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Old 12-19-2009, 01:27 AM   #76
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Older air compressor wiring help


Thanks for all the help. I believe I have it wired correctly. I will try in the morning. The drawings really helped. No one ever answered about the grease type for the motor. Will standard high temp grease work or does it need to be some special type? LOL it does take grease doesn't it. Those sure look like grease serts to me.

Thanks again for all the help I have learned alot more than I knew when I started. Alway a good thing!!

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Old 12-19-2009, 01:47 AM   #77
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HI Lash

You need air compressor oil which is usually a 30 wt. non detergent. Go to the big box then to the air compressor department should be on the shelf.

As for the switch I would mount a handy box at one of the knockouts on the compressor starter enclosure.

The grease fittings are for bearings high temp grease is fine.
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Old 12-19-2009, 02:08 AM   #78
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Thanks stubbie. I have already drained and replaced the compressor oil. I plan to run it for a while and change it again because the oil I removed was a bit gummy. Would it be ok to mount the switch inside the box? There are a couple of knock outs on the front that look like they would fit it.
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Old 12-19-2009, 12:21 PM   #79
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Be careful when greasing an electric motor. Just about any kind of grease that's made for ball bearings will work, but stay away from synthetic. Even though it's actually a better lubricant, the bearings would have to be removed and cleaned of all mineral grease first.

Don't use too much. Two full pumps would be about right for a motor this size. Using too much will force the grease through the seals, and it'll be flung onto the end turns of the windings. All oils and grease will attack the insulation of the windings.

This usually isn't necessary, but to insure that no grease gets past the bearing seals, remove the drain plugs below the bearings first (if there are any). Then squirt the grease in. Then run the motor for 10 minutes or so. Then put the plugs back in. Usually, nothing comes out, but if it does, better here than on the windings.

Once every 3 years is about right for your application.

Rob
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Old 12-19-2009, 12:52 PM   #80
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Originally Posted by lash-1295 View Post
Thanks stubbie. I have already drained and replaced the compressor oil. I plan to run it for a while and change it again because the oil I removed was a bit gummy. Would it be ok to mount the switch inside the box? There are a couple of knock outs on the front that look like they would fit it.
Yes there are switch knockouts on the cover. The one on the right side of the cover is where a momentary start/stop goes. You just might get a decora type switch to fit right in that knockout. Or make a nice little plate and mount behind the knockout hole with a regular toggle switch to the backside of the plate. But yes one of the cover knockouts would be an excellent place for the switch but I wouldn't mess up the cover unless I had a perfect fit or nowhere else to mount the switch on the unit.

I'm not sure what the factory on /off switch costs. This mounts on the left in the 2 small rectangular knockouts. Might be worth checking out. You could just wire in the single pole and if no other issues get the factory on/off...I'll try to price it sometime today or tomorrow.
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Old 12-19-2009, 05:42 PM   #81
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The two knockouts on the left side of the cover are not for an on/off switch. They are for indicating pilot lights to tell you the status of the starter.

All switches go in the right hand knockout. the off/on is about 20 bucks through my supplier so you should be able to get similar pricing. It appears to be a selector type switch rather than a push button maintained.
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Old 12-20-2009, 11:23 AM   #82
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Lash

Just wanted to point one thing out. On the front of the starter you will see a small rectangular black button. This is the indicator that pulls in when the coil energizes closing the motor contacts. It is spring loaded to the coil solenoid. If you manually push it in the motor will run regardless of the on/off switch being in the off position. What you are doing is hand closing the motor contacts by overriding the control circuit. So be aware that if you push that button in and hold it in the motor will run regardless of the oil pressure switch, on/off switch or air pressure switch position. Once you release it the button will pop back up (spring ) and the motor will stop. It has a few useful purposes when trouble shooting or if you want to jog the motor a bit. Otherwise just be aware and keep your hands and clothing clear of moving parts if you push that button in.
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Old 12-20-2009, 12:14 PM   #83
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Older air compressor wiring help


Quote:
Originally Posted by Stubbie View Post
Lash

Just wanted to point one thing out. On the front of the starter you will see a small rectangular black button. This is the indicator that pulls in when the coil energizes closing the motor contacts. It is spring loaded to the coil solenoid. If you manually push it in the motor will run regardless of the on/off switch being in the off position. What you are doing is hand closing the motor contacts by overriding the control circuit. So be aware that if you push that button in and hold it in the motor will run regardless of the oil pressure switch, on/off switch or air pressure switch position. Once you release it the button will pop back up (spring ) and the motor will stop. It has a few useful purposes when trouble shooting or if you want to jog the motor a bit. Otherwise just be aware and keep your hands and clothing clear of moving parts if you push that button in.
Glad you pointed out that fact. (about the override switch. All of the above is provided the magnetic starter is wired correctly). As I said in the beginning of this journey. (The present thread.) Because if it's miswired all bets are off. As I encountered in my capacity as part of a maintenance crew in an HRF. (Health related facility) It seems that the Construction electricians (it was a brand new building) made a ton of mistakes in the wiring. For example, some of the "Mushroom" exhaust fans on the roof (those that ran on 3 Phase) had their motors burned out due to the fact that the installers never checked the direction of rotation. A lot of them spun the wrong way, burning out the motors!
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Old 12-22-2009, 01:57 PM   #84
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Originally Posted by lash-1295 View Post
Was told it was a 5 hp single phase so what I am missing is the full load amps. Any idea how to determine that? The only labels I can find at all are on the low oil cutoff and I think on the pressure switch itself.

