Who’s really being silenced on Twitter? | Circuit Breaker Parts

Why do the US still use 110v mains and 20A room circuit breakers? Those currents are dangerous, not the volts.

The skin depth varies with the magnetic permeability of the material. Iron for example reacts at very low frequencies, so much so that it becomes useless for wires at 50 Hz.

Great reasons to add L2 to your own garage, carport, parking spot: preconditioning vehicle will not reduce your SOC, lower fire risk than overloading an existing 120V circuit, more efficient charging, added resale value to your house, NEMA 14-50 outlet can be used for other things (welder, RV, heater, etc.), two EVs in the same garage, maximize off-peak charging, cool factor, etc.

We recently watched [MakeItExtreme] turn a couple of microwave oven transformers into a somewhat ill-advised wall-climbing rig. It looks like that may have been the inspiration for this build, and the finished product appears to be a tad more useful this time. The frames of three MOTs are cut open to remove the secondary coils and leave the cores exposed as poles for the future magnets. A shallow dish is fabricated out of steel and the magnets are welded in place.

This. An isolation transformer can be a very useful thing, but also very dangerous. If you touch ONE end no problem, but if you touch both ends you will get cooked and the RCD will NOT trip. Or more directly: An isolation transformer does NOT allow you to switch off your brain! And NEVER connect a scope to such a transformer.

And even today people give the advice of plugging a computer in the wall and grabbing the metal case as you’re working inside it. Bad idea – if the PSU has failed, you may very well have live voltages in the boards.

Five vs Ten amps is a big difference in heating in the power factor correction circuit of his power supply. If you find a data sheet for similar power supplies, they are always 1-3% more efficient on 220Vac and run cooler because of it.

However, experience tells me that this very minimal standard is not good practice. Modelling for 240V will only cause problems with the first over voltage transient or spike.

If you really have to work on a live circuit, electrically isolate yourself and try to work with only one hand. Put the other one in your pocket. That way the risk of closing a circuit through your body is much smaller. Also don’t work in a hurry, carefully plan your actions and slowly do them. Use nonflammable clothes. Use electrically protective gloves. Use face protection.

Knocking over a candle would be an accident. Keeping barrels of petrol in your living room would be negligence. Doing your own mains wiring without the proper qualifications, I dunno which side that falls on. Real accidents can’t be foreseen, but you have to take reasonable precautions.

I worked in telephony for many years, and the ring voltage can be as high as 180 bolts at various frequencies, but, rather low current. In really old telco systems it may also be a square wave.

HVDC interties certainly simplifies some things (stability, voltage control, and frequency syncing & phasing is a non-issue), particularly in lines where their length approaches a quarter wavelength (which makes voltage control at the load end difficult). There are quite a few already: http://en.wikipedia.org/wiki/List_of_HVDC_projects and the list is growing rapidly.