I only learned of this item from an online forum. It has been worth every penny. This has ONE job and does it perfectly! The moment power is restored by local utility company, it sounds a distinct alarm notifying me to turn off my portable generator and swap back to utility source.Easy to install.Image: Green line = Ground wireYellow line = Sensor wire

Installing on an outside panel and this was installing on an outside panel and this control is not rated to be placed outside. I purchased the weather proof box  from Amazon and installed the control inside the box. When I have to go out and turn it on in a power failure i just leave the door open so I can hear it when power is restored. Then I turn it off and close the door. Wiring it. To test it without the meter being pulled and power still on in the panel i did this. I used a branch circuit from the panel. A 15 or 20 amp will work. I turned off the breaker and wrapped the white section of the wire around the circuit wire leaving the breaker and used a wire tie to temp hold it around the wire. Then turned on the power to the was installing on an outside panel and this control is not rated to be placed outside. I purchased the weather proof box  from Amazon and installed the control inside the box. When I have to go out and turn it on in a power failure i just leave the door open so I can hear it when power is restored. Then I turn it off and close the door. Wiring it. To test it without the meter not being pulled and power still on in the panel i did this. I used a branch circuit from the panel. A 15 or 20 amp will work. I turned off the breaker and wrapped the white section of the wire around the circuit wire leaving the breaker and used a wire tie to temp hold it around the wire. Then turned on the power to the unit no sound. but when I restored power to the break the alarm sounded telling me the system was working. . Now turn off the breaker remove the white wire and install it around one of the 2 wires going to the main breaker in the panel Either wire will work. Be careful as those wires will have current on them unless you pull the electrical meter or have a disconnect switch before the panel which you can turn off. no sound. but when I restored power to the break the alarm sounded telling me the system was working. . Now turn off the breaker remove the white wire and install it around one of the 2 wires going to the main breaker in the panel Either wire will work. Be careful as those wires will have current on them unless you pull the electrical meter or have a disconnect switch before the panel which you can turn off. control is not rated to be placed outside. I purchased the weather proof box  from Amazon and installed the control inside the box. When I have to go out and turn it on in a power failure i just leave the door open so I can hear it when power is restored. Then I turn it off and close the door. Wiring it. To test it without the meter not being pulled and power still on in the panel i did this. I used a branch circuit from the panel. A 15 or 20 amp will work. I turned off the breaker and wrapped the white section of the wire around the circuit wire leaving the breaker and used a wire tie to temp hold it around the wire. Then turned on the power to the THP108 no sound. but when I restored power to the break the alarm sounded telling me the system was working. . Now turn off the breaker remove the white wire and install it around one of the 2 wires going to the main breaker in the panel either wire will work. Be careful as those wires will have current on them unless you pull the electrical meter or have a disconnect switch before the panel which you can turn off. Yes the white wire can be loosely wrapped as I did because the white wire picks up the inductive current from the power wire to the mail breaker

A very handy device for generator owners to be alerted when the electric service has been restored to your house. The unit emits a piercing 100dB tone once the “antenna” senses the electromagnetic field in the service line. Then turn off the unit to quiet it and then you can safely shut off your generator breaker and then flip your main breaker back on and you’re back on the grid. No more looking to see if the neighbors lights are on etc. my electric panel is down in my garage and it can be heard up in the living space, if you are listening for it. Very very loud in the garage!01/31/2024 Update. I have to credit Robert with the excellent idea of using a baby monitor to extend the range of the Power Return Alarm. While I can hear it on my first floor, I do have to be listening for it. With the investment of ~$17 I purchased the VTech baby monitor. https://a.co/d/5FZNhAv With the transmitter plugged into an outlet in the garage, I just turn it on and let it “listen” for the alarm to sound. Then I just kept the small receiver near me, either plugged in or on battery power, and when I hear the alarm, wherever I am in the house or yard (most likely on the 2nd floor sleeping) I can promptly shutdown the generator and switch back over the the utility provided electricity. Then I can power down my warming equipment and be ready for the next outage. Thank you, Robert, for sharing that great idea!Installation was not too bad. BUT remember, unless the meter has been pulled or the grid is down, even with the main breaker OFF, the lugs that the two hot legs are secured to, are ENERGIZED, and you need to be careful. If you aren’t comfortable, contact a licensed electrician or someone who is comfortable working in an electric panel. The white antenna (wire) is very springy so you’ll need to hold it securely or it will easily unwind. You will need to wrap it very tightly around one of the hot legs before the breaker. At least 4 wraps. Once you have it wrapped secure it with either the supplied zip ties or use electrical tape. I used both. The green wire will need to be secured to the ground bus in the panel. You’ll need to punch out one of the knockouts and feed the wires from outside the panel to inside. Secure it with a knockout clamp to hold the wires in place. The white control box has a magnet secured to the back allowing you to simply place it on the panel box, it also has. Threads that allows it to be mounted right into the knockout opening . The face of the control box has a power switch, a power light and a low battery light. It,takes 1 9 volt battery (not included) I’m not sure how long the battery will last, but most times the unit will be off and not in use. Since the service line is energized, even with the main breaker off, you can test your installation to make sure it is done properly. It does seem that if the white tip of the wire is not wrapped securely and enough times it may not be able to sense the electric field and it will not alarm even if the power is on. Another issue some folks noted is that I’d the two hot legs are too close together, the one without the antenna wrapped around it may “offset” the electric field from the one that is wrapped. There is a lower cost ($10 cheaper) unit, but this one is much louder. It is a fairly easy (when safely done) installation, this is a great way to know the power’s back on!!Sorry for the long windedness of what was supposed to be a product review but morphed into a hybrid review and installation tips.

Easy to install and 110 decibels loud. My only issue is with the mounting. My breaker box is recessed in the wall so I can’t put it through a knockout. I put a metal brace on the wall to stick it to but the magnet on the back is not strong enough to hold it on. There are no mounting holes to attach it to the wall so I had to just stick it on the door of the box. I’ll just have to remove it each time I open it.

Très utile lorsque l’électricité reviens suite à une panne.

Worked perfect to tell me when to shut the generator off.

It installed easily and we were using it for a backup generator use. We are manually switching the main and Generator breakers to facilitate a change from Hydro line power to Generator power. When running on Gen power and should the Hydro power becomes active/available, this device alerts you to switch generator breaker off and activate the Main breakers.

Fonctionne très bienIl faut avoir quelques notions en ElectriqueSi non demander a un professionnel pour l’installerPs: il doit y avoir une distance de 1/4 pouce et + entre les deux filles entrée 240vac du panneau électrique pour que le voltage soit détecté(Si non l’alarme ne fonctionne pas bien)

Fonctionne très bien lorsque bien enroulé de façon serré autour d`un des 2 fils isolée en amont du disjoncteur principale.