On Thu, 06 Sep 2007 23:07:32 -0700, Bruce L. Bergman
wrote:


Two times to worry: One is if you have 120/208V Wye power, because
it is only 208V phase to phase. Most small motors are dual-voltage
rated 208V/240V and will gladly run on 208V but at a higher current
draw. But there ARE pieces of gear that do not take kindly to running
on 208V - this is when you connect a simple 16V/32V Buck-Boost
transformer between the utility and the load to kick 208V up to 240V.

The other: If you have 120/240 Open Delta or "High Leg" power - the
High Leg (usually coded Orange and connected as B phase, but not
always) is 208V to ground, not 120V.

When you run across Open Delta panels in the field, it is
considerate to put a big note on the breaker panel to warn the less
enlightened among us that 'The B Phase is 208V to ground, and
connecting 120V loads to the B Phase is a Very Bad Idea.'

You can connect 240V loads between any two phases on Open Delta, but
you can only connect 120V light loads between A-N and C-N. Try
placing them on B-N and they won't live very long - but they glow
really bright before they blow...

Indeed. Even if they dont have a light source..they can glow really
nicely.

Then the magic smoke comes out.
-- Bruce --


Gunner, who has been putting orange tape on all manner of things the
last few months......

Orange County is nearly all Open Delta and 240 vts