# Wirenuts in motor



## Cow (Jan 16, 2008)

I only use wirenuts up to #10. That's my preference. After that it's Polaris connectors or Burndy insulated taps.

Everyone has their own ideas about what's right. I also wrap my wirenuts with tape when doing motor splices. I can't remember ever having an issue with one of my connections, so I stick with what works for me.


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## backstay (Feb 3, 2011)

I was taught, linen( Scotch® Varnished Cambric Tape 2510), rubber, and vinyl or friction, over bolted ring terminals.


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## sbrn33 (Mar 15, 2007)

I use the copper sleeve crimps on any motor under #6's. Then I cover it with the rubber covers.


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## micromind (Aug 11, 2007)

I use wire nuts for #8 and smaller. Often a motor that needs #8s is a 12 lead ∆ so you'll have 1 - #8 and 2 - #12s or #14s. About 95% of the motors I work with are 480. 

I tape the wire nuts only if they're subject to a lot of vibration. I also arrange the splices with as much distance between them as possible though a lot of motors I work with are fed by SO cord so this becomes somewhat of a joke.......

I've seen more Polaris connectors burn up in motors than anything else, about as many fine-strand ones as normal ones. 

I don't think I've ever had a split-bolt splice burn up and usually there's 3 wires involved. I always put the incoming wire between the 2 motor leads, and remove the spacer. Of course, this is in violation of the manufacturers instructions, and multiple other requirements but it works and I will continue doing it.


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## MechanicalDVR (Dec 29, 2007)

micromind said:


> I use wire nuts for #8 and smaller. Often a motor that needs #8s is a 12 lead ∆ so you'll have 1 - #8 and 2 - #12s or #14s. About 95% of the motors I work with are 480.
> 
> I tape the wire nuts only if they're subject to a lot of vibration. I also arrange the splices with as much distance between them as possible though a lot of motors I work with are fed by SO cord so this becomes somewhat of a joke.......
> 
> ...


Only issue I have seen with split bolts was a poor wrap job and the tape melted and the bolt shorted out to the motor housing.


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## Southeast Power (Jan 18, 2009)

just the cowboy said:


> Tried to post this to an old thread but it would not let me so started a new one.
> 
> I had a 25 HP motor burn up this week due to wirenuts in a motor. I never use wirenuts in any motor over 3 HP, but it looks like these were red wing nuts and should never of had 1 #8 and 2 #12s.
> 
> ...


Would you expect the OL to trip if the bearings were dragging enough to heat the shaft up that much?
Did the wirenut connection open and cause the motor to single phase?


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## NC Plc (Mar 24, 2014)

I use split bolts in anything larger than 1HP and I have never had a failure because of them, this is in regular and low rpm motors sized in the 7.5-100HP range.


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## MechanicalDVR (Dec 29, 2007)

NC Plc said:


> I use split bolts in anything larger than 1HP and I have never had a failure because of them, this is in regular and low rpm motors sized in the 7.5-100HP range.


Agreed 100%, same here.


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## Big John (May 23, 2010)

We still use the crimp-ring/nut-and-bolt method on everything. I will admit it works and we don't have failures, but it sure seems like there should be better solutions.

For a while I thought Polaris greys were the answer, but have heard from a lot of guys about failures.


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## varmit (Apr 19, 2009)

I do mostly industrial maintenance at a variety of industrial facilities. The most common failure, that I see, are wire nut motor terminations. This is especially a problem on DC motors and AC motors on a VFD.

My method, old school though it is, is crimp lugs, bolts and lock washers. this is covered with (1) 33 back wrapped- sticky side out, (2) friction tape- for punch thru resistance, (3) cover with 33. 

I have seen several " modern" methods that are a little faster, but none that provide as reliable a termination.


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## sparky970 (Mar 19, 2008)

Cow said:


> I only use wirenuts up to #10. That's my preference. After that it's Polaris connectors or Burndy insulated taps.
> 
> Everyone has their own ideas about what's right. I also wrap my wirenuts with tape when doing motor splices. I can't remember ever having an issue with one of my connections, so I stick with what works for me.


Make sure you're buying Polaris gray. They are listed for the fine strand motor leads, Burndy is not.


