New service on a house.

Per NEC 250.53(A)(2), if you driven a single ground rod and its resistance exceeds 25 ohms, you must add a second rod. However, most jurisdictions now require two rods regardless, spaced at least 6 feet apart, because achieving ≤25 ohms with one rod is rarely practical.

Since you've already driven one 8-foot rod, install a second rod at least 6 feet away. Both rods must be at least 8 feet long and in contact with the earth for their full length (NEC 250.53(F)).

Bond both rods together with a continuous #6 AWG copper conductor (or #4 AWG if more than one electrode conductor is used). Connect using approved clamps listed for direct burial.

If your local AHJ has adopted the 2017 or later NEC edition, note that GFCI protection is now required for detached structures supplied by a single feeder (NEC 250.4(A)(9) and 250.68(A) Exception).

Bottom line: Add the second rod. It's required in nearly all cases and costs little extra.

Yes, you almost certainly need a second rod.

NEC 250.53(A)(2) Exception: A single rod is permitted only if you test it and prove the resistance to earth is 25 ohms or less. Without a documented test result (using a 3-point fall-of-potential tester), you must install a second electrode.

Practical Rule: Driving a second rod is faster and cheaper than renting a tester and documenting results.

Installation Requirements (NEC 250.53(A)(3)):

• Spacing: Minimum 6 feet apart (8–10 ft preferred for effectiveness).
• Depth: Driven 8 ft minimum below grade (NEC 250.52(A)(5)).
• Connection: Bond both rods together with a continuous Grounding Electrode Conductor (GEC) (typically #4 Cu for 200A service, NEC 250.66). Use listed acorn clamps (NEC 250.70) or exothermic welds.
• Protection: If the GEC is exposed to physical damage (e.g., along foundation), run it in PVC or RMC (NEC 250.64(B)).

Better Alternative (if applicable): If this is new construction with a concrete-encased electrode (Ufer ground)—#4 rebar ≥20 ft in the footing/foundation—that is your primary electrode (NEC 250.52(A)(3)). You only need one supplemental rod (or none if the Ufer tests ≤25 ohms, but rarely tested). Bond the GEC to the rebar before the pour.

Bottom line: No Ufer? Drive the second rod 6+ ft away. Bond them together. Connect GEC to the first rod. Done.