I'm in deep shi*t... blew it up.

EL1NOR

Member
Apr 14, 2003
227
0
16
Hampstead, NH
The $500 compressor I bought... yeah, I just blew the motor on the first power-up.

For those of you that helped me out with the wiring earlier... something went wrong.

Here are the final details.. I have no idea what went wrong:

-=Generator=-
240V output at 30amps

-=Compressor=-
240V input at 15amps

http://www.sears.com/sr/javasr/prod...vertical=TOOL&pid=00918419000&tab=des#tablink


I purchased a small sub-panel to run alone just for the use of the compressor. I also purchased a double breaker for the 240V input from the generator. The breaker was rated at 15amps so as to not blow the compressor.

The wiring used was 4-strand 240V outdoor electrical wire. Heavy duty and expensive.. $2/foot!! Inside of the large cable were the four colored wires:

1.)Black ----120V power
2.)Red ----120V power
3.)White ---- Neutral
4.)Green ---- Ground

Let's start at the generator where the power comes from... The 4-pronged plug I bought was wired onto the 4-wire cable and plugged into the generator. That wire then ran 15 feet into the garage and was hard-wired into the sub-panel.

The wiring in the sub panel is as follows:

1.)Black ----onto 1st post inside sub-panel for power
2.)Red ----onto 2nd post inside sub-panel for power
3.)White ---onto one open slot on the ground/neutral strip post
4.)Green ---same as white

Unlike full panels, the sub-panel only had one strip post for the ground and neutral wires... Full panels have a strip for ground wires and a strip for neutrals that is typically connected as one by a jumper.

The main connection on the ground/neutral post that actually supplies the ground to the green and white cables I got by tapping into a ground on a nearby 120V power outlet.

The 15amp circuit breaker was then plugged into the sub-panel. And since it was a double breaker for 240V, it took power from both the black and red wires that were coming in from the generator.

Still with me?????

Now for the wiring to the compressor:

Using the same type of 4-strand wire, I hard wired inside the sub-panel box as follows:

1.)Black ----onto 1st post of 15amp double breaker
2.)Red ----onto 2nd post of 15amp double breaker
3.)White --- Not wired at all due to compressor
4.)Green --- onto one open slot on the ground/neutral strip post

That set of wires then left the sub panel box and was hard wired into the compressor as follows:

1.)Black ---onto 1st post for power
2.)Red ---- onto 2nd post for power
3.)White --- not wired at all due to compressor not having a spot for it
4.)Green --- onto ground on compressor

-------------Here's what happened-----------------

Turned on the generator... it ran great as usual....
Flipped the switch on the double breaker...... no problems still
Flipped the switch on the compressor.... it ran, but rather violently... no smoke though....

When I turned the compressor on I noticed the generator started shaking violently, so I walked out of the garage to look at it... When I got to the generator, I turned around to notice a TON of BLUE SMOKE POURING out of the compressor.. I ran to it and shut it off and the generator stopped shaking so violently... The circuit breaker never flipped off. I knew I was in deep ***** when I saw that the smoke was coming out of the ELECTRICAL MOTOR. Through the screen I can see the hundreds of copper wires... about 20 are pitch black now and the compressor won't turn on anymore.

What went wrong folks? What did I do wrong? The motor is $250+ when the compressor was $450. Maybe I can try to return it...

wtf,
-Tim
 
There are a couple things to check. What is the voltage the generator is putting out? Even if the cord end was wired wrong and you had the only 110 going to it it would't start. What you want to do is check voltage at the compressor switch.On most pressure switches there are a set of contacts.One hot goes on the left and the other on the right.Hope this helps


















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mdjay said:
Man you scared the crap out of me! I thought you were talking about your car!!!

hahaha... no, no.. nothing THAT bad. I'd have a lot more curse words in the title then.

Swede,
I mentioned in my post that the generator gives out 240V @ 30amps. I also mentioned that the compressor DID turn on but then maybe 30 seconds after it was running, the motor started smoking. Very odd.... And yes, you're correct, there are two posts for each 120V line.

-Tim
 
EL1NOR said:
hahaha... no, no.. nothing THAT bad. I'd have a lot more curse words in the title then.

Swede,
I mentioned in my post that the generator gives out 240V @ 30amps. I also mentioned that the compressor DID turn on but then maybe 30 seconds after it was running, the motor started smoking. Very odd.... And yes, you're correct, there are two posts for each 120V line.

-Tim

there are several things that could have gone wrong.

#1 you can smoke a motor with low voltage, is your generator large enough to run the compressor?

