Attaching Service Drops

Use back supports in walls that are not strong enough to support a service drop in adverse conditions (wind, snow, or ice) (Figure 11). A 2-inch by 4-foot back support gives added strength to the wall.

Figure 1-11.  Back support installed in wall.
Figure 11. Back support installed in wall.

A single-cable system supports hot conductors and is hooked to the feed-through dead end (Figure 12). The cable that supports the service-drop conductors is clamped by the feed-through clamp and coupled to the ground conductors. The cable support is part of the ground system.

Figure 1-12. Grounded messenger cable providing support.
Figure 12. Grounded messenger cable providing support.

The bare neutral conductor is used as the messenger cable (Figure 13). By wrapping the hot conductors around the messenger cable, all the weight of the service drop is on the uninsulated neutral/messenger cable.

Figure 1-13. Hot conductors wapped around a neutral/messenger cable.
Figure 13. Hot conductors wrapped around a neutral/messenger cable.

In a typical service-drop cable, the neutral conductor is used to attach the cable to the dead end (Figure 14). The feed-through clamp is built so that the pull of the conductors makes the clamp tighter on the neutral/messenger cable.

Figure 1-14. Feed-through clamp attached to the service spool.
Figure 14. Feed-through clamp attached to the service spool.

Service drops are also dead-ended to a building by using secondary racks (Figure 15). When heavy service drops are installed on buildings, use secondary racks.

Figure 1-15. Service drop attached to a secondary rack.
Figure 15. Service drop attached to a secondary rack.

When individual conductors are installed, many of the installations are dead-ended by using service spools made of porcelain (Figure 16). One service spool is screwed or bolted to the wall.

Figure 1-16. Service drop attached to service spools.
Figure 16. Service drop attached to service spools.

Service masts can dead-end individual conductors and an insulator bracket is used for this purpose (Figure 17). An insulator bracket can also be used when service conductors are wrapped around a messenger cable but feed-through clamp will be required.

Figure 1-17.  Use of insulator brackets.
Figure 17. Use of insulator brackets.

Most service masts use a single, dead-end bracket and a service cable (Figure 18). This makes a neat installation. Although time-consuming to install, a service mast is the best method for service installation.

Figure 1-18.  Insulator bracket with feed-through clamp.
Figure 18. Insulator bracket with feed-through clamp.