3way sw. problem

[westelectric]

Today I spent about 2 hours trying to figure out what was wrong with these 3way systems in this circa 1900 house. 2 3ways at the top of entrance hall stairs, 2 3ways at the front door. Most of you will recognize this as a bast_ _ _ hook up or a dutchmens hook up. Maybe you have some other terms for this. Hot and neutral in each box pigtailing onto the travelers of each sw. Commons I believe are the hot and neutrals of the sw. legs. Hot in 1 box on the common, neutral in the other box on the common. Common practice with Knob and tube wiring. I think thats how this is wired. Anyway I changed all 4 3way switches and after about 10 or so trys on each switch, the breaker tripped. Funny thing is it doesnt trip instantaneously. I am very familiar with wiring this as I have seen it alot in old houses. Put the old switches back on and after about 20 trys they never tripped. So I had bad switches right? Nope put 4 new switches and guess what? Tripped again. So bad switches again? Nope happened again. Put the magic switches back on and they work. Whats up? Told the customer have to rewire to bring up to code and what does she say? But it works now. Please help. Any suggestions.

 

[ultramegabob]

Today I spent about 2 hours trying to figure out what was wrong with these 3way systems in this circa 1900 house. 2 3ways at the top of entrance hall stairs, 2 3ways at the front door. Most of you will recognize this as a bast_ _ _ hook up or a dutchmens hook up. Maybe you have some other terms for this. Hot and neutral in each box pigtailing onto the travelers of each sw. Commons I believe are the hot and neutrals of the sw. legs. Hot in 1 box on the common, neutral in the other box on the common. Common practice with Knob and tube wiring. I think thats how this is wired. Anyway I changed all 4 3way switches and after about 10 or so trys on each switch, the breaker tripped. Funny thing is it doesnt trip instantaneously. I am very familiar with wiring this as I have seen it alot in old houses. Put the old switches back on and after about 20 trys they never tripped. So I had bad switches right? Nope put 4 new switches and guess what? Tripped again. So bad switches again? Nope happened again. Put the magic switches back on and they work. Whats up? Told the customer have to rewire to bring up to code and what does she say? But it works now. Please help. Any suggestions.

the short of the long answer is, make sure you are dealing with one circuit to both switches, brass screws get a power and a neutral (grounded conductor) black screws go to the single wire going to the lamp, what you wind up with at the lamp depending on the position of the switches is going to be- hot and hot= off, hot and neutral= on, neutral and netral= off, or neutral and hot= on

 

[Dennis Alwon]

Today I spent about 2 hours trying to figure out what was wrong with these 3way systems in this circa 1900 house. 2 3ways at the top of entrance hall stairs, 2 3ways at the front door. Most of you will recognize this as a bast_ _ _ hook up or a dutchmens hook up. Maybe you have some other terms for this. Hot and neutral in each box pigtailing onto the travelers of each sw. Commons I believe are the hot and neutrals of the sw. legs. Hot in 1 box on the common, neutral in the other box on the common. Common practice with Knob and tube wiring. I think thats how this is wired. Anyway I changed all 4 3way switches and after about 10 or so trys on each switch, the breaker tripped. Funny thing is it doesnt trip instantaneously. I am very familiar with wiring this as I have seen it alot in old houses. Put the old switches back on and after about 20 trys they never tripped. So I had bad switches right? Nope put 4 new switches and guess what? Tripped again. So bad switches again? Nope happened again. Put the magic switches back on and they work. Whats up? Told the customer have to rewire to bring up to code and what does she say? But it works now. Please help. Any suggestions.

It seems that neutrals are involved as travelers and that the switches are fed at both ends.

Could this be what you have

 

[LarryFine]

Mike, all that should matter is that the wire from the old switch's common gets attached to the common terminal of the new switch.

I suggest using a continuity tester or ohmmeter to double-check which terminal really is the common on the old switches.

Not indicating you, but a lot of people go by terminal position, rather than terminal color/marking, when swapping out 3-ways.

 

[al hildenbrand]

Put the old switches back on and after about 20 trys they never tripped. So I had bad switches right? Nope put 4 new switches and guess what? Tripped again. So bad switches again? Nope happened again. Put the magic switches back on and they work. Whats up?

