# Wiring air compressor in to shop



## J. V. (Jun 1, 2007)

Something is very fishy here for starters. You order a high priced air compressor and the manufacturer will not allow you (the owner) to view a PDF user manual. I think I would call my credit card company and put a dispute on the purchase today. The means Ingersoll Rand gets no money. And of course you are just using this method as a way to get them to fax you a copy if necessary.
Theres got to be more to this story as you cannot possibly have the serial number unless you have the compressor.. But here goes.

1) 70 Amp 2 pole breaker.
2) 10/2 wire


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## frenchelectrican (Apr 12, 2006)

J. V. said:


> Something is very fishy here for starters. You order a high priced air compressor and the manufacturer will not allow you (the owner) to view a PDF user manual. I think I would call my credit card company and put a dispute on the purchase today. The means Ingersoll Rand gets no money. And of course you are just using this method as a way to get them to fax you a copy if necessary.
> Theres got to be more to this story as you cannot possibly have the serial number unless you have the compressor.. But here goes.
> 
> *1) 70 Amp 2 pole breaker.
> 2) 10/2 wire*


 I put in bold that only if the motor do have interal protection or overload relay on the contractor if do not have either one then you have to use smaller breaker to protect the motor.

Myself I rather have contractor to protect the motor from abuse and what more the pressure switch are not really designed to handle large blast of current during startup.

Merci,Marc


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## KAdams4458 (Jan 29, 2006)

I'm guessing it has something to do with running changes. They've been making the same model compressor for years, and surely individual parts have changed a few times here and there, so the serial number may only be a means of ensuring you end up with the proper version of the manual. Some folks selling them, like Grainger, for example, seem to have them built with a different brand motor, as well.

On top of that, they seem to offer two levels of each model, i.e., a high-end version with all the bells and whistles, and a value-series, which comes pretty much bare, and may also make some difference in which manual is needed. I do believe I ordered the value line, which comes without an automatic tank drain, etc. (I already own some goodies that I can use with it, so I didn't figure I needed them.)

To be honest, I'm not really sure what I ordered. I know that sounds strange, but I really needed a compressor, as my old one locked up, and my business depends on having functional equipment. I ordered something that met my current air needs, plus a little extra for cushion.

So, 70 amp? Why 70 instead of 60? The math involved in sizing a motor circuit is beyond me still, but I'm trying to wrap my brain around it.


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## Stubbie (Jan 7, 2007)

Hi

Unfortunately as you pointed out the online info for your compressor is not available. *If* the motor has internal overload protection and the motor *nameplate* states that it is 5 hp 230 volts then 28 amps is a good bet and you could start running some wiring. Many compressors in the general specs. show peak horsepower and we cannot use this to size your conductors for the branch circuit. We need motor nameplate data.

I would just wait for the compressor to arrive and then post the information from the manufacturer or the motor nameplate for us. It is possible that this motor may require a starter with overload but I think in the end it will be a simple branch circuit sized by the motor rules of the nec unless it comes with a cord and plug.

For your information if both horsepower and running amps are listed on the motor nameplate *and *the unit carries a lab listing like underwriters limited (UL). Then the nameplate amps can be used for sizing the branch circuit conductors. This is because the testing laboratory has verified that the motor does indeed operate at those running amps under load. Otherwise we have to use the table FLC amps from article 430... table 430.248 which happen to be 28 amps for a 5 hp 230 volt motor.

Rregardless we take the applicable amps and increase them by a factor of 1.25. If 28 amps then the branch circuit conductors would be required to carry 1.25 x 28 = 35 amps. The circuit breaker can be as much as 2.5 times the running amps in order to be sure that the compressor will start due to the surge of amps when starting before dropping off to its running amps. That would mean the circuit brekaer could be a maximum of 70 amps. These are special rules for motors that have internal overload protection.

In this case if you need 35 amp conductors you could serve the compressor with 10 awg copper thhn conductors in conduit. If you use a cable like nm-b (romex) then you will need #8 copper nm-b. 

