# Wondering why these contactors keep burning up



## Family guy (May 15, 2016)

Hopefully the above comes out to be a picture of contactor in question. The story behind it is that this is the third one that has melted in the same way. Line Two burned all the way through and line 1 showing minimal in comparison. This is installed on a grain bin and has automated control that is giving the signal to start and stop the fan. I am the second electrician called out to look at it about three months ago. I replaced a contactor that had failed about identical to the pic. I did a fairly thorough step by step with voltage readings. The only noticeable thing at that time was that there was not a true neutral that went through the overload. I was able to correct this and added a breaker in the panel. Upon replacing I once again checked voltage and amp draw. Everything tested fine, and a couple days later I had the farmer take a look at it for physical signs of overheating and all was good, but just received word that that this one burned up in like manner.
Someone suggested a brown out has been used in cases that there were repeated motor failures. I am not familiar with what exactly they do to give an opinion- it says overvoltage and under voltage protection. Wondering what some thoughts were.
Another thing mentioned is the mars relay in the motor, and once again I am lacking in experience to make a solid decision. 
My thoughts are a recording meter would be nice. It is interesting to me that all heat is on line side and nothing on the load. It is a application where a second fan was added and there was mention that they are one of the last ones on utility line.


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## Wirenuting (Sep 12, 2010)

Improper torque, undersized starter, motor going bad, improperly set o/l’s... Pick your poison and go from there.


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## Family guy (May 15, 2016)

Torque question-I don’t have torque Allen wrench but tightened well thinking of vibration especially being on fan and first failure. 
Undersized starter and o/l I wish I had better memory I believe them to be right but cannot say beyond a shadow of a doubt because I have made mistakes. The farmer bought the contactor and had it there. The overload was used was the same on both so possibility the overload may be the problem. I did not change setting.


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## CoolWill (Jan 5, 2019)

The problem is there is more than one device in the enclosure. Everyone knows that more than one contactor or relay in an enclosure is the source of most failures.


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## Going_Commando (Oct 1, 2011)

Is that aluminum wire feeding the contactor? Are LC1 contactor terminals rated for aluminum? I never thought to check since I always wire them with copper.


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## Family guy (May 15, 2016)

Looking back at pic. I am more aware of the need for a little tidying up and organizing of wires. 
I am thinking the only other wiring that goes through there is the wiring a heater.


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## MikeFL (Apr 16, 2016)

You say it's supply side overheating. What condition are those conductors in after so many times of overheating?


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## Flyingsod (Jul 11, 2013)

I thought this was a post about spontaneous human combustion. 


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## Family guy (May 15, 2016)

Going_Commando said:


> Is that aluminum wire feeding the contactor? Are LC1 contactor terminals rated for aluminum? I never thought to check since I always wire them with copper.




Looked on line and could not verify specs for terminal, but talked to someone at Schneider dealer and he said possibility so will splice some copper to aluminum before landing again.
Also mentioned that could change out coil from 120volt to 110 if it is 120 that is currently on it, in case voltage does drop and cause chattering. Thanks. 
Hoping to have good game plan because it is 2 1/2 hours from the house to the site.


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## Family guy (May 15, 2016)

MikeFL said:


> You say it's supply side overheating. What condition are those conductors in after so many times of overheating?




I cut back what I can see, but the integrity of the cable itself probably is somewhat compromised. The only thing with that is direct burial with no raceway so that would make it a lot bigger job then the onset if I supply a new feeder. Hoping that it is salvageable.


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## Cow (Jan 16, 2008)

Seeing that red jumper, tells me this is a single phase application?

This is what I would do:

Verify motor HP, FLA, phase.

Verify aluminum wire size is correct.

Verify starter is rated for single phase HP rating. I'm not a fan of IEC, I would lean towards a NEMA starter replacement myself, I'd even buy a used and tested NEMA starter from one of our surplus dealers if cost was an issue.

Pigtail to copper at the starter.

Verify all connections are good from the service through the starter and to the motor.

I'd start the motor and verify voltage is good at the line terminals at the starter.

If the motor is a good distance away, I'd also measure voltage when starting at those terminals for good measure.

It also never hurts to verify control wiring is good and tight at it's terminals.

Also, verify control power is good while starting the motor as well to make sure the starter is not dropping out or chattering during inrush.


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## FishinElectrcian (Jul 18, 2019)

Everything Cow said +

When you tail some copper on softer (more strands) is better for control wiring. Aluminum sucks, I feel like that's the issue.

