Ariston NIMBUS COMPACT M NET 40 M EXT Technical Instructions For Installation And Maintenance page 63

Electrical connections between internal and external unit
Before any work on the system, shut off the power at the breaker. Electrical connections between internal and external units must be performed using
the three low voltage terminals: GND, A, B.
Connect «GND» on the terminal block of the internal unit with «GND» on the external terminal block.
Connect «A+» terminal block on the internal unit with «A» on the external terminal block.
Connect «B-» terminal block on the internal unit with «B» on the external terminal block.
EH1 EH1 ST1 ST1
B T
NOTE
It is strongly recommended to verify the presence of a surge protection device (SPD) on main power line and of circuit breakers
connected to the external and internal unit's control box
* See table of electrical connections
WARNING
After carrying out the connections between the indoor and outdoor unit, put back both panels of the respective units.
L N
ANODE
+24V
1 ph
T
ON
OFF
XXA
30mA XXA
N N N
BUS
TA 1 TA 2 SE TNK BUF
B T AUX 1
3 ph
*
T
ON
OFF
30mA XXA XXA
N N N
IN
63 / GB