# Motor rotation question.



## erics37 (May 7, 2009)

Go old school and just bump the motor.


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## eric7379 (Jan 5, 2010)

erics37 said:


> Go old school and just bump the motor.


Some machinery does not like to be ran in the wrong direction. Bad things can happen.

The proper method is to use a phase rotation meter. 

IF you can get away with just bumping the motor (or an inch or jog function if the motor is connected to a drive) without the possibility of causing machine damage, then this can be done (as long it is done safely by means of a switch or pushbutton, not by pushing in on the contactor)

In a case in which machine damage can occur by being ran backwards, then you must isolate the motor from whatever is being driven by the motor, whether it be removing belts, line shaft coupling, etc.


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## John (Jan 22, 2007)

John's laws concerning electricity......

#107. When installing a new motor or machine you have a
48% chance of running the correct direction
48% chance of running the wrong direction
4%. Chance of not running at all due to............:jester:

Buy the correct tool for the job.:thumbsup:


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## Hippie (May 12, 2011)

John said:


> John's laws concerning electricity......
> 
> #107. When installing a new motor or machine you have a
> 48% chance of running the correct direction
> ...


Mathematically that's true but in my experience its more like a 25% chance of going the right way the first time :-\

Edit~ it was wired by the master of all things electrical so never mind it will be right the first time


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## John (Jan 22, 2007)

Hippie said:


> Mathematically that's true but in my experience its more like a 25% chance of going the right way the first time :-\
> 
> Edit~ it was wired by the master of all things electrical so never mind it will be right the first time


For some electricians the 4% is slightly higher. :whistling2:


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## Hippie (May 12, 2011)

:whistling2::jester:


John said:


> For some electricians the 4% is slightly higher. :whistling2:


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## mrmike (Dec 10, 2010)

These are very good posts here. I want to add that you can just bump this air compressor without hurting it, as I have "bumped" quite a few. 
And if it is running backwards, you would swap 2 of the leads on the 480.....


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## drsparky (Nov 13, 2008)

Uncouple the motor from the equipment to test rotation.


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## local134gt (Dec 24, 2008)

kaboler said:


> Any tricks to know phase rotation? I know I can get the phase rotation measuring tool for $150 but heh. Use it like once a year.


Ask your Journeyman. And the phase rotation meter should be supplied by the shop not the apprentice-foreman


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## nitro71 (Sep 17, 2009)

Bumping most motors is not a problem. But, know what you are working on. The easy method would be to not couple the motor to what it's driving before testing rotation if you don't have a phase rotation meter.


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## wdemos (Nov 27, 2008)

Uncouple the motor.
It is safe.
It is fool proof.


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## kaboler (Dec 1, 2010)

But my question remains! If motors are fine through the transformer, it stands to reason that the service isn't reversed, right?


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## oldtimer (Jun 10, 2010)

kaboler said:


> But my question remains! If motors are fine through the transformer, it stands to reason that the service isn't reversed, right?


 :001_huh:


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## local134gt (Dec 24, 2008)

oldtimer said:


> :001_huh:


I think what he's trying to ask is: If the rotation is CW going into the transformer will it be CW coming out?


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## wildleg (Apr 12, 2009)

so you plan on opening up every transformer that feeds equipment you are wiring just to see if h1 h2 h3 line up with l1 l2 l3 and then convince yourself that the chinese guy who spun the windings didn't mix two up ? that's just plain crazy and a waste of time. it's also a recipe for getting it wrong. get a phase rotation meter.


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## micromind (Aug 11, 2007)

kaboler said:


> But my question remains! If motors are fine through the transformer, it stands to reason that the service isn't reversed, right?


Though I wouldn't bet an expensive machine on it, yes; if the phase rotation is CW on one side of the transformer, it will be CW on the other.

This doesn't matter unless there's metering involved, but if one side of the transformer is wye and the other is delta, there will be a 30º phase shift from the input to the output.


