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I'm considering having an electrician install a whole house surge protector. The house gets 200 amps from the grid. The surge protector would protect appliances and the new electric car (a Leaf). Some manufacturers claim that their surge protectors save energy. Is that because variable inductive loads can send energy back to the electrical panel and the surge protector can re-route that electricity back into the house instead of putting it back into the grid? If so, would the savings depend on our inductive loads? Our heating is geothermal so we have a heat pump and an air handler. Both I think are inductive loads.

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    It uses energy to monitor the system. Mar 8, 2023 at 5:53
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    What does the asterisk on the product box say for the products making this claim about saving energy? Perhaps something like “*Compared to using 12 or more typical point of use surge protectors throughout a home”? Mar 8, 2023 at 11:54
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    "Some manufacturers claim that their surge protectors save energy." - Can you show us these claims?
    – marcelm
    Mar 8, 2023 at 17:09
  • Anytime it protects from a surge it saves energy. About enough to run an electric toothbrush for zero seconds.
    – Mazura
    Mar 9, 2023 at 4:14

6 Answers 6

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No. That isn't their function.

A surge protector only kicks in when the voltage goes over a reasonable level (typically about 600V for the units I've seen), to prevent that excess voltage from damaging things downstream. It will help guard you against lightning strikes on the power lines and things like that, but it does not save power, and in fact probably costs a minuscule amount of power itself, to power its status LEDs if it has any.

A surge protector is really a fancy case around a few metal-oxide varistors (MOVs), which you can look up if you want more details on how they work. Plus a few extra components if it has a status light, though the MOV does all the real work and the status light just tells you it isn't necessary to replace the MOV yet.

Now, there are power strips which act to turn accessories plugged into them off when the main device is turned off. For example, powering down your PC would cause these to also turn off your printer, scanner ,or whatever else is plugged into them. I use one so turning off my amplifier turns off my whole stereo system. Since a lot of modern devices burn a bit of power even when supposedly turned off (so they can turn on instantly or respond to an IR remote), this process of powering them down completely does save some power. Some of these outlet strips also have surge protectors built into them. But the power saving function is separate from the surge protection, and you need to shop for one that has the features you need.

Of course none of that "avoid standby power" behavior is applicable to a whole house surge protector.

.....

Since comments may not persist:

The other thing that may have gone into this question is that there are devices being sold which falsely claim to reduce your power usage. These are marketed by the same kinds of scam artists who sell miracle devices to improve fuel efficiency in cars,

DavidLevner has pointed out that the National institute of Science and Technology has explained why the phase-correction-device-as-power-saver argument is based on a misleading description of the basic physics: https://www.nist.gov/news-events/news/2009/12/nist-team-demystifies-utility-power-factor-correction-devices. Thanks, David!

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    Easy way to find devices that vampire a meaningful amount: it's warm to the touch while un-used.
    – dandavis
    Mar 7, 2023 at 23:56
  • If the status light is an old-fashioned neon bulb it will actually be a (small) part of the protection, because their current rises dramatically once you pass their voltage threshold. I don't know if anybody uses them anymore though. Mar 8, 2023 at 20:40
  • @MarkRansom: A neon bulb which glows during normal operation will need to have a series resistor that would limit the current during e.g. a 5x overvoltage event to five times the level of current that would pass through the bulb during normal operation.
    – supercat
    Mar 8, 2023 at 22:26
  • @supercat yes it will have a series resistor, but the bulb takes the majority of the voltage drop in normal operation. That voltage doesn't change much as current goes up, so the current goes up much faster than linearly - that 5x over voltage might result in 12x the current. Of course the bulb will probably burn out rather quickly, but self destructing surge protectors are quite common. Mar 8, 2023 at 22:38
  • @MarkRansom: If a neon bulb uses 20mA during normal operation (much higher than typical), and passed two full orders of magnitude (100x) more during a surge (absurdly higher than typical), that would yield a clamp current of two amps. That's a drop in the bucket for mains power surges.
    – supercat
    Mar 8, 2023 at 22:47
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A central surge protector may save energy compared to individual surge protectors on every wall outlet. I'm not sure that you'll see that saving on the energy bill, tough.

The reason is that surge protectors usually provide a small capacitive load. Lots of wall outlet surge protectors in your home will cause a noticeable load.

This capacitive load of lots of wall outlet surge protectors may can also cause a noticeable current in your grounding/earthing. The foundation earth electrode may corrode prematurely.

