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Is there such an animal that would trip a circuit breaker when there is a loss of input power? Similarly with the relay system which energized to close the main contact to apply main/grid power to the service panel, but when there is a loss of grid power = loss power to the relay which disengage the main contacts which isolate the grid to the service panel. I am wondering if there is such a compact plug and play device to do that.

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    I don't know of a device that would trip a breaker because breakers aren't meant to operate like switches. There are relay devices that would/could open a circuit after a power loss and have to manually be reset to restore the power.... think of a motor starter with a momentary "on" button.
    – JACK
    Dec 24, 2019 at 19:34
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    Where are you on this planet, and why do you want this device?
    – ThreePhaseEel
    Dec 24, 2019 at 19:36
  • There are remote trip and reset units but these are usually found on commercial breakers not molded case, an easier way to accomplish this is with a relay. once pulled in it can keep the circuit active but if the power drops out it opens and has to be reset to energize the line and the breaker is left alone.
    – Ed Beal
    Dec 25, 2019 at 22:02
  • @EdBeal you know Eaton has remote trip/reset breakers in its CL and BR lines ( and possibly CH and CHQ), right?
    – Harper - Reinstate Monica
    Dec 26, 2019 at 6:20
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    I still think a relay or starter is a better way to go, I find the cheap addons to molded breakers don’t last or the ones I have used are definitely not up to commercial grade and the cost is more than a mag. without the overload unit the Fuji solution would be much better in my opinion.
    – Ed Beal
    Dec 26, 2019 at 16:36

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A magnetic starter switch or magnetic contactor can do what you want. Most are designed for fairly heavy loads (8A and up), and they are not consumer-style plug-in devices but rather bulky boxes intended for permanent wiring. There are circuit breakers with this feature that you can mount in a panel (hopefully you have a panel type that one of these can fit). The on/off buttons are provided on the breaker itself and/or via a separate switch connected with its own wiring and mounted near the load (usually a machine of some sort).

The Fuji SC-03 is one example of such a circuit breaker: https://www.fujielectric.com/products/mc/mc_ms_tr_sc_neos.html

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    I should have read further before posting a comment, a starter is a heavy duty relay and could use an auxiliary relay to maintain power to the coil keeping the contacts pulled in unless there was a power loss then it would open until reset.+ there are many sizes sc02 , a source for these available to the public is automation direct I use them for these exact parts.
    – Ed Beal
    Dec 25, 2019 at 22:08
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In answer to your original question, Yes there are breakers and devices that trip out breakers when the is a loss of prime power. Usually they are found in larger industrial sites where large motors create voltages at loss of power or there are parallel and redundant systems. They are not compact and they usually cost more than a Homeowner DIY is willing to pay.

Example see @John Zwinck go ahead and price his Fuji SC-03 and an Enclosure it would go in. I was thinking more along the line of Bassler's relay protection or a Smart Breaker depending on use.

What would be the residential need for such a device?

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  • Table saw comes to mind.
    – Harper - Reinstate Monica
    Dec 26, 2019 at 6:21
  • Many (not all) table saws have their own contactors so they won't restart until start button is pushed.
    – keshlam
    Feb 12 at 1:44
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From your description, you seem to want a device that cuts the connection after power loss (and, perhaps, low voltage), to prevent something from restarting when power comes back on.

A simple DPST (or DPDT) relay, of the voltage and current required, could be used. Put the relay coil in series with one set of normally open (NO) contacts, and across the mains. Put a momentary contact NO switch across the relay contacts.

The other set of relay contacts control the load.

When the switch is pressed, the relay will pull in, and stay in, until the mains voltage drops below the holding point. It will then stay off until the switch is pressed.

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Smart switches have various behaviors on power cycle. I am pretty sure that some will allow setting a status on "power restored", though it may take some digging to figure that out - fortunately manuals are generally available online before buying. But if you go that route, you have to be careful about what you are connecting. Limitations may include:

  • Total power (actually, every switch has that limit, but it is generally far below the 15A or 20A capacity of a circuit breaker)
  • LED/CFL/Incandescent compatibility
  • Motor compatibility
  • Neutral vs. ground vs. leakage current for getting power, which may affect compatibility with various devices
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