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Are all split bolt clamps Listed to be used for connecting copper grounding electrode conductors to steel rebar direct buried in earth, and if so how can these clamps be identified?

Posted By Underwriters Laboratories, Tuesday, May 01, 2007
Updated: Sunday, February 10, 2013

Question: Split bolt clamps

Are all split bolt clamps Listed to be used for connecting copper grounding electrode conductors to steel rebar direct buried in earth, and if so how can these clamps be identified? Have they been investigated to ensure there are no electrolysis problems related to the dissimilar metals involved?

Answer

Typical split bolt connectors are not Listed for connection of a grounding electrode conductor to rebar, they are intended for connection of two conductors in an ordinary dry location inside an enclosure and are Listed under the category Wire Connectors, (ZMVV) located on page 307 in the 2006 UL White book or online atwww.ul.com/databaseand entering ZMVV at the Category Code Search. These type of split bolts connectors are not intended to be used for grounding applications to connect a grounding electrode conductor to rebar or any other component of the grounding electrode system. The Listing Mark on the connector or packaging would identify it as a wire connector.

Split bolt connectors evaluated for grounding applications as well as other types of grounding clamps are Listed under the product category Grounding and Bonding Equipment, (KDER) located on page 122 in the 2006 UL White Book or online atwww.ul.com/databaseand entering KDER at the Category Code Search. As part of the Listing evaluation of a grounding or bonding device, they are required to be constructed of a metal or metals that, when the device is installed under conditions of actual service and exposed to moisture, will not be likely to be adversely affected by electrolysis.

Clamps Listed under Grounding and Bonding Equipment (KDER) are evaluated for compliance with The Standard for Grounding and Bonding Equipment, UL 467. A grounding or bonding device marked as acceptable for burial in earth or embedment in concrete shall be provided with all screws necessary for assembly or connection of the device, and shall be constructed of copper or a copper alloy containing not less than 80 percent copper, or stainless steel.

Grounding-type split bolt clamps or connectors Listed for use with rebar will be marked on the connector or a tag on the connector identifying the size range of the rebar and conductor size the device was Listed for use with. In addition, connectors Listed for direct burial in earth or encased in concrete are marked "DB” or "Dir Bur.” The Listing mark on the product, or on a product tag or product container will identify the product as grounding and bonding equipment.

Read more by UL

Tags:  May-June 2007  UL Question Corner 

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