Yep, talking about lots of individual wall outlet surge protectors (or lots of surge-protected power strips) here.

Regarding any surge protector where the scammer manufacturer claims "energy savings"...stay away from these, they can't be legit. If you're getting your distribution box rewired, you can have a surge protector installed. The main cost is the work of the electrician rewiring the box (in some legislations, the electrician also needs to hold a special license if he works in front of the electricity meter, where such a surge protector is usually installed). A three-phase surge protector from a reputable brand is around 200€ (German prices here, as that's where I live). Prices can vary a lot; you may encounter products from reputable brands in the range from 140€ to very well above 1,000€. Regardless of price, it will not pay back via the electricity bill, but it might make you sleep better. Especially if you live a region where power lines are still above ground.

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    I think you meant to say it will not pay back via the energy bill...
    – keshlam
    Mar 8, 2023 at 12:12
  • @keshlam Thank you. Yes, indeed. Edit done.
    – Klaws
    Mar 8, 2023 at 12:43
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    FWIW, there are surge protectors for some brands which are actually built into circuit breakers and install as easily as a dual breaker. I slapped one of those into my own panel a year ago. The manufacturer only promises that it will protect the house wiring, not anything plugged in, but it should help generally and wasn't expensive. It doesn't even need to have a load attached to it to provide the protection, though since it can be used as a pair of normal breakers too you have that option.
    – keshlam
    Mar 8, 2023 at 17:29
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Does the ‘surge protector’ you’re considering resemble the one discussed in this answer?

If so, stay far, far away. It will not save you money, and may even cost you money while providing bupkis in terms of protection for your house.

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They don't save energy, they usually clip the voltage when a surge occurs and turn it into heat or to trip a breaker.

A power factor corrector PFC ensures that the optimal power factor is reaching your home and the voltage and that the phase between voltage and current are near 90deg.

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    It should be noted that correcting power factor actually uses power, which is why it's called "active power factor correction". There's passive correction too, but that need to be custom designed for a specific load like a motor or lamp ballast or laptop charger, and thus won't work whole-house.
    – dandavis
    Mar 7, 2023 at 23:50
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    It can work for a whole house, if it's an active power corrector. And usually for a 'small load' like a house the return is negligible. For an industrial plant with big motors or other inductive loads, its a necessity Mar 7, 2023 at 23:56
  • I don't think 90% is correct. A power factor corrector is used with inductive loads (like motors), where the current and voltage may be out of phase, to try to bring the current and voltage into phase, with a 0 deg difference between current and voltage being ideal.
    – SteveSh
    Mar 8, 2023 at 2:16
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    @keshlam PFC won't save any money in a home, typical or otherwise, because power companies bill residential customers for apparent power, which ignores power factor. The only beneficial residential application is with a generator, where you do pay for real power, where (eg) a cheap 5w LED bulb looks to the generator like a 12w bulb (a 60w tungsten still looks like 60w)...
    – dandavis
    Mar 8, 2023 at 6:11
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    Two misconceptions to clear up. First, residential utility meters don’t bill for apparent power, only for real power. Second, a generator engine powering a low power factor load will only be putting real power onto the shaft. Reactive power circulates through the generator windings, but the engine doesn’t ‘see’ it. Mar 8, 2023 at 8:52
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Will a whole house surge protector save energy?

Yes.

It won't save energy that you see on your power bill. But you'll still save money.

It saves energy indirectly, by protecting equipment from damage. Manufacturing replacements certainly takes energy and all costs are passed to you, to purchaser. So, while it doesn't save you energy, it saves you money that you'd spend to pay someone else for the energy and other resources they have used to produce replacements for damaged devices.

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No.

On contrary, it will cause the house to use minimally more energy.
A whole house surge protector uses varistors to clamp voltage when it goes beyond safe limits. Those are non-linear elements, as they don't suddenly turn-on at specified voltage, rather they begin to 'let through' the current more and more as they approach the set voltage at which they conduct.
As long as they are the correct voltage for your power grid, everything will be fine, but there is a minimal current going through them at nominal voltage. The currents are really small and wont show on your power bill, but it is incorrect to claim the device makes the house use less electricity. If any manufacturer claims that, I suggest to stay away from them.

If you want a surge protector with zero leak current, sparkgaps provide that. A good quality whole house surge protection should have both spark gap and varistors, but due to space constraints we usually install varistors only.

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