Air compressor tripping the breaker

[JGayman]

I recently replaced my Harbor Freight 2.5HP compressor with a Campbell Hausfeld 2HP 30 gallon air compressor. Unlike the HF unit, this one has a separate motor and belt-driven 2-cyl compressor so it runs very quiet and works great.

Except for one thing, it likes to trip the circuit breaker. Sometimes it happens when I first turn it on and other times when the motor kicks in while in use.

It's driving me crazy. I have a dedicated 20 AMP circuit and the only thing plugged in is the compressor. I assume it is somehow exceeding 20 AMP for a few milliseconds while it starts.

Is it possible to have a 30-AMP 110V breaker installed? I assume no one will wire a 20 AMP outlet to a 30 AMP breaker. Could I have one of those 30-AMP twist-locks installed and then use a 5-20R pigtail like is used with a portable generator?

I also have a Hobart Handler 140 MIG welder that runs on 115V and when using it on it's highest setting it too occasionally trips the breaker on my dedicated circuit. Perhaps I could solve both issues with a heavier 115V circuit.

I'm looking for options. Weird thing is my old HP 2.5 HP unit never tripped the breaker.

 

[Chris(WA)]

Make sure it is unloading when it stops. Should hear a hiss. That will make it trip the breaker for sure.
If there is no problem, you can get an inverse time delay breaker for it with the correct 20 amp rating. That type breaker will allow for starting current.

 

[Bob Bancroft]

Hopefully a motor that big can be wired 220V. That's what you really need.

 

[Anonymous-0]

Check your line voltage, if it is low, that could be the reason.

 

[buickanddeere]

IF it really is 2HP continuous on 120V. The old compressor may have been 2.5HP peak which is approx 3/4HP continuous.
A 20 amp breaker is too small to handle the full load current let alone the startup current.
2HP on 120V is approx 24amp. The required breaker according to code would be 60amp. Wire would be sized for 30amp.

 

[tomturkey]

I would check the motor to see if it can be wired for 220. I believe most 2hp motors will have that capability. I had to have the real electrician at work walk me thru it and I drew some pictures of L1, L2, etc and how they hooked up. Lights don't go dim in the shop when the comp starts up. my .02 worth gobble

 

[John T]

Okay, lets take this one step at a time: As a poster recently complained and with which I agreed (Sorry Billy Bob lol) there's too few "solid answers" here to electrical questions I, as I have done for 15 years, will try my best to provde a somewhat at least "solid answer" although, Im rusty on the latest codes grrrrrr too long retired SO NO WARRANTY I advise you check with local authority and professional electricians and engineers and take their advice NOT mine.......

YOUR 20 AMP BRANCH CIRCUIT IS UNDERSIZED, YOU NEED A 30 OR 40 AMP BRANCH CIRCUIT!!!!!!!!!!!


1) Yep, if its tripping, assuming the circuit breaker is operating correctly, THE LOAD IS SIMPLY TOO MUCH CURRENT FOR TOO LONG OF TIME.

FIRST COMPUTE THE LOAD

2) A 2 HP single phase motor operating at 120 volts will draw, at full load, around 24 amps AND THE START UP CURRENT WILL BE MUCH GREATER FOR A SHORT TIME PERIOD depending on if the unloader valve is operating correctly to unload head pressure and a few other factors not limited to type of motor etc.

SECOND SIZE THE BRANCH CIRCUIT FOR THE LOAD

3) For a motor branch circuit using a motor that has a full load of 24 amps, THE MINIMUM BRANCH CIRCUIT USED TO SUPPLY IT WOULD BE 3O AMPS but thats crowding the 80% rule i.e. 80% of 30 amp circuit = 24 amps max continuous full load current. While a 30 amp circuit can legally supply a continuous load of 24 amps, if the circuit distance is long, one might bump that up to a 40 amp branch circuit, which will also reduce voltage drop.

