Motor Termination Protection inside the Peckerheads.

[gilly]

Hello,

Looking for some advice, I am terminating many large motors that have or are prone to a large amount of vibration. Currently what I plan to use are One hole lugs crimped on with a hydraulic crimper bolted together and then covered with a T&B rubber boot. (PT# MSC250 / MSC500 FYI) I would also like to have some added protection on the wires where they enter the peckerhead, and around the T&B boots. I would like to use a rubber sheet that is very pliable so I can wrap around the conductors where they leave the LT flex and enter the peckerhead, then zip tie into place. Also would like to do the same in addition to the T&B boots so that the boots to not vibrate/rub aginst the termination Housing. The problem I am having is finding a rubber that is NON-conductive or has some kind of electrical rating. I do not want to use the rubber matting that is typically used to lay on the floor in front of gear or switchboards. The style we have used seems to be to rigid for this. Along the same lines I do not like Mastic in this application since over time it seems to get sticky and messy. Have any of you used any type of rubber sheeting that would work well in this application??

Thanks.

 

[don_resqcapt19]

In motors with excessive vibration, we terminate and tape them as we would normally do, and then pack the motor junction box completely full of duct seal to prevent any movement of the wires inside the junction box. The duct seal is also packed into the end of the liquid tight flexible conduit connection to the motor junction box. This was actually specified in the instructions for some sand screener that we hooked up. As I recall it was a 7.5 or 10 hp motor and the instructions called for 5 pounds of duct seal. The duct seal does not get gooey unless the motor gets excessively hot. It does take some time to clean out when you have to unwire the motor, but it does come out.

 

[jumper]

What NEC code section would address vibration other than maybe 300.4?

 

[Jraef]

Old school, as I was taught:

• Bolted connection, star washers, make sure the bolt is a short as possible, barely sticking through the nut when fully tightened. In fact I like acorn nuts, they are smoother.
• Wrap the connection with varnished cambric tape, two wraps minimum. The VC tape should not be sticky, so it makes it easier to remove later. If you only have the sticky version, put the sticky side out.
• Wrap the VC tape with 3M #88 Rubber Splicing tape, 4 wraps minimum (half-lap wraps), more if there is high vibration. On vibrating feeders for rock crushers, I've done as many as 10 wraps if the peckerhead is big enough. #88 has no adhesive, but it does fuse with itself to form a solid rubber mass over time and temperature.
• Wrap the #88 with 33+ vinyl tape to protect the #88 from unraveling until it fuses. 2 wraps minimum, half-lap of course.

http://multimedia.3m.com/mws/mediawebserver?mwsId=SSSSSu7zK1fslxtUm8mZPY_Bev7qe17zHvTSevTSeSSSSSS--

 

[gilly]

Thanks for the feedback. Don't think we will go totally old shcool but I do like that option.

 

[iwire]

In motors with excessive vibration, we terminate and tape them as we would normally do, and then pack the motor junction box completely full of duct seal to prevent any movement of the wires inside the junction box. The duct seal is also packed into the end of the liquid tight flexible conduit connection to the motor junction box. This was actually specified in the instructions for some sand screener that we hooked up. As I recall it was a 7.5 or 10 hp motor and the instructions called for 5 pounds of duct seal. The duct seal does not get gooey unless the motor gets excessively hot. It does take some time to clean out when you have to unwire the motor, but it does come out.

I wish I knew that years ago. We used to service a gravel pit and we always had blow ups in shaker motors.

 

[RichB]

Old school, as I was taught:

• Bolted connection, star washers, make sure the bolt is a short as possible, barely sticking through the nut when fully tightened. In fact I like acorn nuts, they are smoother.
• Wrap the connection with varnished cambric tape, two wraps minimum. The VC tape should not be sticky, so it makes it easier to remove later. If you only have the sticky version, put the sticky side out.
• Wrap the VC tape with 3M #88 Rubber Splicing tape, 4 wraps minimum (half-lap wraps), more if there is high vibration. On vibrating feeders for rock crushers, I've done as many as 10 wraps if the peckerhead is big enough. #88 has no adhesive, but it does fuse with itself to form a solid rubber mass over time and temperature.
• Wrap the #88 with 33+ vinyl tape to protect the #88 from unraveling until it fuses. 2 wraps minimum, half-lap of course.

http://multimedia.3m.com/mws/mediawebserver?mwsId=SSSSSu7zK1fslxtUm8mZPY_Bev7qe17zHvTSevTSeSSSSSS--

Then only thing I do differently is to add a wrap or two(half lap) of 33+ sticky side up for the first layer--then the VC etc.--In fact I always do that with VC or mastic or rubber splice tape--makes it easier to remove in the future

 

[don_resqcapt19]

Then only thing I do differently is to add a wrap or two(half lap) of 33+ sticky side up for the first layer--then the VC etc.--In fact I always do that with VC or mastic or rubber splice tape--makes it easier to remove in the future

I never use VC. I don't see a need for it. If we tape the connection, we wrap the splice with 3M 130C tape, sticky side out (per the instructions on the tape) and finish with 33+. For removal, just cut the tape lengthwise and use two pair of pliers to open the tape slit and pull the tape off in on piece. The tape does not stick to the termination and does not leave any residue on the connections.
Most of the time, I now use the Raychem GelCaps in place of any tape. They are quicker and easily removable and are re-usable.

 

[BPoindexter]

Whe have had pretty good luck with these:

MOTOR TERMINATION KITS

Only issue is that they are pretty bulky and sometimes cannot be used if the terminal housing is small. In that case we use cambric or glass, then 130C, then 33 over over that.