Dannmar Two Post Lift Wiring

[racer8432955]

Hello All. I would like to fully understand making the final electrical connections on my newly installed Dannmar Two Post Lift.
My goals are in some sort of order are:
1. Learn something
2. Get in Working
3. Not burn up something or myself.

I drew up this diagram (first image) after studying others and reading thru similar posts on other lifts, such as Bend Pak, which mine is a copy of... Included in the lift is a 4 conductor cord (R,BLK,GRN,WHT). I understand that are just colors, you could use any two (mark properly). This is shown in the diagram as being used to wire in the switch. If i understand correctly, the Normally Closed switch that shuts lift off from crushing your car, cuts off power to one of 240v power feed lines?
What confuses me is the manual appears to show wiring going back to the contactor (see second image)? The third image shows my contactor as wired from factory. I'm not even going to begin to pretend to understand that...
The forth image shows a diagram that is inside power unit. But as I read it, this does not include wiring detail for upper NC cut-off switch.
What further confuses me is while the installers were putting it in they ran it, to get the cables adjusted, etc, off of a 120v "jumper wire" by pushing in a button on top of the contactor. He said you can do this without the weight of the car on it. If this is the case, wouldn't only cutting off one of the 240v power feeds be the same thing?
Are contactors black magic? Please help me understand and let me know if my wiring diagram is correct.
Thanks!
View media item 92030View media item 92031View media item 92032View media item 92033

 

[racer8432955]

Had to add images

 

[mm08822]

Hello All. I would like to fully understand making the final electrical connections on my newly installed Dannmar Two Post Lift.
My goals are in some sort of order are:
1. Learn something
2. Get in Working
3. Not burn up something or myself.

I drew up this diagram (first image) after studying others and reading thru similar posts on other lifts, such as Bend Pak, which mine is a copy of... Included in the lift is a 4 conductor cord (R,BLK,GRN,WHT). I understand that are just colors, you could use any two (mark properly). Use blk and red since they are both hot, green for ground, white not used.
This is shown in the diagram as being used to wire in the switch. If i understand correctly, the Normally Closed switch that shuts lift off from crushing your car, cuts off power to one of 240v power feed lines? That is correct. It is done this way so if the contactor sticks or welds closed, the limit switch will open the motor circuit. It’s a backup to the contactor and the pushbutton.
What confuses me is the manual appears to show wiring going back to the contactor (see second image)?
The third image shows my contactor as wired from factory. I'm not even going to begin to pretend to understand that...3rd and 4th image are the same.
The forth image shows a diagram that is inside power unit. But as I read it, this does not include wiring detail for upper NC cut-off switch. That is correct.
What further confuses me is while the installers were putting it in they ran it, to get the cables adjusted, etc, off of a 120v "jumper wire" by pushing in a button on top of the contactor. Pushing in the contactor manually by hand eliminates the need for the control circuit to the contactor coil. Not sure what “120v jumper” you are referring to. Circuit looks complete in pic 3 matching w/d on cover.
He said you can do this without the weight of the car on it. If this is the case, wouldn't only cutting off one of the 240v power feeds be the same thing? The limit switch is a safety once hooked up. The contactor opens both conductors to the motor which is the proper method under normal conditions.
Are contactors black magic? No, but the wiring diagram in the manual is terrible – hard to follow with lines on top of each other, and connections poorly made. Unnecessary complexity - hard to follow stuff like: L2 of supply connected to L3 on contactor, L2 left of L1 on supply line, L2 and L3 of contactor used when the supply is labeled L1/L2. Electrically correct, but spins your head 720. The “UP” button completes the circuit to the 240vac coil. The coil pulls in the armature are the circuit is closed to the motor.
Also the w/d in the enclosure doesn’t match the w/d in the manual for the control circuit.
Please help me understand and let me know if my wiring diagram is correct.
Thanks!

Sorry but after seeing all that junk in the w/d, I made a quick one for you with a little more consistency.
Also notice in my w/d, I moved everything to L1/L2, T1/T2. I also used L3 on the contactor as a terminal point to be able to pickup the o/h microswitch cable from the existing j-box. This is different than your method interrupting the feed at the microswitch before the j-box. My way you can troubleshoot all from the j-box.

It would be interesting to know the rating of the "microswitch".

 

[racer8432955]

mm08822: Thank you very much for your detailed response. Just a couple more questions if i may. Please see blue text.

What further confuses me is while the installers were putting it in they ran it, to get the cables adjusted, etc, off of a 120v "jumper wire" by pushing in a button on top of the contactor. Pushing in the contactor manually by hand eliminates the need for the control circuit to the contactor coil. Not sure what “120v jumper” you are referring to. Circuit looks complete in pic 3 matching w/d on cover.

He said you can do this without the weight of the car on it. If this is the case, wouldn't only cutting off one of the 240v power feeds be the same thing? The limit switch is a safety once hooked up. The contactor opens both conductors to the motor which is the proper method under normal conditions.


