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PathTested Team

September 1, 2026

Are ground rods in outbuildings really a good idea?

Are ground rods in outbuildings really a good idea? It's conventional wisdom, and indeed NEC requirement, that a subpanel in a detached building have a ground rod (or even two), nothwithstanding a few exceptions. I've recently read some pushback on this. The argument is that when a lightning strike occurs, it creates a voltage potential (probably thousands of volts) over the ground. If you have multiple ground rods - say the required two for your main dwelling, and another one or two in an outbuilding - there's potentially a huge voltage differential between them. And thus potentially a high current in the ground conductor between the two buildings, which is potentially pretty small (just whatever amperage and wire gauge the feeder requires). I guess the counter-argument (copied from a related thread) is that although for the duration of that lightning strike’s discharge a large current would flow through the feeder's ground wire (because of the voltage difference between the house’s grounding rod and the outbuilding's), the current would only last a few milliseconds and therefore the ground wire would not be harmed. Has anyone else heard this argument? Does it make sense to you?
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