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## kaboler (Dec 1, 2010)

micromind said:


> Though I wouldn't bet an expensive machine on it, yes; if the phase rotation is CW on one side of the transformer, it will be CW on the other.
> 
> This doesn't matter unless there's metering involved, but if one side of the transformer is wye and the other is delta, there will be a 30º phase shift from the input to the output.


I could see that, ty for the info. With the 30 degree phase shift, that's normal because it's delta, right? I mean, it goes from wye's nicely balanced form to the bumpy but good delta right? hahaha, I sure don't know tech talk.

Well, we called up the Ingersoll Rand guy and he told us to bump it and watch the belt direction. Has to match up to the arrow. It did. So it's all good.

I guess I'm 100% for getting the phases right


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## kaboler (Dec 1, 2010)

wildleg said:


> so you plan on opening up every transformer that feeds equipment you are wiring just to see if h1 h2 h3 line up with l1 l2 l3 and then convince yourself that the chinese guy who spun the windings didn't mix two up ? that's just plain crazy and a waste of time. it's also a recipe for getting it wrong. get a phase rotation meter.


Thought about getting one last week, but didn't, because I said to myself, "when do I ever hook up motors?"

Anyway, I just opened up a few disconnects and looked. If the phases were reversed, I'd swap 2 at the bottom of the disconnect. I just assume every other electrician does it exactly the same as I would, all the time.


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## qckrun (May 18, 2009)

kaboler said:


> Thought about getting one last week, but didn't, because I said to myself, "when do I ever hook up motors?"
> 
> Anyway, I just opened up a few disconnects and looked. If the phases were reversed, I'd swap 2 at the bottom of the disconnect. I just assume every other electrician does it exactly the same as I would, all the time.


If your going to assume your in for a reality check and u honestly shouldn't be doing. Assuming things will get you killed. 

Always check and recheck everything done by yourself or others. 

I bought a phase rotation Meter and have used it countless times, at least a dozen in the last week.


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## nolabama (Oct 3, 2007)

My batteries are dead in my rotation meter. I should fix that. I would not swap the wires in the disco, I would do it in the peckerhead. And not change the colors. Making sure it spun backards next time I hooked it up.


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## SteveO. (Oct 17, 2011)

kaboler said:


> But my question remains! If motors are fine through the transformer, it stands to reason that the service isn't reversed, right?


Depends which direction the transformer is turning. :blink:


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## eric7379 (Jan 5, 2010)

nolabama said:


> I would not swap the wires in the disco, I would do it in the peckerhead.


 
That's how I do it, too. Keep everything the same going to the motor. Change it in the peckerhead.


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## nitro71 (Sep 17, 2009)

So you guys would take the peckerhead off. Strip tape and rubber tape and whatever the last genius used, then have to retape, put the cover back on, instead of just swapping two wires in the motor controller.. Sounds inefficient to me..


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## Hippie (May 12, 2011)

nitro71 said:


> So you guys would take the peckerhead off. Strip tape and rubber tape and whatever the last genius used, then have to retape, put the cover back on, instead of just swapping two wires in the motor controller.. Sounds inefficient to me..


No reason not to change it in the disconnect or starter. Just because you have correct colors all the way to the motor doesn't guarantee it will run right. I can have it reversed in the disco and back on in half the time it would take just to open the peckerhead


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## Widestance_Politics (Jun 2, 2010)

When we are commissioning new distribution gear, i.e transformers, Mcc's, etc......We use a phase rotation meter to prove a CW rotation throughout the system.....
That being said, we always bump the motor for a visual rotation.....also all motors are uncoupled from machinery if allowed to be "ran in" to check for high temps/vibrations......
Even if you have a proven CW rotation to the motor you have no idea how the manufacturer tapped his windings unless the motor was made specifically for your project (and it could still be wrong) So always rely on a visual bump for rotation.

And personally I always swap leads at the starter, do not change the phase tape of course, and note the A/C/B rotation inside the door with a sharpie....


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## nolabama (Oct 3, 2007)

nitro71 said:


> So you guys would take the peckerhead off. Strip tape and rubber tape and whatever the last genius used, then have to retape, put the cover back on, instead of just swapping two wires in the motor controller.. Sounds inefficient to me..