Thanks
The procedure below is based on the requirements of the 2008 NEC.

430.6(A) 1 states;
(1) Table Values. Other than for motors built for low speeds (less than 1200 RPM) or high torques, and for multispeed motors, the values given in Table 430.247, Table 430.248, Table 430.249, and Table 430.250 shall be used to determine the ampacity of conductors or ampere ratings of switches, branch-circuit short-circuit and ground-fault protection, instead of the actual current rating marked on the motor nameplate. Where a motor is marked in amperes, but not horsepower, the horsepower rating shall be assumed to be that corresponding to the value given in Table 430.247, Table 430.248, Table 430.249, and Table 430.250, interpolated if necessary. Motors built for low speeds (less than 1200 RPM) or high torques may have higher full-load currents, and multispeed motors will have full-load current varying with speed, in which case the nameplate current ratings shall be used.

Table 430.248 indicates 28 amps for a 230V 5HP single phase motor.

430.22(A) General states;

(A) General. Conductors that supply a single motor used in a continuous duty application shall have an ampacity of
not less than 125 percent of the motorís full-load current rating as determined by 430.6(A)(1).

28A x 125% = 35A

Table 310.16 indicates #8AWG is rate for 40A.

Next we look at sizing the ground fault, short circuit, overcurrent protective device.

430.52 states;

430.52 Rating or Setting for Individual Motor Circuit.
(A) General. The motor branch-circuit short-circuit and ground-fault protective device shall comply with 430.52(B) and either 430.52(C) or (D), as applicable.

(C) Rating or Setting.
(1) In Accordance with Table 430.52. A protective device that has a rating or setting not exceeding the value calculated according to the values given in Table 430.52 shall be used. (Also read the exception.)

Table 430.52 states that for an inverse time circuit breaker (ITCB) protecting a single phase motor it is to be sized at 250% of the FLA as stated in Table 430.248.

28A x 250% = 70A

Based on the above calculation a 70A ITCB is correct.

If the motor fails to start and run then 430.52(C) (1) Exception No. 2(c) can be applied which states;

(c) The rating of an inverse time circuit breaker shall be permitted to be increased but shall in no case exceed 400 percent for full-load currents of 100 amperes or less or 300 percent for full-load currents greater than 100 amperes.

28A x 400% = 112A

Since we canít exceed 400% of the motor FLA we round down to a 110A ITCB on a piece of #8 AWG conductor.

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Old 12-22-2009, 03:09 PM   #85
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Stubbie, thanks for pointing out the momentary switch. I was wondering what that was.

Hopefully this thread will help someone else with a simular problem. I didn't have any luck googling it when I started this project. There are alot of smart guys on here. Thanks for the help.

I do have a few more questions though. Right now I am using the plug which came with the compressor. I cut the end off and used a universal plug that will fit into the dryer outlet. I want to run an outlet to garage. I want to be able to plug in a 220 welder as well. So here are the questions.

Most plugs I have seen have a three prong configuration. Should I wire it with a ground if I use one of those?
What type of plug would be best?
What type (gauge/size)wire would I need to run from the main panel to the outlet?
I have space in the box for breakers so no problem there.
It would be alot easier if I could run the wire inside the attic and drop it down both walls. Any code problems with doing that? (Texas)

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Old 12-22-2009, 08:36 PM   #86
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Older air compressor wiring help


Quote:
Originally Posted by lash-1295 View Post
Stubbie, thanks for pointing out the momentary switch. I was wondering what that was. Hopefully this thread will help someone else with a simular problem. I didn't have any luck googling it when I started this project. There are alot of smart guys on here. Thanks for the help.

I do have a few more questions though. Right now I am using the plug which came with the compressor. I cut the end off and used a universal plug that will fit into the dryer outlet. I want to run an outlet to garage. I want to be able to plug in a 220 welder as well. So here are the questions.

