Interesting question.

Can you guarantee that each relay will deliver back EMF at exactly the
same time relative to the digital switch off?  I couldn't.

I would be tempted to use a diode for each coil, so that the back EMF
of one coil didn't activate the other.  I guess that depends on when
they release, how much energy they release, and how much energy is
needed to close.

Twenty feet of cable is going to have other problems for me though,
and I don't know what they would be.

I'm no expert in this.  It sounds like it would be worth measuring in
real-time.

--=20
James Cameron
http://quozl.linux.org.au/
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