Help...Seen a lot of threads reguarding air compressors but nothing about wiring for 220. I recently bought a used Dayton speedair compressor to replace my well worn and blowed up craftsman. It is a 2 hp that can run on 110/220. It currently has a two pole pressure switch that has the hot and neutral from the power cord on one side and another 14/2 cable with black and white wires going to the motor. Inside the motor wiring cavity, I have four spade connectors ( numbered 1,2,3,4 oddly enough) with two wires coming out of the motor labeled t2 and t3. The diagram on the motor label is vague but it show line on #1 and #4 and t2 and t3 on #3. I don't want to blow this thing up by switching wires around. I have all the numbers off the motor and compressor. Any ideas? Thanks....Shawn
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You should have 2 diagrams on the motor, one for high and one for low voltage. You want to follow the high voltage diagram.

The "line" they refer to (in 2 places) are your black and white wires coming from the switch. If you follow it exactly like the diagram it will work.

If you can post the diagram I could help further.

 

What model Speedair do you have, because I have an old 2HP, 20 gallon 110/220 volt Speedaire compressor.

 

The model number on the compressor is 3Z355. and the motor itself has a model number of 9K324. What I didn't understand about the diagram is that it currently is wired with a 20 amp 110 volt cord. The 110 cord goes into the pressure switch with black and white wires on one side of the switch and then has another cable wired the same way to the motor. The motor looks to be wired the same as the 220 diagram. The diagrams are as follows
110
4 Line
t2

3

2 t3

1 ungrounded side of line

220
4 Line

3 T2, T3

2

1 Line
What is confusing me is do I run one hot to number 1 and one to number 4? If so where does my neutral go? and what about the switch? Sorry to be so stupid but I really like to be sure with AC power. Hate to burn the house down.

 

It's hard to decipher your table from your posting. Maybe some tabbing/formatting got lost in the process of posting.

I will explain what you are trying to accomplish. Maybe with some idea of the theory involved you can figure out the diagrams.

For a single phase, dual voltage, capacitor start motor, the main winding is split into two halves, and 4 leads are brought out of the motor. These correspond to two sets of windings (coils) within the motor. Two of the wires (typically but not necessarily ) labeled T1,T2 are opposite ends of one coil. Two of the wires (typically lablled T3,T4) correspond to opposite ends of the other coil.

To operate the motor off 120 volts, the two coils are connected in parallel with each other. So, in this example, we could connect T1 and T3 to "HOT" and T2 and T4 to "neutral". Two wires run back to the pressure switch. It is sufficient to switch just the hot line, but it is acceptable to switch both hot and neutral.

To operate the motor off 240 volts, the two coils are connected in series with each other. So T1 is connected to L1 (one hot lead), T2 and T3 are connected to each other (and nothing else), and T4 is connected to L2 (the other hot lead). Two hot wires run back to the pressure switch. Both are switched by your two pole switch. In this arrangement, the neutral wire IS NOT USED AT ALL. Not on the motor, not in the pressure switch. It need not be in the cord going to the pressure switch, nor in the receptacle on the wall.

The start capacitor is often brought out into the motor junction box. This allows it to be wired to the proper terminals for starting, and allows for rotation to be reversed. This would create an additional pair of leads, for a total of 6 leads coming from the motor case to the junction block. It isn't clear exactly what you have.

Don't hook up anything based on the labels I gave above. You need to refer to the connection diagram. But maybe the diagram will make more sense to you, given my explanation.

 

woodzracer, Exactly what do you want to do? Run the compressor on 110 or 220?

I have the exact same compressor; same model; same motor.

The cord from the pressure cut-off switch to the motor should have 1-black wire;1-white wire and 1-green wire (ground).

THIS IS HOW MY COMPRESSOR IS WIRED FOR 220 VOLT.

The BLACK wire (from the cut-off switch) goes to terminal #1

The WHITE wire (from the cut-off switch) goes to terminal #4

Both #2 & #3 motor wires go to terminal #3

Terminal #2 should be empty.

NO MODIFICATIONS HAVE BEEN MADE TO MY COMPRESSOR, BECAUSE I'M THE ORIGINAL OWNER (1979)

SO THIS IS HOW MINE IS WIRED.

Don't forget to use the proper plug and outlet designed for your application.

Hope this helps.

 

sieraben;
Yes I am looking to run 220, and at the moment I have the unit hooked up to 110 using the 110 diagram, and if I understand it I should just be able to switch the motor leads and use the same cable from the swich to the motor, but how did you hook up 220 to the pressure switch. I am confused by three wires coming in(4 if you count the ground) and only two srews in the switch. Someone on another forum said I should hook the red and black hot leads from the breaker to the switch and not hook up the neutral, but I am sure that can't be right. Maybe I wasn't clear when I described it, but I wasn't sure if I could use that same cable from switch to motor or if that would have to be changed as well. If I am finally getting it, then that cable is ok and my question now is how do I connect the 10/3 cable from the subpanel breaker box to the switch? Thanks for letting your wisdom creep into my thick and distorted head. appreciate the help....Shawn

 

Are you saying that the power cord going to the pressure/cutoff switch has 3 wires not including the ground?

My power cord has only 2 conductors plus the ground. It's also the same type of power cord that goes between the pressure and motor. No need to change it because the amperage draw will be 1/2 that of 110 volt set-up.

If you're asking about the wires from the circuit breaker, I have 1 black and 1 red wire hooked up to my 220 volt.

