# Air Comressor wiring question



## gunrunnerx (Dec 27, 2014)

I just picked up a really nice Porter Cable 60 gal compressor for the shop/garage.  In the owners manual it states that there should be an on/off switch between the main power and the pressure switch.  I've never heard of or seen this before.  It's a 3.7 HP 240v single phase 17.2 FLA.


Anyone heard of this?  What should I use for the switch?  It actually says it will void the warranty by not having one.


Thanks all.


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## darkzero (Dec 27, 2014)

You could use an eletrical disconnect box available at any hardware store. They're on the expensive side to be used just for this purpose. For my lathe & mill I used manual motor starter switches, sort of like a light switch but properly rated for power & cuts all the terminals.

I could be wrong but I think they recommend some sort of disconnect switch assuming the compressor is going to be hard wired. I used a plug & socket on my 60 gal  compressor with no additional switch.


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## Dman1114 (Dec 27, 2014)

Did u get it from Tractor Supply??? http://www.tractorsupply.com/en/store/porter-cablereg;-stationary-belt-drive-air-compressor-60-gal

They are pretty nice for the Money.... was checking them out the other day. i have a crappy 30 gal from home depot.   gotta upgrade soon....


anyhow a compressor like that should be hard wired.   So depending on how you have your wiring setup.    run power to a 4" box with a switch ( proper one for 240 v of course)  and then to your compressor.  

gotta have a way to shut off the power to the compressor....

something like this for a switch   http://www.homedepot.com/p/Leviton-...e-Toggle-Switch-White-R52-0CSB2-2WS/202027029.   screws right to the cover of a 4" steel box....  then run the power out of the box with a piece of BX or similar..  to your compressor.


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## JimDawson (Dec 27, 2014)

I just have mine wired to it's own dedicated breaker.  I use a number of my breakers as switches for lighting and service disconnects.


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## Terrywerm (Dec 28, 2014)

Mount an air conditioning disconnect box on the wall at the compressor, hard wire into it.  Under $20.   If you need something with a higher amp rating, they have similar disconnect switches in 50 amp rating for a few dollars more.


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## arvidj (Dec 28, 2014)

I uses a 30 amp dryer plug and outlet. This provides an easy way to disconnect the compressor when I work on it ... like change the oil, etc. ... and also allows me the ability to move the compressor when I need to get behind it ... like to sheet rock and paint the wall per the instructions provided by my wife.

The outlet is on a circuit dedicated to the compressor so in that sense it is "hard wired", just the wiring can be easily separated when it needs to be.

Those that are suggesting it be hard wired ... is there a reason to *not* use a plug and outlet? Note that I am not suggesting that it *must* be on a plug and outlet, just wondering what the down side is of the plug and outlet.


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## Terrywerm (Dec 28, 2014)

Nothing wrong with using a plug and outlet at all. Simple, inexpensive, and effective.


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## rmack898 (Dec 28, 2014)

JimDawson said:


> I just have mine wired to it's own dedicated breaker.




This works for me too. I only shut off the compressor when I will be away from the shop for a few days or more.


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## John Hasler (Dec 28, 2014)

arvidj said:


> I uses a 30 amp dryer plug and outlet. This provides an easy way to disconnect the compressor when I work on it ... like change the oil, etc. ... and also allows me the ability to move the compressor when I need to get behind it ... like to sheet rock and paint the wall per the instructions provided by my wife.
> 
> The outlet is on a circuit dedicated to the compressor so in that sense it is "hard wired", just the wiring can be easily separated when it needs to be.
> 
> Those that are suggesting it be hard wired ... is there a reason to *not* use a plug and outlet? Note that I am not suggesting that it *must* be on a plug and outlet, just wondering what the down side is of the plug and outlet.



There isn't any.


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## Eddyde (Dec 28, 2014)

According to the national electrical code; there must be a means of disconnect within 5 feet of an installed machine or appliance. It could be a switch, circuit breaker, fuse box w/switch, or plug and receptacle (of correct amperage). If the load is in the 200v range, that is, using two phases (hot lines), then the switch must be double pole.


