The double single point connection ( or “mid-point bonding” connection ) is used when the length of the route is too long to use a connection end-point bonding.

In these connection systems, the cable can be connected to earth somewhere in between (using the location of a joint, which should be designed to separate screens) and is isolated from earth at each end by sheath voltage limiters or SVLs.

It is also possible to ground at the ends and maintained isolated the screens via SVLs at the midpoint as shown in the figures above.

As can be seen, this system doubles the length of the possible route, since the maximum induced voltage is reduced because the length insulated from earth is half that in an end-point bonding system.