How far can the concrete-encased grounding electrode (aka Ufer Ground) be from a main service panel?
There is no distance criteria for concrete-encased electrodes (no minimum or maximum distance from the electrical service panel). If present at a building, then a concrete-encased electrode (CEE) is required to be part of the grounding electrode system for the building. In other words, you are not required to install a CEE, but if one is present, it must be used as part of the grounding system.
A CEE consists of at least 20 feet of ½-in. or larger bare conductive steel reinforcing bars or rods installed in one continuous length, or in multiple pieces tied together with the usual tie wire, exothermic welding, approved clamps or other effective means, with the goal of creating an overall length of 20-feet or more. Another option is to use 20-feet of bare copper conductor not smaller than #4 AWG embedded in the concrete. The rebar or bare copper conductor must be encased by at least 2-inches of concrete and needs to be located horizontally in the footing or foundation that is in direct contact with the earth.
But wait…what the heck is a Ufer Ground anyway? Well, during WWII Herbert G. Ufer discovered that a CEE is a much better electrode than driven ground rods, especially in dry desert regions, so eventually the Ufer Ground found its way into the National Electrical Code.
Always check with your local electrical inspector about the specific code requirements in your area.
Question Answered by John Williamson, Chief Electrical Inspector, Minnesota Department of Labor and Industry
John Williamson has been in the electrical industry for 40 years and is a licensed master electrician and certified building official. John has worked for the state of Minnesota for over 23 years and is the Chief Electrical Inspector. For the past 25 years John has also provided electrical code consultation to various book and magazine publishers
Click here to learn about some common code violations.