A.O. Smith 120 through 250 Series, Installation, User And Service Manual

Page: 37 / 104

Instruction manual BFC 35
is
Terminal block
3.10.3 Connecting the mains power
The water heater is supplied without a power cable and isolator.
Note
In order to receive electrical power, the water heater has to be connected to
the mains power by means of a permanent electrical connection. A double-pole
isolator with a contact gap of at least 3 mm must be fitted between this
permanent connection and the water heater. The power cable must have cores
of at least 3 x 1.0 mm
2
.
Warning
Leave the water heater electrically isolated until you are ready to
commission it.
1. Connect neutral (N), live (L) and earth ( ) of the power cable to
terminals 1 thru 3 of the terminal block as shown in the
table (3.10.2 "Preparation").
2. Fit the power cable in the strain relief.
3. Connect the power cable to the isolator.
4. If you have no more connections to make:
- Fit the cover on the terminal block.
- Fit the covers onto the water heater.
3.10.4 Isolating transformer
An isolating transformer should be used if there is a case of 'floating neutral'.
Note
The total power consumed by the appliance goes via the isolating
transformer.
1. Refer to the fitting instructions provided with the isolating transformer.
(Contact the supplier for details of the correct isolating transformer.)
2. Connect the neutral (N), live (L) and earth ( ) of the power cables to
terminals 4 through 9 of the connection block according to the
table (3.10.2 "Preparation").
3. Fit the cables in the strain relief.
4. If you have no more connections to make:
- Fit the cover on the terminal block.
- Fit the covers onto the water heater.
5. Connect the power cable to the isolator.
Mains
voltage
Isolating transformer
Alarm Out
Program-
controlled
pump
External
ON/OFF
BUS
link
primary secondary
N L N L
1
N L
2
X
1
X
2
N L
3
X
3
X
4
X
5
X
6
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