yes,my questions is about a new air compressor i got.its a 6hp 30 gallon craftsman.i have it in my garage and the outlet where the compressor is pluged in at runs directly to the panel box and the breaker is a 20 amp and the wire is 12nm-b(i think)every time i plug it in the breaker trips.can anyone help me please.oh and the panel box is about 3years old.so all the wiring is newer.so thanks for all the help i get.
I ran the wire from the outlet straight to the panel box and it is on a 20amp breaker also its a stand up compresser.it trips when i turn the compressor on.i reset the breaker and pluged in a radio in the same outlet and that did not trip the breaker.but when i unpluged the radio and pluged in the compressor to the same outlet ,the breaker trips.
p.s the model no.is919-167311

max developed hp 6

voltage-single phase 120v/60hz/1ph

minimum branch circuit requirement 15 amps

tank size is 30 gallon

and the color is red.if you need any more info on this just ask.i hope ididnt leave any details out.

 

A couple of things we need to know. Is this on a 120V circuit? 30 gallon, I take it that its not an upright unit? What is the FLA rating on the nameplate on the motor? Does it trip when you plug it in or when the comp tries to start? Or is it trying to start when you plug it in,, is that what you are saying?

 

Please submit the exact information that appears on the motor name-plate; HP, voltage (110 volts, 220 volts, or 220/110 volts) and the Full-load amps. This information is neccesary to determine the rating of the circuit-breaker. This load will require a "dedicated" circuit.--Good Luck!!!!

 

If it's a new Craftsman compressor and it came with a plug that will plug into a regular receptacle, I think we can assume that it should operate on a 20 amp circuit.

Does the compressor try to start at all? If you can hear the motor kick in and it tries to start and then the breaker trips, that's one thing. Could just be a defective breaker. Try plugging it in somewhere else.

If it trips the instant you plug it in without anything happening on the compressor, that's something else. Since this is all relatively new wiring, panel and breaker and it's in the garage, I assume it is a GFCI-equipped receptacle or the breaker is a GFCI breaker. Could be a wiring problem. If no other device trips the breaker, perhaps the pigtail on the compressor motor is wired improperly. One of the wires could be shorted against the case, allowing for a situation where all the current on the hot (black) wire does not return on the neutral (white) wire and some returns through the case ground (green) wire. That is the whole idea behind a GFCI protected circuit. If it's not a GFCI circuit and it's tripping that fast, you would almost have to have a direct short.

 

You can't run a 6 HP compressor on a 20A 110 circuit, and I would be surprised if 20A 220 were enough.

 

Well, I think it is really about a 3 h.p. motor and it has a "maximum developed" rating of 6 h.p. (whatever that means).

I have never really understood what that meant except that it is designed to mislead the buying public.

I'm telling you, the durn thing comes with a three prong plug that will plug into an ordinary 120 volt, 15 or 20 amp receptacle.

From the Sears.com website:

Features Description

Product Overview:
Portable Tank Compressor Type Vertical compressor

Item Weight 151.0 lbs.

Tank:
Compressor Tank Capacity 30 gal.

Maximum Compressor psi 150 psi

Compressor Regulator Yes

Compressor Tank Type Portable

Hose:
Type High pressure air hose

Diameter 3/8 in.

Length 25 ft.

Motor-Engine:
Horsepower, Maximum Developed 6.0 hp

Chassis:
Wheels Type Pneumatic tires

Wheel Number 2

Color:
Overall Color Gray

 

I found this on the Department of Energy web site:


Ask A Scientist©
Engineering Archive
--------------------------------------------------------------------------------
Horsepower Labels

name Ken
status educator
age 40s

Question - A certain retail store (Sears) at one time, not too long ago, advertised a table saw with a 1.5 horsepower electric motor as being able to provide "3.0 horsepower maximum developed". Do you know how they arrive at this without running the risk of a lawsuit for false advertising? I contacted Sears directly but only got a "run around."

---------------------------------------------------------------------------

Well, first of all, Sears isn't worried about a suit for false
advertising. Were you to buy a saw and assert that it did not
function as advertised, they could simply replace it or refund your
money and be rid of you. If you sued them, you'd have to prove you suffered serious financial damage as a result of Sears' grossly
negligent action. *Grossly*, I said: an advertiser is allowed a
certain amount of ``puffing'' in vending his wares. ``Caveat emptor'' is an ancient free-market tradition. Also, if you failed to prevail in such a suit, you could be ordered to pay Sears' legal expenses, which would dwarf the cost of all the hardware you will ever buy.