Most plugs I have seen have a three prong configuration. Should I wire it with a ground if I use one of those?
What type of plug would be best?
What type (gauge/size)wire would I need to run from the main panel to the outlet?
I have space it the box for breakers so no problem there.
It would be alot easier if I could run the wire inside the attic and drop it down both walls. Any code problems with doing that? (Texas)
I'll just address your question about the Momentary Switch. That's a switch that makes contact only while you hold it (or press it, in our case.) The purpose of it is to power the "Latching circuit". Meaning. the loop that energizes the coil and keeps it pulled in, closing the contacts of the Motor. That could run continuously until the contact is broken by pressing the OFF button, which breaks the "Latching circuit" (loop), releasing the coil and the contact points are opened, stopping the motor. (Oversimplified).
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Old 12-22-2009, 11:25 PM   #87
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If you're going to install an outlet to run the compressor or welder, I'd use a 50 amp 250 volt one. The NEMA number is 6-50. It looks a lot like a standard outlet, except it's about 3X larger.

If you're using NM cable (Romex), it'll need to be 6/2 with ground. If it's conduit, #8s will be OK. Use a 50 amp 2 pole breaker.

These outlets and plugs are readily available. The welder might come with one from the factory.

On another note, the post above that quotes the code is exactly accurate, but I'd like to add one thing. 110.14 (1) (a) (4) states that motors can use the 75C column in table 310.16 This does not apply to type NM cable though. 334.80 says you have to use the 60C column.

Unfortunately, to get down to the nitty-gritty of connecting a motor, you have to look at several different articles in the code. Too bad it wasn't just one that'd cover it all.

To sum up; if the wire is in conduit, use the 75C column. If it's NM, use 60C.

Rob
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Old 12-23-2009, 01:25 AM   #88
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Quote:
Originally Posted by lash-1295 View Post
Stubbie, thanks for pointing out the momentary switch. I was wondering what that was. Hopefully this thread will help someone else with a simular problem. I didn't have any luck googling it when I started this project. There are alot of smart guys on here. Thanks for the help.

I do have a few more questions though. Right now I am using the plug which came with the compressor. I cut the end off and used a universal plug that will fit into the dryer outlet. I want to run an outlet to garage. I want to be able to plug in a 220 welder as well. So here are the questions.

Most plugs I have seen have a three prong configuration. Should I wire it with a ground if I use one of those?
What type of plug would be best?
What type (gauge/size)wire would I need to run from the main panel to the outlet?
I have space it the box for breakers so no problem there.
It would be alot easier if I could run the wire inside the attic and drop it down both walls. Any code problems with doing that? (Texas)
Rob has it correct. If your wanting to run both a welder and this compressor out of the same receptacle you need a 2 pole 3 wire grounding type. Meaning 2 hots and a ground in the plug. No neutral is required for 240 volts. The compressor needs a 40 amp branch circuit if it is a actual 5 hp motor. Seems we determined that it was a 5 hp.

If you know the electrical requirements of the welder that would help but in general stick welders like the ole lincoln 225 needs a 50 amp circuit on 6-2 with ground nm like Rob mentioned. If your doing car restoration I have a feeling your talking a wire welder so a 40 amp branch circuit using #8-2 with ground on a 50 amp breaker should be more than enough for the welder. You will still use a 250 volt rated nema 6-50 like these... left is the receptacle and right is the plug. The top upside down D is your ground terminal, the other two are your hots. It does not make any difference which hot goes to which terminal. You need a double pole breaker. I take it you have the compressor running??

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Old 12-23-2009, 08:15 AM   #89
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Quote:
Originally Posted by micromind View Post
If you're going to install an outlet to run the compressor or welder, I'd use a 50 amp 250 volt one. The NEMA number is 6-50. It looks a lot like a standard outlet, except it's about 3X larger.

If you're using NM cable (Romex), it'll need to be 6/2 with ground. If it's conduit, #8s will be OK. Use a 50 amp 2 pole breaker.

These outlets and plugs are readily available. The welder might come with one from the factory.

On another note, the post above that quotes the code is exactly accurate, but I'd like to add one thing. 110.14 (1) (a) (4) states that motors can use the 75C column in table 310.16 This does not apply to type NM cable though. 334.80 says you have to use the 60C column.


Unfortunately, to get down to the nitty-gritty of connecting a motor, you have to look at several different articles in the code. Too bad it wasn't just one that'd cover it all.

To sum up; if the wire is in conduit, use the 75C column. If it's NM, use 60C.

Rob

110.14(1)(a)(4) is not a code section. I believe you meant 110.14(C)(1)(a)(4) which only applies if the motor is marked with design letters B,C, or D. Otherwise 110.14 (C)(1)(a)(1) applies which requires the use of the 60 degree column.

In my previous post I wrote out the procedure for sizing the conductors for this motor. #8/2 romex will work on a 70A breaker.

The welder is going to require a different size conductor and OC device.

Good luck!

Last edited by electures; 12-23-2009 at 08:28 AM.
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Old 12-23-2009, 11:28 AM   #90
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Hey lash

Check this out ... a 5 hp speedaire on ebay with your same manufacturer magnetic motor starter...

Also the blue button in the center of the cover is your overload contact reset in case the overload ever trips


http://cgi.ebay.com/SPEEDAIRE-BY-DAY...item4838c916d8

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