When locating utilities with EML the first point of call should always be to utilize the direct connection method. Be this directly to a steel asset, a tracer wire conveniently run with the asset or by inserting a rodder into the asset and tracing this. These methods are the best at minimizing bleeding into other assets and give the most positive outcome for the locator. In the ideal world locators can find a handy piece of grass next to their work space to insert the earth stake into and the job can be completed with minimal fuss. What happens though when the asset is surrounded by asphalt or concrete and the earth stake becomes redundant. Often by looking around the area you can find existing infrastructure already in place that will do a more than adequate job. Manhole lids, steel bollards, and signs are just some of the possibilities that a locator can use. Some of these may require you to remove some rust to get a decent connection but will give you a good alternative. Things that don’t typically work well are streetlights or building earth stakes. Using electrical infrastructure will induce a signal into the power services as well as the target asset and cause a fair bit of confusion. Steel fences should also be largely ignored as these will create a lot of extra induction and may be running parallel with the target asset.
A typical commercial building surrounded by asphalt can make placing an earth stake impossible. Below are 3 options that all worked equally well in this situation. Next time you are on site think outside the box to increase your locating capabilities.
A small crack in the asphalt was enough to insert a small screwdriver and provide a good earth.
A vehicle bollard near the site was bolted down and offered an earth connection to the bolts. Yellow paint on the bollard would not let the signal through but check to see if there is a scratch in the paint and you can often use the magnet to get this to work.
The coms pit lid works well. Sewer and stormwater manholes also work fine although you may need to clear some rust to make a good connection.
Article By; Brent Lowry, Nulca President