[aprssig] 3' snow emergency (generators)

Bob Bruninga bruninga at usna.edu
Mon Feb 8 18:52:42 CST 2010

> as long as no-one accidentally flips the main 
> breaker back on while you are back-feeding power 
> into the house... will never be safe. 
> The 120V that you are feeding from the car 
> could be thousands of volts the other side 
> of a transformer.

Not according to Ohms law.

Lets see, a house without power is say about 1 ohm or less (since every thermostat in the house eventually closes).  Parallel that with about 100 more houses in my neighborhood and we are talking about maybe 0.01 ohm.  Now even if my 1 kW inverter COULD remain operating into this dead short (it cant), AND if I forgot to flip the main breaker, the voltage it could deliver across that 0.01 ohm would only be about 0.1 volt.  And it CANNOT happen, not from a 1kw inverter backfeeding my house through a 20 amp breaker.  It shuts down instantly unless I have EVRYTHING turned on and only bring the lights back in breaker by breaker..

I agree of course with the potential for a fool with a big 10kW generator pumping back 100 amps trying to live in full american style through a disaster is a significanly greater issue and is the reason that fail-safe transfer switches are mandated...

> Toyota is recalling over 7 million cars 
> that go when you don't want them to go.

You've been feeding on too much media pablum...

No, only a few dozen had the problem, and it was the clueless driver that did not have the sense to 1) shift to neutral, 2), or turn off cruise control, 3)or turn off the ignition, or 4) stomp on the gas to unstick the pedal. Everyone who pilots a plane, drives a boat, or drives a car needs to think about and practice for the obvious emergencies such as stuck acceperators, or loss of brakes.

> and 270,000 of the Prius variety that don't 
> stop when you want them to stop. 

Every one of them stops.  There is just a fracion of a second overlap in the stopping torque as the regenerative braking is ramping down and the hydraulic fricion is ramping up and it occurs at under 10 MPH.  It just feels a bit different, and is not worth the media hype...


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