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## arvidj (Dec 28, 2014)

Eddyde said:


> ... that is, using two phases (hot lines), then the switch must be double pole.



I think it is split-phase ... single phase with neutral grounded ... not two phase, and you are correct, it will require a double pole switch.


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## Fabrickator (Dec 28, 2014)

JimDawson said:


> I just have mine wired to it's own dedicated breaker.  I use a number of my breakers as switches for lighting and service disconnects.



Technically, you're not supposed to use a breaker for a disconnect except for lighting if its rated to do so  (HD).  I've done the same thing with my compressor for years until I finally hard wired it to a 20a circuit with wall switch.


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## Eddyde (Dec 28, 2014)

arvidj said:


> I think it is split-phase ... single phase with neutral grounded ... not two phase, and you are correct, it will require a double pole switch.



You are correct in that common 200+ volt service isn't officially called "two phase", it is called "single phase" but it does in fact use two phases and no neutral. One phase and a neutral is also commonly called "single phase" or "split phase" yielding typical 115-125 volt service. Then of course there is "three phase" which uses all 3 phases....All of which is a common source of confusion for many trying to understand AC electricity.


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## John Hasler (Dec 28, 2014)

Eddyde said:


> You are correct in that common 200+ volt service isn't officially called "two phase", it is called "single phase" but it does in fact use two phases and no neutral. One phase and a neutral is also commonly called "single phase" or "split phase" yielding typical 115-125 volt service. Then of course there is "three phase" which uses all 3 phases....All of which is a common source of confusion for many trying to understand AC electricity.



Electricians often refer to the two hot lines ("L1" and "L2") of a single-phase 240VAC center tap grounded service as phases.  They're wrong (but there's no point in trying to tell them so).  A two phase service would have two pairs of wires with their voltages 90 degrees out of phase.


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## Wreck™Wreck (Dec 28, 2014)

gunrunnerx said:


> I just picked up a really nice Porter Cable 60 gal compressor for the shop/garage.  In the owners manual it states that there should be an on/off switch between the main power and the pressure switch.  I've never heard of or seen this before.  It's a 3.7 HP 240v single phase 17.2 FLA.
> 
> 
> Anyone heard of this?  What should I use for the switch?  It actually says it will void the warranty by not having one.
> ...


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## f350ca (Dec 28, 2014)

Fabrickator said:


> Technically, you're not supposed to use a breaker for a disconnect except for lighting if its rated to do so  (HD).  I've done the same thing with my compressor for years until I finally hard wired it to a 20a circuit with wall switch.



That was my thought too, but the electrical inspector said it was ok (again with the right type of breaker) if the device was in sight of the panel. Been going to add a push button operated relay between my phase converter and the panel but the project went way down the list when he said it was ok the way I had it.

Greg


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## Eddyde (Dec 28, 2014)

John Hasler said:


> Electricians often refer to the two hot lines ("L1" and "L2") of a single-phase 240VAC center tap grounded service as phases.  They're wrong (but there's no point in trying to tell them so).  A two phase service would have two pairs of wires with their voltages 90 degrees out of phase.



I never called it "two phase" I simply noted that it uses 2 "phases" and no neutral, which is correct. A "Phase" being an alternating wave of electrical energy. In this case they are 180 degrees apart. I know they are split at the transformer from one single phase but what most people are dealing with to make 2xx volt power are essentially "two phases".

The 90 degree "true two phase", 4 wire system you describe is long obsolete.


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## gunrunnerx (Dec 28, 2014)

Thank you all for your insight and advice.  

Dman1114, that is the one!  I got it for $351.  :rubbinghands:
I love it.  Can't wait to finish getting the sub panel wired up and then deal with this.

Ill look around for a disconnect box and see what I can find fairly reasonably and try to get it up and going.  I did pick up a "dryer" whip and socket but am having second thoughts.


