DIYbanter - View Single Post - Electric Problem or overloading the circuit

Twayne[_3_]

In ,
typed:
On Mon, 28 Dec 2009 02:08:24 -0600, bud--
wrote:

Doug Miller wrote:
In article , bud--
wrote:
Doug Miller wrote:
In article , "Twayne"
wrote:
I don't think that makes sense so, assuming I'm right, how is
it that an overload on one isn't affected (delayed, held from
tripping) by the force the other needs to be opened?
It trips with ample force to bring the other one along with it,
even if the only connection is an external tie.

Move a breaker handle from the 'off' position to the 'on'
position; notice
how
much force you have to apply to it. Now nudge it from 'on' to
'tripped' --
see
how easy that was, and how forcefully it snaps over? More than
enough to trip a second handle tied to it.

Nice answers to some bizarre misinformation. I would disagree only
that if you have multiple breakers with a handle tie, one breaker
tripping will not necessarily trip the other breaker.

Perhaps you'd like to explain how it's possible for one handle of a
pair tied
together to move from the on to the tripped position, while the
other member
of that tied pair remains in the on position...? :-)

The handle of a breaker does not have to move to a tripped position
when
a breaker trips. If there is enough force (as from another breaker)
the handle can stay in the on position. Breakers are "trip free"
(which you edited out).

As a matter of experience, handle-tied breakers do not always both
open
if one is tripped by overload. Some brands might.

Any that passes CSA approval WILL. Don't know about the lame US
regualatory bodies.

UL 1459, its successor, and CSA are the same on these points. What's
important in reading them is "properly installed" w/r to their "purpose".
Ganged breakers are expected to have the same current in each leg; thus they
don't impede each other. Using a ganged breaker in a split or multi-
situation would be an improper application. All breakers and fuses are
specced and include a time-chart of current vs time for opening so that
makes it obvious too.

Cheers,

Twayne

You can handle-tie 3 breakers for 3 phase circuits. I would expect
them
to be less likely to all trip.

I would not rely on handle-tied breakers to all trip open. If you
want a reliable trip of all poles use a multi-pole breaker instead
of a handle tie.

The NEC requirement (if I
remember right) is for a common disconnect, not a common trip.

There's no practical difference.

"Common disconnect" means that when the breaker is *manually* turned
off all breakers are opened. (The language is "simultaneously
disconnect".)

"Common trip" means if one breaker trips by *overload* both breakers
open.

They are not the same.

Handle-tied breakers are necessarily "common disconnect". They may or
may not be "common trip".

--
--
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but Toast lands PB side down;
A cat glued to some jelly toast will
hover in quantum indecision forever.