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## Big John (May 23, 2010)

sparky970 said:


> Make sure you're buying Polaris gray. They are listed for the fine strand motor leads, Burndy is not.


A simple rule of thumb: If it uses a set screw directly against the conductor it's likely not fine-strand.

Set screws do not apply even, adequate pressure against all the fine strands and can lead to failure.

All the fine strand mechanical connectors I've used have some flat surface between the tightening screw and the cable.


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## just the cowboy (Sep 4, 2013)

*???*



Suncoast Power said:


> Would you expect the OL to trip if the bearings were dragging enough to heat the shaft up that much?
> Did the wirenut connection open and cause the motor to single phase?


 
The motor runs 27 amps with 29 amp FLA nameplate, OL's set at 29. For the shaft to turn blue and it was very hard to turn by hand, I would think it should of added some load.

The wirenut connection opened when we started it I guess, we were running it with no problems that we could tell. Shut it off to do something on the machine, when we went to restart it fuse blew. Found ground and open when testing at motor starter. Pulled pecker head and found problem.


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## glen1971 (Oct 10, 2012)

I use marrettes on motors up to maybe a #8 at the largest.. I usually don't tape them and haven't had an issue.. Larger than #8 I use 1 hole crimp lugs, 1/4" bolts, washers, and lock washers. Once tight, the fist layer is Scotch 88, sticky side out. This is to cover up the sharp edges. Then over top I use an MSC motor boot.. 

https://west.nedco.ca/heat-shrink/t...2-shrink-kon-splice-insulator/product/THSMSC2

I'll finish the black phase (B) 100% including tightening and cutting the ty-raps on the boots. The other two phases are bolted tight, the boots left loose, with maybe another ty-rap of tape to hold it in place until the motor is checked for rotation. After the rotation check, I'll either finish the Red and Blue phases, or swap them at the motor if it's wrong, then re-verify rotation and then complete the splices.. 
I keep the MCC's, starters, VFD's, etc, terminated Rd/Bk/Bl.. If I go there and change a motor, I'll fix the starter first to make it Rd/Bk/Bl, then do the motor up as above..


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## Cl906um (Jul 21, 2012)

I like to use the 3m rubber lead boot covers. Fast and rated 1 kv. I hate un taping leads where people only put rubber tape then 33. Usually cut the whole ball of &#55357;&#56489; Off if there will be enough wire to make up new motor. The boots I only use where it is spec or the mill provides since they cost a bit more. They are a lot faster.


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## sparky970 (Mar 19, 2008)

We use scotch 70, 130C, and 33+ whenever we tape


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## glen1971 (Oct 10, 2012)

Cl906um said:


> I like to use the 3m rubber lead boot covers. Fast and rated 1 kv. I hate un taping leads where people only put rubber tape then 33. Usually cut the whole ball of �� Off if there will be enough wire to make up new motor. The boots I only use where it is spec or the mill provides since they cost a bit more. They are a lot faster.


I've used these before on most motors I've done from 1 to 5 kv..

https://midwest.westburne.ca/hidden...onid=1FFC3A6D9A14029D2203574194700A1A.hybris2


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## backstay (Feb 3, 2011)

varmit said:


> I do mostly industrial maintenance at a variety of industrial facilities. The most common failure, that I see, are wire nut motor terminations. This is especially a problem on DC motors and AC motors on a VFD.
> 
> My method, old school though it is, is crimp lugs, bolts and lock washers. this is covered with (1) 33 back wrapped- sticky side out, (2) friction tape- for punch thru resistance, (3) cover with 33.
> 
> I have seen several " modern" methods that are a little faster, but none that provide as reliable a termination.


Non sticky cambric is good for that first layer. When you need to open the connections, a cut with a knife gets it coming off. Nothing stuck and superior abrasion resistance.


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## Going_Commando (Oct 1, 2011)

backstay said:


> Non sticky cambric is good for that first layer. When you need to open the connections, a cut with a knife gets it coming off. Nothing stuck and superior abrasion resistance.


Yup, we do it the old fashioned way. Varnished cambric, then rubber, then 33+


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## micromind (Aug 11, 2007)

I use cheap tape, like 1700, sticky side out, then 130C then 88. 

This way, as noted above, when the splice needs to be taken apart, simply slit it with a knife and it'll peel right off. Nothing is stuck to the wire or terminals.


