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Site Requirements - Page 5
990-7164-001
Electrical Requirements - EPO Switch
The Symmetra
TM
Power Array can be connected to either a dry contact or 24Vdc Emergency Power Off switch.
The terminal connections for the EPO switch are physically isolated from the primary circuitry of the Power
Array system.
EPO Specifications
The EPO circuit is considered a Class 2 and SELV circuit.
SELV is an acronym for “Safety Extra Low Voltage.” SELV is a common term in Europe and IEC standards. A
SELV circuit is isolated from primary circuitry through an isolating transformer and designed so that under
normal conditions, the voltage is limited to 42.4 Vpeak or 60 Vdc.
A Class 2 Circuit is a common term in North America and in UL and CSA standards. It is defined in the
Canadian Electrical Code (C22.1, Section 16) and in the National Electrical Code (NFPA 70, Article 725).
SELV and Class 2 circuits must be isolated from all primary circuitry. Do not connect any circuit to the EPO
terminal block unless it can be confirmed that the circuit is SELV or Class 2. If there is a question, use a contact
closure switch. Use one of the following cable types to connect the Symmetra
TM
to the REPO switch:
CL2 - Class 2 cable for general purpose use.
CL2P - Plenum cable for use in ducts, plenums, and other space used for environmental air.
CL2R - Riser cable for use in a vertical run in a shaft or from floor to floor.
CL2X - Limited Use cable for use in dwellings and for use in raceway.
For installation in Canada, the cable should be CSA Certified, type ELC (Extra-Low-Voltage Control Cable).