Check all the way down the line.. Just because the supply side burns off it doesn't necessarily mean that's where the problem is... could be a loose splice in the device

Double check the contactor assembly to the overloads sometimes it gets loose. 

The further down it is on the utility line the greater the possibility of fluctuating low voltage or high voltage dependent on draw and time of day. IE if utility company had to boost voltage with a xfmr for daytime because of low voltage, at night it's possible that a 115V low can turn to 128V high as others aren't consuming as much power.

There's a cheap logger you can get by MTP about $150, sold as a secondary metering device.


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## Wirenuting (Sep 12, 2010)

Always check the motor for size, never trust the guy before you in setting the o/l’s correctly. 

+ What Cow & Fishinelectrician said. 
A fused NEMA Starter all the way. I hate IEC sizing, no room to fart or wiggle out of the way.


* Is that held in place with Zip Ties?


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## Family guy (May 15, 2016)

Thanks guys, I really appreciate this forum. It helps get an overall perspective. I sometimes think I should be contributing more on certain feeds, certain ones at certain times I have felt like I can offer back. I have increased my learning every time I have scanned through posts and comments. Thanks again. Hope everyone is having a good weekend.


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## Peewee0413 (Oct 18, 2012)

Family guy said:


> Torque question-I don’t have torque Allen wrench but tightened well thinking of vibration especially being on fan and first failure.
> Undersized starter and o/l I wish I had better memory I believe them to be right but cannot say beyond a shadow of a doubt because I have made mistakes. The farmer bought the contactor and had it there. The overload was used was the same on both so possibility the overload may be the problem. I did not change setting.
> 
> 
> Sent from my iPhone using Tapatalk


I dont see smashing of copper. Are you sure its tight terminals? Did you do the wiggle wiggle retight? 

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## micromind (Aug 11, 2007)

I would not land AL directly on the contactor terminals. It looks like there's room for pin connectors but you'd need a crimper. Another way would be to use setscrew butt splices and a short piece of CU. Use some sort of anti-oxidation AL joint compound (like NoAlOx or Penetrox) on the AL termination. 

That contactor is rated for 15 HP single phase. If the motor is 12 - 15 HP, I would consider going to a larger contractor. A NEMA 15 HP contactor will handle a 15 HP motor, and IEC one is questionable.


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## Family guy (May 15, 2016)

Peewee0413 said:


> I dont see smashing of copper. Are you sure its tight terminals? Did you do the wiggle wiggle retight?
> 
> Sent from my SM-G965U using Tapatalk




I see what you are saying. Got me thinking now. I tightened them then used Klein’s to give extra torque, but would be nice to see more indentation on the conductors for conscience sake at this point.


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## joebanana (Dec 21, 2010)

Just out of curiosity, did you pull the cover and check the contacts themselves? Or at least do a V/D (FOP) test across them?


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## telsa (May 22, 2015)

Big motor loads pretty much demand copper conductors.

So much so that this is spec'd in the typical contract.

Aluminum -- even the more modern alloys -- just expand and contract too much.

And... they're SOFT.

So they deform under expansion and then pull away and back off during no load// cooling off.


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## Family guy (May 15, 2016)

joebanana said:


> Just out of curiosity, did you pull the cover and check the contacts themselves? Or at least do a V/D (FOP) test across them?




I checked line side voltage when energized and again after fan was running. I replaced it with a new contactor so I did not check contacts, probably should have on the one that had previously failed.


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## macmikeman (Jan 23, 2007)

I hate automatic spell checkers. I spend more time fixing the spell checker's 
re-wording errors than I used to do fixing my own spelling mistakes......... I still use the damn thing though.. Screw you Siri, I'm gonna punch your nose if you ever come out of this computer........


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## Cow (Jan 16, 2008)

Peewee0413 said:


> I dont see smashing of copper. Are you sure its tight terminals? *Did you do the wiggle wiggle retight?*


Peewee makes a good point. I can't over emphasize how critical this step is. Especially on something that vibrates or shakes every time it engages.

We all do it (or are supposed to do it) in our shop. But someone that may not work with larger conductors on a regular basis may not realize this step is critical to get the strands to "flatten" out and allow the lug to retain it's torque without loosening over time.


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## Family guy (May 15, 2016)

Cow said:


> Peewee makes a good point. I can't over emphasize how critical this step is. Especially on something that vibrates or shakes every time it engages.
> 
> We all do it (or are supposed to do it) in our shop. But someone that may not work with larger conductors on a regular basis may not realize this step is critical to get the strands to "flatten" out and allow the lug to retain it's torque without loosening over time.




