Our Neighborhood Transformer Is An Antique

My all-electric house is powered by an antique.

I love old stuff, but the PG&E distribution transformer serving my house doesn’t inspire confidence. It’s on a pole leaning at a scary angle, and uses glass insulators that could be 100 years old.

This is what I’m pulling eleven kilowatts through every time I charge my car, on top of whatever all my neighbors are pulling.

The box steps down high voltage from the topmost wires to single-phase 120/240 volt service that comes into our homes. Inside it are some wire windings, surrounded by oil: a technology which hasn’t changed that much since the 1890s when it was invented (and when my house was built!). And if it was made before 1979, the oil could be PCBs… so don’t stand under it in a lightning storm.

It doesn’t seem to have any smart circuitry or monitoring, or the ability to relay its condition back to PG&E HQ.

But it does seem to be operating ok. My Sense Energy Monitor, which also keeps tabs on the power quality coming from the street, hasn’t detected any concerning voltage spikes, dips or floating neutrals yet (see screenshots below).

The bad news is that this transformer is probably typical, and completely inadequate for decarbonizing and hardening the grid with distributed generation (e.g. solar) and storage.

If I’m ever going to share power efficiently with my neighbors, it won’t be through this box. We need a total hardware do-over for microgrids (which allow clusters of buildings to be ‘islanded’ from the grid and share power locally).

Since there aren’t standards for this hardware yet, let’s hope our vintage transformer keeps handling the load for another few years, so they don’t have to spend major capital on upgrading it to another outdated box.

P.S. Here’s a very old diagram showing almost exactly the configuration of my local transformer today, in 2022:

Via EdisonTechCenter.org

And here’s a simple three-minute YouTube video explaining how and why step-down transformers work (using coils of wire wound around a core):

And finally, some screenshots from my Sense Monitor app showing our vintage neighborhood transformer hanging in there electrically!