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Discussion Starter · #1 ·
First...thanks for all of the responses to my previous air compressor post. Here's the new problem:
i purchased an air compressor, but I can't run it in my garage. It is constantly tripping the breaker regardless if the tank is at 40psi or 100psi. The compressor requires a 15 amp circiut, and according to my breaker I have a 20. It appears that my whole garage(rental house) is wired to the same circuit, so i tried turning off all lights, etc, but it still tripped the breaker. Could it be the breaker is bad and needs replaced, or a crappy wiring job in the garage? What can I do, It's frustrating to buy a new toy and not be able to use it! Thanks for any response.

Dan 84 CJ-7,Weber,HEI. 95 ZJ,V8. http://netnow.micron.net/~wdohrn/
 

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First what did you buy? What size motor, etc. Looking at the old post and what you were considering,
15 amps would be about right for 208/220 volts, not for 117/120. A Mr. Coffee draws 15 amps at 117
volts.

Circuit breakers don't usually go bad and when they do, usually it's because they won't reset. I've
changed my share. I also doubt the problem is in the wiring. It might burn your house down, but it
should still run the compressor.


 

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Discussion Starter · #3 ·
I ended up getting a Craftsman 4.5hp, 20 gal. Unfortunately my budget wouldn't allow me to take the advice that most people gave me. I had to go with a lower-end single cylinder compressor.
In the specs for the compressor it says "Voltage-single phase 120." Electrical stuff isn't my specialty, so I thought if it fits into the wall plug it would work. But after seeing the 120, I'm not sure. Does that mean it won't work in a 110v typical garage outlet? I thought the important thing was the amperage and since I have a 20 amp circuit and it requires a 15 I figured i'd be ok.
If anyone wants to give a quick lesson on electricity, I'm willing to "listen."
Thanks,

Dan 84 CJ-7,Weber,HEI. 95 ZJ,V8. http://netnow.micron.net/~wdohrn/
 

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/wwwthreads_images/icons/smile.gif Hi Dan. The truth of the matter is, that no matter what size it is, an air compressor wants your BEST stuff. They are probably the toughest electrical load that you will find in everyday homes, shops, and industry. If the breaker will not stay in, several things could be causing it: (1)...It could have a poor "bite" on the bus bar in the circuit breaker panel itself. The dinky spot where the breaker actually pulls the current off the center conductor of the box may be slightly burned. The jaws of the breaker may be softened from prolonged overheating and no longer have spring tension, or it may be crooked and not getting a good bite, reducing the "footprint" for current to actually flow through. All of those conditions will cause heat and trip the breaker. (2)...the conductor from the breaker to that dinky wall plug may be too small to do the job. PLUS....the wall plugs may be "daisy-chained" where the current goes from one to the other, to the other, gathering up more connections as the chain grows, and more losses and places to heat up. (3)... the plug itself may be kaputzo....softened from prolonged overheating, and only rated 15 amps to begin with when it was brand new. You can probably get this to work, but it means that you will have to "sweep out the corners"....in other words, start from the circuit breaker panel and make everything perfect all along the line. As I said before, air conmpressors want your "best" stuff./wwwthreads_images/icons/wink.gif The other thing that doesn't add up here is the HP. A 4.5 HP motor on 115 volts would draw a MINIMUM of 48 AMPs. If it were on 230 volts it would draw at least 24 AMPs...../wwwthreads_images/icons/crazy.gif

CJDave
I never believe any statistics unless my moonguys /wwwthreads_images/icons/crazy.gif/wwwthreads_images/icons/wink.gif made 'em up themselves.
 

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What was commonly referred to as 110, now referred to as 120, is typically 115 to 118 volts.

I'm not getting an amperage as high as Dave, but I get about 30 amps on 117 for a high efficiency motor.
My vacuum cleaner is rated at 9 amps! Does the compressor you bought happen to come in two
models and say 120/240 volt, 30/15 amps? That's 15 amps at 240 volts or 30 amps at 120 volts.


 

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As CJDave said, you probably have problems with your power delivery system. Get a multi-meter and check voltage at the compressor. As voltage goes down, amperage goes up. The house could also have problems with light guage wire (14ga) and or aluminum conductors. Run a seperate 20A 12/2 copper w/ground circuit to your garage just for the compressor. Keep it as short as possible, under 100'.

As far as the amperage not adding up, they never will with consumer goods. The reason is the manufacturers always list the amperage rating at maximum draw for showing how powerful their equipment is. With a compressor or any motor, that figure is usually only reached when starting. Yes, the unit may draw 28 amps at 120v at startup, but only for a brief period, not enough time to typically heat up the breaker and trip. In reality the unit is probably 1 hp or less. Electrical motors and subsequent energy requirements is very complicated, and only more confusing when you pay attention to manufacturers marketing propaganda.