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## umahunter (Dec 28, 2014)

Heres like what I have


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## umahunter (Dec 28, 2014)

Can take pics if ya need them


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## kd4gij (Dec 28, 2014)

gunrunnerx said:


> Thank you all for your insight and advice.
> 
> Dman1114, that is the one!  I got it for $351.  :rubbinghands:
> I love it.  Can't wait to finish getting the sub panel wired up and then deal with this.
> ...






Nothing wrong with the dryer cord, Been using one for years on my compressor. But if you prefer a disconnect here is about the cheapest way to go. http://www.homedepot.com/p/GE-60-Amp-240-Volt-Non-Fuse-Metallic-AC-Disconnect-TFN60RCP/100674085


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## darkzero (Dec 28, 2014)

Here's a pic of the manual motor starter switches I was talking about that I use for my lathe & mill (one for each machine). They're made by SquareD, mine are p/n 2510KG2, rated for 30A & works with both 1 phase & 3 phase. I got them for $20 ea on ebay. There's various models & Leviton also makes them. They're not like light switches that require very little effort to flip the switch. I don't think they sell these in hardware store though.







As I mentioned I didn't bother with my air compressor as I also just always leave it on unless I go out of town.


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## Dman1114 (Dec 28, 2014)

gunrunnerx said:


> Thank you all for your insight and advice.
> 
> Dman1114, that is the one!  I got it for $351.  :rubbinghands:
> I love it.  Can't wait to finish getting the sub panel wired up and then deal with this.
> ...





sooo...


how you get it for that price?  where ?  i want one:whistle:


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## Wobbles (Dec 30, 2014)

My current shop came pre-wired with the wall-mounted 30A oven receptacle approach. That allows me to power a compressor, lathe, or welder.... just not all at the same time. It fits my needs because those 3 tools are used on 3 different types of work which never overlap. 

While at Siemens Energy I learned that Europeans most often use the breaker as the On/Off switch. As was said, that's not common here due to local disconnect rules which vary from region to region.


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## gunrunnerx (Jan 1, 2015)

Dman1114 said:


> sooo...
> 
> 
> how you get it for that price?  where ?  i want one:whistle:




I got really lucky.  I actually picked up a CH from Tractor Supply.  I had family pick it up in another town.  Got it to my house and noticed it was bent.  It was a floor model and someone tipped it over.  So I took it back but they didn't have the CH model anymore and upgraded me to the Porter Cable.  So $349 for the Black Friday CH and $5 for the upgrade to the Porter Cable.  Sorry my math was off.  I thought it was $351 but looking at the receipt it was actually $354.

I bought a lottery ticket later that day but must have used all my luck on the compressor.  :lmao:


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## master53yoda (Jan 1, 2015)

Eddyde said:


> You are correct in that common 200+ volt service isn't officially called "two phase", it is called "single phase" but it does in fact use two phases and no neutral. One phase and a neutral is also commonly called "single phase" or "split phase" yielding typical 115-125 volt service. Then of course there is "three phase" which uses all 3 phases....All of which is a common source of confusion for many trying to understand AC electricity.



to help satisfy the understanding of single phase power,   single phase is one phase that is 240 volts leg to leg,   this phase is center taped and grounded generating a neutral.   It is not 2 180 phases added together.   some very small transformers have 110 volt parallel taps that are series connected.  The power supply into the house or shop is center-taped single phase.






Art B


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## jbollman (Jan 1, 2015)

1-1-15 - 9:43 PM

Dear : Gunrunnerx

My sugestion would be to install a disconnect switch ( 2 pole ) at the incoming power to your compressor
assuming that the pressure switch is connected to one leg of the 240 service  & one to ground ( 120 volts? )                                             
If so,  I would install the main  - 2 terminal switch (fused on both legs) as
listed above.  Make certain that the box has fuses in it.  You will have to determine what fuses would be compatable
for that compressor.  Also check you region for electrical requirements.  Our county here in Indiana a license one 
does not need a license. 

 I  have a 5 horse compressor for my shop & I installed a 2 poll disconnect with 2 fuses. The pressure switch I believe is a 120 VAC  not certain - but I will check & reply.

If you have any questions please feel free to contact me on this site.

Kindest regards)

jbollman


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