14/2 On A 3 Way - Help

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  #1  
Old 03-12-07, 07:26 AM
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14/2 On A 3 Way - Help

My 40 yr old house in south jersey has a 3 way switch controlling the basement light. Its wired entirely with 14/2 cable as follows-

switch 1
Incoming Hot black to common on sw-1, NEUTRAL WHITE NOT connected. Black and white of outgoing 14/2 cable are connected to the traveler terminals on sw-1.

switch 2

Incoming travelers from switch 1 are connected to sw-2 traveler terminals. Outgoing (to the light) 14/2 black is connected to sw-2 common, NEUTRAL WHITE IS CONNECTED to white neutrals from another switch (DIFFERENT CIRCUIT) in same box.

I believe this is the original circa 1960 wiring - is this safe ? should i rewire the travelers to 14/3 so the neutrals can be wired correctly?
 
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Old 03-12-07, 07:29 AM
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This is NOT safe, and is a fire waiting to happen.

Replace the cable between the switches with 14-3 and wire properly, so that the correct neutral is used.

Even if the neutral used were from the same circuit it would not be proper.
 
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Old 03-12-07, 07:36 AM
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I will reinforce Bob's comments. This is NOT safe.
 
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Old 03-12-07, 07:55 AM
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Thks for the the quick replies- what surprises me is it apparently was wired that way by the original electricians- 46 years ago. The house is in a large subdivision so its not a one of a kind situation. Does anyone know if it was ever safe (ie code compliant) to wire a 3-way with 14/2 ? I mean was this a common practice on the part of electricians back in the 60's to save wire, time and money?
 
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Old 03-12-07, 08:05 AM
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It was common place many years ago, well before the 60s, to do this with knob and tube. I have never heard of it done legally with NM type cable, and can't imaging that it was ever legal by code to do this. . I have heard of it done by people who don't know any better.

Are you sure this was original? Often basements in houses are unfinished, and as such only have a light switch at the top of the stairs. Is it possible that the original owner (or a subsequent owner) finished the basement and re-routed the cable from the light to a new switch added at the bottom of the stairs, to perhaps avoid having to try to fish a wire to the top of the stairs switch?
 
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Old 03-12-07, 08:29 AM
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Its a walk-in basement so that would account for the builder putting a three way at that location. The other reason it looks original is all the cable is the old style with the fabric cover and its run thru the attic (its a ranch) as is all the other original wiring.

I guess it will remain a mystery - anyone have any idea as to where the danger lies in this- is it in the unconnected neutral in switch 1 or the use of another circuits neutral in switch 2? Just wondering how its worked without any problems for 40+ years.
 
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Old 03-12-07, 08:40 AM
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There are two issues.

The first and most serious is the use of another's circuit's neutral. By using the neutral of another circuit you put the return current on another circuit. This means that the current on the return could exceed the rating of the cable, causing the cable to overheat, causing a fire, etc. An additional related concern would be that someone could power off the other circuit and get shocked by the (unexpected) neutral current.

The other issue is mainly theoretical. Hen the current one way through a cable does not equal the current the other way, an electromagnetic field is generated. This field is not particularly dangerous by itself, but it could cause problems with the circuit breaker tripping (or fuse blowing) as fast as it normally would I the event of an overload.
 
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Old 03-12-07, 09:32 AM
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Thks, I appreciate the info. Yes i'm going to remove the neutral in sw-2 which is tied into the other circuit asap. If I tempoarily leave the neutral in switch 2 unconnected ( cap it off) would my light still work?
 
  #9  
Old 03-12-07, 09:59 AM
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Without a neutral the light will not work. Alternating current (any current for that matter) needs a path through the load and back.
 
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Old 03-12-07, 10:12 AM
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Disconnecting the neutral will make the light non-functional. Making the light non-functional will also make it safer (unless you now fall down the stairs because it is dark).
 
  #11  
Old 03-12-07, 10:18 AM
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Here's a suggestion, if you can live with it.

Use only the switch at the top of the stairs, temporarily (until you can fix this properly).

Connect the neutral at the top switch and completely bypass the lower switch (fixing the problem of the wrong neutral). Then you will be using the proper neutral for this circuit. Yes, you won;t have control at the top and bottom of the steps, but at least you can turn the light on (and off).
 
  #12  
Old 03-12-07, 01:03 PM
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Thks again for the speedy and sound advice. I'll bypass it till I'll can rewire the travelers with 14/3.

I really shouldn't be surprised that the original electricians would do this kind of shoddy work based on other things I've discovered around this house.

A few years ago I was replacing a kitchen light fixture and found the wires in the junction box fried. Went up to the attic and found the junction box covered with a piece of CHARRED brown paper and then buried in insulation. Appears the flush light fixture with two 75 watt bulbs had cooked everything in the box. Talk about a fire waiting to happen.
 
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Old 03-12-07, 01:55 PM
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Don't be too quick blame the electricians for the light issue. It's likely that the fixture is not rated for 75 watt bulbs, and the person who installed the bulbs is the one responsible.
 
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Old 03-12-07, 02:05 PM
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Originally Posted by racraft View Post
Don't be too quick blame the electricians for the light issue. It's likely that the fixture is not rated for 75 watt bulbs, and the person who installed the bulbs is the one responsible.
Could be - but I believe nowadays flush fixtures call for cable with a higher heat rating.
 
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Old 03-12-07, 02:08 PM
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Could be, but few ceiling fixtures allow more than 60-watt bulbs, even with used with modern 90-degree wire. Many homes have burnt down for no greater sin than using overwatt bulbs.
 
  #16  
Old 03-15-07, 08:41 AM
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Originally Posted by racraft View Post
Here's a suggestion, if you can live with it.

Use only the switch at the top of the stairs, temporarily (until you can fix this properly).

Connect the neutral at the top switch and completely bypass the lower switch (fixing the problem of the wrong neutral). Then you will be using the proper neutral for this circuit. Yes, you won;t have control at the top and bottom of the steps, but at least you can turn the light on (and off).
racraft- decided to use your advice - heres what i found- connecting the previously unused neutral in sw-1 to my new 2-way switch resulted in open neutral at the switch. i opened the recpt closest to the switch and got lucky and found the other end of the unstripped neutral not connected to anything- my plan is to connect it to the neutral terminal on the recpt and problem solved.
 
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