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## LuckyLuke (Jun 1, 2015)

Regular preventive and predictive maintenance is the best solution in my opinion. :thumbsup:


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## John Valdes (May 17, 2007)

To really go old school how about sticky cambric turned sticky side out for first few turns, (there was a time when cambric did not have a sticky side btw) then rubber, then 33 and finally friction tape?

I still have a roll of friction tape downstairs somewhere. lol


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## splatz (May 23, 2015)




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## Jhellwig (Jun 18, 2014)

John Valdes said:


> To really go old school how about sticky cambric turned sticky side out for first few turns, (there was a time when cambric did not have a sticky side btw) then rubber, then 33 and finally friction tape?
> 
> I still have a roll of friction tape downstairs somewhere. lol


That is how I like to do it on bolted lugs. I have it down to second nature and can go fast. Use the right width of tape and pile the tape on the end before you wrap around it. 

I have seen people mess it up though. Taping it loosely without stretching the linerless is a pain to get off. Use lots of cambric to round it up and tape it tight. Only put one strip of linerless in the crotch. It doesn't need any more.

If you do it right it should pull itself off the connection when you cut it unless it has been baked on there for 10 years.


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## John Valdes (May 17, 2007)

Jhellwig said:


> That is how I like to do it on bolted lugs. I have it down to second nature and can go fast. Use the right width of tape and pile the tape on the end before you wrap around it.
> 
> I have seen people mess it up though. Taping it loosely without stretching the linerless is a pain to get off. Use lots of cambric to round it up and tape it tight. Only put one strip of linerless in the crotch. It doesn't need any more.
> 
> If you do it right it should pull itself off the connection when you cut it unless it has been baked on there for 10 years.


I had a call late one night about a big motor not running. Got to the plant and found a blown fuse.
Replaced it and bang another fuse gone.
Megged it and found a dead short. Opened the peckerhead and found the split bolts taped with no more than two layers of 33. Nothing more.
Turns out they let a mechanic connect it that day instead of calling me.


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## Cl906um (Jul 21, 2012)

splatz said:


> https://www.youtube.com/watch?v=x-RZXO1iz1Q


The dude from this video surely must be dead by now.


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## oliquir (Jan 13, 2011)

John Valdes said:


> I had a call late one night about a big motor not running. Got to the plant and found a blown fuse.
> Replaced it and bang another fuse gone.
> Megged it and found a dead short. Opened the peckerhead and found the split bolts taped with no more than two layers of 33. Nothing more.
> Turns out they let a mechanic connect it that day instead of calling me.


lucky there was not vfd, it would probably have failed also


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## John Valdes (May 17, 2007)

oliquir said:


> lucky there was not vfd, it would probably have failed also


If it was on a VFD, highly unlikely it would have had motor fuses.


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## Going_Commando (Oct 1, 2011)

splatz said:


> https://www.youtube.com/watch?v=x-RZXO1iz1Q


Holy crap. You can tell he works for the manufacturer considering how much fricken tape that dude is using!


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## Electricman3 (Apr 7, 2020)

For 35 years in the electrical industry I have worked for the largest electrical companies in my area and across the state and I can state with certainty that I have NEVER used wirenuts in motors for a number of reasons. The main reason is vibration. Yes, people tape them and whatever but heat will most likely goo the tape all up and the wirenut will either vibrate off or in some cases heat up and melt. The best method, in my opinion, is split bolt burndy connectors with cambric tape, then rubber tape, the Scotch 33 tape or crimp on ring terminals with nut and bolt. I have never had a connection fail either way. I currently work in a sawmill with steam heated kilns and the previous "electricians" used ceramic wirenuts to terminate the fan motors in the attic of these kilns that circulate the heat around. This environment is in excess of 220F minimum when running and many of these wirenuts are failing due to the heat and also vibrating loose. Often we'll get a ground fault alarm on one of the motors and sure enough, the wirenut has disintegrated and has shorted out against the peckerhead. I strongly advise against using wirenuts to terminate connections in any motors under 1/2 HP.


