May be more or a rant with some questions thrown in…..In an attempt to refine my skills, I have been searching this forum for new/better techniques on terminating large motor 50HP and larger. Went back about 10 pages in my search and came up with basically 3 techniques (the ones that have been around for awhile)….Split bolts, Polaris taps, and nut and bolted ring terminals. I have 25 years of electrical work experience, the last 10 doing service work generally revolving around heavy industrial environments. Today I was sent to work on a 200HP motor that had burnt up in the peckerhead, every time I see this I always wonder why new technology hasn’t solved this issue of bad installations. Some of you will say the new tech is Polaris taps, but I would say motor vibration eliminates that option. I have seen those fail many times in my experience. Polaris taps have their place in the field but motor connections are not one IMO. Split bolts or nut and bolted crimped rings are the only options that I’m aware of, but there are limitations to both of these. With crimped rings, 6, 9, 12 lead motors….how to get the flat end of the crimps/rings together on 3, 4, 5 wire connections without it being an oversized mess or bending the rings? I’m a proponent of split bolts in most situations, since I’m usually working against the clock where customer needs equipment to run ASAP. Carrying different sized split bolts is easier that carrying the unknown number of lugs I could possible run into. Here is the question tho….are there no better solutions? Has this part of the field still not evolved away from methods that have existed for decades? Show me the way boys and girls, I want to learn, what am I missing? Do I need to start my own R&D to develop the solution?
Motor Connections
- Thread starter FizzNasty
- Start date
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Split bolts are generally not listed for more than 2 conductors so they're out. IMO the crimped ring bolt method is the best available.
ptonsparky
Tom
- Occupation
- EC - retired
I've done them about any way possible, but agree. Crimped and bolted.
My first job was at a large slaughter house where water & vibration caused problems. On motors over 7.5 HP we liked to use T & B crimped lugs with grade 5 hex bolts, flat washers & new lock washers. Every week we sent out at least one bad motor and had the motor shop only bring out 3 motor leads. Would install lugs on rewound motors before putting them in storage. We went as far as to install grease on motor shafts & have cut a new spare shaft key to speed up replacements. Motor shop told us we had the record being we replaced three bad 100 HP motors in a single day. Luckily all had the motor leads & easy to cut off varnished cambric tape. Even though most split bolt bugs are not approved for more then two wires never had a failure when there were 3 or 4 wires . In that case would strip the wire jacket longer to facilitate easier & more compact taped over area. Good to speak to motor shops over motor short lives. We had a lot of 1/2 HP blower motors in -40 F low ceiling freezers that burnt out too often. Motor shop either added or subtracted some motor windings to account for such low temperature and these lasted a lot longer.
It always feels a little archaic wrapping tons of rubber splicing tape and electrical tape around nut and bolt lug connections. I think its the still the best way to go though. I haven't used split bolt connectors inside a motor junction box, but its good to know they can work. I am waiting for them to start making supersized industrial wagos 
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ptonsparky
Tom
- Occupation
- EC - retired
Split bolts seemed to be the preferred choice in 50-70s.
Rick 0920
Senior Member
- Location
- Jacksonville, FL
- Occupation
- Electrical Instructor
I've used both Kearneys and bolted ring terminal connections. Both work well. However I think insulating them properly is the biggest challenge. The best way that I have found is using a cheaper brand of electrical tape for your first layer starting by turning the sticky side up for your first wrap. Then use Varnished Cambric tape. This is extremely tough tape and is very hard to rub through when vibration is an issue. Then a layer of Scotchfil rubber splicing tape. Dont stretch it too thin, it's designed to be a thick layer of protection. Then finish off with 33 or 88 wrapping over and over to keep the Scotchfil from leaking out when it heats up.
Eddie702
Licensed Electrician
- Location
- Western Massachusetts
- Occupation
- Electrician
I go with split bolts. Regardless of how many wires you have when a split bolt is torqued down you have a good connection. I then put splicing tape one layer on backwards and then splicing tape sticky side down or scotch Fill depending on the split bolt size, then 33+
Never had an issue.
Never had an issue.
eric stromberg
Senior Member
- Location
- Texas
How do you handle rotation? if it needs to be changed, do you do it at the motor or the controller? If you do it at the motor, what kind of temporary connections are you making before the rotation check?
- Location
- Illinois
- Occupation
- retired electrician
My connections would be ring terminals and screws and nuts or bolts and nuts based on the size. The screws or bolts with a length that only has a thread or two showing outside of the nut.
If I have them, I prefer the Raychem GelCaps for the insulation at motor terminations. If not, 130C, sticky side out, multiple wraps, to get a well covered and very smooth surface, followed by 33+ with no wrinkles showing.
If there is a large amount of vibration at the motor, the motor junction box will be packed completely full of duct seal...typically only where the vibration is server enough to require the motor connection to be SO cord.
If I have them, I prefer the Raychem GelCaps for the insulation at motor terminations. If not, 130C, sticky side out, multiple wraps, to get a well covered and very smooth surface, followed by 33+ with no wrinkles showing.
If there is a large amount of vibration at the motor, the motor junction box will be packed completely full of duct seal...typically only where the vibration is server enough to require the motor connection to be SO cord.
