line-to-line voltage

The line to ground voltage is half the line-to-line voltage.

This guarantees that no short-circuiting of an input line-to-line voltage can occur.

The line-to-line voltage magnitudes are all the same:

In the delta circuit, loads are connected across the lines, and so loads see line-to-line voltages:

Specifically, power is given as total (not per-phase) power, and voltage is line-to-line voltage.

One only has to ensure that no overlapping of turn-on intervals of power transistors in a bridge half occurs, because this would result in a short circuit of an input line-to-line voltage.

The slash rating, under the United States National Electrical Code, is given to circuit interrupt hardware and specifies a maximum line-to-ground voltage rating in combination with a maximum line-to-line voltage rating.