Compressor Start/Stop for an Eaton Magnetic Starter

[Pontiac787]

I want to add a start/stop switch to the mag starter on my Saylor-Beall VT-735. It’s got a 230v Baldor 5hp motor. The enclosure has a slot for the switch. Does anyone know if this is the correct part?

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I have an email out to SB but they haven’t gotten back to me on a question from a few weeks back.

As an alternative I may just wire a three way light switch in line with the pressure switch so I can turn the pump on from 2 different locations.

 

[Stuart in MN]

Go to https://www.eaton.com/us/en-us/skuPage.C400GK1.resources.html , from there scroll down to Catalog and click on that. The control switch kit on eBay is listed on page V10-T2-7. In the same catalog you then need to look up the part number on your motor starter, and then you should be able to figure out if that particular kit works with your particular starter.

If you have problems figuring it out, post the starter part number here so we know just which one it is.

 

[Norcal]

3-wire control like shown with the cover control kit does NOT work with compressors, no way for the compressor to start/stop to keep the tank filled, 2-wire control is what is required.

 

[alfredeneuman]

A 3 wire control would require you to push the start button every time you want the motor to start.

 

[Pontiac787]

Thanks for the link. The catalog is a little overwhelming. Here is what I’m working with…. The SB part number for the starter is 4587-c

Any help would be appreciated.

 

[Iron Beaver]

I want to add a start/stop switch to the mag starter on my Saylor-Beall VT-735. It’s got a 230v Baldor 5hp motor. The enclosure has a slot for the switch. Does anyone know if this is the correct part?

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Find many great new & used options and get the best deals for Cutler-Hammer C400GK1 Industrial Control System at the best online prices at eBay! Free shipping for many products!

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I have an email out to SB but they haven’t gotten back to me on a question from a few weeks back.

As an alternative I may just wire a three way light switch in line with the pressure switch so I can turn the pump on from 2 different locations.

Do yourself a favor and don't use a light switch to control an inductive load. I've been there, done that, and burned up way too many light switches.

 

[Norcal]

Do yourself a favor and don't use a light switch to control an inductive load. I've been there, done that, and burned up way too many light switches.

The switch it will only be handling the coil if wired correctly.

 

[Pontiac787]

Correct. It would be on the 120v wire from the pressure switch. Mag starter would be handling the load.

 

[alfredeneuman]

It would be on the 120v wire from the pressure switch. Mag starter would be handling the load.

The pressure switch is on a 240V circuit. It must be rated for the voltage.
Make sure you use a 120/277V rated switch. (that's all that's available in a residential type switch besides 120V only)

 

[SarcasticDwarf]

X

 

[wyliesdiesels]

3-wire control like shown with the cover control kit does NOT work with compressors, no way for the compressor to start/stop to keep the tank filled, 2-wire control is what is required.

So OP you need an "auto/off" switch not a start stop switch...

Do yourself a favor and don't use a light switch to control an inductive load. I've been there, done that, and burned up way too many light switches.

Did your inductive load have a mag starter? If not, then that's why you burned them up. The light switch should only be switching the coil load which is all of an amp or so @ 240v NOT the inductive load. Also, as said above, the switch needs to be rated for 240v(120v/277v is whats available for snap switches)....

 

[Iron Beaver]

True, but a coil in a magnetic starter is still an inductive load.

I burned mine up with a 1/4 horsepower induction motor. Don't know how long one would last on a motor starter coil, and it would likely be quite a while, but inductive load rated toggle switches are cheap

 

[wyliesdiesels]

The inductive part of the load is not the issue. the amperage and voltage is however.

but my guess is you wired it direct to the motor since it was so small.

lots of members on this forum have light switches switching their compressor starters for years and years with no issues.

 

[TRWham]

And a conventional fluorescent light is also an inductive load.

I think the 20 A/ 1 hp rated light switch on my compressor control circuit will handle the contactor coil load just fine.

 

[Pontiac787]

The pressure switch is on a 240V circuit. It must be rated for the voltage.
Make sure you use a 120/277V rated switch. (that's all that's available in a residential type switch besides 120V only)

According to SB there is 120 running to the switch. It's only 16 gauge wire.

 

[Norcal]

According to SB there is 120 running to the switch. It's only 16 gauge wire.

It’s control wiring that is why it does is 16 AWG unless the manufacturer supplied a control transformer you have line voltage control which I assume is 240V, you are breaking one leg of 240V.

 

[wyliesdiesels]

According to SB there is 120 running to the switch. It's only 16 gauge wire.

If the coil is rated for and running on 240v, then the switch will see 240v.

 

[Pontiac787]

How will the switch see 240 when only one leg is being used/broken? I’m genuinely asking.

 

[Terry D]

How will the switch see 240 when only one leg is being used/broken? I’m genuinely asking.

A 2 pole switch

 

[alfredeneuman]

A 2 pole switch

Huh? It doesn't have to break both legs if it's a control wire.
The photo of it shows it doesn't have enough room for a control transformer.
The coil sees the same voltage as the pressure switch and the control switch. 240V

 

[Bert_]

How will the switch see 240 when only one leg is being used/broken? I’m genuinely asking.

The pressure switch is also breaking only one line to the coil. With the power on and the tank full, go measure voltage across the terminals of the pressure switch. Don't measure to ground, the coil doesn't use the ground.

 

[Iron Beaver]

The inductive part of the load is not the issue. the amperage and voltage is however.

but my guess is you wired it direct to the motor since it was so small.

lots of members on this forum have light switches switching their compressor starters for years and years with no issues.

An inductive load is an issue, as it stores energy that causes arcing when a switch breaks contact. However, it seems like a small enough issue not to matter. A motor starter coil has miniscule inductance compared to a motor. I personally would still do the job with a toggle switch, but that's just me.

 

[TRWham]

How will the switch see 240 when only one leg is being used/broken? I’m genuinely asking.

Both lines are present at the coil. One side is wired to one leg, while the other side is wired through the switches (pressure and convenience) to the other leg. Only one leg must be broken to open the circuit.

 

[Pontiac787]

The part number I got from SB is C600M141A. Unfortunately, the stock photo on-line doesn’t match to the part so I can’t see what it actually looks like. Would other switches from the C600M1 line work? I found the following…

Eaton Switch

 

[engineer2]

Insert a switch in one of the wires between the pressure switch and the relay coil. Example is a Champion with an Eaton starter.

 

[Terry D]

The part number I got from SB is C600M141A. Unfortunately, the stock photo on-line doesn’t match to the part so I can’t see what it actually looks like. Would other switches from the C600M1 line work? I found the following…

Eaton Switch

Yes, this on/off switch will fit your starter enclosure

 

[66cj225]

It’s control wiring that is why it does is 16 AWG unless the manufacturer supplied a control transformer you have line voltage control which I assume is 240V, you are breaking one leg of 240V.

No, you are breaking the operation of the mag coil across the poles of the 240v. It conducts pole to pole, not pole to neutral, once again using the assumption of no control transformer.

 

[alfredeneuman]

If the switch wiring extends beyond starter enclosure you'll have to replace the #16 with #14.
NEC Table 430.72(B) covers that.