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[pete8314]

I purchased 3 of these from an eBay X10 seller that I've used before.  I don't think I would have got 3 defective units, but for some reason I cannot make any of them work.  It's possible I'm doing something very dumb, but I don't think so...

To keep my testing super simple, I'm trying the XPS3 on a single-pole 2-way under-counter fluorescent light.  I pulled out the existing light switch, which had a hot wire, load(switched) wire and earth.  Bundled at the back were 4 white neutral wires, so I pulled one of those out, and connected to the XPS3.  I connected the hot wire to the Line input, and the switched wire to the load.

And...nothing...the LED has a faint flicker, but pressing the rocker does nothing.  A multimeter shows 120v on the hot wire, and by probing the neutral wire (with the other probe touching the remaining bundle of neutrals) it shows 230v, which doesn't make any sense.  It's a cheap digital multimeter, so maybe whatever is leaking out to the neutral circuit is screwing it up.

Anyway, in theory this is a complete normal install (in a new house), so am I doing anything obviously wrong?

Thanks, Pete

[glb7272]

How many switches are in that box? The only reason I could see that there are 4 white wires wrapped together is that the black and white from the source (breakerbox) enters that box then the white wires are fed to the neutral side of the lights or other outlets (not the way most houses are wired).

Did the switch have a black and white wire hooked to it originally? or were there 2 black wires?

the 230 has me confused as well. Do you have a picture of the box?
 Look at this site for a diagram The first 2.  http://www.make-my-own-house.com/light-switch-wiring.html

[Brian H]

Did you ADD a white wire from the XPS3 to the bundle or REMOVE one from the bundled whites and use it?
If you removed one and didn't add one. You broke the Neutral wiring in the house and that is probably why you have funky operation and maybe other devices now not working. That would also explain the 230 volts on the White bundle as one or more of the circuits on the bundle are on the other phase of the homes wiring. That also means that other devices on the phases may act funny or be damaged by unequal load balance.

[glb7272]

Brian H I thought that it may be "back feeding" through the neutral as well. He said it was a new house, is that to code? I cant imagine a reason to have multiple wire runs in one box off 2 breakers (now on my old house its a whole new story  )

The way I understand it is that one of 4 were removed.

[pete8314]

Yup - I pulled one of the neutral wires from the bundle, rather than chasing back a new wire to the neutral circuit. Now I've done that, the switch works locally, but of course it's not receiving any commands...I spent most of last night reading about those issues, so I'll post separately on that!

Sorry for the newbie question, I've been using X10 on and off for probably 15 years, but 12 of those were in the UK, so now I'm here in the US I'm having to start over on the basic principles of wiring a house! (not least that that phases are split apart for most circuits).

Thanks for the input.

Pete

[Brian H]

No I can't think of why two branch circuits had the same Neutral wire.

[dave w]

No I can't think of why two branch circuits had the same Neutral wire.

I had home in Florida where two breakers used same neutral. I found out the hard way when I broke the bundle and became a path for the breaker that was still energized. Appearently it was not against code (at the time the house was built), or the building inspector got paid off.

[Brian H]

Yes I remember you pointing that out.
In your case and pete8314's. I am glad no permanent damage was done.

[dave w]

Yes I remember you pointing that out.
I am glad no permanent damage was done.

Thanks for the vote of confidence, but you might want to check with my wife first, she' been saying for a long time that I ain't right....

[glb7272]

Sorry for the newbie question, I've been using X10 on and off for probably 15 years, but 12 of those were in the UK, so now I'm here in the US I'm having to start over on the basic principles of wiring a house! (not least that that phases are split apart for most circuits).

newbie? I am a newbie and it was a good question IMO. You have me asking questions to myself. Still want to know what happened. Why do we have 110v 115v 120v standards? Why do we have 50hz and 60hz standards? UK outlets make more sense as well. less wire more amps just no redundancy on the "neutral" or "ground".

I had home in Florida where two breakers used same neutral. I found out the hard way when I broke the bundle and became a path for the breaker that was still energized. Appearently it was not against code (at the time the house was built), or the building inspector got paid off.

dave w my house is the same way....I think the previous owners said add a wire here add a wire there and don't use a box and if you do,do not put the cover back on. 