What I called a jumper wire was a three prong plug, plug into existing 120v wall outlet. The ends were alligator clipped to the exiting blk, wht, grn coming out of the control unit on the lift. Since they were able to operate the lift on 120v, would cutting the feed of only one of the 240v lines not cut off power completely?

Sorry but after seeing all that junk in the w/d, I made a quick one for you with a little more consistency.
Also notice in my w/d, I moved everything to L1/L2, T1/T2. I also used L3 on the contactor as a terminal point to be able to pickup the o/h microswitch cable from the existing j-box. This is different than your method interrupting the feed at the microswitch before the j-box. My way you can troubleshoot all from the j-box.

It would be interesting to know the rating of the "microswitch".

Thank you for taking the time to draw up the w/d. Are you saying that either your / or my method of wiring will work? I guess this question hinges on the above about only cutting off one of 240v feed lines. Just curious.
Below is a pic of the NC Microswitch. In case the image is too small, it reads 25A / 125-250VAC Pilot Duty .
View media item 92057

 

[mm08822]

mm08822: Thank you very much for your detailed response. Just a couple more questions if i may. Please see blue text.

What further confuses me is while the installers were putting it in they ran it, to get the cables adjusted, etc, off of a 120v "jumper wire" by pushing in a button on top of the contactor. Pushing in the contactor manually by hand eliminates the need for the control circuit to the contactor coil. Not sure what “120v jumper” you are referring to. Circuit looks complete in pic 3 matching w/d on cover.

He said you can do this without the weight of the car on it. If this is the case, wouldn't only cutting off one of the 240v power feeds be the same thing? The limit switch is a safety once hooked up. The contactor opens both conductors to the motor which is the proper method under normal conditions.


What I called a jumper wire was a three prong plug, plug into existing 120v wall outlet. The ends were alligator clipped to the exiting blk, wht, grn coming out of the control unit on the lift. Since they were able to operate the lift on 120v, would cutting the feed of only one of the 240v lines not cut off power completely?

If I’m understanding correctly, they under voltaged the (208-230v) motor with 120vac and manually pushed in the contactor and the motor ran. Not the best practice but for a few seconds should be ok. Do not make a habit of that method and do not use the pushbutton when (if ever again) connected to 120vac. Opening either of the 240v lines will stop the lift. The requirement is to have all hot conductors disconnected simultaneously in standard operation. As I stated earlier, the microswitch opening one of the 240vac lines is only a failsafe – it is not the correct method to be used to for permanent control.

The 120v temp is a circuit between hot and neutral. The neutral is at the same potential as ground. There is a complete flow of electrons from hot to motor back to neutral. The grd does nothing during normal operating conditions.
In a 240v circuit each hot wire creates the total 240v difference. Each hot wire, if measured to ground = 120vac. Measuring across each hot wire = 240v. Your contactor and motor does not use the ground wire to operate. The ground wire is only for a safe return path of fault current. In 240v circuit (“two hots”), there is a complete flow of electrons from “L1” to motor and back through “L2”.

Easiest analogy I can think of: place 2 batteries in series with voltages additive. Call the junction of the two batteries neutral and ground. Across each battery measures 1.5v in magnitude. Across both bats measures 3v in magnitude. However the neg term of bat 1 is 1.5v below the junction and the voltage of the pos term of bat 2 is 1.5v above the junction. Think of the 1.5v’s as 120vac and the 3v as 240v. To get the 3v potential you don’t need any connection of the meter to the junction.


Sorry but after seeing all that junk in the w/d, I made a quick one for you with a little more consistency.
Also notice in my w/d, I moved everything to L1/L2, T1/T2. I also used L3 on the contactor as a terminal point to be able to pickup the o/h microswitch cable from the existing j-box. This is different than your method interrupting the feed at the microswitch before the j-box. My way you can troubleshoot all from the j-box.

It would be interesting to know the rating of the "microswitch".

Thank you for taking the time to draw up the w/d. Are you saying that either your / or my method of wiring will work? I guess this question hinges on the above about only cutting off one of 240v feed lines. Just curious.

As stated earlier, the contactor is used to open both hot wires so no voltage exists at the motor (relative to ground). This is the proper “off state” at the motor and required by code. The pushbutton energizes the contactor coil and that pulls in the contactor armature and the motor gets 240v to run b/c both hot wires are connected between motor and power supply.
For emergency back-up control (only), the microswitch gets tripped if the lift doesn’t turn off in time before sending the car through the roof. The motor will stop under load as the 240v circuit is opened.

Your method will work. However, executing it is difficult. Your method shows wires into microswitch and wires coming out of it. The switch only has provisions for one cable entry and no room to splice grd and neutral. My method brings 240v into the existing j-box on the lift. The 4 conductor cable is then used as a switch leg between j-box and microswitch. All connection points reside in the j-box and no other boxes required.


Below is a pic of the NC Microswitch. In case the image is too small, it reads 25A / 125-250VAC Pilot Duty .Microswitch should be ok.