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## John Valdes (May 17, 2007)

This thread is 5 years old. You would use split bolts and the rest of it on a fractional hp motor? 
I can say I have used wire nuts many times over the years on motors with small leads and most every time in residential.
If possible I used crimp sleeves where I could. 
Today with the new ideas and products split bolts would be my last choice. To much work and it takes forever to insulate them


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## macmikeman (Jan 23, 2007)

I joined up some #6's and #8's together (6 lead 3ph motor) yesterday using split bolts. So I thought I would be laughed at using those, but I guess I'm not the only one. It had blue wire nuts, but the connections were fine. This was at a junction box, not the motor pecker head. That thing is just about impossible to get to thanks to the bracing of the stucture the motor is bolted to. So I did my meggertesting out at the junction box. All good. It is outdoors. It was raining sideways for days and days in March. I thinks rainwater got in the motor housing when nobody was looking and that's what blew the 2 fuses. Everything with the fan was kosher , spins like it is supposed to do. Meggered fine. Amped out fine once I restarted the thing. Had to be the rain. Cars, trucks, houses were underwater all over the place from rain. It mighta been..........


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## MotoGP1199 (Aug 11, 2014)

I've said this many times. Anything #10 or smaller and I use Wago 221's they are rated for 600v and independent test show them holding up to over 100a (not a joke). Anything larger I use split bolts and 3 tapes or crimp lugs, bolts, and tape. Nothing fails. I work on a lot of large commercial pool pumps 20hp to 100hp and they get vibration and cavitation as air gets into the pumps. It will happen on every single one of them eventually as the fill system fails or something clogs the pump baskets.

Almost every pool pump I see that has had Polaris in the pecker head eventually fail due to vibration(and/or heat). I think it has to do with the dissimilar metals and the set screws backing off when heat cycled and the different metals heat/cool at different rates and then vibration backs them out. I've never had a split bolt connection fail on literally thousands of motors. It takes longer and cost more(due to time) to use the split bolts, but I don't replace $3000 to $30,000 of motors/equipment when a Polaris fails.


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## Electricman3 (Apr 7, 2020)

John Valdes said:


> This thread is 5 years old. You would use split bolts and the rest of it on a fractional hp motor?
> I can say I have used wire nuts many times over the years on motors with small leads and most every time in residential.
> If possible I used crimp sleeves where I could.
> Today with the new ideas and products split bolts would be my last choice. To much work and it takes forever to insulate them


dude, I work heavy industrial, not residential. We hook up 300 HP motors not puny fractional motors. I am a 35 year master electrican as well. try branching out in the industry.


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## John Valdes (May 17, 2007)

Electricman3 said:


> dude, I work heavy industrial, not residential. We hook up 300 HP motors not puny fractional motors. I am a 35 year master electrican as well. try branching out in the industry.


I hear ya. I worked in heavy industrial as well. We had up to 500 hp DC and one 750 hp AC motor with all sizes in between. Of course you can't use nuts on those monsters. But smaller motors in peripheral equipment got nuts most of the time. We had many 1/2-3/4 blowers to cool big DC and those got wire nuts.
I think its the installer that makes it okay or not. A bad connection is a bad connection no matter the connection device.
I was raised up on split bolts. I have installed countless split bolts. Today I would look for another way. Taking apart bugs is a pain in the ass. So I would spend a little more money and use something like Polaris connectors.


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## 460 Delta (May 9, 2018)

John Valdes said:


> I hear ya. I worked in heavy industrial as well. We had up to 500 hp DC and one 750 hp AC motor with all sizes in between. Of course you can't use nuts on those monsters. But smaller motors in peripheral equipment got nuts most of the time. We had many 1/2-3/4 blowers to cool big DC and those got wire nuts.
> I think its the installer that makes it okay or not. A bad connection is a bad connection no matter the connection device.
> I was raised up on split bolts. I have installed countless split bolts. Today I would look for another way. Taking apart bugs is a pain in the ass. So I would spend a little more money and use something like Polaris connectors.


The Polaris connectors are a bit of a mixed bag with me. While I do like them, I have had some failures, and I see that I’m not alone. I use wire nuts up to about the 7 1/5 hp level, and then either ring terms and bolts or Kearneys depending on just whatever I have handy. I have used the crimp sleeves with the rubber galoshes with good results, but for whatever reason they are not in my truck or service bag when I need them. 
Skinning a Kearney isn’t that bad if it was taped first with cambric, but bigger Kearneys are easier than the smaller ones.
The magic in my opinion is to cover the 130C with 1755 friction tape and forget the 33+. I’m sure this will get this thread moved to controversial talk.