Worst thing about rubber tape during a rush motor replacement too often a major pain to remove if rubber tape is applied directly to split bolts ( bugs ). Several times we did not have replacement bugs so had to use a steel brush to removed baked on rubber on threads of bugs then take them and clean them up on a wire wheel. Never had silicone or Scotch varnished cambric tape fail.Just have to use at least enough wraps. On motors under 50 HP would leave the motor and supply wires long so could just cut off bugs and use new ones to speed job up. Would never use wago for motors especially if there was vibration &/or dampness. At least one size of wago's are only rated for 400 volts. ( might have been a knockoff brand ).It always feels a little archaic wrapping tons of rubber splicing tape and electrical tape around nut and bolt lug connections. I think its the still the best way to go though. I haven't used split bolt connectors inside a motor junction box, but its good to know they can work. I am waiting for them to start making supersized industrial wagos
Eddie702
Licensed Electrician
- Location
- Western Massachusetts
- Occupation
- Electrician
In the old days with the rubber tape with the liner we would rip off the liner and wrap the split bolts with that first then use the rubber tape or Scotch fill then 33+.
They stayed clean that way and you could razor knife off the stuff with little trouble. I imagine you could wrap it with 33+ backwards first instead of the liner.
They stayed clean that way and you could razor knife off the stuff with little trouble. I imagine you could wrap it with 33+ backwards first instead of the liner.
I would always recommend lugs/bolt and nut for a quality connection, but I have seen that some people won't bother with that for very low horsepower motors.
Wagos (221-412) are UL listed for 600V and 20A according to their website.
COMPACT splicing connector (221-412) | WAGO USA
COMPACT splicing connector; 2-conductor; with operating levers; 12 AWG; transparent housing (4050821808435) Online at WAGO USA!
www.wago.com
Unless you need to change direction of rotation for high amperage motors with stiff large gauge wire that has already been terminated, usually we just change the wiring around at the MCC bucket, motor controller, or local disconnect set screw terminations.
- Location
- Illinois
- Occupation
- retired electrician
If wrapped sticky side out, as required by the instructions for 130C, it removes easily. Just a length wise cut and split it open using two pair of pliers. It does not stick to the parts.
I never used split bolts for anything other than temporary power....just never liked them. Motors always got ring terminals and screws or bolts.
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Crimped single hole lugs and T&B motor stub boots. Motor leads are a fine stranded wire, standard crimps are not listed for fine stranded
Thing about approved crimps for fine stranded wires sparkies have been using conventional crimps on fine stranded wires for over 75 years. Never had a quality crimp fail on any motor leads even on hammer mills, crushers, vibrating screens or nightly high pressure hose down on where some water ended up in motor pecker heads. Think that its only been in the NEC about using crimp on lugs for maybe what the last 15 years or so. Retired & out of the loop but hope the approved lugs for stranded conductors can be used on plain Jane THHN/THWN . It cost a lot of money to stock quality crimp lugs from #10 to 500 MCM. Also usually stocked them with two different hole sizes. Back years ago only stocked crimp lugs & bugs for copper use only.
Amazing that IEC limits this model to 450 volts and 32 amps but the UL to 600 volts but only 20 amps. Have noticed extremely generous highly ampere rating on IEC contactors & starters compared to UL rating. I would never load up a questionable IEC contactor pass 75% of the UL listing. Had to replace IEC starters on numerous motors that cycled on & off 24/7 once every year. Replaced them with an Alien Bradley or Square D NEMA starter and still running ten years later.I would always recommend lugs/bolt and nut for a quality connection, but I have seen that some people won't bother with that for very low horsepower motors.
Wagos (221-412) are UL listed for 600V and 20A according to their website.
COMPACT splicing connector (221-412) | WAGO USA
COMPACT splicing connector; 2-conductor; with operating levers; 12 AWG; transparent housing (4050821808435) Online at WAGO USA!
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
If you size IEC contractors equivalent to NEMA starters they will last just as long.
Take a 10HP 480V application: A NEMA size 1 starter is actually rated for 27A. An IEC 10HP starter is often only 9A or maybe 15A.
IEC starters, should be selected using their published life curves not simply by HP rating.
Not sure how an equivalent to NEMA starters can last even a quarter the life of a rugged real deal quality starter ( A&B or Square D ) when the inferior IEC starters believe are only rated for 100,000 operations & guessing NEMA starters are a million. I asked our Alien & Bradley salesman from a large supply house
40 years ago who made the best IEC starters. Told me nobody .We had over thirty 35 year old A&B starters in a 95 degree chocolate room that operated 15 minutes on/15 minutes off 24/7 for 15' high chocolate tanks.Never replaced the contacts and maybe replaced two 120 volt cooks a year. We had well over 200 bypass VFD'S with a 3 IEC contactors. When we performed monthly ATS testing one or two of the M2 ( drive output) IEC contactors would fail ( would not pull in even with 120 VAC to coils). These contactors pulled in with no current because the NO contact would give drives a start command,most were in clean climate controlled rooms. Would place replacement date and some did not last 5 years with only operating less then a hundred times. So to me they are junk!