Enjoying Montana's Big Sky (& rocks & rivers & mountians etc, You get the picture.)
 
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I'm not "electrical" either, and made the same "mistake" you did when I bought my compressor a few months ago. My mistake was not asking for help on this board first, but have since learned that the oil filled, 220 volt is the way to go. I got a 5.5 hp, single cyl, 20 gal tank, 110 volt. When it kicks in, you can sure tell what all is on the same circuit. Lights dim almost completely out etc., but it does crank up and run.
Visualize starting your Jeep IN GEAR. We do that. In fact, Jeep manuals recommend that in some circumstances, but the load on the starter is VERY noticable. That's exactly what you are doing with your compressor. It is in gear ALL the time. If it had a clutch to engage the compressor AFTER you get the motor going, it would not be near the pull on the electric current.
I'm with CJDave. The first thing I would look at in your case would be the breaker itself. They are not expensive. Install a new one and see what happens. Don't go over the rating of the one you are replacing, or you might move the compressor to different circuits to see if that makes a difference.
Are you using an extension cord? If you are and if it is too small, that may be the problem. My compressor manual says not to use anything less than 10 guage, I think. May even be bigger, but it sure ain't no Christmas tree light extension cord. /wwwthreads_images/icons/smile.gif
Lastly, there really could be a problem with the compressor. Not likely, but possible. If you can get it to a known very good circuit, you might try that. That happened to me. The first compressor I got ran very very hot the first time or two I used it, and then it quit altogether. Returned it to the store. They couldn't get it to run either. Second one works - not fine - but at least the way it is supposed to. I say - not fine - cause it is the cheap, non oiled 110 volt kind.

Doug '97 TJ
Creator of the CBrack
My Web Site
 

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Just a note on the use of extension cords. Don't use one. The compressor has a short cord for a reason, to limit current drop. Instead of an extension cord, use an extra air hose. Probably cheaper and much more handy. As far as 10 ga. extension cords are concerned, that is like having a 1/2" pipe feeding a 1" pipe. Skip the extension and make sure the curcuit is 12 ga. copper.

Enjoying Montana's Big Sky (& rocks & rivers & mountians etc, You get the picture.)
 
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Just another thought . All of the above are very good points. I have had to
do some of the fixes above with my 220V buss box welder.
but if they used the cheap plugins with the low amp rateing you could try
to change one to a better grade of plug in. If they are daisy chained you
are still running amps thru cheap plugins so try to get the first plugin
in the chain.
If Your compresser is cold it will take more amps to start it also.
I don't know how cold your garage is??
Taz knows more on this stuff its his field not mine./wwwthreads_images/icons/smile.gif
 

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Just thinking here, it's funny how you get a picture of something in your mind. I had pictured you garage
as part of the house, a ranch or split level, then it occurred to me that it might be detached and a
hundred feet away. And if the garage is detached, it could have been wired with anything. At any rate,
the wiring between the house and the garage would be just like using an extension cord. I think the
circuit breakers instead of fuses made me think of a more modern house.

Did you know that electricity was once thought to be a passing fad? Houses built during that time had
gas pipes run for lighting for when electricity would no longer be available. I owned one, rewired the
whole thing. It was knob and tube wiring. Switches, lights and outlets were just stuck in the ceilings and
walls with no boxes.
 

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/wwwthreads_images/icons/smile.gif In 1949, Thomas Watson, founder of IBM figured that there would probably be a world market for FIVE computers, and his helpers figured out that the time may actually come when a computer would weigh less than a ton and a half./wwwthreads_images/icons/crazy.gif

CJDave
I never believe any statistics unless my moonguys /wwwthreads_images/icons/crazy.gif/wwwthreads_images/icons/wink.gif made 'em up themselves.
 

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When I bought this house in 1980, the first thing I did was replaced all the #14 AWG wire with #12 but I protected each circuit with 15amp fuses to be sure the wire would never see its rated 20 amps. I live in an old neighborhood, row homes and all that. I figure it would be a good idea considering the danger of fire in an old house such as this. The previous owner obviously didn't understand basic wiring because the 3 way switches for the second floor hallway light were not wired correctly.(Shunts were wired where the travelers were supposed to be and the first floor switch was actually a 4 way...you get the picture.)