I don't consider this compressor to be industrial but more like light commercial so I doubt your going to need more than 10 awg and a I would probably see if it would start on a 40 amp breaker.

Really can't say without more information from the manufacturer.

Hope this helps.


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## KAdams4458 (Jan 29, 2006)

Stubbie said:


> Hi
> 
> Unfortunately as you pointed out the online info for your compressor is not available. *If* the motor has internal overload protection and the motor *nameplate* states that it is 5 hp 230 volts then 28 amps is a good bet and you could start running some wiring. Many compressors in the general specs. show peak horsepower and we cannot use this to size your conductors for the branch circuit. We need motor nameplate data.
> 
> ...


Good stuff. Now I get it. Thank you!

Yeah, you're right. It's more of a light commercial than an industrial unit, but at least it is rated for continuous duty. (Guess how I killed my oil-free Devilbiss compressor!)

I hate to do this, as it means more down time, but I will just wait until the compressor is delivered. It is apparent that there is not much else I can do before then without potentially shooting myself in the foot.

Oddly enough, I found that I already have an unused dedicated circuit run in my shop with 10 thhn wire and a 30 amp two pole breaker. I might get lucky enough to only need to swap in a breaker.


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## Stubbie (Jan 7, 2007)

> Oddly enough, I found that I already have an unused dedicated circuit run in my shop with 10 thhn wire and a 30 amp two pole breaker. I might get lucky enough to only need to swap in a breaker


.

If the unit only needs 10 awg you might get lucky enough to not have to do anything.....


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## J. V. (Jun 1, 2007)

frenchelectrican said:


> I put in bold that only if the motor do have interal protection or overload relay on the contractor if do not have either one then you have to use smaller breaker to protect the motor.
> 
> Myself I rather have contractor to protect the motor from abuse and what more the pressure switch are not really designed to handle large blast of current during startup.
> 
> Merci,Marc


Marc. All I had to work with was 28 amps, 240 volts and a single phase motor. We may get more info as he is waiting for the compressor to show up. 

I still do not understand how Ingersoll Rand could not get him the specs BEFORE it's delivered. They would not get away with that if I had ordered it. I would not have given them the order without the specs first. Is that not how we do business in this trade? Buy something without knowing the specs first? Naw, not me. :no:


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## Stubbie (Jan 7, 2007)

I think the OP tried to get the specs online after ordering the compressor based on its scfm and tank size. Generally speaking the electrical requirements would be the last thing you would worry about as long as it was single phase motor operated. It is much more important to know if the compressor will supply the necessary scfm at the necessary psi for your needs. Wiring the thing is generally an after thought.

I'm sure if he contacted them e-mail or phone they would get the motor specs to him for the branch circuit.


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## slogarage (Aug 12, 2009)

I just had the same compressor delivered last Friday to my house. I'm using s 30A breaker, and I believe 8 AWG wire.


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## KAdams4458 (Jan 29, 2006)

Stubbie said:


> I think the OP tried to get the specs online after ordering the compressor based on its scfm and tank size. Generally speaking the electrical requirements would be the last thing you would worry about as long as it was single phase motor operated. It is much more important to know if the compressor will supply the necessary scfm at the necessary psi for your needs. Wiring the thing is generally an after thought.
> 
> I'm sure if he contacted them e-mail or phone they would get the motor specs to him for the branch circuit.



You got it. Having a shop with its own 200 Amp service, I paid no attention to electrical requirements beyond it being single phase. What mattered to me the most were my air demands. Everything beyond that was just details.

Now, as far as getting specs from IR goes... I did write to them, and received a response today. The email I received asked me to please supply the serial number of my unit. I would not have been at all shocked by their response if I had not already specifically expressed in my initial email to them that I had not yet taken delivery of the compressor, and so I could not supply a serial number. Someone clearly has poor reading comprehension.

To be clear, I didn't order this thing from IR, or any other company experienced with compressors by any means. Once I tell you who I ordered it from, you're going to die, but you're also going to understand the lack of sales support. Just let it be known that it was the best price that I could find, even with tax and delivery charges. That said... I admit that I purchased it from Sears.  

