On Sep 16, 8:37*pm, wrote:
On Fri, 16 Sep 2011 06:41:00 -0400, Paul Franklin









wrote:
On Thu, 15 Sep 2011 22:55:39 -0700 (PDT), Ivan Vegvary
wrote:

Want to install several X10 relay switches in the house to turn on lights remotely. *This would obviate my walking across the room in the dark to get to the light switch.

Problem: *The X10 switch/relay requires full power at the wall switch location. *Several of my switches have only a hot leg coming into the box with no neutral. *X10 docs. recommend simply running a neutral wire into the box. *
Question: *Most of my wiring is within the attic and some of the switches are on the exterior walls. *These locations are inaccessible from the attic since this is where the roof meets the ceiling ergo providing mere inches of crawl space. *It would be much easier to run the neutral wire from below (I have a generous 42" high crawl space). *
Question: *Does this neutral have to come from the same circuit? *Can I simply come from any circuit (even a separate new circuit) and run a white neutral wire to each switch box? *Does it have to be from the same phase? *X10 docs. do mention that if not from the same phase, then the phases can be joined at the box.

All comments, advice and suggestions appreciated.

Ivan Vegvary

It will work if you connect any neutral, but don't do it and here's
why: *Suppose you are doing some remodeling or repairs down the road.
You kill the breaker to a circuit, check with your meter to make sure
the circuit is dead and start unwiring the circuit to replace a bad
outlet say. *You disconnect the neutral, and all of a sudden it's hot
because upstream somewhere you connected your X10 from a different hot
circuit to the neutral of the one that you turned off. *When you break
the neutral, the X10 provides a path to the other hot leg, and the
disconnected neutral becomes hot. Yes, it's current limited by the x10
and wouldn't power a toaster say, but there's more than enough current
available to make *you* toast.

This exact situation (doorbell xfmr, not x10) happened to me and I got
a good shock. *It's especially dangerous because you can check the
circuit with a meter all you want before you break the neutral, and it
won't show that it's hot (because it's not, at that time). *This is
why I always treat the neutrals as hot until they are disconnected and
verified to be dead.

So bite the bullet and do this some other way. *And it is against
code, if you need another reason.

HTH,

Paul F.

*Can you say "red herring" or "straw man"?

When you shutt of a breaker you ONLY shut off the "line" - not the
neutral.

When you go to replace that theoretical outlet, the neutral is STILL
GROUNDED at the panel - so there is NO voltage differential between it
and ground. Also, the X10 is not a load, like a bell transformer. It
is a voltage controlled device - not current - so it is only
"injecting" a couple of milliamps into the neutral - so even IF it was
ungrounded at the panel (which would make the circuit totally
inoperative) it would be doing good to give you a little tickle -
muchless harm you.

There not talking about the current, if any, from the X10 device.
They are talking about the current from other loads on the circuit
that the neutral is bootlegged from. If, in replacing the X10 device
at some future point in time, the splice in the neutral of the circuit
from which the bootlegged neutral was taken were opened the load side
of that splice will go high to one hundred twenty volts.

I had such an incident with a bootlegged neutral serving a lighting
fixture. I opened the switch to the light and installed a lock out
device on it. I checked for other hot circuits in the box with a
voltage proximity detector and got no voltage indication. I opened
the splice to the neutral, using best practice non contact technique,
and got a spark when I actually broke the neutral continuity. So I
checked again with the proximity detector and got a voltage
indication. I pulled out my Wiggy and got one hundred plus volts to
ground. I applied a tracer transmitter between the two disconnected
neutrals and it came on and produced a signal. When I opened the fuse
it led me to the voltage and the signal went away. I then reapplied
the power by closing the fuse and traced the neutral to discover were
it actually came from. I was able to rework the circuits arrangement
to clear the inter-circuit connection but, had I not used best
practice technique, I might have received a fatal shock.
--
Tom Horne