Help Wiring Magnetic Starter & Pressure Switch

[xJAMx]

I'm in the process of wiring my 80gal 5HP Single Phase(230v~23amps Motor) compressor and need help. I've never wired a magnetic starter and pressure switch.

Q's:

What size breaker and wire size do you recommend? I was told #8 Romex NM-B or #10 THHN(in conduit)

The Baldor motor has 4 wires(See pics below): yello, red, blue, and black. Do I need 2 or 3 wire(w/gorund) running from breaker?

Final question, how do I wire the whole thing up? I posted pictures below and if anyone is willing to help me step-by-step through this process it will be greatly appreciated.

View:

5HP Baldor Motor(230v~23amps)

Square D Magnetic Starter

Square D Pressure Switch

Magnetic Starter Diagram

Pressure Switch Diagram

 

[wyliesdiesels]

Can u post a pic of the motor nameplate as well? That should have motor lead wiring diagram.

The wire sizes u were given are correct. Motor circuit wiring is sized @ 125% of NEC table FLC (28a for 5HP).

U could try a 30a breaker and if u suffer nuissance trips increase to 40a.

It will Need to be hardwired unless u use a plug and outlet rated for at least 5hp which are very expensive.

How far away is the breaker panel and is it in sight?

U will need a disconnect if farther than 50' and not within sight.

Take 1 #14 or #12 wire from L1 and go to one lug on PS. Take another wire from corresponding switched lug on PS and go to X2.

Looks like other side of coil is already wired up.

 

[md21722]

The motor wiring diagram would be helpful to validate. This looks like an existing motor with two leads taped together. If the numbers on the leads match the motor nameplate, then yellow/red and blue/black are your two lines, plus a third with it terminating under the ground screw. These three wires all go to the motor starter. Inside the motor starter, the two motor wires go to the bottom 2 lugs. The ground should be wired to the incoming ground. Power in goes to the top two lugs.

For the coil, you need to duplicate the existing top red wires on the opposite sides, creating a mirror image. The difference is that whereas the red whites connect to the overload switch inside the relay, your two new wires will go to the pressure switch. That means 2 spade connectors, one going to 1L1 (just like is on 3L2.) This wire from 1L1 will go to the left screw on the pressure switch, The 2nd left screw on the pressure switch shall go to the bottom right spade of the magnetic starter completing the 2nd leg of the power circuit for the coil. You can get away with stuffing wires under screws, but the spade connectors clean it up. You can then tie the grounds together and fire it up.

Because of the vibration involved I would use stranded wire between the pressure switch and magnetic starter and the magnetic starter and wall. The wiring for the coil and pressure switch can be smaller gauge because they are only powering the coil.

 

[Norcal]

In addition, the heater coil (thermal element) is missing if you do not have it, one will have to be found, the starter will not function without it, as a SQ D overload relay will not reset if a heater is not in place.

 

[wyliesdiesels]

In addition, the heater coil (thermal element) is missing if you do not have it, one will have to be found, the starter will not function without it, as a SQ D overload relay will not reset if a heater is not in place.

The diagram shows only 1 heater coil....

 

[md21722]

It should be in a box that me with the unit, OP hasn't installed it yet.

 

[Norcal]

The diagram shows only 1 heater coil....

And it is not there...

 

[xJAMx]

And it is not there...

I have the heater coil, just haven't installed it yet.

I'm a little confused about the pressure switch wiring. So, I take my wire from 1L1 and connect it to L1 on the PS. and here's where I'm confused - Do I connect my second wire from T1 on the pressure switch and run it to X2 on mag starter? I'm not sure exactly where the physical connection for X2 is on the magnetic starter.

Here's a the wiring diagram for my motor, there was no diagram on the motor so I pulled this from Baldor's website

 

[md21722]

Take from 1L1 (left side, line in) (opposite the existing red flag spade connector), and connect it to the left most terminal on the pressure switch. Take the 2nd left terminal on the pressure switch and connect it to the lower right contact of the coil. There is a small screw terminal there, or use a spade terminal. The overload heater goes with he letter/number facing up.

 

[md21722]

The motor is wired for opposite (CW) rotation.

The pump may required standard (CCW) rotation.

When powered, if air does not blow across the pump, you'll need to switch the motor leads around to blue,red and yellow,black.

 

[xJAMx]

Ok, I will post pics when I get home of the completed wiring before I start the compressor.

I will switch the wires to proper CCW roatation. I looked up the manual for this pump and it requires CCW rotation.

To be sure, do I run a single wire from each of the two wires tied together in the motor? and do I just run a ground wire from the blue screw in the motor(see pic) to the grounds in the starter?

 

[md21722]

ok, i will post pics when i get home of the completed wiring before i start the compressor.

I will switch the wires to proper ccw roatation. I looked up the manual for this pump and it requires ccw rotation.

To be sure, do i run a single wire from each of the two wires tied together in the motor? yes and do i just run a ground wire from the blue it's green, but yes screw in the motor(see pic) to the grounds in the starter yes

That should do it. If you want to do the starter first before changing the motor wiring that is fine, it won't hurt the pump to run backwards for a test run. Some people run them backwards unknowingly for years. The pump internals do not care, it is not like a car with a camshaft and all that. Its only for the flywheel cooling that this is important.