Yes. My motors do not have a localized means of disconnect. It would take twice as long for me to get to the disco and unlock it as would doing it in the peckerhead. And as for the cambric, I only have met one guy who still uses that....


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## oldtimer (Jun 10, 2010)

nolabama said:


> Yes. My motors do not have a localized means of disconnect. It would take twice as long for me to get to the disco and unlock it as would doing it in the peckerhead. And as for the cambric, I only have met one guy who still uses that....



Would you not have to go to the disconnect switch, and lock it out?

O M G, how far away are they? :001_huh: 

Do you have to take a cab? :laughing:


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## nolabama (Oct 3, 2007)

Far enough for my lazy a$$


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## McClary’s Electrical (Feb 21, 2009)

nolabama said:


> Far enough for my lazy a$$


So you're gonna swap rotation at the motor without locking it out?


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## mrmike (Dec 10, 2010)

In the plant I worked in, we always swapped the leads back at the MCC. We had to go there anyway, to unlock it, and energize the breaker for the motor, as it was locked out for the millwrights to change it. 

Then we bumped it from the local sw, if there was one, or called the control room operator to bump it. This was standard procedure even when we used a Phase rotator. 
The electrician & the millwrights would confirm correct rotation before coupling it up. Of course we had to go back to the mcc again to lock it out for them....................then unlock it all again-

It was a little tricky on air compressors because sometimes you could not find an arrow for rotation on the compressor itself.


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## kaboler (Dec 1, 2010)

Widestance_Politics said:


> When we are commissioning new distribution gear, i.e transformers, Mcc's, etc......We use a phase rotation meter to prove a CW rotation throughout the system.....
> That being said, we always bump the motor for a visual rotation.....also all motors are uncoupled from machinery if allowed to be "ran in" to check for high temps/vibrations......
> Even if you have a proven CW rotation to the motor you have no idea how the manufacturer tapped his windings unless the motor was made specifically for your project (and it could still be wrong) So always rely on a visual bump for rotation.
> 
> And personally I always swap leads at the starter, do not change the phase tape of course, and note the A/C/B rotation inside the door with a sharpie....


All good info.


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## nolabama (Oct 3, 2007)

mcclary's electrical said:


> So you're gonna swap rotation at the motor without locking it out?


Point taken.


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## socalelect (Nov 14, 2011)

mrmike said:


> In the plant I worked in, we always swapped the leads back at the MCC. We had to go there anyway, to unlock it, and energize the breaker for the motor, as it was locked out for the millwrights to change it.
> 
> Then we bumped it from the local sw, if there was one, or called the control room operator to bump it. This was standard procedure even when we used a Phase rotator.
> The electrician & the millwrights would confirm correct rotation before coupling it up. Of course we had to go back to the mcc again to lock it out for them....................then unlock it all again-
> ...


On compressors look at the cooling fan on the pulley


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## captkirk (Nov 21, 2007)

why dont you look at the compressor to see which way the motor is supposed to go and then get a rotation meter and see if it will go that way......just a shot in the dark......
Does anyone know how heavy Alabama is when it rains...?


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## socalelect (Nov 14, 2011)

captkirk said:


> why dont you look at the compressor to see which way the motor is supposed to go and then get a rotation meter and see if it will go that way......just a shot in the dark......
> Does anyone know how heavy Alabama is when it rains...?


The Alabama question is a trick question right. Alot of the time compressors are missing the rotation arrows


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## IBEWRockstar (Nov 10, 2011)

If your motor runs backwards when you first check it, do you check it again after you swap leads or just go with it? I always check it again.


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## micromind (Aug 11, 2007)

IBEWRockstar said:


> If your motor runs backwards when you first check it, do you check it again after you swap leads or just go with it? I always check it again.


Same here; always check it again.


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## captkirk (Nov 21, 2007)

what brand is the compressor..? maybe start there..? modle number..? other wise just bump it... if it has electronic controls it will probably tell you its going the wrong way...