I know. I know. Not the best place to buy anything, period. I did get an acceptable deal on it, though. No one local could touch their price, and the online stores all would have cost me a $50 residential delivery fee, plus a $75 liftgate fee, and they would have only dropped the compressor off in the front of the house, leaving me to move it to 250 feet down a sloping gravel driveway by myself. 

Anyway, back to the compressor itself. I did get _some_ good info. It _doesn't_ include a magnetic starter, but the motor _is_ thermally protected. I'm not sure how I feel about that. Every 5 HP+ model that IR makes includes a magnetic starter except for the model I bought. I thought it would include one, but the small print excludes my model, and my model alone. Should I start cursing?

*slogarage*, it starts on a 30? That strikes me as odd. (Of course, maybe it's one of those evil FPE breakers that never trips. Ha!)

I'm curious if you would mind sharing the data from your motor tag. I'm not going to count on it being identical to the motor on mine, but still, I am curious.


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## frenchelectrican (Apr 12, 2006)

J. V. said:


> Marc. All I had to work with was 28 amps, 240 volts and a single phase motor. We may get more info as he is waiting for the compressor to show up.
> 
> I still do not understand how Ingersoll Rand could not get him the specs BEFORE it's delivered. They would not get away with that if I had ordered it. I would not have given them the order without the specs first. Is that not how we do business in this trade? Buy something without knowing the specs first? Naw, not me. :no:


I know what you mean I do the same thing Always get the specs before I get something or order a item for customer that way it will CYA on that matter.

Now to the OP.,

Speaking of magatic starter the cheaper models under 5 HP useally don't have it but a very good compressor will have magatinc starter on it due some cheap compressor motor have " special " rating if that unit stated 5 HP or 6.5 HP that really more like 2 or 3 HP motor size if you see the motor frame look small then it not really the best for hevey duty useage but for average homeowner use it can go either way.

The cost of magatic starter will varies a bit depending on model and phase and type of overloads.

My shop have 15 hp [ set up for 480 v 3Ø ] yeah big one of course with GE contractor the only reason why I get GE due easy to get into contract buttons real quick if I have issue with it { the compressor is set up for on/off or contouinis running by changeing the slection switch.

However I do get alot of customer asked me to add a magentic switch due their pressure switch got overheated so that something you may want to watchout for it.

Merci,Marc


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## spark plug (May 5, 2009)

*want of (online) help fr. Mfr.?*



KAdams4458 said:


> Hey, folks. I just want to verify something.
> 
> I just ordered a new Ingersoll Rand 2340L5 compressor for my shop, and it will be here on Saturday. I want to get a jump on the wiring, but details on wiring requirements from the manufacturer are sketchy at best, and they want a serial number in order to grant me access to the online version of the owner's manual. I do know that the motor is 5 HP, 230 VAC. It should pull about 28 amps running.
> 
> My shop has its own 200 Amp service, but I'm going to need to add a circuit for this thing. What I don't know is how big it needs to be. Rumour has it the manufacturer suggests a 60 Amp circuit. Does that sound right? I've never installed a compressor before, but I bet some of you have.


I'm surprised to hear that the Mfr./Distributor is slow in forthcoming with the relevant technical information. Especially if you're a customer. Your best bet in this case is to await the NEW arrival. Because you'll have to look at the FLA and LRA (Full load amperage & Locked rotor Amperage) in order to calculate the proper, adequate and Code-compliant power supply and protection. (Now more than ever) :yes::no::drinkon't Drink and Drive!!!


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## slogarage (Aug 12, 2009)

The compressor is an IR 2340L5 I ordered from Ohio Power Tool. I took some pics of the motor label but they were not too clear. I've attached one here.

The FLA stated on the motor label is 21.5 amps. The motor does have a reset button. And I have not hooked it up yet. I just finished mounting the tank. I will have it wired this weekend.

I too was concerned about the magnetic starter, but it appears that the mag starters are installed on the 3 phase models not the single phase which is what I have.

