never wired a gas station but how does a shunt trip comply with 514.11?
That section requires the disconnect to open the grounded conductor along with the ungrounded conductors.
Are gas pumps 208 - 240 ?
Shunt trips won't comply. Pumps may be 208,240 but dispensers on the island are generally 120v. I've seen Shunt trips used by fire suppression guys so flow stops when fire station is pulled. on Unattended locations I have used contactors.
