I've got a 25 year old house, whose light switches I'm converting over
to a powerline protocol called INSTEON (see www.smarthome.com; for
purposes of this question, it's very similar to the old X10 protocol).

Two of the bedrooms are on one circuit breaker (the whole rooms:
lights, outlets, the whole shebang). Each room has a single switch
controlling the lights in that room. I pulled a light switch out this
evening, planning to replace it, when I saw there was no neutral in the
junction box (the INSTEON switches require both hot and neutral). At
first I expected to find neutral in the wall behind the box (I was
guessing they had, for some reason, routed hot through the box and to
the switch while leaving neutral unbroken), but then realized that what
went in the box was a single piece of three-conductor wire, with black
used for hot, white for switched, and ground not connected.

So... before I start digging the junction box out, what are my odds of
finding neutral somewhere in the vicinity? More generally, I'm having a
hard time imagining why someone would wire the ceiling light fixture and
not have power and neutral come from the same place! So, before I get
myself in trouble, how did they likely wire it?

Thanks in advance,
--
As we enjoy great advantages from the inventions of others, we should
be glad of an opportunity to serve others by any invention of ours;
and this we should do freely and generously. (Benjamin Franklin)

On 2009-09-01, Joe Pfeiffer wrote:
I've got a 25 year old house, whose light switches I'm converting over
to a powerline protocol called INSTEON (see www.smarthome.com; for
purposes of this question, it's very similar to the old X10 protocol).

Two of the bedrooms are on one circuit breaker (the whole rooms:
lights, outlets, the whole shebang). Each room has a single switch
controlling the lights in that room. I pulled a light switch out this
evening, planning to replace it, when I saw there was no neutral in the
junction box (the INSTEON switches require both hot and neutral). At
first I expected to find neutral in the wall behind the box (I was
guessing they had, for some reason, routed hot through the box and to
the switch while leaving neutral unbroken), but then realized that what
went in the box was a single piece of three-conductor wire, with black
used for hot, white for switched, and ground not connected.

So... before I start digging the junction box out, what are my odds of
finding neutral somewhere in the vicinity? More generally, I'm having a
hard time imagining why someone would wire the ceiling light fixture and
not have power and neutral come from the same place! So, before I get
myself in trouble, how did they likely wire it?

Thanks in advance,

You would find neutral in the same outlet that is onthe same circuit
breaker.

i

Neutral is probably up in the light fixture. It is perfectly acceptable
to run the hot and neutral to the light fixture, then run a hot and
switched hot to the light switch. Ground wires tended to get ignored
when running to a switch only. Not the best but it was often done.

If you dig around and find a neutral, it is unclear if you would find
the correct neutral. It might work if you found a different neutral but
the loads would be unbalanced. Not to mention unsafe if you wanted to
work on the OTHER circuit.

Joe Pfeiffer wrote:
I've got a 25 year old house, whose light switches I'm converting over
to a powerline protocol called INSTEON (see www.smarthome.com; for
purposes of this question, it's very similar to the old X10 protocol).

Two of the bedrooms are on one circuit breaker (the whole rooms:
lights, outlets, the whole shebang). Each room has a single switch
controlling the lights in that room. I pulled a light switch out this
evening, planning to replace it, when I saw there was no neutral in the
junction box (the INSTEON switches require both hot and neutral). At
first I expected to find neutral in the wall behind the box (I was
guessing they had, for some reason, routed hot through the box and to
the switch while leaving neutral unbroken), but then realized that what
went in the box was a single piece of three-conductor wire, with black
used for hot, white for switched, and ground not connected.

So... before I start digging the junction box out, what are my odds of
finding neutral somewhere in the vicinity? More generally, I'm having a
hard time imagining why someone would wire the ceiling light fixture and
not have power and neutral come from the same place! So, before I get
myself in trouble, how did they likely wire it?

Thanks in advance,

Joe Pfeiffer wrote:
... So, before I get
myself in trouble, how did they likely wire it?

Most likely the feeder with hot & neutral went to the light fixture
junction box. The neutral was wired to the fixture and the hot went out
to the switch. The switched hot back from the switch was wired to the
fixture. Very common.

H --------/\------------
S
N ------- L ----------

Bob

Bob Engelhardt writes:

Joe Pfeiffer wrote:
... So, before I get
myself in trouble, how did they likely wire it?

Most likely the feeder with hot & neutral went to the light fixture
junction box. The neutral was wired to the fixture and the hot went
out to the switch. The switched hot back from the switch was wired to
the fixture. Very common.

H --------/\------------
S
N ------- L ----------

Ah, got it. Makes perfect sense, and given the relative locations of
the light, the switch, and the panel would have involved less wire.
Sucks for me, though. No outlets anywhere near to pull neutral from to
get it that way.

Hmmm... I see how to wire the switches now (certainly not how I wanted
to do it -- if I want to avoid digging holes in and then patching
wallboard, I'll have to run hot and neutral from the fixture to where
the existing switch is, put a switch there to act as a remote control,
and then put a switch up in the light fixture controlled by the switch
in the wall).

Thanks!
--
As we enjoy great advantages from the inventions of others, we should
be glad of an opportunity to serve others by any invention of ours;
and this we should do freely and generously. (Benjamin Franklin)

Joe Pfeiffer wrote in
:

I've got a 25 year old house, whose light switches I'm converting over
to a powerline protocol called INSTEON (see www.smarthome.com; for
purposes of this question, it's very similar to the old X10 protocol).

Two of the bedrooms are on one circuit breaker (the whole rooms:
lights, outlets, the whole shebang). Each room has a single switch
controlling the lights in that room. I pulled a light switch out this
evening, planning to replace it, when I saw there was no neutral in
the junction box (the INSTEON switches require both hot and neutral).
At first I expected to find neutral in the wall behind the box (I was
guessing they had, for some reason, routed hot through the box and to
the switch while leaving neutral unbroken), but then realized that
what went in the box was a single piece of three-conductor wire, with
black used for hot, white for switched, and ground not connected.

So... before I start digging the junction box out, what are my odds
of finding neutral somewhere in the vicinity? More generally, I'm
having a hard time imagining why someone would wire the ceiling light
fixture and not have power and neutral come from the same place! So,
before I get myself in trouble, how did they likely wire it?

Thanks in advance,

It's called a switch leg. Power should actually come in on the white
and leave the switch on the black. There is no neutral in the box or
probably anywhere near. This is normal and probably half the light
switches in the world are wired this way.

Code prohibits you finding a neutral from some other location. All
circuit conductors should come from the same cable.

You could replace the switch leg with a piece of 3 wire (don't count the
ground in a cable with uninsulated ground) from the light to the switch
and abandon the 2 wire you have to gain a neutral for your switch.

Joe Pfeiffer writes:


So... before I start digging the junction box out, what are my odds of
finding neutral somewhere in the vicinity? More generally, I'm having a
hard time imagining why someone would wire the ceiling light fixture and
not have power and neutral come from the same place! So, before I get
myself in trouble, how did they likely wire it?

The term is "switch leg".....

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