I also looked at the sears price, but went with OPT because it was free shipping, included the stater kit (extends the warranty 12 months) and I got an IR 1/2" impact wrench.

Let me know if you want anymore info.


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## slogarage (Aug 12, 2009)

I did get charged for the lift gate delivery, but it was worth it, the guy brought it up my driveway into the garage, very painless!!


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## Gary in WA (Mar 11, 2009)

PDF] *Choosing a Compressor*

File Format: PDF/Adobe Acrobat - View as HTML
nailer requires a _compressor_ with at least a. 6-_hp pump_ and a _60_-_gal_. or 80-_gal_. _tank_. If *...* ton before going into the storage _tank_. _Two_-_stage pump Air_ is compressed *...* For four times the money, an _industrial_-quality, 80-_gal_. machine *....* at 15 amps, *while the 5-hp Ingersoll-Rand's motor is rated at 28 amps. **...*
www.finewoodworking.com/FWNPDF/011164050.pdf - Similar 

Sounds like it....
Be safe, G


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## KAdams4458 (Jan 29, 2006)

slogarage said:


> The compressor is an IR 2340L5 I ordered from Ohio Power Tool. I took some pics of the motor label but they were not too clear. I've attached one here.
> 
> The FLA stated on the motor label is 21.5 amps. The motor does have a reset button. And I have not hooked it up yet. I just finished mounting the tank. I will have it wired this weekend.
> 
> ...


If I squint hard enough, I'm sure I can read that.

This is unrelated to the topic at hand, but Sears automatically extends the warranty from one year to two years without the starter kit. (They don't even offer the starter kit for sale.) Of course, it remains to be seen whether Sears will even exist a year from now. 

Post back up after you get it wired. You'll probably beat me by at least a full day, and I'm curious to see how your wiring works out.

Oh, and I'm still a little bummed by the lack of a starter. I can't help but think it would be good to have.


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## J. V. (Jun 1, 2007)

slogarage said:


> The compressor is an IR 2340L5 I ordered from Ohio Power Tool. I took some pics of the motor label but they were not too clear. I've attached one here.
> 
> The FLA stated on the motor label is 21.5 amps. The motor does have a reset button. And I have not hooked it up yet. I just finished mounting the tank. I will have it wired this weekend.
> 
> ...


Do you need help sizing the breaker or the wires? You did not say.
It's common not to have a motor starter on a single phase compressor of this size. But it's not a bad idea either. As Marc stated, the pressure switch is what starts and stops the motor. If the pressure switch contacts are not over sized and of very good quality, you will be replacing the pressure switch before you should have too. So, if you are relying on this compressor for income, you may want to consider installing a starter and external overload yourself. We can help you if you like. Good luck and GET BACK TO WORK!:laughing:

OP. Whats wrong with Sears? You got a good deal. Thats what counts. You got a very good name in that compressor too.


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## KAdams4458 (Jan 29, 2006)

J. V. said:


> Do you need help sizing the breaker or the wires? You did not say.
> It's common not to have a motor starter on a single phase compressor of this size. But it's not a bad idea either. As Marc stated, the pressure switch is what starts and stops the motor. If the pressure switch contacts are not over sized and of very good quality, you will be replacing the pressure switch before you should have too. So, if you are relying on this compressor for income, you may want to consider installing a starter and external overload yourself. We can help you if you like. Good luck and GET BACK TO WORK!:laughing:
> 
> OP. Whats wrong with Sears? You got a good deal. Thats what counts. You got a very good name in that compressor too.


I think slogarage has a handle on his wiring at this point, or at least seems to. For the record, we both have two-stage compressors. That's why I am disappointed in the lack of a starter. Everything I know about compressors says that any 5 HP two-stage compressor should have one. (Not that I know too much about compressors.)

