How to Connect an EPO Switch to the ATS
66 InfraStruXure Power Generation System
Safety warnings
Hazardous voltage from the branch circuit must be isolated from the 24 VAC, 24 VDC, and contact
closure terminals. 24 VAC and 24 VDC are considered Class 2 circuits as defined in Article 725 of
the National Electrical Code (NFPA 70) and Section 16 of the Canadian Electrical Code (C22.1).
A Class 2 circuit is a source having limited voltage and energy capacity:
a. If an Inherently Limited Power Source, then voltage and energy are limited to less than
30 VAC, 30 VDC, and 8 A.
b. If not an Inherently Limited Power Source, then voltage and energy are limited to less than
30 VAC, 60 VDC, and 250 VA, while current is limited to 1000/V max. The fuse is limited to
5A if less than 20 VAC or 20 VDC; or 100/V maximum if less than 30 VAC or 60 VDC.
If using a 24 VAC, 24 VDC, or contact closure connection to the EPO, include one of the following
UL-listed wire types:
• CL2 Class 2 cable for general purpose use
• CL2P Plenum cable for use in ducts, plenums, and other environmental air space
• CL2R Riser cable for use in a vertical-run shaft from floor to floor
• CL2X Limited Use cable for usage in dwellings or in a raceway
• For installations in Canada, the cable should be CSA Certified, type ELC (extra-low-voltage
control cable).
If not using a CL2 cable, route the EPO wiring in conduit that does not contain any branch circuit
wiring.