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## kaboler (Dec 1, 2010)

I talked about it at the staff meeting, and nobody has a phase rotation meter. They ALL bump. They said I could rent one, but I got the vibe that it was unnecessary. Boss also said that I don't know how they wound the motor at the factory, so even if the phases were right, there's no telling or relying on a machine to know for sure.

Regardless, electricians are seemingly always so pessimistic. I trust the person before me, and I trust the person after me.

Which is why I label 347/600 red black blue, because phase tape colour shouldn't be telling people the voltage, their meters should. (canada 347/600 is red black blue, but people commonly put OBY instead. It's mandatory RBBl.)

I'm thinking of making a website with all my work on it. You guys could trash me all day with that!


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## nolabama (Oct 3, 2007)

Good luck trying to rent a hundred dollar meter.


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## chicken steve (Mar 22, 2011)

Where's Joe the Mechanic when we need him?

~CS~


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## socalelect (Nov 14, 2011)

chicken steve said:


> Where's Joe the Mechanic when we need him?
> 
> ~CS~


Banned I believe


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## wendon (Sep 27, 2010)

kaboler said:


> I talked about it at the staff meeting, and nobody has a phase rotation meter. They ALL bump. They said I could rent one, but I got the vibe that it was unnecessary. Boss also said that I don't know how they wound the motor at the factory, so even if the phases were right, there's no telling or relying on a machine to know for sure.
> 
> Regardless, electricians are seemingly always so pessimistic. I trust the person before me, and I trust the person after me.
> 
> ...



I've got a phase rotation indicator which is handy to check and maintain the same rotation on all the panels etc. but to do it right you would probably also need a motor rotation indicator to make sure it was right before energizing. I still like the "bump" method if possible. Another thing, on the 120/240 3 phase , I like to keep the "wild" leg on the "B" phase where it belongs.


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## don_resqcapt19 (Jul 18, 2010)

Hippie said:


> No reason not to change it in the disconnect or starter. ...


 There might be a reason. If the building has more than one voltage system, swapping at the starter or disconnect would create a violation of 210.5(C).


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## oldtimer (Jun 10, 2010)

don_resqcapt19 said:


> There might be a reason. If the building has more than one voltage system, swapping at the starter or disconnect would create a violation of 210.5(C).


 How would swapping it on the load side of the starter,
affect anything else ?


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## nolabama (Oct 3, 2007)

socalelect said:


> Banned I believe


Why would Joe get banned?


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## socalelect (Nov 14, 2011)

nolabama said:


> Why would Joe get banned?


Im not sure I think it had something to do with the rules


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## don_resqcapt19 (Jul 18, 2010)

oldtimer said:


> How would swapping it on the load side of the starter,
> affect anything else ?


Because the rule I cited requires the conductors to be identified by phase and system. When you change the rotation anywhere other than the motor the conductors are no longer identified by phase, this is assuming you used wire colors as your phase and system identification.


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## Hippie (May 12, 2011)

don_resqcapt19 said:


> Because the rule I cited requires the conductors to be identified by phase and system. When you change the rotation anywhere other than the motor the conductors are no longer identified by phase, this is assuming you used wire colors as your phase and system identification.


Say you had 3 black wires from disconnect to motor labeled 1,2, 3 on each end. If they were landed 1,3,2 in the disconnect they would still be identified appropriately on the motor end and I don't see a violation there.


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## don_resqcapt19 (Jul 18, 2010)

Hippie said:


> Say you had 3 black wires from disconnect to motor labeled 1,2, 3 on each end. If they were landed 1,3,2 in the disconnect they would still be identified appropriately on the motor end and I don't see a violation there.


 If you are in a building with more than one voltage system, the branch circuit conductors have to be identified as to phase and system. A sign is required at each panel speficing the method of identification being used. If that sign says for voltage system 1, A phase will be tagged 1, B phase will be tagged 2 and C phase will be tagged 3, then landing the wire tagged 3 on B phase and the wire tagged 2 on C phase creates a code violation.