SIZE THE WIRE AND OVERCURRENT PROTECTION DEVICE

For a max continuous load of 24 amps, wire having an ampacity of 30 amps will suffice (but 40 would be better especially if a long run) so that requires AT A MINIMUM 10 gauge wire (subject to enclosure and other factors) and better yet 8 Gauge. That takes 10/2 with Ground or 8/2 with Ground for 120 VAC.

For 10 gauge wire the overcurrent protection device (breaker) would be a 30 amp and for 8 gauge wire 40 amp.

NOWWWWWWWWWW NOTE 1: If the branch circuit used a fuse instead of a circuit breaker, a Class K5 Dual Element Time Delay 30 amp fuze is designed to allow a motor to start up (when current is higher a short time) YET NOT BLOW if the current shortly exceeds 30 amps.

NOTE 2 (Circuit Breaker as Overload Protection Device) : If the motor is equipped with thermal overload protection and even though 10 gauge wire normally requires a 30 amp breaker AS I BEST RECALL (no warranty, check NEC) THE CODE ALLOWS UP TO A 175% OVERSIZED BREAKER AS NECESSARY TO ALLOW THE MOTOR TO START WITHOUT TRIPPING THE BREAKER.

NOTE 3: At the motor and within 50 feet I ALWAYS SPECIFIED A SAFETY DISCONNECT METHOD and to allow for vibration I ALWAYS SPECIFIED FLEXIBLE CONDUIT for the last to motor connection.

NOTE 4: Of course, the motor should have thermal overload protection, be it internal or an external starter.

NOTE 5: Id prefer it if the motor could be wired for 240 volt operation IS THAT AN OPTION???? Thats only 12 amps in which case a 20 amp (No 12 wire) 240 volt branch circuit would suffice.

Im sure I missed a lot (been too long) so hopefully the other fine electricians and sparkies can add to or correct this as were never too old to learn.

Ol John T

 

[IH2444]

How long is the wire run from the breaker to the air compressor?

 

[Ken Combs]

First things first: up until a couple of years ago all air compressors makers lied about HP. So, comparing the two or sizing a circuit based on compressor HP ratings is a shot in the dark. Take a look at the motor label and let us know what the amp and voltage ratings are.

I think it likely that the 2HP is 'optimistic' and the real load is less.

 

[M-MAN]

Any motor over 1 hp really needs 220v. There's a lot less headaches that way. JMO

 

[MarkB_MI]

Voltage drop is the enemy of air compressors and other devices with high starting loads. It is highly unlikely that your compressor is really 2 horsepower. What does the data plate on the motor say is the amperage rating? Probably 15 amps or less. Most likely voltage drop is causing the motor to draw too much current for the circuit. An electric motor can draw much more current than its rating, and will do so if it can't get the torque it needs to get up to running speed.

First, what gauge wire is running to the compressor, and how long is the run? Just because you have a 20 amp breaker doesn't mean the circuit was wired with 12 gauge conductors; if it's only 14 gauge it's not going to work. If the run is over, say, 30 feet from the panel, you probably need 10 gauge to get acceptable voltage drop.

What's your voltage drop at the panel? Plug your voltmeter into an outlet that's on a different circuit and check how much the voltage drops when you fire up the compressor. If you see any measurable voltage drop, you have a problem that's not going to be solved by heavier wiring downstream of the panel.

Are you using any cord other than the factory cord? If so, it needs to be at least 12 gauge.

My guess is you'll have no problems if you can run 10 gauge wire from circuit breaker panel to the compressor outlet. Run a new dedicated circuit for the compressor and be done with it.

 

[bjb in TX from Ne]

My CH 60 gal compressor requires a 20A @ 220V at that is for a 3HP motor.

 

[Sparktrician]

I had one of those damn things....same exact compressor. I had to plug it into a 50 amp ckt to get it to start. That motor had a heck of a startup draw.

 

[mkirsch]

IT's this one, right?

http://www.external_link/product__10151_-1_10051_18827

It's a 120V-only motor, and comes with a conventional 15A plug wired from the factory.

That indicates you should be able to plug it right into a regular wall outlet and run it. Of course, RTFM (read the fine manual) may be a prudent course of action to see if the compressor has any special electrical requirements.

