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Essentially, I would like to connect a breaker to a smoke detector and have it trigger when it activates.

Are there any breakers that can be triggered by a separate external signal and which have to be manually reset by hand?

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    \$\begingroup\$ Sounds like a code violation waiting to happen. \$\endgroup\$
    – Scott Seidman
    Dec 9, 2022 at 22:49
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    \$\begingroup\$ An MCB with auxiliary shunt trip? \$\endgroup\$
    – winny
    Dec 9, 2022 at 22:53
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    \$\begingroup\$ this looks like an XY problem ... asking a question about a perceived solution to an unspecified problem ... what problem are you trying to solve? ... please add a description to your post \$\endgroup\$
    – jsotola
    Dec 9, 2022 at 22:56
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    \$\begingroup\$ Why does it has to be a circuit breaker you want to trip? You just want to cut power to something if a trigger event happens? \$\endgroup\$
    – Justme
    Dec 9, 2022 at 22:57
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    \$\begingroup\$ When asking about devices to be connected to mains, it's always useful to mention the country where you are living, since electrical systems specifications, regulations and products availability may vary a lot according to country. \$\endgroup\$
    – LorenzoDonati4Ukraine-OnStrike
    Dec 10, 2022 at 19:12

2 Answers 2

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It's not a problem. Several ways to go.

This answer is confined to products authorized by competent, recognized testing laboratories which meet first-world standards. Obviously you can get anything from certain countries on certain sites, but in AC mains power, you shouldn't.

Note that remote reset of a tripped residential-market breaker is forbidden by the standards bodies of most first-world nations.

Shunt-trip breakers

Shunt-trip breakers have 2 extra wires or terminals. You apply power (typically 24 volts) to them and this trips the breaker.

The breaker must be manually reset once tripped.

In European "DIN Rail" breaker lines, the shunt-trip is typically an additional module stacked with the breaker, with an interconnecting rod that taps the common trip mechanism built into breakers with this capability. Consult your supplier.

These are readily available in all major circuit breaker lines (Square D "HomeLine", talk about truth in advertising, does not support them; however Eaton supports HomeLine panels with their "CL" line of breakers.)

Generally, "shunt trip" breakers occupy one additional standard-size breaker space to house the shunt-trip equipment.

"Smart" Shunt-Trip breakers

Some new "smart panels", for instance Leviton's, provides a way to shunt-trip a breaker remotely via the smart controls/app/API/whatever. It's doing the exact same thing: shunt-tripping the breaker.

The breaker must be reset manually.

Remote-Control Breakers

This appears to be an Eaton exclusive in North America.

This breaker provides extra wires: "Common", "On" and "Off". Placing a 24V impulse for a short period (around 1 second) between common and "On" or "Off" causes an internal switch to throw that way. Yes, you have remote turn-ON.

Why is this legal? Because the onboard switch is separate and in addition to the circuit breaker, and with a separate throw handle separate from the breaker. If the breaker itself trips it must be hand-reset. Functionally this is a regular breaker + a GE RR7 style latching relay.

You can accomplish "must be reset by hand" simply by only connecting wires to "Off" and "common" and leaving the "On" terminal connected to nothing. However you have a perfect right to command it "ON" since you are not controlling the breaker.

Eaton makes these available for almost all 1" wide residential breaker lines including legacy lines, and their BAB line of bolt-on breakers. Competitor support is via Eaton's "CL" breaker line, which is specifically designed and UL-Classified for competitor panels. Other than that, North American breakers do not interchange.

Smart breakers

This is the emerging world of true "smart breakers" which are networked with some sort of supervisory system in the panel, and provide full on/off control via an app or API. The SPAN panel is the first North American example of this, but I expect it to take off very quickly due to the pressures acting on the power marketplace. Particularly around demand-side management and electric vehicle home charging.

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    \$\begingroup\$ Presumably the reason the "smart" breakers must be reset manually is that you don't want an automated system to reset breakers. \$\endgroup\$
    – user253751
    Dec 10, 2022 at 1:02
  • \$\begingroup\$ I don't like the idea of something important as a breaker depending on something as unreliable as computer networking (I would hope it's something more solid than Internet Protocol, for a start!). \$\endgroup\$
    – Toby Speight
    Dec 11, 2022 at 10:23
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Industrial circuit breakers often can be fitted with optional undervoltage release and/or shunt trip coils. These coils operate the trip mechanism when voltage is applied (shunt trip), or only allow the breaker to be reset and closed while voltage is present on the coil (undervoltage release). The operating voltage may be the same as that which is connected to the breaker's main contacts, or it may be any other AC or DC voltage (although typically 12V, 24V, or 120V as used in control circuitry.

There are also closing coils, which are often actually motors which drive gears to close the contacts and reset the trip mechanism.

http://www.electricalterminology.com/shunt-trip-vs-undervoltage-release-vs-closing-coil/

You can purchase remote controlled circuit breakers that are sized for residential distribution panels:

https://breakeroutlet.com/circuit-breakers/cutler-hammer/babr1020-remote-controlled-circuit-breaker-by-cutler-hammer/

Another DIY option might be to use a GFCI outlet (or circuit breaker) and operate the test switch, or connect a 5 mA ground fault load from line to GND. For 120 VAC a 20k resistor should work.

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    \$\begingroup\$ I have used the "intentional GFCI trip" method, it works great and has the benefit that no extra cabling to the panel is needed, just a normal outlet is enough. An SSR can be used to isolate the high-voltage side from the control signal. \$\endgroup\$
    – jpa
    Dec 10, 2022 at 9:17
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    \$\begingroup\$ I would be very careful with that approach. It desensitizes the operator to actual GCFI trips. \$\endgroup\$
    – TLW
    Dec 10, 2022 at 21:38
  • \$\begingroup\$ Would a capacitative fault load be a better choice? \$\endgroup\$
    – Toby Speight
    Dec 11, 2022 at 10:24

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