Humbling comment but it is good to hear at this point.


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## joebanana (Dec 21, 2010)

Family guy said:


> I checked line side voltage when energized and again after fan was running. I replaced it with a new contactor so I did not check contacts, probably should have on the one that had previously failed.
> 
> 
> Sent from my iPhone using Tapatalk


Sometimes arcing contacts cause excessive heating of the terminals, and can indicate other problems. It only takes a couple of times opening at the wrong phase angle under an inductive load to blow contacts into a bad place.


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## joebanana (Dec 21, 2010)

macmikeman said:


> I hate automatic spell checkers. I spend more time fixing the spell checker's
> re-wording errors than I used to do fixing my own spelling mistakes......... I still use the damn thing though.. Screw you Siri, I'm gonna punch your nose if you ever come out of this computer........


Whuts rong witt spill chickers? I thik there entertainingg.


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## 3DDesign (Oct 25, 2014)

Did you take amperage readings on all three phases, both line and load?

How do these compare to the motor nameplate?


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## FishinElectrcian (Jul 18, 2019)

macmikeman said:


> I hate automatic spell checkers. I spend more time fixing the spell checker's
> re-wording errors than I used to do fixing my own spelling mistakes......... I still use the damn thing though.. Screw you Siri, I'm gonna punch your nose if you ever come out of this computer........


Why isn't there a "nice" button on this forum??.. Or "like" or whatever the kids are calling it.

+ what Tessa said haha Telsa said... and vibration + aluminum + coldflow + ....

Anti ox-.. Required for aluminum, good for copper. I saw a hot tub control melt recently... Aluminum. Heat+ vibration = more problems more money


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## PSmitty (Aug 19, 2019)

*Interesting statement.*



CoolWill said:


> The problem is there is more than one device in the enclosure. Everyone knows that more than one contactor or relay in an enclosure is the source of most failures.


Will, 
Enclosures with more then one contact/relay is pretty common. See it every day when working. Please explain you view?


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## MikeFL (Apr 16, 2016)

PSmitty said:


> Will,
> Enclosures with more then one contact/relay is pretty common. See it every day when working. Please explain you view?


You have to understand the culture and a little bit of the history of this forum to understand his statement. He's mocking a rule (Canada?) that says more than one device in a cabinet constitutes a control panel and can only be fabricated by a listed shop, or something thereabouts.

Please fill out your profile including occupation and location per the terms of use of this site.

And welcome to the forums.


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## MechanicalDVR (Dec 29, 2007)

PSmitty said:


> Will,
> Enclosures with more then one contact/relay is pretty common. See it every day when working. Please explain you view?


Welcome aboard @PSmitty!

Thanks for filling out your profile.

As for your comment, get used to the_ sarcasm_ here bro!


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## just the cowboy (Sep 4, 2013)

*Too short of wire*



Family guy said:


> Sent from my iPhone using Tapatalk


Add wire to the existing wire. If you look at your Picture the wire on the middle leg looks to be on an angle due to the bend. If I didn't add wire I would of made the bend in the wire tighter so it came straight in to the lug. Even that little angle won't let it compress correct.

Cowboy


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## PSmitty (Aug 19, 2019)

MikeFL said:


> You have to understand the culture and a little bit of the history of this forum to understand his statement. He's mocking a rule (Canada?) that says more than one device in a cabinet constitutes a control panel and can only be fabricated by a listed shop, or something thereabouts.
> 
> Please fill out your profile including occupation and location per the terms of use of this site.
> 
> And welcome to the forums.


Understood. Thanks for the heads up.


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## JRaef (Mar 23, 2009)

To use Aluminum wire, the termination must SPECIFICALLY state that you can, usually with a marking such as "Cu/Al". I don't have a Tele contactor in front of me, but I have a dozen other contactors here of various make, every one of them, including NEMA contactors, all say "Cu Only" on the conductor ranges.


No mention of it on Schneider's FAQ page, but they do have this interesting exchange regarding their IEC disconnect switches, called "vario":

*



Issue;

Click to expand...

*


> Will the lugs of the vario disconnects accept aluminum wiring? *
> 
> Product Line;
> *Vario Disconnect Switches
> ...


Note the underlined statement. I cannot find any reference in the NEC to this effect, but if the Schneider people believe it, it's a good bet that they would extend that belief to their contactors.


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## MOA (Mar 12, 2008)

The OP states, "It is a application where a second fan was added". BOTH fans together are now out of the contactor amperage rating.


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