The first time I ran into this was a L-o-o-o-ng time ago back when Honeywell "silent" switches were introduced. They had a full sized (not framed) toggle handle. The thing that made them silent was that the contact was made and broken by rotating a hollow "pill" (about the size of a dime and ?" thick) with the toggle, allowing a rather large drop of mercury to roll onto the contacts, or back off the contacts.

Because the drop of mercury wasn't dimensionally stable, in a three way, the mercury would occasionally elongate and for a brief moment be in contact with both travelers and the common.

This only mattered when the switch was used on a Chicago Threeway like you describe. The hot and neutral on the travelers of the switch being operated would short and blow the overcurrent protective device.

Since then, I have, on rare occasions, had mechanical threeways that will do the same thing.

Getting a different manufacturer's switches, or a more expensive grade of switch, will most likely solve your problem.

You can test this by clamping your continuity tester to the traveler terminals of one of the types you just blew up, a new, undamaged switch, and then run the switch back and forth.

Edit typo - Al

 

[LarryFine]

In other words, Al is suggesting that your switches are make-before-break, and you need break-before-make.

One way to double-check the house wiring for hots and neutrals is with an extension cord plugged into a know-properly-wired receptacle, and a tester like a solenoid type, or a small bulb.

 

[Sierrasparky]

Al you've seen a 3-way cross all contacts at the same time?
Wow would never guessed.

 

[al hildenbrand]

Al you've seen a 3-way cross all contacts at the same time?

I've done my share of very early Knob & Tube work.

There was a while there, in this Metro area that was home to Honeywell, that do-it-yourselfers would fall under the spell of that "silent" switch. It was in all of the little hardware stores. And they'd finally get to that stairwell threeway. . .and blammo!

I'd get the call, identify the threeway type as Chicago Threeway (at least, that's what my Master told me it was called :roll: ) and put in a mechanical snap switch.

I like Larry's pithy synopsis :grin:

In other words, Al is suggesting that your switches are make-before-break, and you need break-before-make.

 

[LarryFine]

I like Larry's pithy synopsis :grin:

Don't pith me off! grin

 

[cajun62234]

I agee with the above replies...I too have experienced this 'reverse terminal' construction with old 3-way switches.. lucky you, it took me a week before I discoverd it
Get out the continuity tester and be a happy camper

 

[westelectric]

the short of the long answer is, make sure you are dealing with one circuit to both switches, brass screws get a power and a neutral (grounded conductor) black screws go to the single wire going to the lamp, what you wind up with at the lamp depending on the position of the switches is going to be- hot and hot= off, hot and neutral= on, neutral and netral= off, or neutral and hot= on

Thanks for the response and sorry for the long reply but lost power last nite right after i posted. Definetely only 1 circuit and the way you described it is exactly like i have it wired. Again Ive seen this alot in the past but never had this happen.

 

[westelectric]

It seems that neutrals are involved as travelers and that the switches are fed at both ends.

Could this be what you have

No Dennis, definetely have exactly what Bob described.

 

[westelectric]

Mike, all that should matter is that the wire from the old switch's common gets attached to the common terminal of the new switch.

I suggest using a continuity tester or ohmmeter to double-check which terminal really is the common on the old switches.

Not indicating you, but a lot of people go by terminal position, rather than terminal color/marking, when swapping out 3-ways.

Larry, definetely have the correct terminals. And again, with the hot and neutrals being on the travelers, if I did have them screwed up it would short sooner rather than after 10 or so trys.

 

[480sparky]

I'm wondering why haven't you given the owner a price to fixt the problem correctly instea of cobbling a known violation back together.

 

[westelectric]

The first time I ran into this was a L-o-o-o-ng time ago back when Honeywell "silent" switches were introduced. They had a full sized (not framed) toggle handle. The thing that made them silent was that the contact was made and broken by rotating a hollow "pill" (about the size of a dime and ?" thick) with the toggle, allowing a rather large drop of mercury to roll onto the contacts, or back off the contacts.

Because the drop of mercury wasn't dimensionally stable, in a three way, the mercury would occasionally elongate and for a brief moment be in contact with both travelers and the common.