Off topic again for a moment: Sears is okay, I suppose. They just always seem to have about the worst possible customer service. I know that it boils down to the individuals at a particular store, but holy cow, do they ever excel at hiring folks who know nothing about what they are trying to sell. Adding insult to injury, guess who you have to call to schedule an appointment when something needs service? India.  Of course, they want you to describe the problem in detail, and somehow we never seem to speak the same version of English as "Bob" or "Pat" when we call. On the other hand, it is funny when they begin and end each sentence with "sir" while they are talking to my wife. :laughing:

I do, however, like one particular sales person that works in the appliance department at our local store. She's our go-to for dryers, refrigerators, etc. She knows her stuff, and when we can call her and tell her what we're looking for, she can quickly make appropriate suggestions, and even discuss technical details! To top it off, she will actually tell us when the next sale is that we can take advantage of, and gives us a courtesy call the day before the sale goes in to effect. When we come in, she already has the paperwork done, too. She's awesome. I just wish they'd go back to hiring people like her to run the rest of the store.

Back on topic: I will be relying on my compressor for income. The death of my last compressor has delayed several projects that are meant to be examples of my work. Making the compressor reliable is a top priority for me, because once business is rolling, I do not want this kind of downtime. 
I would like very much to add a starter and external protection to it. Also, I'd like to add an hour meter.

I do have one concern with hour meters, specifically. There are many 230VAC choices, but I'm worried about vibration damaging them. Also, I have found no surface mount options, and will apparently need an enclosure for a flange mounted meter. Suggestions?


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## frenchelectrican (Apr 12, 2006)

The hour meter use on air compressor it should be not too bad but you can have it mounted remote if you want to if you are condering about vibrations and many hourmeter are tested with vibrations with gas/diesel powered unit they do shake a bit more than straght electric units otherwise get a digtail hourmeter they can really take a abuse with it.

Merci,Marc


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## slogarage (Aug 12, 2009)

Thanks J.V. and Marc for clearing up the issue of mag starters. For my home use, I won't have the cycling times a commercial application would have. I can see where you would want to install a mag starter as preventative maintenance and reducing compressor down-time due to burned out switch.

For my application, I will not install a mag starter now. The money pit is getting deeper and I haven't even air'd up a tire yet. I do think, however, that I will be installing one in the near future.

I look forward to KAdams progress on his installation and will be taking notes on the info everyone will contribute.


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## slogarage (Aug 12, 2009)

Kind of a thread hijack...

Can anyone explain the criteria for a disconnect?? I have read on numerous forums that if you can see the panel and its a straight line, you do not need to install one. 

My question is, I can see my panel from the compressor (about 10'), but the wire routing is not in a straight line. It goes up and over and around, etc.

Is this what is meant by not being a straight line??

I am cornfused....:wink:

TIA


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## J. V. (Jun 1, 2007)

Thats correct. If you can see the breaker panel from the compressor you need no extra disco. The breaker will be the disco.

KAdams. How about this starter and ball park price? The model# for the one you need is "ESWS-25V24E-RM33.
NEMA 1 Enclosure. No pilot devices. 208/230 VAC coil. 15-23 amp adjustable overload relay. All included and wired in the enclosure. ($100.00 - $125.00). Just mount, connect pressure switch and motor to starter (We will tell you how). I used 5 hp @ 230 volt to put together this part number. You can always adjust the part number to suit your particular unit. You will need to find a distributor. Weg will not sell direct to you. Where are you located. I may be able to help with a distributor in your area.

http://www.weg.net/files/products/W...arters-esw-series-usa300-brochure-english.pdf

Good Luck. Weg 1-800-275-4934.


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## Stubbie (Jan 7, 2007)

You don't need a starter with overload the motor already has it internal. I would simply get a manual motor starter like this (below) and wire the compressor with 10/2 awg. thhn in conduit or use cable. I'd put the circuit on a 40 amp dp breaker. But if I had a dp 30 I'd give it a shot first.... 

Those magnetic starters with overload will be extremely expensive and really not necessary.

I would just get a simple 2 pole manual motor starter with enclosure probably 40 or 50 dollars and hardwire it to the compressor motor circuit. This one is rated 7.5 hp. and it will be a great disconnect for the compressor also. There are several manufacturers of these.


