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Need more powerful tool! by mwbackus
Started on: 03-23-2000 12:43 PM
Replies: 16
Last post by: mwbackus on 04-07-2000 07:08 AM
mwbackus
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Report this Post03-23-2000 12:43 PM Click Here to See the Profile for mwbackusSend a Private Message to mwbackusDirect Link to This Post
I was hoping that some of you electrical wizards could give me some advice on a problem I have. I recently rented some addtional garage space (ie.. too many projects) specifically for Fiero repair. The problem is that the line voltage supplied to the garage is being limited in some way. It will run some lighting, but is too weak to opererate my air compressor. The compressor is just a little 4hp 120v, 15amp unit and works fine anywhere else I use it. What would be required to condition this line voltage so that it is capable of handling a 15amp load? I have thought about some sort of transformer setup, even a large computer system UPS, but that gets expensive real fast. I am also limited by the fact that this is a rental unit and the managment is not likely to cooperate with any modifications to the property itself..

Thanks in advance for any advise and input you can provide!

Mike

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fierospeeder
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Report this Post03-23-2000 12:54 PM Click Here to See the Profile for fierospeederClick Here to visit fierospeeder's HomePageClick Here to Email fierospeederSend a Private Message to fierospeederDirect Link to This Post
My garage only has one line of 15 amp going in. I turn off everything in the garage and run the compressor until it gets full. Then turn the lights on again. It draws 15 amps.
Another thing is, plug in the compressor and turn it on by the switch, that helps stop popping circuit breakers.

Im suppose to have an electrician come to hook up lights for me and another line, something like 30 bucks an hour, this summer.

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mwbackus
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Report this Post03-23-2000 04:32 PM Click Here to See the Profile for mwbackusSend a Private Message to mwbackusDirect Link to This Post
Problem with this garage is it is part of a large complex of garages, built like the storage units you can rent. So rewiring is out of the question. I know there is an easy way to do this, buy my electrician expertise is somewhat limited. With my dedication to the forum what it is, offering my help whenever I can, I am certain that there is an electrical expert here that could help me out with this little setback.

Mike

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DRH
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Report this Post03-23-2000 05:10 PM Click Here to See the Profile for DRHClick Here to Email DRHSend a Private Message to DRHDirect Link to This Post
I'm not an electrician but I know something about this stuff. I'll take a stab until someone better jumps in.

Voltage should not drop significantly unless you are putting more load (amps) than the supply can handle. Usually the limiting factor is a circuit breaker or fuse that blows. What happens when you try to run the compressor?

Most standard 120v circuits can handle at least 15 amps. What else is on the circuit?

It sounds like the problem is that the circuit for whatever reason can only supply say 5 or 10 amps. I'm not sure what you can do.

A transformer won't help. You would still only be getting "n" amps

A UPS might work. One that could handle that kind of load would probably be very expensive though. Also, not sure if those are made to "smooth out" a power supply. More to provide power for a short period if line is off.

Of course a separate gas powered generator large enough to supply the comp. would work but would be rather expensive.

Hmmm...

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mrfixit58
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Report this Post03-23-2000 05:21 PM Click Here to See the Profile for mrfixit58Click Here to Email mrfixit58Send a Private Message to mrfixit58Direct Link to This Post
mwbackus,

The problem is the electrical service to the storage area is too small. The wire size is probably a AWG 14 if it is protected by a 15 amp breaker. And, to compound the problem, if your a long way from the panel, your voltage is probably between 100 and 110.

ELECTRICAL LESSON ONE: Your motor will consume the same amout of power reguardless of the voltage. That means that the current will go up when the voltage goes down! This is why circuit breakers pop even if your motor nameplate says it should pull less than the size on the breaker. Initially start up of the motor is even worse.

The way I see it is like this, you have two choices: Ask the landlord to upgrade the service to your stall; or see if you can re-wire your motor for 240. If you can't do one but can do two...

ELECTRICAL LESSON TWO: you will have to find a second outlet that is off of a different phase. If you can find two (using a voltmeter and a couple of long leads) you can make a 240 volt cor using two seperate cords: hot leg one, hot leg two, a common neutral, common ground. Above all... BE CAREFUL!!!

Hope this helps,
Roy L.

P.S. I'm an electrical engineer.