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## joe-nwt (Mar 28, 2019)

Electricman3 said:


> dude, I work heavy industrial, not residential. We hook up 300 HP motors not puny fractional motors. I am a 35 year master electrican as well. try branching out in the industry.


Dude, why did you bring up wirenuts if you were talking about 300HP motors?


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## Breakfasteatre (Sep 8, 2009)

most recent 100hp motor we did had a terminal block inside with studs. Compression crimped lugs on the cables and bolted them up

i have done 100s of motors over the years, up here in canada, most of them have a stud terminal block inside.

most of these are also smaller motors.

the odd time i see a motor with loose leads are usually fully enclosed wash down, and the pecker head is a round outlet with a threaded cap


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## just the cowboy (Sep 4, 2013)

MotoGP1199 said:


> I've said this many times. Anything #10 or smaller and I use Wago 221's they are rated for 600v and independent test show them holding up to over 100a (not a joke). Anything larger I use split bolts and 3 tapes or crimp lugs, bolts, and tape. Nothing fails. I work on a lot of large commercial pool pumps 20hp to 100hp and they get vibration and cavitation as air gets into the pumps. It will happen on every single one of them eventually as the fill system fails or something clogs the pump baskets.
> 
> Almost every pool pump I see that has had Polaris in the pecker head eventually fail due to vibration(and/or heat). I think it has to do with the dissimilar metals and the set screws backing off when heat cycled and the different metals heat/cool at different rates and then vibration backs them out. I've never had a split bolt connection fail on literally thousands of motors. It takes longer and cost more(due to time) to use the split bolts, but I don't replace $3000 to $30,000 of motors/equipment when a Polaris fails.


Just a question, was it the special gray Polaris for fine wires that failed or did someone just use the standard black ones.


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## Breakfasteatre (Sep 8, 2009)

I looked at some photos of those grey polaris, and they look no different than the black polaris. What differentiates them? they loook like setscrew connectors still, which i wouldnt think would work with fine strand wire


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## just the cowboy (Sep 4, 2013)

Breakfasteatre said:


> I looked at some photos of those grey polaris, and they look no different than the black polaris. What differentiates them? they loook like setscrew connectors still, which i wouldnt think would work with fine strand wire


I think it is the thread on the set screws are finer. They are more money I know that.


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## John Valdes (May 17, 2007)

460 Delta said:


> The Polaris connectors are a bit of a mixed bag with me. While I do like them, I have had some failures, and I see that I’m not alone. I use wire nuts up to about the 7 1/5 hp level, and then either ring terms and bolts or Kearneys depending on just whatever I have handy. I have used the crimp sleeves with the rubber galoshes with good results, but for whatever reason they are not in my truck or service bag when I need them.
> Skinning a Kearney isn’t that bad if it was taped first with cambric, but bigger Kearneys are easier than the smaller ones.
> The magic in my opinion is to cover the 130C with 1755 friction tape and forget the 33+. I’m sure this will get this thread moved to controversial talk.


I have not used the Polaris. I learned about them here. Sounded like the better choice over bugs. I have not used a crimp sleeve in years. I learned about them when we were out of wire nuts one time. But seem perfect for small lead motors.
Back when I was an apprentice, there was no sticky side cambric. It was a pain to get started and it wanted to slip off. Then when sticky cambric came out I thought it was great. But I learned in a hurry to wrap the first couple three layers sticky side up. Bugs are just to much work IMO. If I could not get a polaris type I would be looking at lugs with bolts and nuts. Unfortunately these require insulating.
I'm using cambric then rubber then 33 and finally (drum roll) friction tape!!!!



Breakfasteatre said:


> most recent 100hp motor we did had a terminal block inside with studs. Compression crimped lugs on the cables and bolted them up
> 
> i have done 100s of motors over the years, up here in canada, most of them have a stud terminal block inside.
> 
> ...


When I worked in the motor shop we had a line of metric motors. Lafert North America and some metric Weg. Every single one had a terminal block. Our other lines of motors had nothing but leads unless it was a special build.


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