Square D lighting contactor wiring diagram

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I am trying to trouble shoot a Square D 8 pole lighting contactor. Mechanically held, the part # on the face of it is 9998 LH44 0103. It is controlled by two 24 volt momentary contact SPDT (three way) switches, through two ice cube relays. The lights mysteriously stayed on recently, and won't turn off. I can make the contactor switch from on to off by jumping across the latch and 120v terminals on the base of the ice cube relays. I have replaced the relays, but can only get one to work. I am embarrassed to say, but I have very little to no experience in these, and how to trouble shoot them. This is for an important customer. Any suggestions, or ideas on where to go for instructions on trouble shooting would be GREATLY appreciated.

PS. I tried to attach pictures, but not sure if that worked.
 

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GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
What sort of control input is normally used to switch the contactor state? Push buttons? Timer?

Rather than just jumping terminals on the relays I would be inclined to do continuity and voltage checks on the various control wires first.
You could have an open or short circuit in the wiring rather than a problem with the relays.
 

James L

Senior Member
Location
Kansas Cty, Mo, USA
Occupation
Electrician
I think your description of the switching needs help.

SPDT is single pole, double throw...which is not 3-way. Momentary contact is either normally open or normally closed,

can you start over?

what kind of lighting, and what are the switches supposed to make the lights do?
 

kwired

Electron manager
Location
NE Nebraska
I think your description of the switching needs help.

SPDT is single pole, double throw...which is not 3-way. Momentary contact is either normally open or normally closed,

can you start over?

what kind of lighting, and what are the switches supposed to make the lights do?

I agree more details would be a big help, but a three way switch is a SPDT device, it has a common terminal that closes to one or the other terminal depending on the position of the operating handle.
 

James L

Senior Member
Location
Kansas Cty, Mo, USA
Occupation
Electrician
I agree more details would be a big help, but a three way switch is a SPDT device, it has a common terminal that closes to one or the other terminal depending on the position of the operating handle.
Thanks. I'll have to take better care with those knee-jerk responses

:)
 

sii

Senior Member
Location
Nebraska
I must be spoiled by working mostly on industrial machinery but the lack of wire numbers/labels is very disturbing to me.
 

GrayHair

Senior Member
Location
Nashville, TN
The job was for several low voltage systems in an old multi-story building. Lead installer went on vacation leaving very detailed instructions for his relatively new helper.
  1. Number all cables you pull
  2. Sleeve and fire caulk all penetrations
  3. Pull cables as listed
  4. Test conductors for shorts and grounds
  5. etc
The helper followed his instructions to the letter and the lead was happy; until he started terminating. All cables pulled while he was gone were numbered 23. :lol:
 
Yes, the switches are spring loaded, momentary contact, NO.
YES, I was dismayed when I first started to try to trouble shoot this, with no # tags, all red wires etc.

What other details? I tried to post other pix in the original post, but either I don't know how to do this, or that is not an option, I will include more here now.

This has two remote switches as previously described, wired in thermostat wire, red, blue, and white as the common, they are using the NEG side off the 24V transformer for the switching. To eliminate any other issues, I removed one switch and took it into the equipment room, wired directly to the strip below. At that point I observed the ice cube relay on the right responding to the switch, but not the relay on the left. I don't have my notes with me right now, and forget if the latch or un latch was on the right. The problem seems to be 120 volt through one of the relays to the latch side is on all the time. When I disconnect the voltage source, and tough the un latch, it DOES switch the lights off.
 
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mgookin

Senior Member
Location
Fort Myers, FL
Trying to understand from what you've said so far, correct me if I'm wrong.

You have a momentary push button switch (NO) which upon pressing sends power to the control side of an ice cube relay. The load side of the ice cube relay sends a control signal to a latching contactor for the duration that the momentary push button switch is pressed. Am I correct so far?

And it worked fine until shortly before you were called and nobody else was in there doing anything? (you're not the second guy they called because the first guy couldn't fix it?)

And you've replaced both ice cube relays. Right?

I'm guessing the momentary push button switch is remote to the ice cubes & contactor. Having a 2nd person press that switch and being in radio communication seems in order while you check voltages (because you said in the OP that you can manually short the relay load side and shut lights off).
 
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Trying to understand from what you've said so far, correct me if I'm wrong.

You have a momentary push button switch (NO) which upon pressing sends power to the control side of an ice cube relay. The load side of the ice cube relay sends a control signal to a latching contactor for the duration that the momentary push button switch is pressed. Am I correct so far?