 

[wyliesdiesels]

And it is not there...

On my tiny little phone's screen i thought i saw it.

 

[Norcal]

On my tiny little phone's screen i thought i saw it.

Am using a iPhone 5 ATM. At least the OP has the heater coil though.

 

[xJAMx]

Im at homedepot right now, will 10AWG primary wire be fine for wiring between mag starter, PS, & motor? Hopefully someones sees this while I'm here

 

[wyliesdiesels]

When u say primary wire do u mean building wire?

Primary wire is for automotive use.

I would use #14 for the PS and coil wiring. Doesnt need to be large as its only carrying the amperage of the coil.

For the starter to motor wire u should use #10 THWN.

 

[xJAMx]

Thanks wyliesdiesels

Take from 1L1 (left side, line in) (opposite the existing red flag spade connector), and connect it to the left most terminal on the pressure switch. Take the 2nd left terminal on the pressure switch and connect it to the lower right contact of the coil. There is a small screw terminal there, or use a spade terminal. The overload heater goes with he letter/number facing up.

Is this the bottom right terminal you are talking about. See yellow circle.

 

[md21722]

The other bottom? Circled is the overload switch contacts. Go diagonal to the top right, the terminal screw closest to your compressor. The screw will be about the same size as what is pictured.

 

[xJAMx]

Ok, I think I got it. One last question, does it matter what set of motor wires go to the left or right bottom terminals on the magnetic starter? Let me know if this is right. See below...

 

[matt_i]

If you wire the pressure switch to L1, L2 as I see pictured (labeled) above, you are going to blow a fuse, trip a breaker, have a small arc flash event as the contacts burn up or all of the above. That will short across the phases.

I've posted this a number of times but there are only 3 elements in the control side and they all go in series.

 

[md21722]

xJAMx,

What you have pictured and circled is perfect.

The motor does not care what color the two hot wires are or if they are flipped.

The overload heater still needs to be installed...

matt_i,

OP has a 230V coil Square D magnetic starter. What's he's got pictured is how they're wired. Note that in the starter, the coil terminals are not connected to the big lugs up top.

 

[-Brent-]

Those pictures will help lots of folks in the future.

 

[xJAMx]

If you wire the pressure switch to L1, L2 as I see pictured (labeled) above, you are going to blow a fuse, trip a breaker, have a small arc flash event as the contacts burn up or all of the above. That will short across the phases.

I've posted this a number of times but there are only 3 elements in the control side and they all go in series.

If its not right, where is the PS supposed to be wired to?

 

[md21722]

Matt is probably not familiar with the terminal connections on this starter. Nothing is going to arc.bl. I have 2 in my shop.

 

[xJAMx]

Cool! I will wire it up later this evening and will let you know how it goes. Thank you everyone for all your help. Hope this thread helps others.

 

[matt_i]

Just so I'm not crazy...

is functionally identical to this.



Follow either diagram and it will work

I can't see if the L1 and L2 on the top of the starter are jumpered to the A1, A2 coil terminals...those may already be in place for you as a connection that's not a wire.

This is where the labelling breaks down as I interpret it. One of (starter L1, starter L2) would be correct but the other terminal has to wire to either the pressure switch or coil.

 

[wyliesdiesels]

If you wire the pressure switch to L1, L2 as I see pictured (labeled) above, you are going to blow a fuse, trip a breaker, have a small arc flash event as the contacts burn up or all of the above. That will short across the phases.

I've posted this a number of times but there are only 3 elements in the control side and they all go in series.

Look a little closer at the pics. The overload relay is connecting L2 to the left side coil terminal.

The Pressure switch will then connect L1 to the right side coil terminal as he circled.

Nothing will arc or blow.

The coil terminals are on top behind the line terminals.

 

[md21722]

Not saying you're crazy, we aren't going to get into that in this forum, just seems unintuitive to brake the circuit Square D installed for the O/L when you also need to install the other hot leg of the coil. Might as well install it with the pressure switch so there are switches on both legs, X2 to L1 in this case as indicated in the picture. An Eaton starter is likely different. The compressor shops I talked to prefer the Square D, said older design, and more reliable. For on/off switch, use a pressure switch that has one, or drill a hole and put one in the mag starter housing, inline with the PS switching side.

 

[xJAMx]

Question, I noticed that the wires coming from the motor are XLPE and if you look at the picture the wires look aluminum. Is XLPE tinned copper? I want to make sure before I connect it to copper THHN.

 

[Norcal]

Question, I noticed that the wires coming from the motor are XLPE and if you look at the picture the wires look aluminum. Is XLPE tinned copper? I want to make sure before I connect it to copper THHN.

It's plated copper, fine stranded aluminum that small would be prone to break also.

 

[alfredeneuman]

To add to Norcal's post.....
XLPE refers to the insulation = Cross Linked Polyethylene

 

[Lonstar]

Those pictures will help lots of folks in the future.

Helped me. I was going to wire the pressure switch to L1 and a lower left terminal on the coil before I read this.
Thanks guys