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## kaboler (Dec 1, 2010)

don_resqcapt19 said:


> If you are in a building with more than one voltage system, the branch circuit conductors have to be identified as to phase and system. A sign is required at each panel speficing the method of identification being used. If that sign says for voltage system 1, A phase will be tagged 1, B phase will be tagged 2 and C phase will be tagged 3, then landing the wire tagged 3 on B phase and the wire tagged 2 on C phase creates a code violation.


That's pretty anal. We aren't that concerned about it in Canada.


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## don_resqcapt19 (Jul 18, 2010)

kaboler said:


> That's pretty anal. We aren't that concerned about it in Canada.


Sorry, I didn't notice this was a question based on the CEC. Here is the NEC rule that applies. It is often violated.


> *
> 210.5 Identification for Branch Circuits.
> (A) Grounded Conductor.​*​​​​The grounded conductor of a
> branch circuit shall be identified in accordance with 200.6.​
> ...


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## 76nemo (Aug 13, 2008)

nolabama said:


> My batteries are dead in my rotation meter. I should fix that. I would not swap the wires in the disco, I would do it in the peckerhead. And not change the colors. Making sure it spun backards next time I hooked it up.


 
You have a battery in your rotation meter, interesting. What type of meter?


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## kaboler (Dec 1, 2010)

Don, I think they mean that if 2 voltages from different sources are in the same junction box, they should be marked and labeled, and we ALWAYS do that, even with a big sign that says "multiple sources of voltage".

I don't think they mean that if there's 2 services to a building, or a different nominal voltage coming from a transformer, that everything in the entire place must be marked labelled and tagged.

Or what?


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## don_resqcapt19 (Jul 18, 2010)

kaboler said:


> ...
> I don't think they mean that if there's 2 services to a building, or a different nominal voltage coming from a transformer, that everything in the entire place must be marked labelled and tagged.
> 
> ...


That is exactly what it means. Any time you have more than one voltage system in the building, all branch circuit conductors must be identified by phase and voltage. This applies in the complete building, not just to raceways or enclosures that have both systems in them.


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## nolabama (Oct 3, 2007)

76nemo said:


> You have a battery in your rotation meter, interesting. What type of meter?


Amprobe, nine volt battery.


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## JRaef (Mar 23, 2009)

don_resqcapt19 said:


> Because the rule I cited requires the conductors to be identified by phase and system. When you change the rotation anywhere other than the motor the conductors are no longer identified by phase, this is assuming you used wire colors as your phase and system identification.


But Don, I think that technically once you get _*past*_ the motor starter, it is no longer a "branch" circuit, it is a motor circuit and you can swap the leads at the motor starter load terminals without violating the identification rule. I have never had an inspector gripe about that. Ahead of the starter, yes, but not at the load terminals. Maybe I've been wrong all these years and maybe it''s just an accepted practice, I don't know.

Add-on:
After posting this I went into Article 430 and I find nothing that supports my position. I guess it's just been an accepted practice. 
Live and learn...


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## BBQ (Nov 16, 2010)

JRaef said:


> But Don, I think that technically once you get _*past*_ the motor starter, it is no longer a "branch" circuit, it is a motor circuit


I may be wrong but I think it is still a branch circuit, at the least it is not excluded from being considered one.



> *Branch Circuit.* The circuit conductors between the final
> overcurrent device protecting the circuit and the outlet(s).


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## JRaef (Mar 23, 2009)

Oh wait!


*210.1 Scope. *
This article covers branch circuits *except for **branch circuits that supply only motor loads*, which are covered in Article 430. Provisions of this article and Article 430 apply to branch circuits with combination loads.

So being that on the LOAD side of a motor starter you are not allowed to have other unassociated loads, the 215 rules no longer apply.​


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## don_resqcapt19 (Jul 18, 2010)

JRaef said:


> Oh wait!
> 
> 
> *210.1 Scope. *
> ...


Good catch. I often tell others you have to read the scope first and did not do that myself.


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## bgleason (Mar 3, 2012)

I'm sure it is just coincidence, but in the 19 years I have been doing electrical work, I have only had 1 motor run backward on startup after changeout. That is wiring the motors phases exactly as they came off the old motor.


