Supply Side Tap

A supply side tap is a connection that is made to the busbars or conductors on the line or utility side of the main service disconnect. The line side tap the simplest way of interconnection when installing a PV system that exceeds the 120% rule. (The 120% Rule - “What is it and why it is important?”)

When installing a supply side tap, you are physically connecting to a conductor or busbar. Below are some of the most common methods that are employed in performing a tap.

Insulated terminal blocks. These terminal blocks are made to accommodate a variety of wire gauges. They require the service to be disconnected in order to install. The conductor being  tapped may be cut and landed individually on a three-hole version. These tend to be bulky and cumbersome in already cramped enclosures

Parallel tap connectors. These are similar to the terminal blocks in form and function. They promote more flexibility than insulated terminal blocks by allowing connections in cramped, overfilled enclosures. As with terminal blocks installations, the electrical service must be shutdown in order to install these.

Split bolt. These devices are relatively inexpensive and their ease of use make them a method of making a connection to a continuous service entrance conductor run. Like the terminal block, these devices are bulky, but offer a very sturdy connection.

Insulation-piercing tap splice connectors. This device pierces the conductor’s insulation to make electrical contact. These do not require you to have the electrical service shutdown.  This may be an added value where shutting down the service would interrupt essential services on-site. These devices are often very bulky, however, and may not fit in even mildly crowded electrical panels. The down side to this device is that it is very bulky.  So in enclosures that are full or extra wire makes space limited these could be ruled out.