| So typically burying a cable at HV or EHV is an order of magnitude more expensive than overheads. Underground cables are also prone to thermal issues (ironically) so I don't know that you'd be reducing fire risk as much as you'd think. Much of the ignition risk comes from transformer explosions, air-insulated CB arcs, and line-to-tree arcs. Transformer explosions are inherently harder to isolate from flammable material in the American distribution system design than they would be in a European 240v system, that's because the US system has to keep LV (110v) runs short so has extensive HV networks with pole-mounted transformers feeding a small number of properties each. 240v systems can tolerate longer LV runs and use larger pad-mounted distribution transformers with about 20x the power rating of American style pole-mount transformers. In the Euro configuration, you therefore have many fewer transformers which have a least a fence around them with regular vegetation control within it. You can also put these transformers within enclosures. A typical UK rural/suburban arrangement has the transformer air cooled and outside within a fence with breakers and distribution boards inside a brick or GRP hut inside the fence. In urban areas the whole thing is enclosed in its own structure or in the basement of a building. Anyway you can't do that with American transformers as there are more of them. These will therefore always be an ignition risk. Yes you can step up planned replacement of older models, be more aggressive about keeping the load per transformer down to lengthen lifetime and reduce fault risk but fundamentally they are a risk. You can replace air insulated CBs with gas-insulated models at significant expense, that will reduce that risk. Burying cables as I said is horrifically expensive but you could increase the size of the vegetation-cleared right of way around the overheads and step up the clearance schedule. None of these will remove every source of ignition. |
Wait... In the US for household single-phase it is 240V from the pole transformer to the breaker panel, where the 120V is derived by taking one hot or the other against the neutral, and the range/drier/etc 240V circuits are simply across both hots. So there is no difference between EU or US distribution voltages until it gets inside the house. All the US does is add a neutral so that it is easy to get 120V.