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costabius t1_ixwzt09 wrote

Surge protectors are not BiFL, They lose their ability to protect from power surges over time. You should replace them every couple of years.

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2XGSWsurvivor OP t1_ixwzz3s wrote

Well shit I did not know that, thank you. I don’t use it as one anyways I just enjoy the extra outlets.

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Xyspade t1_ixy2ca0 wrote

Still, don't use it if the surge protection light goes out. If any additional surges come in after that, it could potentially violently blow up the MOVs (surge protection component). A good surge protector like a Tripp-Lite Isobar will cut power to the devices once the MOVs are used up.

You could open it and cut the MOVs out, and it would become a basic outlet splitter with no surge protection.

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cherlin t1_ixxvz9b wrote

Aren't surge protectors basically just an inline fuse? How would they lose protection over time? If they protect against the surge the fuse would overload and fail and the surge protector would seize to work, or am I misunderstanding how these work?

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Xyspade t1_ixy3392 wrote

It's not a fuse; fuses are protection for current (amps), surges are spikes in potential energy (volts).

It's a component (or multiple) called a MOV (metal oxide varistor). They divert surges to the ground pin, but somehow they also absorb the surges and fill to capacity eventually. I don't understand how they could do both because that seems contradictory, but I have yet to find a source that explains it properly.

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musclegeek t1_ixy4yln wrote

MOVs resistance changes inversely to the applied voltage. If the voltage across it increases the resistance decreases and vice versa. They are connected to gnd but have a very high resistance for the normal operating voltage. When the voltage spikes their resistance goes extremely low allowing current to pass effectively creating a short circuit to gnd.

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Xyspade t1_ixzbaia wrote

Thank you! What about when there's only one MOV between hot and neutral instead of a group of three, how does it pass that spike to ground? Or does it just pass it to neutral?

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musclegeek t1_ixzcolo wrote

Neutral is there specifically to handle small surges. Especially in wye configurations and neutral eventually goes to ground. Having it connected to both neutral and ground is a fail safe. No neutral goes to ground, surge too high for neutral goes to both or some large f-up voltage spike from neutral goes to local ground.

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PlasmaSheep t1_ixy63lt wrote

Put simply, the MOV acts as an open circuit until the voltage across live/ground or neutral/ground exceeds a "clamping voltage". The MOV then presents almost no resistance, making most of the current flow through it rather than through the device under protection. It gets "used up" because passing current through the varistor affects its structure and increases its clamping voltage.

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Xyspade t1_ixzb2h1 wrote

Ah, thank you! So when the protection light goes out, that's its way of telling you the clamping voltage is too high to be useful anymore?

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PlasmaSheep t1_ixzy297 wrote

That's right.

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Xyspade t1_iy06psp wrote

Makes sense then why people say they should be replaced every few years regardless of whether the indicator is still lit or not. Learned a thing today!

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Eric_the_Barbarian t1_ixyt980 wrote

3-5 years service life.

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19Chris96 t1_iyayclw wrote

I should think about the 21 and 22 year old surge protector I'm using right now. A computer was struck by lightning while connected to said surge protector (the 2001 model) back in 2007.

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Eric_the_Barbarian t1_iybi5do wrote

Broadly, if something is supposed to absorb a destructive energy in order to protect something else (eg. bike helmets, surge protectors, ballistic armor), it should be considered compromised upon such use until it can be replaced or inspected by an expert.

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incasesheisonheretoo t1_ixz4851 wrote

I was never aware of this! I’ve got a bunch of these things plugged in all over my house that I’ve been using for decades. Thanks for educating me!

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