# Hooking Up A Two Phase Switch



## Golden Arc (Apr 28, 2008)

Has anybody ever hooked up a two phase switch? 

We are hooking up an exhaust fan which is located on the roof with a tank located below in a class room so a science class can do experiments. The switch is located in the class room on the tank and it has a line 1, line 2 and a t1. Weve hooked it up every possible way and nothing works. There are two fans in two class rooms and the other fan we just took the switch out and put a regular single pole switch in and it worked. 

By the way the people that installed the thing took the manual with them.


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## Speedy Petey (Jan 10, 2007)

Tim, what is a "two phase switch"?


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## 480sparky (Sep 20, 2007)

Speedy Petey said:


> Tim, what is a "two phase switch"?


 
By his use of Line 1, Line 2 and T1, it sounds like it's a 3-way switch, only instead of sending one source of power over two terminals, it uses 2 terminals to toggle a load between two sources of power.

Tim, does the switch have an "On Off" or "O l" marks on it?


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## Lectritian (Nov 29, 2008)

? There is no such thing as a "2 Phase switch". You mean 2 pole? Line 1 and 2, power. T1 ground? I'm assuming the motor in the exhaust is 208/240 vac? Does the switch have 5 terminals? Our does it have 6 for ground? Need more info bud.


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## nap (Dec 26, 2007)

sounds like _maybe_ he has a manual motor starter.


Tim, give us the manuf and the model number of whatever it is you are using as a switch.

If anybody is wondering, this is what I suspect Tim may be talking about.










http://ecatalog.squared.com/pubs/Mo...e-Unit and Duplex, Type 2510F/1H385A_lres.jpg


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## calimurray (Apr 29, 2007)

yeah we use them all the time there double pole single throw switches , we use for disconnects and for lighting circuits.

Does it look like a four way switch but it says on and off the switch.


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## Golden Arc (Apr 28, 2008)

It has an on and an off. It looks like what is pictured, im not sure of the manufacturer i would have to look like I say the manual has disappeared. If its supposed to work like a three way switch this still doesn't explain why a single pole switch doesn't work when we replaced the other one. Like I say there were two and the other one we just swapped it with a single pole switch since theyre not going to be using all the other controls but the fan on the equipment and it worked fine. The single pole switch worked and its hooked up exactly like this one.


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## 480sparky (Sep 20, 2007)

What's the voltage you're switching?

If it has on/off on it, then it's not a three-way. Sounds more like a 2-pole switch, and you're controlling 208, 240 or 480 volts.


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## Golden Arc (Apr 28, 2008)

120. Yeah its not a toggle its either on or off no middle position.


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## 480sparky (Sep 20, 2007)

Tim Crimson said:


> 120. Yeah its not a toggle its either on or off no middle position.


So there's only two wires to connect? Then that's why a regular toggle switch worked..... you're doing the same thing a standard switch does for lights in a home....turning it on and off.

As to why you are using such an 'exotic' switch like the one you describe is beyond me. Unless that's all they had on the truck, so that's what was left for you.


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## nap (Dec 26, 2007)

480sparky said:


> As to why you are using such an 'exotic' switch like the one you describe is beyond me. Unless that's all they had on the truck, so that's what was left for you.


You're kidding, right? Seeing that this is a permanent install, there is to be overload protection so if it is not within the motor, the manual motor starter with overloads is required.

Tim did state it looks like the pic I provided. If so, I suspect the thermal is not installed or he may be not connecting it correctly. Here is a link that shows how these are connected. scroll to page 4. If yours is a 2 pole switch and you are runnning 120 volt, you would use the pic laleled: 2 pole. You do have to have the correct thermal unit though. The thermal mounts on the two screw_ holes_ (screws are with the thermal unit) on the left hand side of the switch in the pic

http://ecatalog.squared.com/pubs/Motor Control/Manual Starters and Switches/2510CT9701.pdf


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## 480sparky (Sep 20, 2007)

nap said:


> You're kidding, ....


Lessee.... 120v load. Switch marked 'On & Off' on it. Kinda sounds like a toggle switch, doesn't it? Tim says he put a standard toggle in, and it worked. 

No, not kidding.....


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## nap (Dec 26, 2007)

480sparky said:


> Lessee.... 120v load. Switch marked 'On & Off' on it. Kinda sounds like a toggle switch, doesn't it? Tim says he put a standard toggle in, and it worked.
> 
> No, not kidding.....


 
sure, it will work but it isn't right. He stated the pic I posted was what the electricians installed. I would suggest if they installed a near $100 manual motor starter, there was a reason for not installing the $2 toggle switch.

There be rules we follow and an overload on a motor be one of them.

Is there some reason you believe a starter with overloads is not required here?


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## Mountain Electrician (Jan 22, 2007)

Tim Crimson said:


> Has anybody ever hooked up a two phase switch?
> 
> We are hooking up an exhaust fan which is located on the roof with a tank located below in a class room so a science class can do experiments. The switch is located in the class room on the tank and it has a line 1, line 2 and a t1. Weve hooked it up every possible way and nothing works. There are two fans in two class rooms and the other fan we just took the switch out and put a regular single pole switch in and it worked.
> 
> By the way the people that installed the thing took the manual with them.


Sounds like you have a 1 pole manual starter w/o the overload installed. Maybe a toggle switch is fine, maybe not. Read NEC 430.32 which tells you about overcurrent protection for continuous duty motors.