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## frenchelectrican (Apr 12, 2006)

Let me add to Stubbie's part is the maganatic switch and yes you can get them without any overload sensors I know pretty good percentage of single phase motor useally I say useally have thermal protection if your nameplate stated have thermal protected motor then you are good to go however if don't show thermal protection at all on the nameplate then yes you have to get overload thermal unit/

Check out couple electrical supply centre I am sure they will have something like this on stock or order { usealy not very long at all }

Merci,Marc


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## J. V. (Jun 1, 2007)

Stubbie said:


> You don't need a starter with overload the motor already has it internal. I would simply get a manual motor starter like this (below) and wire the compressor with 10/2 awg. thhn in conduit or use cable. I'd put the circuit on a 40 amp dp breaker. But if I had a dp 30 I'd give it a shot first....
> 
> Those magnetic starters with overload will be extremely expensive and really not necessary.
> 
> I would just get a simple 2 pole manual motor starter with enclosure probably 40 or 50 dollars and hardwire it to the compressor motor circuit. This one is rated 7.5 hp. and it will be a great disconnect for the compressor also. There are several manufacturers of these.




He already has a switch. The pressure switch. He also has a disconnect. The breaker in sight from the compressor. Why add another switch? He said he needed a magnetic starter to extend the warranty to two years. He also recognizes that his pressure switch will be doing all the on/off cycling. A motor this size (5Hp) is going to really put that pressure switch to task. It's a commercial application. Thats why they recommend the mag starter. What he wants to do is extend the life of the pressure switch. The switch above will not help in any way.

I also think $100.00 or less is a pretty decent price for the starter and OLR in a NEMA 1 enclosure. Prewired. Even though he needs no OLR. It comes with it. It's not an option.


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## Stubbie (Jan 7, 2007)

That's fine JV if that is what the op wants. I don't understand how this magnetic starter increases the warranty. Maybe someone can explain....?? 
The 'starter kit" mentioned in post 14 has nothing to do with a magnetic starter for the 2340L5 two stage, it is not offered on that model. I suppose you could arrange to get one from the supplier.

If your wanting to save the pressure switch from the current inrush I guess you can intertain yourself thinking that mag starter will do that by only having to energize the mag starter coil. But I kinda think the pressure switch will do just fine cycling the motor load.

As Marc said there are magnetic starters without overload I have no problem with that.

I'm also not sure you have an on-off switch at the pressure switch, might be since this is the value model.

At any rate if it were me I'd locate a manual starter ahead of the pressure switch for sake of a nice convenient disconnect rated switch located on the wall. The pressure switch is rated for the inrush load of that motor. I see no reason to install a magnetic starter with overload for this compressor. 

Now if you start getting up there around 7 hp and higher with single phase and high running loads I would bet they (ingersoll rand) put magnetic starters on as standard equipment.

The primary pupose of magnetic starters is to provide overload and low voltage protection of a motor. On 3 phase this is quite common due to lack of internal overload on the motor.

They do have a souped up all bells and whistle version of the 2340L5 that comes with a magnetic starter for what it is worth. 

Again I do not think you get a warranty extension because you have a magnetic starter. I do think you get one if you are tricked into buying the 'Starter Kit' which is sythetic oil and 'better than the best' air filters...


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## KAdams4458 (Jan 29, 2006)

About that warranty extension... Somewhere along the line, a few people got confused about that, and I can understand why. The IR _starter kit_ that adds a year of warranty coverage is indeed only some oil and air filters. With all this talk of mag starters and starter kits, it's easy to see where someone might get confused. Adding a mag starter to the compressor doesn't do squat for the warranty. 

Okay. Everyone on the same page, now? Yes? Good. :thumbsup:

My compressor has arrived, and I am happy to announce that it does include an auto/off switch. For the time being, I'll skip the starter. Really, I'm installing the compressor some place where I don't want it, because my preferred location in in a part of the shop that has some structural integrity issues that will keep me from being able to install an overhead door for some time. I don't want this thing out in the cold, so I had to compromise. That said, the future location will be on the other side of a wall from the load center, and I will need a disconnect, so I am still very much interested in starter discussions.

