Thread: Five Pole Double Throw Light Switch

I came across a light switch in a building probably over 30 years old. The room was used by an eye doctor for surgery. There are eight 120 volt incandescent fixtures in the ceiling on one circuit and one 4 by 40 watt, 120 volt flourescent fixture on the second circuit. One switch controls the incandescents and the other controls the flourescent.

The two throw switch has five poles. One is for the 240 volt feed with a 10 guage black wire. Two appear to be 120 volt lines on blue wires. The other two wires are red and appear to be the neutrals. No ground wire.

My best guess is that the higher voltage is required to maintain the incandescent power demand which had 100 watt bulbs with the 160 watt flourescent. I haven't performed the calculations.

The customer was asking about moving the switch about 10 feet down the hall. When I saw the wiring with no ground I backed off.

Anyone out there have any experience with this type of switch?

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Originally Posted by William Galbraith

There are eight 120 volt incandescent fixtures in the ceiling on one circuit and one 4 by 40 watt, 120 volt flourescent fixture on the second circuit. One switch controls the incandescents and the other controls the flourescent.

The two throw switch has five poles. One is for the 240 volt feed with a 10 guage black wire. Two appear to be 120 volt lines on blue wires. The other two wires are red and appear to be the neutrals. No ground wire.

My best guess is that the higher voltage is required to maintain the incandescent power demand which had 100 watt bulbs with the 160 watt flourescent.

First, though, you would not run 120 lights off 240 volts, they would burn out relatively fast (probably minutes - I used to know and had tried it on occasion 'just to see'). If the 120 volt lights were connected with 2 in series with each other on 240 volts, that would work (not allowed, but would work), but when one burned out, the other would go out too.

Do you have a photo of the switch?

Could you describe the switch?

I am visualizing a knife switch with five poles at the bottom, five poles at the center, and five poles at the top, with the line feeding the five poles at the center and the switch either connecting the top pole or the bottom poles?

But I cannot figure out where the 240 volts comes in??

Let me take a SWAG at this!

The switch you are looking at has 5 wires attached to it. Five wires does not mean it is 5 pole. I think it is a double pole double throw with the throws tied together in the switch. One direction of the switch turns on the incandecents and the other the flourescents. The black wire is most likely supposed to be 120v source, but you said you measured 240v somewhere.

If you measured from the black wire to the closed position you would measure 0v. If the switch is switching neutral instead of the hot, and you measured from the black wire to the open side of the switch, (and the other lights are on the other side of the 240v buss) then you would measure 240v.

That's my best guess.

Jerry,

I will be back at the location tomorrow and take some photos.

According to my voltage measurements, the voltage to the lights is 120 due to the step down from the 240 to 120 and then to the light circuit. Again, no ground wires from the conduit and no ground screw on the back of the switch.

The back of the switch has two screws on one side, one for the black feed and another for one of the blue wires. The other side has one blue and two red wires. The bottom red wire screw is at an angle but is not a ground, not green.

The front of the switch looks like a standard two throw switch, one on top of the other in a horizontal throw position. Turn the top switch to the right and one circuit is on. Turn the bottom switch to the right and the other circuit is on.

Thanks, Bill

Originally Posted by William Galbraith

Jerry,

I will be back at the location tomorrow and take some photos.

According to my voltage measurements, the voltage to the lights is 120 due to the step down from the 240 to 120 and then to the light circuit. Again, no ground wires from the conduit and no ground screw on the back of the switch.

The back of the switch has two screws on one side, one for the black feed and another for one of the blue wires. The other side has one blue and two red wires. The bottom red wire screw is at an angle but is not a ground, not green.

The front of the switch looks like a standard two throw switch, one on top of the other in a horizontal throw position. Turn the top switch to the right and one circuit is on. Turn the bottom switch to the right and the other circuit is on.

Thanks, Bill

I'm not Jerry but that is not at all what you described in the first post!

You have two seperate single through switches! The question now is where did you come up with 240v?

Sounds like you have a combination switch. 1 switch is a single pole and the other is a three way.
You shouldn't have neutrals on a switch.
Are you reading 240 volts as you have 2 separate 120 volt circuits feeding that switch?
Pictures and more details will help


Just guessing here but could it be that you have a black feed and a blue feed on 1 side of the switch and a blue switch leg and 2 travelers on the other side of the switch.
Sounds like your 2 reds are travelers for a 3 way set up.