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## 480sparky (Sep 20, 2007)

nap said:


> sure, it will work but it isn't right. He stated the pic I posted was what the electricians installed. I would suggest if they installed a near $100 manual motor starter, there was a reason for not installing the $2 toggle switch.
> 
> There be rules we follow and an overload on a motor be one of them.
> 
> Is there some reason you believe a starter with overloads is not required here?


 
Ok, for the record, it's an exhaust fan. Which kind is it? (since I don't see anywhere in the thread it's been revealed) Let me know which one it is:


*A:*









*B:*










*C:*


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## Golden Arc (Apr 28, 2008)

480sparky said:


> Ok, for the record, it's an exhaust fan. Which kind is it? (since I don't see anywhere in the thread it's been revealed) Let me know which one it is:
> 
> 
> *A:*
> ...



The type of exhaust fan is B although there is no switch or receptacle on the side like that one. We havent been able to fool with it in a couple of weeks because its in a class room where they are still conducting class. I believe ive told you wrong the switch we replaced it with was just a normal three way because I was thinking about it and there are two switches that control the fan one on each side. I might also add that they replaced the fan and it wasnt the motor.


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## nap (Dec 26, 2007)

code

over 1 hp;

requires one of the following.

seperate overload
thermanl protection
integral protection

under 1 hp if permanently installed 430.32 D- refers back to 430.32 B

under 430.32 B, one of the following

seperate overload
thermal protection
integral protection
impedance protected.

so, unless this is a little fart fan (which is impedance protected), which I doubt (and has been confirmed),since this is a school science classroom, it has to have protection. Unless it is internal, the motor starter I posted is what is typically used. Since the electricians did leave this much higher cost than a toggle style switch, I suggest it is wht is needed in this app.

Every school I have worked on used a mushroom style ex fan for the science classrooms so I was guessing this was the type of fan we were dealing with from the beginning where Tim said it was a science classroom.

So, with Tims last post, it appears that the room has two switch stations to control the fan. If this is the case, there is a bit of a problem because to do this, you would need a magnetic starter with the swithes as control switches. (presuming the overloads are needed in this app)


So Tim, it's up to you. You need to tell us if there is integral protection in this motor and if so, is it simply internal thermal protections or is it a thermal protection that runs the "P" labeled leads into the peckerhead. 

If the latter, you can use those and a magnetic starter or ignore them and use a system like the electricians left.

If there is simply internal thermal protection, you can get away with horsepower rated switches (switches used for this purpose MUST be HP rated for the motor being controlled. It will state it right on the switch if it is rated) and get rid of the unit the electricians left.

So, once we know something about the motor, we can work on the two station starting.


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## 220/221 (Sep 25, 2007)

> I suspect the thermal is not installed


 
Yeah...that^

Are there a couple of threaded open holes on the side of the switch :jester:


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## Unclejim725 (Dec 4, 2008)

Tim Crimson said:


> Has anybody ever hooked up a two phase switch?
> 
> We are hooking up an exhaust fan which is located on the roof with a tank located below in a class room so a science class can do experiments. The switch is located in the class room on the tank and it has a line 1, line 2 and a t1. Weve hooked it up every possible way and nothing works. There are two fans in two class rooms and the other fan we just took the switch out and put a regular single pole switch in and it worked.
> 
> By the way the people that installed the thing took the manual with them.


I ran into two-phase several years ago. An old time motor winder told me that two-phase is actually two different circuits, like two coils. One set of leads will have a different voltage than the other, and you should be able to ring the two "circuits." That's all I remember about it, and glad I forgot the rest!

Uncle Jim 725


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## Golden Arc (Apr 28, 2008)

nap said:


> code
> 
> over 1 hp;
> 
> ...



We kind of put this on the back burner so I cant really dont have time to go back and look at it for awhile. Not sure about the thermal protection, I believe the same set up was on the motor T1, T2, and P. I do remember it was multi tap 120/277. What would bet the neutral in this case P? Thats how we hooked it up.


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## nap (Dec 26, 2007)

the p leads are to a thermal cutout in the motor. You wire them in series with a magnetic starter so if the motor overheats, it will drop out the starter and the motor shuts down. There would be 2 of them.

to utilize this type of thermal overload , you would have to use a magnetic starter, not the type you have.

you wire a motor to the schematic on the motor. If it is a dual voltage motor, there would be more than 3 leads though.

when you get a chance, check it out and let us know.


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## Golden Arc (Apr 28, 2008)

nap said:


> the p leads are to a thermal cutout in the motor. You wire them in series with a magnetic starter so if the motor overheats, it will drop out the starter and the motor shuts down. There would be 2 of them.
> 
> to utilize this type of thermal overload , you would have to use a magnetic starter, not the type you have.
> 
> ...


Im pretty sure there was a T1 and a T2 and a P not sure about the P though but im certain there was nothing about a neutral on the schematic. Two other guys went back and tried to fix it today they said a neutral was loose somewhere back from the panel. Last I checked they were ohming it out and nothing was loose thus far.


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## nap (Dec 26, 2007)

On a schematic for a motor, it often simply lists the line side of the power as L1 and L2. They would attach to T1 and T2.


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## Golden Arc (Apr 28, 2008)

The guys that worked on it said it was a broke neutral going from the unit up to the fan on the roof. I knew it had to be something simple since the other one was hooked up the exact same way and it worked.


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