Have you considered that the compressor may be defective right out of the box? It does happen.

 

[JGayman]

I appreciate everyone's feedback. I will try to provide additional detail. The outlet is approx. 35 feet from the breaker and uses 12/3 wire. I had it installed by an electrician.

The compressor unit is a Kobalt Model #: VT6389. It is made for Lowes by Campbell Hausfeld. The motor is a Marathon. The tag lists 120V, 1PH, HP = SPL, RPM 3450, 15A, SF 1.0.

It appears to be 110V only although 220V isn't an option for me anyway because this is a portable compressor and while it lives in the basement most of the time I can wheel it outside if needed.

The compressor appears to be off-loading each time it stops as there is a big hiss each time.

I ran it for about 25 mins yesterday and it started and stop/started the whole time fine.

I have a Reliance Electric AmWatt Appliance Load Tester that I attached this morning. The compressor started up and indicated 10 AMPs of continuous draw. My old HF compressor would draw 16 AMPs and it never tripped the breaker. Obviously my little load meter is too slow to indicate the startup current.

So obviously the motor is drawing a big spike at startup. The question is - is it normal and what can I do to correct it.

The compressor is only a couple months old so I guess it could have a defect.

 

[Geo-TH,In]

"I assume it is somehow exceeding 20 AMP for a few milliseconds while it starts."

Why ASSUME? Amprobes are so cheap get one and measure the amps. HF has them real cheap. Also HF gives away volt meters. Measure the voltage at the plug when there is a load.

Rarely, the circuit breaker goes bad. Remove breaker and look at the back and the buss bar for heat stress.

I'm sure people will find fault with what I'm about to tell you, but it does work. I have a 60 year old air compressor, 1.5 hp 2 stage. It came with 2 belts. I removed one belt and don't have the one belt real tight. So in the winter, when it has trouble starting, the belt slips a little and takes stress off the motor. Been doing this for decades. Belts are cheap.

 

[JGayman]

"Why ASSUME? Amprobes are so cheap get one and measure the amps. HF has them real cheap. Also HF gives away volt meters. Measure the voltage at the plug when there is a load. "

I have plenty of multimeters so measuring the voltage isn't an issue. Measuring the instantaneous current is the problem. Even if I had a clamp on AMP meter and tore the outlet apart to reveal the individual wires, most digital AMP meters will not show an instantaneous current draw lasting only a few milliseconds.

 

[JGayman]

Actually it is this one from Lowes...

http://www.lowes.com/pd_268707-1126-VT6389_4294795218__?productId=3824207&Ns=p_product_qty_sales_dollar1

 

[John T]

OKAYYYYYYYY thanks for the update and now that we have the CORRECT information (it was quoted as 2HP before so thats how I based my reply) the answer changes......

If the compressor draws 15 amps (or less) at full load, THEN A 20 AMP BRANCH CIRCUIT SUFFICES AND IS CODE COMPLIANT. HOWEVER subject to the total length from the panelboard to the compressor if voltage drop is excessive and thats causing a problem???????? increasing the wire size to 10 Gauge wouldnt hurt and that would allow a 30 amp breaker which might allow the motor to start!!!!!!!!!!!!!!

ALSO if the motor has thermal overload protection the code (as I recall, been too long) allows a bigger circuit breaker that would allow it to start without tripping the breaker.

I would try 10 Gauge wire and/or a 30 amp breaker n see what happens IFFFFFFFF THE MOTOR IS OKAY AND NOT DEFECTIVE THAT IS

Is it a capacitor start motor?????????? If so the start capacitor may be defective!!! and that might fix it with NO wiring changes????

Dont give up yet, a bigger breaker or bigger wire or perhaps a capacitor (if so equipped) might cure the problem.......

PS I used to go to auctions where there were always a ton of what looked like new Campbell Hausfeld Compresors that were store returns under warranty BECAUSE THEY WERE DEFECTIVE sooooooooooo it may be junk even if new grrrrrrrrrrrrrrrrrr

John T

 

[Geo-TH,In]

Amprobes can measure LRA, voltmeter can't.

