Just in from Square D [RE-wrenches]

[R. Sparks Scott]

>That way both lines flow through the breaker. I think this is to help the
>breaker to pop in an overload situation.

	Bob;

	No, the two independent poles of the breaker still react to the
load/overload without interaction.
	The use of two poles to interrupt the current undoubtedly is because this
*doubles* the air gap interrupting the flow of current, allowing higher
voltages to be switched without the attendant arcing. If you were to run
the current through two poles on a single conductor (in the line side of
one pole, out the load side of that pole into the line side of the second
pole, then out the load side to the load), you'd get the same result, but
you wouldn't be able to use a standard load center.
	Similarly, using a four-pole breaker and wiring it for
in/out-in/out-in/out-in/out as above would again double the voltage
handling capacity, without changing (in theory) the current rating.
	Having the toggle handles of the breakers ganged is a very important
requirement of this type of installation, it guarantees that the two (four,
whatever) poles switch at the same time, opening the (doubled, quadrupled)
air gap, instead of just a single breakers gap, which might invite arcing.
	Obviously, there are code issues related to this, even using a two pole
breaker as described in the SqD document. Systems over 50 volts are
required to have one conductor grounded. How does that work into having the
pos and neg going through a two pole breaker?

	-S

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