Motor lead splices

[podo]

I know that we have all tape-spliced motor leads in motor junction boxes, but I have never seen any written procedures for this process, i.e. what type of tape(s) to use, how many layers, etc. These would be 50 - 200 HP AC motors, 1000 volt or 4000 volt. The terminal boxes are rather small and the splices would have to be taped. There is no room for the pre-formed splice boots. Any help would be appreciated.
Thanks,
Podo

 

[AFab]

My personal preferance is to use high press type lugs, bolted together with S/S bolts. One layer of good quality PVC tape to allow easy removal, 3 or 4 layers of linerless 44KV splicing tape. More layers the higher the voltage. Then cover with good quality cold weather electrical tape.

 

[busbar]

Use of non-commodity-grade unshielded MV cable may be considered for controller-to-motor cabling to limit the increased volume generally required for shielded-cable installation.

I second AFab’s callout of seamless-copper-tubing tool-compressed lugs for compact and reliable connections. Silicon-bronze hex-machine bolts with phosphor-bronze internal-star lockwaxhers are have a good track record.

Various splitbolts or aluminum setscrew lugs with assorted junkbin hardware get used when nobody’s looking, until their failure blows holes in motor j-boxes. For ANSI regions, tight quarters may be somewhat relieved with application of NEC 430-12 terminal-box sizing.

Suggested is the tried-and-true non-adhesive-backed varnished-cambric / linerless-rubber or silicone / 10-mil vinyl-tape finish. (Cambric permits convenient “clamshell” stripping during teardown.) in MV splicing, this method is sometimes refferred to as a built-up/field-fabricated
(compared to kit) application.

Tape “insulation equivalent…” thickness implied by NEC 110-14 seems a bit vague and of marginal guidance. Kerite has drawings of MV-unshielded splices, for they are a long-time major proponent of unshielded 5kV-class [NOT unishileded] materials. Kerite prints are available through

http://wwww.kerite.com/catalog/catalogfiles/terminating_splicing_power.htm

EPR/CSPE (or CPE) insulation/jacket flexibility {stranding aside} is typically more desirable versus XLPE/PVC versions. The increased material cost is typically offset by reduced installation effort and increased long-term durability. 1kV circuits may be specified with 2kV unshielded EPR RHW-2 cable. 4kV circuits may be specified with 5kV unshielded EPR/CSPE MV90 or MV105 cable.

Minnesota Mining and Plymouth Rubber are two popular brands of insulating materials.

 

[advidana]

3m makes high voltage splice kits for high voltage stress cones terminations, check with them.