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CAUTION: The provided contacts can only switch very low amounts of electrical current. To
control high current, AC line-operated devices, the provided contacts must be used to control
yet another set of contacts that are rated for the actual load being switched (see examples
below).
Example 1 – Blower Relay Contact (Single Phase AC)
The Blower set of contacts (Relay 1, pins 2 & 3) will indicate when the cabinet’s blower is on.
On an A2 cabinet, this contact will close once the blower key is pressed on the cabinet’s
keypad, and remain closed while the blower is at Normal Speed.
However, on a B2 cabinet, the contacts will close when the blower key is pressed to signal
(through this Relay 1 contact) a remote exhaust blower to start. The cabinet’s blower will NOT
start until the internal Airflow Sensor verifies proper exhaust airflow from the remote exhaust
blower. Once the blower successfully starts, the contact will remain closed.
The generalized circuit shown below indicates how to interface the cabinet’s provided contacts
to power a single phase high current device (like a remote exhaust blower).
Note: The cabinet’s provided contacts are used to actuate the low-power coil of a user-
supplied external power relay/contactor. Never run high current or AC voltage through
the cabinet’s provided contacts!
The relay in the example below is: Hasco HAT903ASDC12 (Labconco P/N 1289200), the 12V
coil draws only .08Amps (the provided +12VDC is fused at 0.5 Amps total, so choose a relay
with an amp draw for the actuator coil less than 0.5 A) If using two or three of the provided
relay contacts, the sum total of all current draw from three relay actuator coils must be
less than 0.5A.
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