[Elecraft] Subject: 240V Line

[Vic Rosenthal 4X6GP/K2VCO]

Yup. Last year I was changing the primary taps on a massive 3.5 kVA Dahl 
transformer on a homebrew amplifier. Instead of connecting the line to 
the 0V and 220V taps as I intended, I connected it to the 220V and 240V 
taps.

When I turned it on, it popped

1. The 15A breaker in the amplifier,
2. The 20A breaker on the wall where my 240V line (#10) came in, and
3. The 30A breaker at the service entrance.

It also temporarily welded the contacts of the contactor in the 
amplifier. It did NOT blow any diodes (maybe because they were 6A10's) 
or capacitors. I can only imagine what the secondary voltage might have 
been if the diodes and capacitors hadn't looked like a short in the 
instant (it seemed instantaneous to me) before the breakers went.

Don't do this, but if you do it's good to have lots of breakers.

On 25 Dec 2014 18:34, Edward R Cole wrote:
> Having the 240v 20A breaker in the room is handy if the PS trips it off.

-- 
73,
Vic, 4X6GP/K2VCO
Rehovot, Israel
http://www.qsl.net/k2vco/