I will submit photos and voltage diagrams tomorrow.

I stated 5 poles because there are five wire connections on the back of the switch. There are no other switches in this area that control the lights.

More tomorrow.

Thanks, Bill

Based on the revised description I agree with Ken that this sounds like a combination switch with a single pole and a three way together.

If this is in metallic conduit that would provide the grounding.

Basic Electricity Tutorial - Switches
Try this link for clarification of switch "poles".
Sounds like we have a breakdown in terms if not knowledge.

Based on the revised description I agree with Ken that this sounds like a combination switch with a single pole and a three way together.

If this is in metallic conduit that would provide the grounding.


Jim,

I understand your explanation. I do not know how to correctly explain the connection points other than what I have already stated. I have never seen this type of switch. Keep in mind, it is probably over 30 years old.

When I measure voltages diagonally I get 20 and 40 volts,which leads me to believe their are resistors in the switch. Voltage on some circuits measure 240 volts when switched on and 120 volts when off. This is the strangest thing I have ever observed.

Again, more later after can photo the switch and make some circuit and voltage diagrams.

Thanks, Bill

Gentlemen,

Please keep in mind there is one 240 volt feed into the switch. 120 volts goes to the lights. Simple enough? The switch connects 120 volts to the lights and with the 240 volt feed, there is ample amperage to supply current to meet the demand of the eight incandescent and one flourescent fixtures. Makes sense to me, but I have never seen this type of switch.

I will provide more info tomorrow so we can all learn from this experience. My post is to offer assistance for these types of observations, and learn as well.

Bill

William,

Eagerly awaiting additional information photos, and drawings.

Some of the above posts are what I was thinking of with your newer description, but your 240 volts threw it all off kilter ...

BUT ... ... I DO have a guess as to what you have with 240 volts present and 120 volts to the lights ... but ... I will wait and see if anyone else comes up with it. And, of course, wait for your drawings and photos.

c s p t w s o m w c w b o s y

Frankly I think you're in way over your head. The total load here as you've described it is 7 or 8 AMPs.

There's no reason to run 240 volts to a general lighting load like this and I suspect there's probably just 2 different hot legs present at the switch that give you the measurement. If no white wires are present in the box then you most likely simply have 2 switches (one single pole and one 3 way), 2 hot wires, one set of travelers, and a switch leg. The odd voltages you read are probably induced voltage and most likely not related to anything the switch does or has inside. As to the switch being 30 years old, I can still buy what I think it is at any supply house. The bigger wire is likely a result of somebody not having the right stuff on the truck when the work was being done.

Measuring voltages from each wire to the box SHOULD give a better indication of what's there (the wire colors tell me it's a conduit wired circuit and old enough it is probably all metal. Assuming the conduit is intact voltages to the box will be close to hot-neutral voltage)

What you describe isn't uncommon but what you relate about it indicates a complete lack of knowledge. Hate to be blunt but this is the kind of stuff that gets people dead. I'd be happy (and VERY relieved) if you can provide info to prove me wrong.

Originally Posted by Jerry Peck

c s p t w s o m w c w b o s y

combination
single pole
three way
switch
on
multi wire circuit
with
both
on
same
yoke

That would have 240 volts at the switches when measured between circuit hots, yet each switched load is only 120 volts.

Gee - isn't that what I posted about 2 1/2 hours prior to your "lets see if anyone else can get it" remark?

Originally Posted by ken horak

Are you reading 240 volts as you have 2 separate 120 volt circuits feeding that switch?

Originally Posted by ken horak

Gee - isn't that what I posted about 2 1/2 hours prior to your "lets see if anyone else can get it" remark?

Nope. (And you should know that.)

You stated "2 separate 120 volt circuits feeding that switch".

I stated "multiwire" circuit.

NOT the same thing.

a multiwire circuit IS 2 different circuit with a common neutral.
Thus it's 2 separate 120 volt circuits. I did not say if it was a multiwire or not.

So you should know not to assume

Originally Posted by ken horak

a multiwire circuit IS 2 different circuit with a common neutral.
Thus it's 2 separate 120 volt circuits. I did not say if it was a multiwire or not.

No a multiwire circuit is ... drum roll ... a multiwire circuit, it is *not* "2 different circuits - BECAUSE OF the common neutral.