I have a 5000W generator and it wont run my small 1.5hp emglo compressor.

What is the generator wattage and how big is the compressor?
 
WORTH said:
there are several things that could have gone wrong.

#1 you can smoke a motor with low voltage, is your generator large enough to run the compressor?

I have a 5000W generator and it wont run my small 1.5hp emglo compressor.

What is the generator wattage and how big is the compressor?

Generator Link:

http://www.generac-portables.com/generators/generator.cfm?id=148

Compressor Link:

http://www.sears.com/sr/javasr/prod...vertical=TOOL&pid=00918419000&tab=des#tablink

Generator is 5500 watts and compressor is 7 hp...

I thought the generator would do more than enough... what do you think?? :shrug:

-Tim
 
Interesting.. I just found this:

http://www.sawdustmaking.com/AirCompressors/air_compressor.htm

"RUNNING OFF A GENERATOR

There is often a problem using an electric compressor powered by a generator. Most electric tools have a "start-up surge" they need more current to start than they do to run. Electric compressors use about three times as much power to start as they do to run. A compressor that runs on 15 AMPS may need 45 AMPS (or more!) to start. The reason compressors don't blow your house's circuit breakers is that the demand is for a very brief time (thousandths of a second). The power lines have all the power your compressor needs, so the compressor starts, and the "spike" is so short in duration that your circuit-breaker doesn't have time to react. But your generator probably doesn't have that starting power available, so it will make a valiant effort, fail, and shut down - and your compressor won't start at all. Make very sure your generator is big enough to handle that huge start-up surge or consider using a gas powered compressor."

Why is it that the 2 "electricians" at the hardware store I talked to didn't even mention this? Hmm.. but why would mine SMOKE and blow?
 
Well, I'd try and take it back to Sears. Could have been wired wrong. (I had a MSD 6AL that was wired backwards, they fixed it for free and paid the shipping) If they'll trade you out for a new compressor, don't plug it into that generator, just in case.

You might also take a multimeter to your setup and see if everything checks out right.
 
Yeah, I'm definitely taking it back to sears tomorrow to swap it out.

I'm also going to check the polarity of the 2 120V lines.... the motor should have only tried to run but failed.... when it smokes and burns out that seems like a tell-tale sign of a polarity issue. It fried when it should had just sputtered.

Damnit,
-Tim
 
The one for my house is a small 25gal 5hp unit. It does blow the fuse from time to time on start up. IMO you're overloading the generator and starving the compressor. It would be the same thing as running a long low gauge extension cord to it. It just wouldn't start!
 
1320stang said:
Well, I'd try and take it back to Sears. Could have been wired wrong. (I had a MSD 6AL that was wired backwards, they fixed it for free and paid the shipping) If they'll trade you out for a new compressor, don't plug it into that generator, just in case.

You might also take a multimeter to your setup and see if everything checks out right.

don't tell them you ran it off a generator.

I think your gonna have to run that off house current. I know my 5000W gen wont run it.
 
EL1NOR said:
Yeah, I'm definitely taking it back to sears tomorrow to swap it out.

I'm also going to check the polarity of the 2 120V lines.... the motor should have only tried to run but failed.... when it smokes and burns out that seems like a tell-tale sign of a polarity issue. It fried when it should had just sputtered.

Damnit,
-Tim

There is no polarity on 220AC current, you can hook it up either way and it will run.
 
You still haven't told us what voltage you were getting at the compressor and which wires the voltage are on. I would check this before hooking anything else to it.Are you sure the compressor isn't 110? That would smoke it if you put 220 to it.
 
Swade and 2nd Mustang,
While I appreciate your help, the questions you are asking I answered in my original post already.

Yes, I filled it with oil, and yes it's a 240V.

You can also simply click on the links I provided which also answer those questions.

WORTH, thanks for the clearup with the polarity issue.
I will definitely end up using house current which is gonna suck due to wiring $$. I'm heading out this morning to exchange it, I'll just say it never worked and I want to try another one.

-Tim
 
lol, they took it back no questions asked... just like their policy.

Too bad I had to go through literally 6 different clueless goons to find someone who knew what they were doing. I ended up in Human Resources.. lol

This time I'll have it hard-wired and triple check everything.

I'll be back,
-Tim
 
EL1NOR said:
lol, they took it back no questions asked... just like their policy.

Too bad I had to go through literally 6 different clueless goons to find someone who knew what they were doing. I ended up in Human Resources.. lol

This time I'll have it hard-wired and triple check everything.

I'll be back,
-Tim
You lucky bastige :D

How far away is your main panel?