Rod electrodes
The most common and well understood option, sometimes known as 'stakes' or 'vertical rods'. These can be driven from 1m to 5m deep (soil dependent).
Deep electrodes of upto 30mtrs deep need a drilling rig to pre-drill out the soil, then the electrodes are placed in the borehole and backfilled/grouted up with bentonite or similar highly conductive media.
The upside to these is that they are relatively cheap to buy and install. The downside, is that they only have a small contact surface area and rely on the moisture content for their connection.
Strip electrodes
Strip electrodes can take the form of burying copper tape (25mm x 3mm, 50mm x 6mm, etc.) either radially from one point or any no. of configurations.
This too can be a relatively cheap means of getting an earth in good soil conditions.
Plate electrodes
A slightly more expensive option. These consist of 600mm x 600mm solid copper plates increasing the contact area substantially. They can be deployed vertically or horizontally if you've only got a shallow top soil to work with.
The benefit of plates is that one plate can replace upto 4-6 standard rods, therefore, you can keep the space required for deployment down; plus you only need to allow for some very simple trenching.
The drawback is that plates still rely heavily on moisture content.
Chem-rod™
Sometimes known as Chemically Activated Ground/earth Electrodes (CAGE). This solution has a very large contact area with the earth (critical cyclinder).
In addition, the chem-rod™ chemically 'conditions' the surrounding soil in contact with the unit, so that if the moisture drops off it still has the best possible contact via the natural electrolytes/minerals it uses.
Typically, one chem-rod™ can replace up to 10 standard rods, which makes it the preferred choice in difficult ground conditions or where there isn't a lot of space for deployment.
