Specification

To ensure that Eaton Corporation’s safety switches are applied cor-
rectly and safely, many factors need to be addressed. One important
factor to consider is that the wire that is being used is suitable for
use with the lug, or wire connector. In addition to ensuring that the
lug is rated for the wire material (copper or aluminum), size, and
insulation temperature rating the customer wants to use; also, it is
likewise important that the lug is rated for the number of strands
that make up that wire.
This instruction leaflet is presented to guide the installer when utiliz-
ing Eaton switches with fine stranded wire. This instruction leaflet
should eliminate the possibility of product failure due to inappropri-
ate lug/wire combinations.
There are eight major classifications for the stranding of wires. The
classifications include B, C, D, G, H, I, K, & M which go in order from
fewer strands to more strands. Thus, class B has the least amount
of stranding, classes C, D, G, and H have intermediate amounts of
stranding, and classes I, K, and M have the most finely stranded
cables. Class B is the most common type of stranded cable and
is the common stranding of building wire. The majority of lugs are
designed to accommodate Class B stranding. (More information can
be found in Table 1 on determining strand classifications and
Table 2 can be used in conjunction with Table 1 to determine the
common types of building wire that fall into each class.)
Fine stranded wire usually falls within classes C or D; however, it is
becoming more common to see wire falling between classes G to
M. Fine stranded wire is commonly known as “welding cable” and
Effective February 2013
Instruction Leaflet IL008004EN
Safety Switch Fine Strand Wire
Guidelines
is very flexible and easy to install. Because of these characteristics,
fine stranded wires are becoming more popular in control equip-
ment to provide a durable, flexible routing solution against vibrations
and infrequent motion. However, all lugs are not rated to be used
with these higher classes of stranded wire.
With no marking or factory instructions to the contrary, most lugs
may only be used with up to Class B stranded conductors. Many of
the lugs that Eaton uses in the manufacture of Safety Switches are
not currently listed by the lug manufacturer as suitable for use with
fine stranded wire. However, Eaton has done independent testing
of many of these lugs in conjunction with the safety switch and has
achieved approval for fine strand wire compatibility.
The lugs that were approved, qualified under UL 486A-486B stan-
dards and passed the static heating testing. To pass the static
heating test, the combinations of lug, fine strand wire, and ferrules
must follow these specified criterion: the temperature rise must not
exceed 50°C, the joint between the connector and conductor must
remain intact, there must not be any breakage of the conductor or
any strand of a stranded conductor, there must not be any stripping
of threads, shearing of parts, or any other damage to the connector.
Table 3 illustrates the lug, fine strand wire, and ferrule combinations
that are approved for use within the applicable safety switches.
Currently, these are the only known compatible combinations that
can be used and other combinations could result in failure. It is the
installers’ responsibility to make sure that the lug within the safety
switch being ordered is approved for the type of cable intended for
the installation of the product.