The new compressor location is right in front of a 240V receptable wired with about 35 feet of 10-2 NMB. I'll either get lucky and it will work, or it won't, and I'll need to run a new line to the area. Let's see what happens when I run the numbers... 

So, with an FLA of 21.5, it would seem the conductors only need to carry 26.875 Amps. The 10-2 NMB can do that, so it looks like I can make use of the existing line in the new location. 

If I can go up to 2.5 times the FLA for the breaker, then that gives me a maximum of a 53.75 Amps. Do I round up or down for that? It's either a 50 or a 60 Amp breaker for the maximum. In the owner's manual, they specify a 60 Amp.


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## spark plug (May 5, 2009)

*issue of overload protection on compressor*

KA Adams #28. In the last paragraph you say that since the NEC allows you to have overload protection up to 2.5 times of the FLA, which comes to approx 53... amps., you'll round out to the nearest larger breaker, 60Amps. You have to keep in mind that the farther away that you go from the true FLA, you're diminishing your protection of the line in case you have a sustained overload above the LRA of the motor and the breaker will not open the line. (Now more than ever) :yes::no::drinkon't drink and Drive!!!


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## kbsparky (Sep 11, 2008)

J. V. said:


> Thats correct. If you can see the breaker panel from the compressor you need no extra disco. The breaker will be the disco.....


Only if that breaker is within 50 feet of the utilization equipment!!


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## Stubbie (Jan 7, 2007)

Yeah they are just giving you the maximum breaker and calling it good. If it don't start on that then it ain't gonna start.... it also keeps you from playing with breaker sizes to see what the lowest breaker you can get by with would be. I can't imagine that compressor not starting on a 50 amp breaker and frankly I think it will start fine on a 40. Not much cost difference though so I'd just follow the manual instructions if you want.

Circuit breakers are tested under UL489 (I think it's 489) for multiple inrush currents. A typical residential 30 amp inverse time breaker will hold 6 times its current rating from 2 to 6 seconds. The torque rest to start inrush back to running amps on your motor will be less than a second. Locked rotor or start current will be 6 times 21.5 or pretty close...so call it 130 amps motor inrush current at start up. To play it safe lets just say that inrush is 6 x 30 = 180 amps. That breaker will hold that somewhere between 2 and 6 seconds before tripping. If it is less it will hold longer lets say starting inrush is 130 amps which would be 6 times the nameplate fla. A 30 amp inverse time breaker will hold that from 4 to 20 seconds depending on what the circumstances are and design type of motor your starting. Just very basically explaining just to give you an idea whats going on with the breaker and start currents. The thing to remember is the maximum inrush current (much higher than locked rotor) or the current needed to establish the magnetic field is only seen briefy by the motor before it rapidly starts falling towards running amps as the motor comes up to speed. That high inrush current will actually diminish due to the cycling of the motor on the air compressor retaining residual magnatism in the motors steel core needing less current to establesh the magnetic field. The chief obstacle in getting a motor started is the locked rotor current which generally is 6 times the FLA of the motor. It is possible your existing 30 amp breaker will start that motor on the compressor. So it's worth a try IMO. 

Sorry for the long wind it really is going too far technically but thought you might be interested.


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## KAdams4458 (Jan 29, 2006)

Thanks for breaking it down. I'll see what it does on the 30 Amp that's in there. If it trips, I have spare 40 and a 50 Amp breakers on hand, but I went ahead and picked up a 60 at the big orange box while I was there for a whip and some concrete anchors.

For what it's worth, the manual vaguely suggests that during heavy cycling, anything short of a 60 Amp breaker may trip under some circumstances, but doesn't get in to why that is. Anybody want to tackle that one? We seem to be making one very informative thread, so we may as well keep at it.

I'm gonna go make some sparks, now. What better way can a guy spend a quiet Friday night? :laughing:


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## Stubbie (Jan 7, 2007)

Being more specific your nameplate shows the code letter "L". This equates to a value of 9.0 to 9.9 kva per horsepower at locked rotor. Using the mean of 9.5 KVA the calculation becomes 9.5 x 5 hp x 1000/ 230 volts which is a locked rotor current of 207 amps. Probably a big reason they want it on a 50 or 60 amp breaker. This is all revolving around NEC 430.7 and table 430.7(B).