From the 2008 NEC. (and you should know this stuff Ken, Wannabe Jim would be doubtful)
Branch Circuit, Multiwire. A branch circuit that consists of two or more ungrounded conductors that have a voltage between them, and a grounded conductor that has equal voltage between it and each ungrounded conductor of the circuit and that is connected to the neutral or grounded conductor of the system.

Notice that even the NEC defines a multiwire circuit (wait, there it is again ... "a" multiwire circuit) as " *A* branch *circuit* ", note the singular reference. "that consists of", again, note the singular refer to "A" "circuit" (singular) "that consists of" ... "two or more ungrounded conductors ... "

Ken, a multiwire circuit is "a" "circuit" meaning *one circuit*.

It is not 2 different circuits.

I would expect more from you. I would expect no less from Wannabe Jim.

Jerry,

Is your ego so small that you feel you must take a shot at people everytime someone disagrees or challenges your opinion? What does this really get you? How does it add to the professionalism of this board or the HI field?

Disagreement is natural and healthy if something is learned from it. You just make it a mean spirited game hoping to demean anyone that does not share your same views.

You have grown old. Now maybe you should grow up.

Originally Posted by Jim Port

take a shot at people everytime someone disagrees or challenges your opinion?

Jim,

Only those few, maybe one or two, you being one, who ONLY posts shots at me.

I find it hard to recall ANY post you posted with useful information.

I know you have, as we've had this discussion before and you started posting useful and helpful information ... for a very short while, then it was back to your old ways.

I think you need to look in the mirror and examine just who you are and why you post, and why you do not post useful and helpful information.

Kind of like Watson, only you are even worse.

Watson simply cannot bring himself to post useful information without first degrading someone in the post in an effort to help build himself up. He will stay away a while, come back, made a couple of posts which appear to be helpful, then he can no longer control himself and his ways and he goes back to making posts which first must take a shot at someone.

You, with RARE exceptions, do not even attempt to provide useful and helpful information, you are so intent as taking shots at me that it is all you do.

Thus, that is all I expect you to do. And that is how I respond to you. And you are so weak in your knowledge that you only repeat hearsay and do not even know what it should apply to, so you post it as though it was related to something to which it is not even applicable.

Ken, on the other hand, actually knows stuff, I've seen it, he just does not know it all and is wrong at times, just like we all are, just like I am, only Ken does not admit it, he just hopes it goes away and no one thinks about it.

Me? Show me I am wrong and I say so, have many times before, will many times again.

But say something which is wrong when trying to correct me, and which most of the country does what I am saying, and you will not prove me wrong, you will only show that I am right and think like most of the AHJ around the country.

Some guys work in AHJ areas where the AHJ either: a) knows nothing; or b) knows but does not care. Those are likely the AHJ types which are still operating off the 1984 NEC and have never adopted a newer code (yes, there are still a couple of AHJ out there which are still using the 1984 NEC).

Other guys work in AHJ areas where the AHJ is always trying to improve and keep up with ever changing codes. I try to be like them - not stuck in a rut and always trying to learn.

Ken Horak, Jim Port and Bill Kreigh had the correct answer. This is a single pole switch on top and a three way switch on the bottom. Ground is via metal conduit.

There were two situations that I could not understand. There are two separate phase leads into the box. This caused the 240 volt phase to phase voltage reading.

A wall containing the other three way switch was removed, and this switch was deactivated. I discovered this today.

After checking all leads to ground, they all checked out at 120 volts. Two leads and two neutrals. The transfer line to the inactive three way switch was closed.

Thanks for all of your responses.

Bill Galbraith

edited as William was posting as I was writing and he answered my question

Originally Posted by William Galbraith

Two leads and two neutrals.

(underlining is mine)
Thus, as Ken said "you have 2 separate 120 volt circuits feeding that switch".

Dang, Ken, you must have posted only a second before I did. Cool.

I guess it all comes down to who has the faster internet connection at that second.

As far as multiwire circuits-
Now that you need to install them on a common trip circuit breaker - they would be considered "1 circuit" as they are controlled by "one circuit breaker"

Prior to needing to install on a common trip circuit breaker one can state they are 2 circuits as they are controlled by 2 separate circuit breakers.

I would say that due to this WE BOTH were correct - scary huh ?
Then again I may be totally wrong as this is my opinion

There are two breakers, one for the flourescent with other outlets, and another for the incandescents.