How do electronic rodent repellers work?

How do electronic rodent repellers work and do they really work? Are questions often asked.

The short answer is yes they do work, but it helps to understand the different features and functions on rodent deterrents and what can be expected from them.

Ultrasonic Sound:

Ultrasonic sound, is sound that is at a higher frequency than normal human hearing. Rodents hear and communicate in frequencies much higher than people. When this type of sound is pulsed and varied in a certain way, rodents perceive it to be threatening and annoying. Overtime rodents associate this annoyance with the area covered and learn to avoid this area.
Tips for using ultrasonic sound:
Ultrasonic deterrents are best used to cover open room areas. This sound will not penetrate through walls or other obstacles, so place units so the speakers are not blocked in anyway and point out into the room.
Ultrasonic sound is also directional and pointed, a bit like light from a torch. Place units nearer to ground level so the sound is concentrated across the area where rodents move around.
Ultrasonic repellents are limited to covering one room area only, to cover multiple rooms with ultrasonic sound, multiple units are required.

Electromagnetic Pulses:

Electromagnetic deterrents send random pulses along the power cables in a building, on the circuit the unit is plugged into.
Like ultrasonic sound, these pulses are also perceived by rodents to be threatening causing them pain and annoyance. Once again, it is association of this pain with the area covered, that causes rodents to move on.
Tips for using electromagnetic pulses:
This type of deterrent is best uses to cover walls and cavity areas, which are common places where rodents hide. Unlike ultrasonic sound, this feature can be used to help protect areas inside walls and other confined areas, where the power cables run.
Most of the effect will be limited to the areas near the power cables and on the power circuit the unit is plugged into. In larger homes and buildings, there will be multiple power circuits, so multiple units will be required to protect different areas.

Ionic:

An ionic function, puts negatively charged atoms into the air. This can have a purifying effect, helping to remove smells from the air that can attract rodents. Ions can also warn rodents of an approaching storm, as they are emitted into the air by lightening.
An ionic unit is often not enough to deter rodents when used on it's own, but does help add to the deterring effect.

Single function and combination deterrents:

Some electronic rodent repellers have a single deterring function, others have multiple features. The best type to use, does depend on the size and type of area you need to cover.
Read our tips for rodent control for more information on the best unit for you.

What can we expect from electronic rodent deterrents?

Prevention is better than cure, it is far easier to keep rodents out with deterrents before there is a rodent problem, than it is to drive out a large, resident rodent population. Read our tips for rodent control, for best practice.
It is best to put deterrents in place by autumn and before winter. With cold approaching, rodents move into houses and buildings, but are far less likely to take up residence if deterrents are in place.
Electronic deterrents are best used to cover and protect specific areas. Keep in mind how the different features work and the types of areas they will cover. To cover an entire home or building, multiple units are normally required to cover all areas.
It can take up to 2 weeks after installing deterrents to see results. Rats are more tolerant than mice, so can take longer to deter. Expect to see more visual rodent presence in these first 2 weeks, as rodents are driven out of their hiding places and move into other areas.