[Boiler]

Kicking in the time machine...I was once licensed in the state of Illinois (Nixon was in office) where I helped my uncle in the construction business.  Code at that time in Chicago allowed you to run 12/3 (or 14/3) 220V with a shared common for lighting.  Once the 12/3 was run to a room, it was split into traditional 12/2 circuits for the 110V loads. 

The theory was that, with a balanced load across the 220V line, current would be shared across the hot wires.  Under worst case conditions (all units off on one phase) the neutral would be required to carry all of the return current.  For 12/3 the breaker would be 20amp which would not exceed the neutral rating.

Chicago code at the time required conduit.  Running 220v to rooms and splitting into individual 110V branches made pulling the wiring far easier.  This is the only time I've seen this used.

Fast forward to the 90's - working on my Aunts home (Chicago) I got bit while lifting a neutral connection.  I had turned off one phase, but forgot that the rooms were wired 220V with a shared neutral.  I won't say I'll never forget to check for 220V wiring, but I've remembered so far.

This is a good thing to note when we forum members are giving wiring advice.  I have a feeling that 220V shared common is standard practice in larger cities that require conduit.  When installing a switch, it's necessary to turn off two breakers to ensure that there is no current flowing on the common.

Boiler

[Mellowmark]

The new code cycle will require that the breakers that share a neutral will have a common handel like a two pole breaker

This common neutral shareing is very common and cost effective insallation tech. 

[glb7272]

Boiler excellent piece of knowledge

This is a good thing to note when we forum members are giving wiring advice.  I have a feeling that 220V shared common is standard practice in larger cities that require conduit.  When installing a switch, it's necessary to turn off two breakers to ensure that there is no current flowing on the common.

Now that this post has been hijacked how would we test for that before pulling a neutral?
Another thing I always do after checking visually from a light, toaster or whatever is plugged in, then reading a meter on bare wires (without touching them) is to take a screwdriver (plastic handle) and triple check. Do not want to go to far into this but electricians will understand where I am coming from. You also point out a good point. Its electricity and can be deadly in the right circumstances and I should always consider that anytime i post.

[Boiler]

Now that this post has been hijacked how would we test for that before pulling a neutral?
Another thing I always do after checking visually from a light, toaster or whatever is plugged in, then reading a meter on bare wires (without touching them) is to take a screwdriver (plastic handle) and triple check. Do not want to go to far into this but electricians will understand where I am coming from. You also point out a good point. Its electricity and can be deadly in the right circumstances and I should always consider that anytime i post.

glb7272,

The best way that I know of to test for a shared neutral is to inspect the load panel.  If you see adjacent breakers wired with 12/3 (or 14/3) you have a shared neutral connection (or a true 220V circuit).  You'll need to turn off both breakers to eliminate the possibility of return current on the neutral.

This is not an easy thing to test for away from the panel unless you have a current probe (not voltage).  Here's a scenario:

1) You disable one breaker of a shared common run (Phase A).  The hot leads in your outlet box are now dead.
2) Since Phase A of the 220V run is off, all of the return current from Phase B will be carried by the neutral.
3) All of the loads on Phase B are currently off.  There is no current flowing in either branch.
4) You lift the neutral to work on your switch/outlet.
5) Someone turns on a load on Phase B (breaker still on at the panel).  Since you've interrupted the neutral connection, the return wire will be energized to 120V (waiting to bite you).

As I indicated above, you can test for current (current probe) on the neutral.  You may still get fooled if none of the loads are switched on (no return current).  The best method here is to simply inspect the panel.

To be honest, I'm surprised that code hasn't required the use of 220V breakers for these applications.  This would eliminate the possibility of leaving one leg powered.

Sorry for the hijack,
Boiler

[Boiler]

The new code cycle will require that the breakers that share a neutral will have a common handel like a two pole breaker

This common neutral shareing is very common and cost effective insallation tech. 

Mellowmark,

Thank you for the info on the "common handle" breaker.  As you can tell, I've been out of the business for a little while.

Glad to see that the code caught up with this one - and it hasn't even been 40 years yet.