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## kaboler (Dec 1, 2010)

bgleason said:


> I'm sure it is just coincidence, but in the 19 years I have been doing electrical work, I have only had 1 motor run backward on startup after changeout. That is wiring the motors phases exactly as they came off the old motor.


From what ive heard, some equip runs backwards just fine. Others can self-adjust. Could be one of those situations.


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## SteveO. (Oct 17, 2011)

kaboler said:


> From what ive heard, some equip runs backwards just fine. Others can self-adjust. Could be one of those situations.


:confused1:


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## JRaef (Mar 23, 2009)

kaboler said:


> From what ive heard, some equip runs backwards just fine. Others can *self-adjust*. Could be one of those situations.


What the heck would "self adjust" mean in the context of running in reverse?


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## socalelect (Nov 14, 2011)

JRaef said:


> What the heck would "self adjust" mean in the context of running in reverse?


It's kaboler anything is possible in this kids world


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## BBQ (Nov 16, 2010)

BBQ said:


> I may be wrong but I think it is still a branch circuit, at the least it is not excluded from being considered one.








JRaef said:


> Oh wait!
> 
> 
> *210.1 Scope. *
> ...





don_resqcapt19 said:


> Good catch. I often tell others you have to read the scope first and did not do that myself.


Notice it is still called a branch circuit.


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## eric7379 (Jan 5, 2010)

JRaef said:


> What the heck would "self adjust" mean in the context of running in reverse?


I think that means that after shear plates and shear pins and gear teeth break off during the "self adjusting" period, anything can run in reverse just fine!


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## SteveO. (Oct 17, 2011)

JRaef said:


> What the heck would "self adjust" mean in the context of running in reverse?


The boxes that wanted to go "up" the conveyor would give up and be happy going "down" the conveyor to a big pile on the floor? :thumbup:


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## CheapCharlie (Feb 4, 2011)

kaboler said:


> Regardless, electricians are seemingly always so pessimistic. I trust the person before me, and I trust the person after me.


I'm surprised nobody jumped on this one yet. If you trust someone that has told you that a circuit is dead without testing it yourself you're a fool. I don't care if I'm looking over the shoulder of someone testing for voltage, I'll do it myself if it's my fingers in there.


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## yungun (Oct 7, 2011)

kaboler said:


> I talked about it at the staff meeting, and nobody has a phase rotation meter. They ALL bump. They said I could rent one, but I got the vibe that it was unnecessary. Boss also said that I don't know how they wound the motor at the factory, so even if the phases were right, there's no telling or relying on a machine to know for sure.
> 
> Regardless, electricians are seemingly always so pessimistic. I trust the person before me, and I trust the person after me.
> 
> ...


No one at the whole company owns a phase rotation meter? Maybe most electricians are so seemingly pessimistic because they understand the potential hazards that they encounter on a daily basis. Maybe you just haven't seen the reality of what a simple mistake can cause. In my personal experience, taking someone else's word will inevitably lead to finger pointing, or perhaps worse. The last time I took someone's word I cost the company a couple grand. Luckily no one was injured. Those old electricians might be on to something when they say so pessimistically "always check for yourself"...


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## Wireman191 (Aug 28, 2011)

kaboler said:


> On tuesday they're going to start up an air compressor. I am hoping it will not run backwards. The question is this:
> 
> If my 480 service goes through a 208 transformer, and motors running at 208 forwards, without running backwards (and no wires swapped over), it would be logical to assume that the 480 service won't need wires swapped over for forward rotation?
> 
> ...


 Only trick is a rotation meter on both sides. So a meter that tests the motors rotation, and a meter that tests the incoming power rotation.


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## McClary’s Electrical (Feb 21, 2009)

nolabama said:


> Why would Joe get banned?


 
All the good members get banned


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## nolabama (Oct 3, 2007)

mcclary's electrical said:


> All the good members get banned


I guess he shoulda shut up and watch cletus run emt.


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