Last time we looked at how to get electricity to an outbuilding by burying the cable. This time we’ll explore the other option â€“ overhead wires.
As we said last time, before you start, check the code for details, but these fundamentals should give you an idea of what you’re going to need to do.
Overhead wires should generally be out of reach and “out of harm’s way”, and a height of about 14 1/2 feet is recommended. Now, that height’s not always that necessary or possible, but make sure you check with the inspector before making a decision. It’s also not usually an option to run the wires across a roof. You might need special permission, and before that’s possible, you’ll need to do up plans and specs.
The wire is generally weatherproof triplex cable, which consists of two insulated conductors wrapped around a bare “messenger” cable, which both supports the wires and acts as a conductor between the two buildings. The messenger is attached to the building, and the conductors generally enter a conduit before entering the building.
Two 15-amp circuits can usually be run this way, simply junctioned in the outbuilding, but if you have more circuits, you’ll need a subpanel. If you only have one circuit (and no animals in the outbuilding), you can use the messenger cable as a ground, but otherwise, you’ll need to ground each circuit from the first junction box or the subpanel to a bar buried in the earth.