Yes that sounds right. Technicality, but the switch is not a push button, but a momentary toggle, looks just like a three way, and acts like a three way SPDT. I am assuming somebody got there before me because there was a short piece of 12 stranded inside the box with the ends stripped, and bent perfectly to jump the 120 V to the switch leg side of the ice cube base. What I don't know is what else may have been changed, and I don't have any background with these.

And it worked fine until shortly before you were called and nobody else was in there doing anything? (you're not the second guy they called because the first guy couldn't fix it?)

And you've replaced both ice cube relays. Right? Yes

I'm guessing the momentary push button switch is remote to the ice cubes & contactor. Having a 2nd person press that switch and being in radio communication seems in order while you check voltages (because you said in the OP that you can manually short the relay load side and shut lights off).
Yes, did that
 

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
151027-1621 EDT

Wire 2 Race:

I believe that you need to develop troubleshooting skills. You need knowledge on how the components in your circuit work. Then you probe and test separate points in the circuit.

Consider a simple 5 tube radio. Symptom --- radio does not work. There may be 100 components in the radio. To sit on the outside and try to guess what one or more components failed is an impossible task. You start this task in the following way. Is power getting to the radio? Simply this may be determined by looking for lighted tube filaments or a pilot light. If any are lighted, then check that all are lighted. Next inject some signal into the final power amplifier. Do you hear the signal from the speaker. If so, then inject signals at various points working toward the first input stage. And so on.

In your problem. I will assume the contactor has two coils --- one a set coil and the other a reset coil. These likely can not be continuously excited without overheating. Thus, the system logic must provided a pulse to the appropriate coil and not a continuous signal.

Determine what is the rated coil voltage. Measure for any voltage at either coil. There should be none. Assume the "ice cube" relays supply voltage to the contactor coils. You can circuit trace this. If the assumption is correct, then pull both relays. Using an approiate voltage apply voltage to one contactor coil at a time and see if the contactor operates as it should. If it does not, then solve the contactor problem.

If the contactor works, then reinsert the "ice cube" relays. Determine what is the rated coil voltage for the "ice cube" relays. Is this AC or DC? Is there any voltage to either relay. Assume no, then from an input switch can you produce voltage at a relay coil. If no, then find out why not. If, yes do you get voltage from the relay to the contactor coil. If no, solve that problem. If first low voltage relay circuit seems to work, then do the same tests on the second low voltage relay circuit.

.
 
Thank you Gar, I am working on my trouble shooting skills, especially with a 5 tube radio.

I think I mentioned in a previous post, I do not have experience with the ice cube relays, that is why I came on here, looking for help. Also, that I have turned the contactor on and off by jumping 120 volt across the line side terminals of the relays. There is no wiring diagram as part of this installation. Maybe I should have gone to Square D first? I thought maybe someone on here who does these all the time might be able to point me in the right direction.
 

jumper

Senior Member
Thank you Gar, I am working on my trouble shooting skills, especially with a 5 tube radio.

I think I mentioned in a previous post, I do not have experience with the ice cube relays, that is why I came on here, looking for help. Also, that I have turned the contactor on and off by jumping 120 volt across the line side terminals of the relays. There is no wiring diagram as part of this installation. Maybe I should have gone to Square D first? I thought maybe someone on here who does these all the time might be able to point me in the right direction.

Do you understand how they work? Many have both NC and NO contacts.
 

Smart $

Esteemed Member
Location
Ohio
In theory yes, but, I do not know how the low voltage side of these work.
Just like any other relay and most general purpose contactors. The [electromagnetic] coil is energized, and the magnetic force pulls the yoke of the contact(s), either making a N.O. set, breaking an N.C. set, or changing the state of a D.T. (double throw) set. The latter is the most common in ice cube relays.
 
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hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
Looks like the contactor coils are 120vac so those auxiliary relays are just there to allow LV (24vac) control. What I'm seeing is that there are five 18ga wires coming into that terminal block. Do three (R,B,W) go to the SPDT center off switch and are the other two 24v from a transformer? Looks like the white is the common and the red and blue go to the coils. Thing is the other side of the coils goes to an unused terminal then off someplace I can't see.

Should be a simple matter to draw a schematic, the relay information is right on the covers. Unfortunately we can't follow the wiring from picture to picture.

-Hal
 
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