This only mattered when the switch was used on a Chicago Threeway like you describe. The hot and neutral on the travelers of the switch being operated would short and blow the overcurrent protective device.

Since then, I have, on rare occasions, had mechanical threeways that will do the same thing.

Getting a different manufacturer's switches, or a more expensive grade of switch, will most likely solve your problem.

You can test this by clamping your continuity tester to the traveler terminals of one of the types you just blew up, a new, undamaged switch, and then run the switch back and forth.

Edit typo - Al

Chicago 3way, interesting. Al, Ive seen these mercury switches also. Sw in the on pos., tilt it a little and the lamp turs off, sraighten it ou and the lamp turns back on. As far as a more expensive grade, Im using Lutron switches because the H.O. wanted a satin color (midnight). Pretty pricy switch and Im guessing a pretty good quality. I was thinking maybe 20 amp 3way switches if they exist.

 

[westelectric]

I'm wondering why haven't you given the owner a price to fixt the problem correctly instea of cobbling a known violation back together.

Left the HO a message today that I want to talk to him about rewiring the switches because they are in violation. If he doesnt want to then I will take the lost time on the call like a man and move on. Not to mention the 4 3way special order switches and plates that will sit on the shelf in my shop forever because im sure they are not returnable.

 

[cal1947]

Larry, definetely have the correct terminals. And again, with the hot and neutrals being on the travelers, if I did have them screwed up it would short sooner rather than after 10 or so trys.

sound,s like a lazy neutral

 

[al hildenbrand]

Im using Lutron switches because the H.O. wanted a satin color (midnight).

Interesting that this is happening with Lutrons.

A lot of Lutron snap switches, behind the pretty colored plastic, are Hubble devices. Is that the case with yours? I wouldn't have suspected them to "make before break".

One brute force common sense kind of approach is to use the Lutron switch that shorts the travelers enough times on the energized circuit to arc weld out of existence the extra length of contact that is permitting the "make before break". I'm not seriously suggesting this. . .but it is something my old Master would have done.

If it seems to still work, at the end, then it ain't broke.

You may give your customer a more meaningful motivation the rewire the stairwell threeway by explaining the momentary shorting of the travelers cause by the beautiful Lutron switches.

If the customer is committed to maximizing the aesthetics of the electrical system, then the loyalty to the special black plastic will make the cost of the stairwell rewire acceptable.

 

[e57]

I want to talk to him about rewiring the switches because they are in violation.

MIGHT NOT HAVE BEEN WHEN ORIGINALLY INSTALLED BUT WERE AFTER YOU TOUCHED THEM.....

(Sorry cap locked - but feeling too lazy to re-type....)

Anyway I know another method than what was pictured with a hot and neutral in each box - and only one wire to the light. When on - it gets a hot and neutral (polarity opposite depending on switch positions)- if off, it gets either two hots, or two neutrals and does not operate. Much like ultramegabob describes.... But agree with others about the wrong terminals - it is so easy to swap, or think you have the right wire on them.

Would you like an expensive product that requires minimal labor or damage to install to correct this? (one may equal the other)

Radio RA (Comes in matching black) or some sort of X-10 device.

 

[westelectric]

Interesting that this is happening with Lutrons.

A lot of Lutron snap switches, behind the pretty colored plastic, are Hubble devices. Is that the case with yours? I wouldn't have suspected them to "make before break".

One brute force common sense kind of approach is to use the Lutron switch that shorts the travelers enough times on the energized circuit to arc weld out of existence the extra length of contact that is permitting the "make before break". I'm not seriously suggesting this. . .but it is something my old Master would have done.

If it seems to still work, at the end, then it ain't broke.

You may give your customer a more meaningful motivation the rewire the stairwell threeway by explaining the momentary shorting of the travelers cause by the beautiful Lutron switches.

If the customer is committed to maximizing the aesthetics of the electrical system, then the loyalty to the special black plastic will make the cost of the stairwell rewire acceptable.

HO going for the rewire. He really loves those black switches. Took me into the din. rm to count all of the 2 recepts and 2 SINGLE POLE SWITCHES that he also wants to change to not black but a lovely RED...... Thanks Guys