The attorney general in your state might sue Sears, on behalf of
all consumers, if your state law is unusually strict about advertising contents (which is rare, because of 1st Amendment complications, and because Sears pays far more taxes and donates far more money to legislators' re-election campaigns than any number of disgrunted consumers). That is, if he has attention and attorneys to spare from pursuing murderers, car thieves, corrupt state employees, credit-card scammers, etc.

I don't think Sears is worried.

That being said, here are two ways I can imagine peak power might differ from average power: (1) the motor could produce 3.0 HP at full on, but be unable to sustain full on indefinitely without damaging itself. (2) the motor could produce 3.0 HP under certain unusual or intermittent conditions of load, electrical power, and so forth, while producing 1.5 HP under more typical conditions. One would guess the 1.5 HP figure comes from some standard measurement, regulated by some independent body (UL comes to mind) or the gummint.
Grayce
===============================

I don't know for sure for it could be as simple as the motor can run at this higher power for short amounts of time, but is unable to get rid of the excess heat if it runs that way for too long. So while it is starting up, or for brief times, it can be depended on to put out this power, but if you do it for long, it will over heat
etc.
S. Ross
===============================

 

What confuses me is that the original poster of this thread doesnt give us more info and then txdiyguy tells us what compressor it is??? Maybe these 2 are talking via email? But at any rate. Is it on a dedicated circuit? The reason that it would matter is that if it is dedicated and that is the only thing this wire feeds you can put a 30 amp breaker on it for the comp. I have seen more than one of these units trip 20's on start. You must make sure the unloader valve is working also to take the load off. It wouldnt matter though if there was no air in the tank,,, so you could eliminate that as a potential problem.

 

No, haven't been in conversation with the original poster. Just went to Sears.com and found the only 6 h.p., 30 gallon compressor they currently sell (there were several 33 gallon models) but he/she said 30 gallon. Since it's probably really a 3 h.p. motor, it should run about 18+ f.l.a. Most of them have unloader valves in the load side, so starting with a full tank of air wouldn't be any more of a problem than an empty tank. Sure, starting current could be several times that (several time 18 amps), but that lasts less than a half second or so and shouldn't (ordinarily) trip a properly functioning breaker.

 

Its not a 3 hp motor, its going to be about 1 1/2 hp which is about as much as you can draw of of a 20A circuit. This would be about 15A at 120V (16 is allowable for continious draw) 3 hp would be about 15-18A at 240 You were on the right track with the advertisers blowing smoke, that is about how much current it draws (6 hp worth) at locked rotor, start up. As I said before, you are allowed to put larger breaker in for motor starting. This is not an uncommon problem,, I have a friend that had one of those and it frequently tripped the breaker and he was replacing it with a larger comp so he didnt up the breaker.

 

the air compressor that you said was gray they have that one as a discontuned model.also the he/she is a he.and the model i have is 919-167311..so look at sears.com and see if there is any info i left out.the info i posted before is the info i got from my owners manual,that is sitting right here in front of me.im not the smartest person in this world.but if i was then i wouldnt need to be on here asking for help.so please keep your smart little comets to your self.im asking questions about my problem to learn something.i dont ask them to see how many little comets i can get or stuff that has to do with how the come up with hp or lawsuits by sears.my question is about circuit breaker triping when i plug compressor in and when i turn it on the breaker trips.thats all i need help with not about lawsuits or where the hp rating comes from.thank you to the people who gave me there input on what to try.ill let everyone know when iget it figured out,what the problem was.

 

I think Tx was talking to others that wonder why the hp ratings are the way they are and not just to you. Does this thing plug into a regular plug in? Again, is it on a dedicated circuit or are there other recepts on the circuit also? Something like this comp needs a wire running from the panel just for it. It is not designed to be plugged in just anywhere despite the plug that allows it to do so. Look on the label on the motor and see what the FLA or amp rating is. You may be able to find that in the manual also, but thats whats needed here.

