Nobody publishes a distance threshold, because distance alone does not decide anything. What gets measured:
- Voltage. 138kV, 230kV or 345kV, rising with the load. A 345kV line five miles away can beat a 138kV line at the fence.
- Distance to an interconnection point. You cannot tap a transmission line mid-span. Power comes off at substations. Distance to a substation with headroom is the number that matters.
- Available capacity. A line with no headroom is not useful at any distance.
- Terrain and easement between you and the connection. Two miles across open farmland and two miles through wetlands, a river crossing and forty landowners are not the same two miles.
A rough working frame
As a general orientation rather than a rule: a parcel within a few miles of adequate-voltage transmission and a substation with headroom is in the conversation. Ten miles with easy terrain may still work if capacity is genuinely available. Thirty miles in difficult country usually does not, because the cost of getting there exceeds what the land discount saves.
This is the real calculation: every mile of line extension is cost, and that cost comes out of what a buyer will pay for the dirt. The full arithmetic →
What to find out about your own parcel
- What voltage crosses or neighbours your land
- Where the nearest substation is, and at what voltage
- Who the serving utility is, and whether they have large-load experience
- Whether that utility has reserve margin
The first two are in public transmission mapping. The second two need a phone call.
How to read the lines on your land → · Who pays for the substation →