By Mike Mensler

At the turn of the century, the Plymouth Rubber Company developed the first rubber and friction tapes in order to facilitate splicing of the early cable constructions… and the world of electrical splicing was born. The following is a look at the evolution of low voltage electrical splicing, citing innovations leading up to today’s labor saving technologies.

Taping of Low Voltage Splices & Terminations

INTRODUCED: 1900 by Plymouth Rubber Company; 1946 by 3M

HISTORY: Developed first vinyl electric tape in response to new plastic cable insulation designs spurred by rubber shortages during World War II. For years, vinyl tapes in combination with rubber mastics and friction tape were the mainstay of low voltage electrical splicing. While the use of tape for splices is gradually being replaced by newer technologies, there are still many excellent craftsmen who carry on the tradition.

CURRENT USES: In low voltage applications vinyl tapes, rubber mastics and fillers are popular in motor hookups, low voltage splices, tapping from feeder cables as well as terminations.

RELATIVE INSTALLED COST: Compared to other splicing solutions, tape is a material and labor-intensive solution that is heavily dependant upon the skill of the electrician to ensure a proper splice.

High Installed cost.

Resin Splicing

INTRODUCED: 1950’s by 3M

HISTORY: Offered as a durable alternative to taping.

CURRENT USES: Still a popular splicing solution in low voltage direct burial and submersible applications, resin splicing technology offers an extremely durable, hardened shell for superior blunt force and abrasion resistance. It is an excellent solution for submersible applications.

NOTES: Resin splices are highly dependent upon installer skill, resin flow (to ensure no air pockets allowing the ingress of environmental contaminants), and proper curing conditions to ensure the integrity of the splice.

RELATIVE INSTALLED COST: Resin splices are comparatively the most expensive splices in terms of material and labor, on average requiring approximately ½ hour of installation time and 1 to 2 hours of setup time. Highest Installed cost.

Heat Shrink Splicing

INTRODUCED: 1962 by Raychem

HISTORY: By the early 1970’s, heat shrink technology was embraced by the electrical industry as a high quality, labor saving alternative to tape and resin kits. Labor savings (compared to tape or resin splices) and ease of installation drove preference for heat shrink splicing technology. Of all methods of splicing, heat shrink most closely resembles the original cable jacket, providing a hardened abrasion and trauma resistant outer jacket. Appropriate for direct burial applications.

CURRENT USES: Widely used for many types of splices.

NOTES: In certain confined space and overhead applications use of the open flame torch can be inconvenient or a safety consideration. It is critical that the installer apply the heat source uniformly over the heat shrink tubing, working from the center to the outer edges, to ensure no air pockets exist, a uniform wall thickness is maintained and proper sealing to the cable jacket.

RELATIVE INSTALLED COST: Heat shrink splicing is slightly higher than cold shrink installed costs and significantly lower than tape or resin kits installed costs.

Moderate Installed cost (lower than tape or resin splice kits).

 Cold Shrink Splicing

INTRODUCED: 1973 by 3M

HISTORY: Cold shrink significantly reduced the labor component of an electrical splice. Cold Shrink is designed to provide a finished installation similar to heat shrink, but without the use of a heat source. There are significant differences in the material characteristics of cold shrink and heat shrink, evident in a hardening of the heat shrink sleeve after installation while the cold shrink sleeve remains a flexible material. The tubing is pre-expanded at the factory; a removable core is inserted into the tubing and unwound during installation, allowing the product to shrink into position.

CURRENT USES: Cold shrink is suitable for direct burial applications and excellent for confined space and vault applications, overhead applications or where an open flame presents a safety hazard.

NOTES: It is critical to ensure that the cable diameter is sized as close to the middle of the cable diameter range of the kit as possible, to ensure a tight seal and adequate insulation thickness.

RELATIVE INSTALLED COST: Low Installed cost (lower than tape, heat shrink or resin splice kits).

PRE-INSULATED MECHANICAL CONNECTORS

INTRODUCED: First available in the early 1980’s. 1993 Polaris™ introduced by NSi Industries.

HISTORY: For splicing and tapping of both copper and aluminum cable constructions. Pre-insulated connectors have eliminated the need for time consuming splicing and tapping with split bolts, mechanical or compression connectors and tape, allowing for easy re-entry for service or moves, adds and changes. Pre-insulated connectors have become an extremely popular solution for distribution in troughs, junction boxes and pull boxes. Pre-insulated connectors save time in the field; simply strip the wire, insert the cable under the set screw and tighten down the set screw.