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mwbackus
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Report this Post03-23-2000 08:32 PM Click Here to See the Profile for mwbackusSend a Private Message to mwbackusDirect Link to This Post
When the motor kicks in seems to be the problem, but only with air in the tank. It will actually fill up the empty tank completly, then shut off as normal. But, when the air pressure drops to the kickin level and the motor trys to come on it lags and runs slower and slower until it actually stops and humms. I am thinking maybe a UPS might be the only way to go. What size would one need to use for this? Would the line-interactive type kick in and use the battery for the short durations of pressure cycling?
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RFMike
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Report this Post03-23-2000 08:55 PM Click Here to See the Profile for RFMikeClick Here to Email RFMikeSend a Private Message to RFMikeDirect Link to This Post
The size of the UPS is way beyond what you want to spend. The best solution is as MrFixit suggested in lesson 2. If your compressor can be switched over to 240, it will run just fine, as it will then only draw 7.5 amps per leg.
When I was doing trimwork, my compressor would usually pop a circuit, since it drew 20 amps at 120 volts. Here was my solution:

Buy a dryer plug and receptacle. Make a pigtail connecting a 120v receptacle and the dryer plug. Wire up the dryer receptacle to 240v. Switch over the compressor motor (this is usually two or three wire lead relocations, and is usually diagramed on the inside of the access plate on the motor). Plug in the dryer plug into the receptacle, and the compressor into the other end of the pigtail.

!!!!!!!Caution: 1) Never leave this plugged in if you aren't there. The pigtail is now 240 v, and will fry any 110v tool in less than ten seconds (some in a second).
2)Never plug in the compressor into the 240v pigtail without switching it over to 240v, for the same reason.

This jury rig is physically safe. It won't start a fire, and won't electrocute you. It allows you to quickly convert your compressor to 240v use, and back to 120v. However, it probably is not a good solution if there are other people around that might inadvertantly plug something in to the pigtail. When I did this setup, I would take the pigtail with to prevent any misuse.
Or you could just wire up a 240v receptacle, cut the plug on your compressor, and install the matching plug. The drawback is you probably wouldn't be able to use it at home, without wiring a matching outlet at home. However, your compressor would probably run better and longer on 240v.

Long winded is my strong suit, once I get going.

Good luck,
Mike

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mrfixit58
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Report this Post03-23-2000 10:43 PM Click Here to See the Profile for mrfixit58Click Here to Email mrfixit58Send a Private Message to mrfixit58Direct Link to This Post
It's me again. I gave your problem a little more thought and jump started a few more brain cells and came up with something a little more do-able.

If you can find another outlet being fed from a different breaker AND it is the SAME phase as the first outlet (volt meter between the hot leg reads zero volts) you can simply connect the two together. This will give you effectively 30 amps at 120 volts. More then enough to start and run your compressor and you would not have to re-wire the motor. Remember, they MUST be fed from different breakers.

Use good quality extension cords that are rated for at least 15 amps. Hint: To find out if two outlets are on the same phase or different phases, plug the cords into the outlets, streach the ends of the cords close enough so you can use your multimeter to measure the voltage between the hot legs (usually the shorter slot on the right)... zero volts between the two hot legs (or very low) mean the outlets are on the same phase; 240 or 208 volts mean that they are on different legs.

You can make a good quality extension cord using #14 or #12 romex and a couple of cheap plugs. Always uncoil your extension cord to prevent excess voltage drop (this is called building a choke in electronics).

Hope this helps,
Roy L.

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cobra427
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Report this Post03-23-2000 10:46 PM Click Here to See the Profile for cobra427Click Here to Email cobra427Send a Private Message to cobra427Direct Link to This Post
mw, heres another thought. If you have access to the fuse panel and can locate your circut,(by blown circut breaker)take the panel cover off and check to see if it is a AWG14 or AWG12 wire that is connected to that c/breaker.(probably a AWG 14 600V wire ).If it is a AWG12 600V wire,you could change the c/breaker to a 20 amp and should cure your problem but if it is the AWG14 wire,you may have to go as previously stated to a 240 volt hook up.A 15amp line is usually a 14 wire. (light duty application)

HTH
cobra427

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Robert
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Report this Post03-23-2000 11:38 PM Click Here to See the Profile for RobertClick Here to visit Robert's HomePageClick Here to Email RobertSend a Private Message to RobertDirect Link to This Post
Two thoughts;
1: I had the same problem with my own compresser when I plugged it in to the outlet at the far end of my property. I solved the problem by plugging it in near the box and getting a longer air line.

