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

Mel Beckman mel at
Wed Aug 25 18:57:16 UTC 2021


It’s really a problem. Several lineman are maimed or killed every year because of DIY ignorance. I’ve already provided one incident. You can easily find more.

It’s virtually impossible for lineman to protect against this risk while working. These guys aren’t idiots, they are highly trained professionals. They make sure power lines are de-energized from the grid before they touch them, but there comes a point where they have to put hands on in order to affect repairs. 

It’s while they are doing this hands-on work that some thoughtles homeowner decides to fire up his DIY wrongheaded generator, feeding 120 V backwards through a cascade of transformers to produce 12,000 or more volts. It takes only a few milliamps through the heart to kill someone. But often these accidents result in horrific third-degree burns.

We all know people, and we might even be people, who have home generators. I suspect many of these use direct attach rather than transfer switches. You could help teach them the right thing to do.


> On Aug 25, 2021, at 11:33 AM, bzs at wrote:
> Ok, I'll be the curmudgeon...
> Is this really a problem in practice?
> Most people I've known who worked around electrical mains etc assumed
> the worst at all times and it isn't all that difficult to protect
> against as one works.
> I realize one can infinitely invoke "better safe than sorry!", "an
> ounce of prevention...!"
> Except maybe that one guy at Harvard who came to replace what turned
> out to be a 100+ year old, home made, "breaker" which fed our machine
> room which was hidden in a narrow dark hallway winding around our
> machine room behind an unmarked metal, locked doorway. I had no idea
> it existed but we had no power so I called for help.
> It was just a single copper bar about the size of a small candy bar
> tensioned into hot clips. Probably 400A but who remembers.
> He removed the old one confidently enough, grabbed the new one with
> rubber-handled pliers and gloves and...
>  Him: Have you ever played football?
>  Me: Actually, yes, I have, why?
>  Him: If something doesn't look right when I put this thing in just
>  tackle me clear of it as hard and as fast as you can.
>  Me: Um, ok.
> It all worked out fine and I wrote a memo that maybe Harvard could
> spring for a proper $500 breaker box?
> -- 
>        -Barry Shein
> Software Tool & Die    | bzs at             |
> Purveyors to the Trade | Voice: +1 617-STD-WRLD       | 800-THE-WRLD
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