# Square D mag starter trouble



## lincoln9 (Dec 20, 2009)

I'm trying to hook up my square d mag starter 8911 with 120v coil to my compressor which is 7.5hp. My supply is only 2 wire 240v with ground no neutral. I know where the supply wires go on the starter and I know where the motor wires go on the starter but I can't figure out where to put the 2 pressure switch wires. 1 is marked line on the switch and one is marked motor. I will post pictures if needed and someone tells me how to post pictures here.

I have a feeling that I need a 240v coil and I told the guy that sold it to me that but he sold me a 120v model telling me it will work 100% for sure

Thanks for any help


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## rlc3854 (Dec 30, 2007)

Sorry friend this site is for professional electricians only. There is a DIY sister site that can help you. DIYTALK.com


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## nolabama (Oct 3, 2007)

Seriously Pro's only here. You have however made good sense of describing you problem. If you prove your in the 'lectrical trade to the mods you may get the help your looking for. 

BTW I do not know the answer.


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## nolabama (Oct 3, 2007)

Just for funsies you gotta have a photobucket account for pictures

upload the pic to photobucket and copy the img location and paste it in your response


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## John Valdes (May 17, 2007)

Since they have not closed this thread I will assume you are a professional and will understand what I am going to tell you?

The pressure switch is connected in series with the 120 volt coil. When the pressure switch closes, it sends power to the starter coil. The pressure switch holds the coil in until pressure reaches preset and then releases the coil.
You are going to possibly need a disconnect and a on/off switch too. There are several ways to wire this up. Each technician has his or her own way of doing things. Here is a drawing I have that one of my colleagues drew just last week for an air compressor. This was for his specific application. But, It should give you an example. This drawing shows a 240 volt coil, not a 120 volt coil. His circuit was 240 single phase. So to make things simple, he used a 240 volt coil.


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## jbfan (Jan 22, 2007)

Without a neutral, he can not use the 120 volt coil.
He needs a 240 coil or a neutral wire.


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## Speedy Petey (Jan 10, 2007)

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