2: What about a gas powered generator?

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mwbackus
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Report this Post03-24-2000 12:14 AM Click Here to See the Profile for mwbackusSend a Private Message to mwbackusDirect Link to This Post
Those are some great ideas guys!! Thanks so much.. Those gas generators are way expensive though, may as well buy a gas operated compressor..
I blew the breaker for the entire section of the complex earlier today.. bad Mike, no no! :0 I am hoping that the managers replace it with something rated higher, may take a few days of blowing breakers, hehe. I hate to rent things, but when you run out of space, the Fiero projects take precidence and it would'nt fit through front door of the ol' homestead. I also like the idea of using a better and shorter cord, will try one and see if that helps. It will be nice if I can get this to work, the garage is just around the corner from me. Thought about running a cord from my place, but thats surely not a good idea. Thanks again!

Mike

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Report this Post03-24-2000 01:16 PM Click Here to See the Profile for DRHClick Here to Email DRHSend a Private Message to DRHDirect Link to This Post
Hmmm... How far?

Running wires probably wouldn't be the best of ideas unless it is really close.

Maybe leave the compressor at home and use a long air hose???

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Report this Post03-24-2000 07:57 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreDirect Link to This Post
From the discriptions I'm reading here...... those buildings do not meet national electrical code, and should not even be allowed to operate. (The better of national or local is what applies.) I'd find someplace else to rent before they have the inevitable fire and destroy your property.

You're best bet, if you stay there, is a portable generator. Keep an eye out..... allot of people bought these for Y2K and don't want them now. (Demand was so high at Northern they couldn't gaurantee shipments.)

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mwbackus
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Report this Post03-24-2000 08:43 PM Click Here to See the Profile for mwbackusSend a Private Message to mwbackusDirect Link to This Post
I would agree entirely, the building is not even up to code. There are 8 garages in each section, each with a light inside. There are also 4 outdoor lights (halogens), one at each corner. It is obvious that everything is on one circuit, since I blew the breaker and not one light (halogens included) in the section has power. Luckily this is only a temporary thing, a couple months from now and I should have cleared enough space in my garage to put her back in there. Too many damn spring projects

I bought a nice thick 12/3 extension cord and a high rated (20 amp) outlet today. It originally had a cheapo 13 amp outlet(where do they get this junk?). I put the new outlet in, but the manager hasn't been around so the breaker is still blown. (I dont know where the panel is). Oh well, I am sure he will get plenty of complaints flying at him when he returns.
If this does not work, then I may be forced to buy a generator. The Y2K thing is real good forsight, may even work out cheaper than a gas powered compressor.

[This message has been edited by mwbackus (edited 03-24-2000).]

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RFMike
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Report this Post03-26-2000 01:17 PM Click Here to See the Profile for RFMikeClick Here to Email RFMikeSend a Private Message to RFMikeDirect Link to This Post
MWB,
Make sure the generator you look at can run your compressor. At one point, I had a generator that was rated at 4500 watts. I theory, this should have run my compressor. It couldn't handle the initial current required at motor startup.
Maybe you should talk to the manager, and offer to run a 220v liine to the unit. It would probably cost you about $30, depending on the length of run, and the type of receptacle you use. Then you wouldn't have to worry about popping a breaker.
Ogre's right, you should probably find another rental.
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Report this Post03-26-2000 01:50 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreDirect Link to This Post
Assuming those are the common 300W out door halogen. the cicuit is already near capacity. add 8 or more 60-100w lamps and it's on the edge.

Just before you leave you should file a complaint with the state fire marshals office. Don't mention the compressor.

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mwbackus
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Report this Post04-07-2000 07:08 AM Click Here to See the Profile for mwbackusSend a Private Message to mwbackusDirect Link to This Post
I just wanted to update my situation with the electical problem. I replace the outlet and got a real nice 20 amp extension cord and it works OK now! Thank you everyone for you help on this, I really do appreciate it!

Mike B. (who now has more powerful tools thanks to my forum partners).

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