Ground testing on asphalt: how can you perform a ground test when you can't drive a spike?

摘要

A new customer has just awarded you a service contract to perform standard electrical maintenance for a large suburban mall. As part of the agreement, you must routinely test the pole grounds on parking lot lighting. But the site has acres of asphalt and concrete roadway or pavement, with little soil except what's around the potted shrubs. Many of the poles are so far from the fringes of open soil that you'd need prohibitively long test leads to reach a spot with access to the soil. Under the circumstances, you'd be unable to meet the critical placement requirements of the potential probe necessary to construct a fall-of-potential graph, but your contract calls for you to perform a full fall-of-potential test, as described in IEEE Standard 81, with the resultant graph included. What can you do?