CURRENT USES: Appropriate for most copper and aluminum cable constructions and widely used. Available as in-line splice, multi-port splice/tap and stub configurations #14 thru 750 MCM.

RELATIVE INSTALLED COST: Moderate Installed cost.

 DIRECT BURIAL AND SUBMERSIBLE PRE-INSULATED MECHANICAL CONNECTORS

INTRODUCTION: 2000 by NSi Industries

CURRENT USES AND NOTES: Polaris Blue™ is rated for direct burial and later this year, for submersible applications and available in multi-port tap applications. Polaris Blue™ is available for underground splices thru 250 MCM. Eliminates the need for expensive and time consuming resin based splice kits in submersible applications, lowering installation costs and allowing for easy re-entry into the splice for service. Simply strip the wire, insert the cable under the insulation sleeve and tighten down the set screw.

RELATIVE INSTALLED COST: Moderate Installed cost.

 PRE-INSULATED MECHANICAL CONNECTORS FOR MOTORS

INTRODUCTION: 2004 by NSi Industries

CURRENT USES AND NOTES: Polaris Grey™ is UL listed for fine stranded flexible and extra-flexible cable constructions such as DLO cable, type G, type W, G-GC, SHD-GC and motor lead wire thru 3/0. Polaris Grey™ is a pre-insulated mechanical connector that includes a ferrule under the set-screw to ensure that the cable strands are tightly bundled and properly crimped to ensure a gas-tight termination of fine stranded wire. These connectors are re-useable and replacement ferrules are available.

An excellent alternative to taping wire nuts, split bolts or compression stub splices, lowering installed costs and allowing for easy access for motor service.

RELATIVE INSTALLED COST: Moderate Installed cost.

ROLL-ON COLD-APPLIED SPLICING

INTRODUCTION: 1986

HISTORY: Cold-applied roll-on direct burial splice kits offer an alternative to cold shrink which eliminates the need for labor-intensive tapes, heat shrink and resin kits. The roll-on splice kits are a fast, simple and durable splice for low voltage compression connector applications. Simply roll the elastomeric sleeve onto one side of the cable, complete the splice, apply mastic, roll the sleeve back over the connector and center the elastomeric sleeve over the splice.

CURRENT USES: Suitable for use in direct burial as well as overhead, vault and manhole applications up to 1000V and available thru 1000 MCM.

RELATIVE INSTALLED COST: Lowest Installed Cost

 COLD-APPLIED GEL SPLICE KITS

INTRODUCTION: 1998

HISTORY: Cold-applied gel splicing technologies eliminate the need for taping, complicated resin molds or the use of a torch in splicing and tapping. Available in several forms for a variety of splicing and stub applications the silicone gel material completely encapsulates the connection and seals out moisture. The sealing material remains pliable for the life of the cable.

NOTES: Silicone Gel has the added benefit of preventing corrosion and oxidation via the encapsulation process and wetting action of the gel on the cable and connector surfaces. This technology combines the benefits of resin type splices, fast installation and reduces splice failures due to installation variables.

CURRENT APPLICATIONS:

-Wrap-Around Gel Splice kits are available for compression and in-line mechanical splices up to 1000V and 750 MCM. The closure sleeve is a stretchable hardened plastic outer jacket combined with a layer of Silicone Gel that conforms to the splice and cable jacket, sealing out moisture and other contaminants.

-Gel closures for in-line mechanical, mechanical splice taps and H taps are available in a molded, hinged, hardened box configuration. These clamshell style closures use the same Gel technology as the Wrap-Around products, making splicing as simple as placing the finished splice in the closure and snapping shut.

-Gel stub kits for street lighting and motor terminations offer a low cost, durable , re-enterable alternative to taping or heat shrink. Gel stub kits for street lighting are available for #14 thru 2/0 feeds and #14 thru #6 taps. Motor stub kits are available from #16 thru 500 MCM. Rated for up to 1000V.

RELATIVE INSTALLED COST: Lowest Installed Cost

From Tape to Gels, low voltage electrical splicing technologies have evolved radically over the past 6 decades and offer a wide range of splicing solutions to the electrician. Ultimately, the electrician has benefited from products that are much easier to work with, offer more efficient use of time and significant reductions in material and installation costs.