Did you try loosening the belt?

Look at back side if breaker?

 

[MarkB_MI]

There seems to be a misconception that high starting current is bad. Not so: Current equals torque, and you need torque to accelerate the motor to its running speed. The problem arises when the motor can't get ENOUGH current to come up to speed. That's what happens when you have excessive voltage drop; the motor wants to get up to speed, but it can't because it doesn't have enough torque to do so. It continues to draw excessive current until the breaker trips.

This being a new compressor, it's not surprising that it is drawing more current than your old compressor, even if its rating is slightly less. I think you have a voltage drop issue, you just need to find the source.

 

[Bus Driver]

Article 430 in the NEC pertains to motors. Far too involved to post details here. But under some circumstances, a larger breaker can be used. Be sure to follow the NEC.

 

[wilson ind]

My electrical credintels specify Billy Bob rating. However in the past I did employ a qualified electrican doing up to 3 phase 440 wiring.He always said I knew enough about electricity to be dangerous. On a couple of large jobs,farm systems we had severe problems with voltage. Local REA would come out and check voltage either very early or just before noon. Voltage problems were always between 7;00am to 9 am. Crafty guys those REA folks. Momma would cook breakfast run dishwasher wash clothes , electric dryer , electric h2o heater possibly vaccum just after kids left for school and dad went to work. Finnaly hog tied REA engineer and checked voltage at 8;30 one morning. 90 volts !!!!Have you started your machine at 5 am with no problems, then in afternoon on hot day with local folks using air condition?

 

[John T]

Geeeeeee Wilson, todays woment wont do all that nowadays, theres no more low voltage problems in the mornings lol

Hope all went well the other day

John T

 

[JGayman]

"Have you started your machine at 5 am with no problems, then in afternoon on hot day with local folks using air condition? "

I will make a point of checking the voltage at the outlet the next time I start it. It is odd that one time it trips the breaker and the next it does not.

 

[JGayman]

"OKAYYYYYYYY thanks for the update and now that we have the CORRECT information (it was quoted as 2HP before so thats how I based my reply) the answer changes......"

Thank you. Yes, sorry about that. I was simply going by the fact that the unit is advertised as having a 2HP compressor motor.

 

[John T]

NOOOOOO problem, hope you get it going

John T

 

[Geo-TH,In]

Bill, that is a great idea, checking the voltage at the recept. Wish I had thought of it
George

 

[vinnied]

try a new 20 amp they get weaker the more times they brake

 

[MarkB_MI]

UL 489 requires testing for 6000 trip cycles at the rated current, plus another 4000 mechanical cycles.

 

[buickanddeere]

What is the actual name plate data?

 

[MarkB_MI]

Per earlier post:

"The compressor unit is a Kobalt Model #: VT6389. It is made for Lowes by Campbell Hausfeld. The motor is a Marathon. The tag lists 120V, 1PH, HP = SPL, RPM 3450, 15A, SF 1.0."

 

[buickanddeere]

So 2HP peak and 1HP continuous. A 20 amp breaker is borderline in such an application.
Have to wonder the utility voltage and then cable size plus cable length .
Sounds like a case of VD.

 

[MarkB_MI]

VD is NEVER good!

 

[JGayman]

"What is the actual name plate data? "

Actual data is:

MOD 5KCR48TN2582Y
HP SPL HZ 60
V 120 PH 1
RPM 3450 Code G
A 15.0 SF 1.0
SFA FR56
AMB 40C Class B
Time Rating Cont
MCO 19200AV
Marathon AC Motor
MC019200AV

 

[JGayman]

I may have "hopefully" found a big contributor to my problem. As someone suggested I checked the belt tension, it was TIGHT! I mean steel-bar tight.

I adjust it to have a more acceptable tension and so far I've started the compressor a half a dozen times and it has not tripped the breaker.

I'm currently in wait-n-see mode. If the breaker tripping problem returns I will look into beefing up the electrical connection as others have suggested.

Thanks all... I really appreciate everyone's feedback on this one!