 

You say you think it's 12gauge wire? Does run ok when the tank is empty then as you use it and it tries to restart it trips?Or does it just trip the second you turn it on?

It may just be that you need larger service. My compressor is the same size and if I try to run it off the outlet in the garage there's such a long run to the breaker when it tries to restart under a load it trips. I ran a 10/2 with ground and ran it to the breaker and never had another problem.

 

Yes, a dedicated wire is what that type of appliance needs. With 10 wire there is no problem of using a heavier breaker on and you did the right thing tp consider the distance. Also, I am not sure about this unit but some motors are dual voltage and can be wired for 240 also and that really helps with wiring performance.

 

Gee, gtreatricardo2, if you had read my posts carefully, you would realize that I was the one who thought you had provided enough information with regards to the motor in question. That is, it was a new (or nearly new) Sears Craftsman compressor, 30 gallon, 6 h.p.. Since it would obviously plug into a regular outlet, it must have come from Sears with a plug that would imply that it "should" work on a plain receptacle. sberry27 and PATTBAA wanted detailed motor nameplate information. Bottom line is that it SHOULD work on any 120 volt receptacle (although it would be sure to frequently trip a 15 amp breaker).

But this is a forum, an exchange of information, ideas and philosophy. All you may have wanted was a solution to your problem, but your question raised another issue (as is often the case in forums). I re-read each post and simply do not see any comments on my part or anyone else that, in any way, could be construed to be derogatory toward you.

 

i have the compressor hooked up to a 20amp breaker all by its self.i also have 12gauge wire running from the outlet to the breaker.the manual says voltage-single phase 120v/60hz/1ph and minimum brach circuit requirement 15 amps.the air tank is empty its brand new,its never been started either.the breaker trips when i turn it on.im sorry for the rude post before,im just getting fustrated over the whole thing.thank you for the help that you have given to me so far.

 

It happens with those things,, something can be a touch off in the motor and I have seen it before. Since you have its own wire put a 30 breaker in and see what happens. I might make a lable for that recept that says,, Compressor only. My chop saw is the same way. After a few starts it trips the breaker and I got it on its own 30. You could have a breaker that is a touch weaker too,, never know,, there could be something wrong with the compressor too. Something you could try is putting a 50 ft cord on it and see what happens. Only run like that for a little bit, 30 seconds or so,, just see if it starts with a cord. That might make it tend to keep from tripping so fast on start. Just stuff to try. Tx,,, Part of the reason we ask for more info is to get people looking for stuff and they know where to find the info on a motor and it helps them learn trouble shooting skills. They get familiar and more comfortable with their equipment.

 

thanks for your help,im going to put a 30amp breaker in and try that.a couple of people said that could be the problem.ill try it and let you know if that fixes it or not.

 

The National Electrical Code defines different types of "Branch-Circuits"and this specific circuit is a Motor Branch-Circuit according to the NEC. The NEC requires that each motor be "marked" with certain information-voltage, frequency, RPM's, HP, and full-load amps.It is the "Marked", or name-plate values which are used for Motor Branch-Circuit design to determine conductor-size and the rating of the circuit-breaker.

 

gtreatricardo2,
Before you go adding a breaker do you by chance have or no soneone that owns a multi meter?

I would check the motor out to see if it's grounded out.

Just because it's new doesn't meen they didn't sell you a bum compressor.

Does it give max circuit size? If you hook it up on a 30amp you may really smoke it.

 

Hello,im glad to say i got the compressor working,i checked out all the things that you said to check and the conections were all in the right places.So i up graded my breaker to a 30amp breaker,and i up graded my wire to 10/2 and its running perfect without any troubles.
Thanks to all and sorry for the jack ass post i made before,i was forgetting you were helping me,by taking time out of your day,to help me with my problem.(its very kind of you)thank you once again.

 

Thats cool,,, as I look back I missread the very first thread of this post. You gave all the info the first time. I dont know why I didnt realize that when I wrote a resopnse. Thats why it sometimes takes back and forth here. Those compressors are all different. I think you could take 2 identical ou of the boxes and they would not run the same. One would start on a 15 and the next one takes a 30 to keep from tripping. You now have a 10 wire which is good. You can use a 10 or a 12 in that case as I believe those motors have internal reset to protect it against overload. I see how it got so goofed up, we didnt reread the post after you edited it.