In contrast if the motor used a Design letter we could use table 430.251(A) and the locked rotor current becomes 6 x the *table* 430.248 FLA of 28 amps which would be 168 amps.

Essentially what this means is that the motor rotors (for lack of a better word) are made out of steel that requires them to use a code letter for locked rotor instead of a design letter like A or B. It takes more current to establish the rotating magnetic field and consequently the LRC goes up considerably. It ends up code L is on the high end for locked rotor current for your type motor.


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## J. V. (Jun 1, 2007)

As usual a very good discussion. What is the "Starter Kit"? The one that extends the warranty. Not the one that starts the motor.


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## frenchelectrican (Apr 12, 2006)

J. V. said:


> As usual a very good discussion. What is the "Starter Kit"? The one that extends the warranty. Not the one that starts the motor.


 If I remember it right some compressor brands do have starter kit which it will have syentic oil plus diffrent air filter to extend the warranty on the compressor but not the magatic starter I think that what happend we may end up on wrong track with the discussion.

However that how some compressor do that.

Mine compressor do not have syentic oil at all due two reason one the size is very large { 15 HP two stage } and run very slow speed driect drive { no belt on this one } and I do change oil twice a year reguards of running hours that how I keep the crankcase very clean.
And the intake port is piped to outside to keep the chuffing noise down it is loud BTW.

Merci,Marc


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## Stubbie (Jan 7, 2007)

The 'starter kit' mentioned in this thread is synthetic oil and super duper air filters. They will extend the warranty *if you buy it from them*....


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## KAdams4458 (Jan 29, 2006)

And... It works!

I had a chance to run the compressor extensively yesterday. (I love how I can media blast now, and it actually catches up and shuts off. I used to wait in the compressor, but now the compressor waits on me. I'm loving this!)

It seems to have no problem running on the 30 Amp breaker. I had it cycling on and off for two straight hours yesterday, and not an issue to be seen. Everytime it kicks on, it's up and running at full speed within two seconds.

Slogarage, from my experience, you're identical compressor should have no problem on your #8 AWG and 30 Amp breaker. You should be good to go. Now we just need to plumb some proper hard lines for air. I don't know what you were using before, but you're gonna love your compressor.


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## J. V. (Jun 1, 2007)

Good job.


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## slogarage (Aug 12, 2009)

congrats KAdams on your install. Good to hear the 30amp breaker works for you. I still have to get it wired up, I was actually waiting to see how yours turned out. 

On a side note, i know that you are using yours in a commercial application, but, how loud is it?? I've read that you can talk to someone standing next to it without shouting. Can you give some feedback??

And to answer your question about what I was using before, nothing. This is my first, and I hope last, compressor.


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## KAdams4458 (Jan 29, 2006)

slogarage said:


> congrats KAdams on your install. Good to hear the 30amp breaker works for you. I still have to get it wired up, I was actually waiting to see how yours turned out.
> 
> On a side note, i know that you are using yours in a commercial application, but, how loud is it?? I've read that you can talk to someone standing next to it without shouting. Can you give some feedback??
> 
> And to answer your question about what I was using before, nothing. This is my first, and I hope last, compressor.


Somehow my post in response to your question about how loud the compressor is fell off the map, and I didn't want to just not respond, even if it has been a while. Anyway, I'm sure you've heard yours by now, but in case you haven't, it's not terribly loud at all. It beats the heck out of standing next to one of those direct-drive oil-less compressors.

I think having a conversation next to it is possible, but will still requires raising your voice. I'm still using the stock air intake on mine, but experimented one day by holding a bucket over it, and it muffled the noise quite a bit. At some point in the future, I'll upgrade the intake and filter to one of the fancy muffled versions. It should be pretty good after that.

And to keep my response at least a little on the electrical topic, I've been running the heck out of the compressor, and the ol' 30 amp breaker hasn't given me any trouble at all.


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