we use a product called "aqua-gel". seems to work better than the old "yellow-77", and evaporates rather than getting sticky and "gluey" like the yellow-77. i have had to pull out cables such as MCM 250-500 before, that had been originally pulled with yellow-77, and they were stuck inside the pipe like super-glue, sometimes, nearly ripping the conduit down, just to get them to budge a little.
Wire-pulling compounds are for use as lubricants in installing electrical conductors in raceways. Listed compounds have been investigated to determine their compatibility with conductor insulation and coverings.
The Listing Mark of Underwriters Laboratories Inc. on the product is the only method provided by UL to identify products manufactured under its Listing and Follow-Up Service. The Listing Mark for these products includes the UL symbol (as illustrated in the Introduction of this Direc-tory) together with the word ²LISTED,² a control number, and the product name ‘‘Wire Pulling Compound’’ .
Here is part of the installation instructions from the PostGlover website. They are a manufacturer of hospital isolated power systems.
All Branch Circuit Conductors of the isolated power system shall be stranded copper having a cross-linked polyethylene insulation, or equivalent with a dielectric constant of 3.5 or less. Type XHHW is suitable for this purpose. Each branch circuit conductor shall be color-coded in accordance with National Electrical Code. Wire pulling compound produces an adverse effect upon the dielectric constant of conductor insulation and shall not be used when pulling the wire of the isolated power system. Use of dry talcum powder is permitted.