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  1. #1
    Join Date
    Aug 2007
    The Great White North

    Default home surge protection

    A good friend of mine had an incident where a huge electrical surge (probably lightning) pretty much destroyed most of the home electronics, electrical appliances , HVAC, and other electrical devices causing a few thousand dollars of damage to the equipment with some being damaged beyond repair.

    The equipment that was attached to the (point of use) common type of surge protectors’ (suppressors) people mostly use didn’t help. These were the typical power bars with surge protection that we all blindly put our faith into. So in researching why these wouldn’t help I ran across information forgotten over the years also some interesting facts.

    Surge suppressors are not all they're cracked up to be. Most surge suppressors employ a device called an MOV (Metal Oxide Varistor). MOVs are variable resistors, typically made of zinc oxide (ZnO), and are very cheap to produce. Surge suppressors generally work by shorting voltage spikes directly to ground. This can, by the way, cause severe damage to any unprotected equipment that happens to be on the same circuit.
    Some MOV surge protectors short hot to neutral instead of shorting hot to ground, and while this may be somewhat safer, it is still not an ideal situation.

    Each time this happens, the MOV degrades, and it will eventually cease to perform. Depending on conditions, this can occur after only one or two lightning strikes or other power fluctuations, yet there is little or no indication that there is a problem.
    In some types the little light only indicates that the protector is still in-line and its internal fuse has not blown. It provides no indication as to the health of the MOV.
    Having a UL listed surge protector does not guarantee better protection. The UL listing for surge protectors does not test how well the MOVs will work, but only assure you that the MOVs will not burn down your building when they fail. Failed MOVs can cause fires; that's why most of them are now fused.

    Now it’s not to say these types of surge protectors shouldn’t be used. Rather than relying on this point of use surge protectors for abnormal surges from lighting or power line surges they seem to be fine for conditions that exist in the home. These would be normal or common mode surges or spikes from things like HVAC , fridges , freezers, washers , hair dryers , etc.

    So … in thinking about better protection from abnormal surges from lighting and power lines had led me to the direction for point of service type of protectors. The research I’ve come across seems to be agreed upon by different sources.... the point of service is the most effective means of protection. There are two types of these where one is mounted to the electrical service panel (example here) and the other is located at the meter box (example here). There is one utility company here offering these to people.
    Depending on the cost with this type of protection may have some financial benefit of insurance premiums being affected by claims and if the cost would offset the deductibles.

    I invite any comments or input to this.
    Last edited by canuk; 10-19-2007 at 11:48 PM. Reason: oops ... spelling errors

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