No white (neutral) wire hooked up.

It sounds weird, but that's how it's set up.

Are you going to hard wire it (no plug invovled ) or install an outlet?

I'd use a proper 220 volt outlet and plug; so you can move the compressor around.

Also make sure that the circuit breaker is of the right amperage. Very important.

Let me know if this helps.

 

A 240 volt single phase compressor with pressure switch DOES NOT USE NEUTRAL. You do not need 10/3 wiring. 10/2 (with ground) wiring is enough.

If you are using a 4 wire 240 volt cord, as from an electric dryer, connect BLACK as L1, RED as L2, cap off and insulate the white neutral, and connect the green ground wire to the ground screw in the pressure switch. Wire the receptacle in the wall as if it were an electric dryer. You can hook up the neutral in the receptacle if you want to, but it isn't needed to operate the compressor.

If you use a 3 wire 240 volt cord (as from an older dryer or electric stove), connect BLACK to L1, (RED or WHITE -- depends on cord) to L2, and GREEN to ground.


Electric dryers do use the neutral in order to get 120 volts to operate the timer and the various relays and controls. Sometimes the drum motor uses the neutral (120volt motor), and sometimes the drum motor does not (240 volt motor) The heater coils do not use the neutral, connecting only to L1 and L2. Older electric dryers and ranges used the ground wire to get a neutral; this practice is no longer code compliant.

Your compressor does not have any controls other than the pressure switch, and the pressure switch is equally happy switching 120 volts or 240 volts, and couldn't care less about any neutral.

The compressor should have a plug and receptacle or at least a disconnect box within sight of the compressor, for servicing and safety sake.

 

All is correct-I just hope woodzracer uses the proper sized circuit breaker.

 

Hi all;

Sorry to doubt anyone but after further investigation (and learning something new for the day) you are right, no neutral wire needed. It seems all this time I have been under the assumption that all power was 110 and all you needed to do was hook two together to get 220. Therefore everything needed a neutral. I found out today that actually all 110 is just the last subdivision that can be made and because it is only truly single phase, it needs the neutral path. When there is 220 acting as two phase the neutral is not nessecary. Again sorry to doubt anyone, it just seemed to go against all i had ever heard so until I learned something new, It didn't make sense. And please rest assured that I am coming out of a subpanel with a 30 amp dedicated breaker for the compressor all running through 10 gauge wire. I went a little big in case I go to a larger compressor someday. Thanks to all for the help........Shawn

 

woodzracer, it sounds like a 30 amp breaker may be a bit on the high side.

I'm using a 2 pole 15 amp breaker with no problems.

I think the compressor uses 12 amps.

I'd ask an electrian what breaker he would use for your application.

Just my honest opinion.

 

In reading what Sierraben Has written, he is the one I would like to direct this question to. I Recieved a 3Z355 Speedaire in good shape except the guy that owed me money and gave this to me in payment, Broke off the plastic "T" that guage, pressure switch, shut off, all in one unit, that screws into the top of the tank. He did this by slamming the hatch of his wifes brand new Subaru SUV on it, needless to say after glass all over his driveway, and one pissed off wife, It finally got it here. My question is, I have no Idea what the max. pressure is for the pop off valve. Nothing written on it. I have new guage, all new piping, and new pressure switch set at 95/on...125/off. I want to put on the right safety air valve pop off in case of switch failure. I have all I could find of literature on this unit and need to know that parameters of the unit . Would a 150 PSI over load valve be ok? It is like new and has had very little neglect, I have the oil change sheet from the day it was new. Origonal owner meticulously took care of it. The guy that owed me money got it at an estate sale. I got the compressor as partial payment for a newly rebuilt 289 mustang engine I did for him that he already has in his ford pickup. Your my only hope on this , as I want to gove it to my brothers wife for her craft work and do NOT want to take any chances on pressure failure. Thanks for your help, Ed. (wrenchit1)

 

wrenchit1, I'm looking at both my compressor and manual and I don't see a safety pop-off valve.

I'm thinking that it maybe be part of that plastic T fitting (guage-switch-air valve) that screws on the top of the air tank.

It might be that hex shape fitting (with the hole in the middle of it) just before the air flow valve (opposite side of the shut-off valve ****).

EDIT: I just looked at the "replacement parts list" and they list that black plastic looking T fitting as a "SHUT-OFF & SAFETY VALVE".

So I think it's built into the black plastic T fitting; possibly that hex shaped fitting opposite the shut off valve I mentioned earlier.

Hope this helps.

 

Yes thats it exactly,, Nothing in your info as to the max ? I do know these are not to be self adjusted or you can wind up with a bomb waiting to explode if you adjust beyond the limits of the structural limits of the tank. Also in testing the pressure switch , I found that the switch was activating the off position at 113 LBS instead of the 125 as it was originally set to do, So I readjusted it to the setting as new- 125 PSI I am sure it due to weakness of ( the spring) old age as we all suffer. In taking the pop off valve out, I noticed a great amount of trash in the safety valve spring area, You might want to remove yours and clean it out and lightly oil it. (DO NOT LOOSEN THE LOCK NUT!) as this is the factory setting, just unscrew the whole valve as a unit, clean, oil, and use teflon tape to reinstall to guarentee against any air leaks. If I find any more info , I will be happy to let you know. Thank you so much for taking the time to assist me!, Ed.