If your garage where the compressor is going to be far away from the electrical panel; it might be a good idea to oversize the wire by one size {ie. if it is going to be a 20amp circuit, use #10AWG wire(which is good for 30amps)} but protect it with a 20 amp breaker. This might help some with the voltage drop. Sometimes breakers fail because people use them as if they are a light switch and they will close but they won't trip on overcurrent. However, that doesn't seem to be the case here. Good Luck!!/wwwthreads_images/icons/smile.gif

Yes, Taz, my house had some knob and tube wiring in it plus a ceramic bodied switches when we moved in./wwwthreads_images/icons/crazy.gif

PS Since I work in a hospital, I replaced all the recepticles in the house with hospital grade.
 

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Im not sure what your problem might be, probably a bad outlet, or an extension cord is my guess!!

but I feel the need to add to the great info so far:

If you dont feel comfortable trouble shooting/replacing/testing these things please dont !! ( they can kill you!)

I would make sure there is nothing else on the same curcuit as the compressor, make sure the compressor is plugged in without any extension cord ( very important for the life of your compressor!), If these conditions are good replace the outlet( pretty easy), if no good still, I'd find a buddy with some electric experience!

just be careful!





ozarkjeep
1977 CJ5 looking for a Hard top near NW Arkansas!
 

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Discussion Starter · #14 ·
Well, after reading all of the posts...
I tried the compressor on a different circuit that is not in the garage and it worked fine. My garage IS detached from my house and quite a distance from the breaker panel. The most reasonable theory is that the wire going to the garage is too small of guage and acts as a long extension cord. I will however check the outlets to see if they are daisy chained or cheap ones. And I'll see if I can figure out how to replace the breaker without electrocuting myself. I don't think cold is the problem, because I tried it outside today and it worked fine.
Any tips on how to check the quality of the plug receptacles? I have an ancient(non-digital) multimeter, but it still works.
Thanks for all the suggestions and replies.

Dan 84 CJ-7,Weber,HEI. 95 ZJ,V8. http://netnow.micron.net/~wdohrn/
 

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Dan do what I did < kiss a little a$$ of an electrition buddy.
Don't hurt yourself!!!
I'll jump into just about anything headfirst except power that willBITE you. I don't know why I never learned any more about it but I did'nt.
At least I can go to sleep at night (not dead) and knowing my house (&family) won't burn down do to somthing stupid I did.
I need to take a course on basic wiring.......I'm a wiz (at least pretty good) at 12v. I guess cause it can't ZAP me/wwwthreads_images/icons/smile.gif

Wider is better but taller is cooler!
 

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Looks like it's down to how much you are willing to put into a rental house to use your compressor. I no
longer keep up with NEC so I don't know if you can run to the garage overhead or if it has to be buried.

What is a hospital grade outlet? It's been 30 years since I worked as an electrician in the base hospital
at McDill. I don't remember anything special back then other than that some where red for special
circuits.


 

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Discussion Starter · #17 ·
I just popped the cover off the breaker panel and about died when i saw the size of the wire coming out of the garage circuit breaker. It's smaller than my mouse cable. I'm suprised I could even run my circular saw on that circuit. Since it is a rental house and my lease is up soon, I think I'll just go with the old wheel the air compressor around to the house, fill it, wheel it back to the garage, use it, wheel it back...routine. Man that's going to get old quick. If anyone has any better ideas...I'm listening.

Dan 84 CJ-7,Weber,HEI. 95 ZJ,V8. http://netnow.micron.net/~wdohrn/
 

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Taz,
To answer your question, a hospital grade outlet (recepticle) is a heavier duty body 120VAC, 15 or 20 amp rated either in duplex or single. They also have a higher clamp tension (I think it is 24oz.) than other grades so that plugs cannot be pulled out accidently. You can recognize them by the green dot that signifies where the ground connection screw is located. They come in many different colors but red is for emergency circuits, orange is for isolated ground. They can also come in GFI form. They are large enough to be a tight fit in wallcases or handy boxes. They are also more expensive than specification grade. We usually only install them in patient care areas. We install them with the ground hole up so anything that falls along the wall hits the ground first and falls off without laying across the hot and neutral prongs. The brand we use is Hubbel.

 
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/wwwthreads_images/icons/blush.gif I think that the hospital grade sockets contacts are a litte deeper where the plug engages the contacts/wwwthreads_images/icons/blush.gif
I think
 

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How far are we talking from the garage to the house? 50 feet? 300 feet? Maybe you can get some long lengths of air hose, and keep the compressor in the house? That's what every Jeep owner should have in his living room - an air compressor! /wwwthreads_images/icons/smile.gif Granted, if your woman lives with you, this can be a challenge. /wwwthreads_images/icons/wink.gif

Pete
Off-road lights still in the living room, CJ grille on the porch. The woman doesn't live with me. /wwwthreads_images/icons/smile.gif

88YJ, 4"susp, 33"BFGMT, 9k#winch, rear homemade swingout, reb.258, 999, 4.10, weber32/36, GMHEI.
 
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