Nortel 7400 Hardware Installation page 294

294 Chapter 39 Hardware procedures
NN10600-175 6.1S2
7 If you are installing a dc power supply, connect the battery wire, the
battery return wire, and the ground wire to the terminal block. See the
figure "Multiservice Switch 7440 dc wiring" (page 468).
or
If you are installing an ac power supply, insert the power cord connector
into the appropriate power connector on the power input panel on the rear
of the device. See the figure "Installing Multiservice Switch 7440 ac power
cords" (page 314).