The transformer that feeds my house decided to give itself an old fashioned Viking funeral around 9pm Thursday night. Unfortunately I missed most of the excitement, since the power wasn't impacted until the power company cut the power to replace it about 45 minutes later. With the house dark, I could see the police/fire/PoCo vehicles' strobes going. There was still some flames coming out of the transformer, but nothing all the exciting. They got it replaced around midnight. Friday morning I took a look at the transformer, and it looks like they've installed a 25kva unit (based on the big "25" sticker on it). I'm surprised it isn't bigger or that they didn't hang two. That single transformer feeds 7 houses (was 4 way back when, but 3 decent sized ones have been added in the neighborhood in the last 10 years). I'm basing that assumption off the fact that 7 houses were dark during the event, we're at the end of the street, and this is the only transformer around. The transformer has probably been flakey for a couple of weeks - I've been noticing lights flickering during the day, but it's stopped now that we have the new one. So my real question - are there any rules of thumb for sizing these things? I know they're typically overloaded, but really, 7 houses (5 are >3000 ft^2) on 25kva?