# Reminder: Never connect a generator to home wiring without transfer switch

Haudy Kazemi kaze0010 at umn.edu
Wed Aug 25 20:47:26 UTC 2021

```It's the specific combination of current and voltage that is hazardous.

Too much current, through/across the heart, is the main, potentially fatal,
hazard. This is why 120v GFCIs trip near 5 milliamps (mA). (20-30 mA in the
wrong place is too much.)

A voltage pushes a current through a resistance, be that insulation or skin
or soil.

A 12 volt car battery can produce several hundred amps current, enough to
weld, if the terminals are shorted together, but a 12 volt battery doesn't
have a high enough voltage to push that current through dry skin. It isn't
dangerous to touch a single battery with dry hands.

Static electricity can be thousands of volts, but at extremely low current.
We feel it as the voltage is high enough, but it isn't actually dangerous
(to people; electronic equipment is another matter).

Holding the current constant at the danger threshold (20 mA), we can also
look at the power levels for various voltages.

20mA at 120v = 2.4 watts. On the other side of the transformer, 20 mA at
7200v = 144 watts. Conclusion: a single small 150 watt inverter is powerful
enough to be create a hazard for linemen working on an islanded section of
7200v powerline.

There are several categories of electrical hazards, as delineated by
voltage. Under 50v is generally considered to not be a shock hazard. More
details on voltage categories:
https://eecoonline.com/determining-safe-distances-from-electrical-hazards/

More details on GFCIs:
https://en.wikipedia.org/wiki/Residual-current_device

On Wed, Aug 25, 2021, 13:16 Lady Benjamin Cannon of Glencoe, ASCE <
lb at 6by7.net> wrote:

> So the issue here is even a small 120vac current becomes a very fatal
> event at 7.2 or 11 or 14.4kV.  It’s a safety issue for linepersons doing
> emergency restoration work.
>
>
>
> Ms. Lady Benjamin PD Cannon of Glencoe, ASCE
> 6x7 Networks & 6x7 Telecom, LLC
> CEO
> lb at 6by7.net
> "The only fully end-to-end encrypted global telecommunications company in
> the world.”
>
>
> Sent from my iPhone via RFC1149.
>
> > On Aug 25, 2021, at 7:24 AM, Ethan O'Toole <telmnstr at 757.org> wrote:
> >
> > ﻿
> >>
> >>> How would this not load the generator or inverter into oblivion?
> >
> > If you hook 100KW of neighbors up to your 5KW/20% THD garden generator
> it would probably trip the breaker, or stall.
> >
> > I suppose it could be an issue if it was a single house on a branch
> where the break being serviced was just that branch (rural customers.)
> >
> > Was just curious why it wouldn't overload the generator trying to power
> all the neighbors houses if connected to the grid.
> >
> >            - Ethan
> >
>
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