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Cake day: March 31st, 2025

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  • in many flats even recently built you don’t get three-phase power, just single phase, but building divides single three-phase supply into three groups of single phase circuits like you say (do you really need 20kW in residential flat? one that doesn’t use EV charger, built in 90s-10s?) i guess it depends on country also. separate houses tend to get three phase connection where i live

    floating neutral will also be a problem in american-type two-phase installation, might be even worse (more frequent) on account of large number of lightly maintained transformers used (why on gods green earth there’s few-kV medium voltage line going down every street, americans make it make sense)




  • you don’t have to have three phase circuit to be affected by floating neutral in three-phase substation upstream. in some places in us there are 208v interphase three-phase circuits, which give 120v phase to neutral, which is distributed as a pair of wires as single-phase circuit. this is also normal way to deliver single-phase power in europe, as it’s most efficient use of conductor. (from 400v three-phase circuits) in case more power is needed than single-phase circuit can deliver, three-phase circuit is installed

    if there’s switch on device, it’s 2p1t meaning both phase and neutral are switched. if it’s permanent, non-pluggable circuit, like lightning, it’s okay if only phase is switched (neutral is connected permanently)


  • it’s a bad practice to design appliance in such a way to assume that neutral will have low voltage, because in case of neutral failure in three-phase circuit you can get full voltage there, and there can be a couple of volts difference (sometimes more) between neutral and ground even in normal circumstances

    it’s better to cut off both live and neutral at the same time anyway, especially if there’s no standard which is which. also, as device designer you don’t know if it’ll be used on a circuit that has neutral and phase where you think it’ll go or not. (ie british appliance used on unpolarized circuit, like type F. adapters exist)








  • Type E and F plugs are not really a thing anymore, today it’s more common to find combined Type E/F plugs.

    Fuses in british plugs are a mistake and only a requirement because of sketchy practices allowed in british electrical code immediately after WW2. Nobody else does that because nowhere else electric code is built in such a way that it is necessary. Switch seems to be mildly useful tho





  • It’s not. He-3 is supposed to be maybe one day used in fusion power, but we’re talking about tons of this stuff. Not only scale is off, also He-3 burning requires much higher temperature than D-T fusion, and this is just around in next 20 years pinky promise

    People who think that it’s a big deal also take Ray Kurzweil seriously, it’s scifi noise

    In practical terms, when DHS wanted to get He-3 neutron sensors, they bought out entire global supply for multiple years, for an application where only grams are needed and it’s not used up. It’s made from decay of tritium currently and it’d be less energy intensive to make it the usual way




  • there’s a couple of big failures in american defense industry (like shipbuilding) but F35 is not one of them. the alleged killswitch is not likely a thing because first, it could be used by the most probable adversary, and they already shown capability in EW; and second, it’s not necessary because it requires constant stream of spare parts and maintenance. as if it’s worth it, ask any remaining iranian radar operator for firsthand opinion

    some countries switched to euro made jets anyway, but these aren’t likely to be doing the job that F35 is cut to do anyway (SEAD)

    there’s already euro alternative in development, for which americans were explicitly not invited (GCAP, FCAS). there’s also the everything else part of military, half of euro countries make now artillery (both tube and rocket) so these can be bought locally too