Resistivity meters are used for a variety of environmental testing purposes. Resistance is generally measured by "injecting" a current into the ground using two electrodes and measuring the difference in voltage at two other electrodes indicating the potential of the current.

Both survey companies and environmental engineering firms commonly use resistivity meters. They can measure mineral content in the soil, salt water content and ground water availability as well as several other soil and water variables. Consider the needs of your business and buy accordingly.

1. Buy the most popular resistivity meter on the market: the ground resistance meter, which is available in a clamp configuration. Clamp meters can save your workers a lot of hassle and time.

2. Test soil for moisture and salt using soil resistivity meters. These measure the corrosive quality of the soil and should be used prior to burying pipes and wires underground.

3. Do quality control for clients by utilizing water resistivity meters. You can test anything from residential wells to industrial water supplies.

Action Steps
The best contacts and resources to help you get it done

Let your crew work more efficiently by using a clamp-style ground resistivity meter

As was explained previously, resistance is usually measured by inserting two probes into the ground and sending a current through them. This can take up quite a bit of time if you have a lot of areas to test. Instead, you can use a clamp meter to simplify things: Simply clamp the device around the ground wire to take your measurements.

I recommend: Save time with earth ground clamp meters, available from Optimum Energy Products. Gisco also makes great clamp resistivity meters.

Get a soil resistivity meter to test for corrosivity

Soil moisture and salt content affect the resistivity of the soil. If soil has a low resistivity, it is most likely corrosive. This is important to know when installing underground pipes, wires and cables. Sandy soil tends to be the least corrosive while clay soils or contaminated soils are the most corrosive.

I recommend: Use a low-cost meter for the four-pin Wenner testing method; buy an economical meter from Advanced Geosciences. The four-pin meter from Farwest Corrosion Control Company allows you to perform a multitude of tests for different applications.

Test water purity using a low-powered water resistivity meter

You don't have to use a high-powered meter for shallow applications, like testing ground water. These resistivity meters are used to test water purity and detect saline levels. You simply take samples of the water on-site and test them back at your lab.

I recommend: Buy a great economical water resistivity meter from Heritage Geophysics. You can find a versatile meter at Siemens Water Technologies.

Tips & Tactics

Helpful advice for making the most of this Guide

• •  You may need a surface resistivity meter for your business. These measure the resistance properties of static control products. It's commonly used as a point ground resistivity meter.