hearsay and the internet.
  14. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Buy one from a place like APC. Keep in mind it is fairly rare to get a direct strike that will destroy one. Also, repeated smaller surges can eat away the junctions on electronic devices that adds up over time and will contribute to early failure. Keeping the power clean is a good goal, regardless of what you do for something that is expensive and has electronics in it. Most of the devices have an indicator that says it is still working. Continuing to use it after that indicator goes out is at your own risk.
  15. Lakee911

    Lakee911 I&C Engineer (mostly WWTP)

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    Coincidentally, I had a SquareD guy in today to talk about surge supression and I asked him that same question, do they wear out from many small surges over time? He said no, they typically wear out from extended over voltage conditions. Surges happen on the microsecond range of time and if you have a 180V, for example, overvoltage for milliseconds to seconds from a fault on the line (from utility, not necessarily your fault) then that is enough to damage the MOV or SAD used in the device. So, yes they do need replaced over time.

    Jason
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