Is this pest repellent safe?

Yes, most repellers rated for sale in the US are safe for use, though an understanding and adherence to the product user guides are recommended.

This is important not only for safety, but also for effectiveness.

Devices which plug into the wall should be given their own outlet and not left in an extension cord. Many of these devices use your home’s in-wall circuitry to amplify and distribute their pulse. Additionally, such a device is designed for constant use, however, most extension cords are not. Therefore, better to avoid the risk of overloading or overheating an extension cord.

Note, the pulse these devices return through the electrical circuitry are within tolerances and do not pose a threat to your electrical system in and of themselves, provided your electrical system is up to code.

Chemicals or poisons should be granted their own set of unique considerations. Most products would not kill an adult but could be fatal to small children. Be very careful when handling or using such products.

As a rule, consider the nature of the product your using. If you want to “annoy” and run off a pest then ensure the product doesn’t also annoy you. If you want to kill a pest, then consider that the product, if abused, could land you the same fate.