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7. Electrical wiring
Precautions on electrical wiring
Warning:
Electrical work should be done by qualified electrical engineers in accord-
ance with "Engineering Standards For Electrical Installation" and supplied
installation manuals. Special circuits should also be used. If the power cir-
cuit lacks capacity or has an installation failure, it may cause a risk of elec-
tric shock or fire.
1. Be sure to take power from the special branch circuit.
2. Be sure to install an earth leakage breaker to the power.
3. Install the unit to prevent that any of the control circuit cables (remote control-
ler, transmission cables) is brought in direct contact with the power cable out-
side the unit.
4. Ensure that there is no slack on all wire connections.
5. Some cables (power, remote controller, transmission cables) above the ceiling
may be bitten by mouses. Use as many metal pipes as possible to insert the
cables into them for protection.
6. Never connect the power cable to leads for the transmission cables. Otherwise
the cables would be broken.
7. Be sure to connect control cables to the indoor unit, remote controller, and the
outdoor unit.
8. Put the unit to the ground on the outdoor unit side.
9. Be sure to connect between the control cable terminal block of the outdoor unit
and that of the indoor unit. (Cables have polarity, so make sure that they are
connected according to the terminal numbers.)
In case of A-control wiring there is high voltage potential on the S3 terminal
caused by electrical circuit design that has no electrical insulation between
power line and communication signal line. Therefore, please turn off the main
power supply when servicing. And do not touch the S1, S2, S3 terminals
when the power is energized. If isolator should be used between indoor unit
and outdoor unit, please use 3-potes type.
Caution:
Be sure to put the unit to the ground on the outdoor unit side. Do not con-
nect the earth cable to any gas pipe, water pipe, lightening rod, or telephone
earth cable. Incomplete grounding may cause a risk of electric shock.
Connecting wiring
[Fig. 7.0.1] (P.3)
A Outer cover
B Inner cover
C Terminal block TB1
D Terminal block TB2
E Terminal block TB3
F Terminal block TB4
G Terminal block TBX
H Operation output
I Error output
7.1. Connecting control cables
Control cable size: cable or wire of 0.8 mm
[Fig. 7.1.1] (P. 4)
A Power supply
B Main switch/fuse (purchased locally)
C Power supply wiring for outdoor unit
D Power supply wiring for indoor unit
E Outdoor unit
F AHU controller
G Connection wiring for AHU controller/outdoor units (polarity)
H Remote controller
I Connection wiring for AHU controller/remote controller (no polarity)
J Grounding
8
J Distant ON/OFF signal (Pulse)
K Transmission
L Distant ON/OFF signal (Level)
M To remote controller
N Thermistor (liquid pipe)
O Thermistor (inlet air)
P Distant signal
Q Thermistor · Remote controller
2
or thicker (12VDC)
[Fig. 7.1.2] (P. 4)
A AHU controller
B Control cable wiring
C Outdoor unit
D Breaker (15 A)
E Fuse (15 A)
F Power cable terminal bed
G Control cable terminal bed
H Remote controller
I Remote controller cable wiring
[Selecting non-fuse breaker (NF) or earth leakage breaker (NV)]
To select NF or NV instead of a combination of Class B fuse with switch, use the
following:
•
In the case of Class B fuse rated 15 A or 20 A,
NF model name (MITSUBISHI): NF30-CS (15 A) (20 A)
NV model name (MITSUBISHI): NV30-CA (15 A) (20 A)
Use an earth leakage breaker with a sensitivity of less than 30 mA 0.1 s.
•
The connection wiring between the outdoor unit and AHU controller can be
extended up to a maximum of 50 m, and the total extension including the crosso-
ver wiring between rooms is a maximum of 80 m.
Caution:
Do not use anything other than the correct capacity breaker and fuse. Using
fuse, wire or copper wire with too large capacity may cause a risk of mal-
function or fire.
7.2. Connecting remote controller cables
(Remote controller is optionally available.)
•
Install a remote controller following the manual supplied with the remote con-
troller.
•
Connect the "1" and "2" on AHU controller TBX to a MA remote controller.
(Non-polarized 2-wire)
•
Connect the remote controller's transmission cable within 10 m using a 0.75 mm
core cable. If the distance is more than 10 m, use a 1.25 mm
•
DC 9 to 13 V between 1 and 2 (MA remote controller)
Note:
Ensure that the wiring is not pinched when fitting the terminal box cover.
Pinching the wiring may cut it.
Caution:
Install wiring so that it is not tight and under tension. Wiring under tension
may break, or overheat and burn.
•
Fix power source wiring to control box by using buffer bushing for tensile force.
(PG connection or the like.) Connect transmission wiring to transmission ter-
minal block through the knockout hole of control box using ordinary bushing.
•
After wiring is complete, make sure again that there is no slack on the connec-
tions, and attach the cover onto the control box in the reverse order removal.
Caution:
Wire the power supply so that no tension is imparted. Otherwise disconnec-
tion, heating or fire result.
7.3. Connecting thermistor cables
Pull the end of the wire through the bunch of wires (Thermistor) at the bottom of
the controller.
Connect the thermistor for the inlet air to T1 and T2 on the terminal block, the
thermistor on the liquid pipe to T11 and T12.
When the lead wire is too long, cut it to the appropriate length. Do not bind it in the
box.
Take proper measures not to miswire. E.g. Attach a label before the cutting part, so
that it is obvious whether the wire is for inlet air or for liquid pipe.
Caution:
Do not route the thermistor cables together with power cables.
2
2
junction cable.
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